chapter 3 - Bentham Science

Was Man More Aquatic in the Past?
Fifty Years after Alister Hardy
Waterside Hypotheses of Human Evolution
Editors
Mario Vaneechoutte
Algis Kuliukas
Marc Verhaegen

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CONTENTS
Foreword i
Preface ii
List of Contributors v
CHAPTERS
1. Revisiting Water and Hominin Evolution
Phillip V. Tobias
3
2. Littoral Man and Waterside Woman: The Crucial Role of Marine and Lacustrine Foods and
Environmental Resources in the Origin, Migration and Dominance of Homo sapiens
C. Leigh Broadhurst, Michael Crawford and Stephen Munro
16
3. A Wading Component in the Origin of Hominin Bipedalism
Algis V. Kuliukas
36
4. Early Hominoids: Orthograde Aquarboreals in Flooded Forests?
Marc Verhaegen, Stephen Munro, Pierre-François Puech, and Mario Vaneechoutte
67
5. Pachyosteosclerosis in Archaic Homo: Heavy Skulls for Diving, Heavy Legs for Wading?
Stephen Munro and Marc Verhaegen
82
6. Aquatic Scenarios in the Thinking on Human Evolution: What are they and how do they
Compare?
Algis V. Kuliukas and Elaine Morgan
106
7. Human Breath-Hold Diving Ability Suggests a Selective Pressure for Diving During Human
Evolution
Erika Schagatay
120
8. Marine Adaptations in Human Kidneys
Marcel F. Williams
148
9. Obstetrical Implications of the Aquatic Ape Hypothesis
Michel Odent
156
10. Superior Underwater Vision Shows Unexpected Adaptability of the Human Eye 164
Anna Gislén and Erika Schagatay
11. Human Aquatic Color Vision 173
Wang-Chak Chan
12. Seafood, Diving, Song and Speech 181
Mario Vaneechoutte, Stephen Munro and Marc Verhaegen

13. Aquagenesis: Alister Hardy, Elaine Morgan and the Aquatic Ape Hypothesis 190
Richard Ellis
14. Just Add Water: The Aquatic Ape Story in Science 199
Tess Williams
15. Langdon’s Critique of the Aquatic Ape Hypothesis: It’s Final Refutation, or Just Another
Misunderstanding? 213
Algis V. Kuliukas
Index 226

FOREWORD
In 2008, Don Johansen noted in his book, Lucy's legacy, that recent palaeo-environmental research “has sounded the
death knell for the so-called savannah hypothesis that reigned supreme when I was a student.” As he explained:
“These latest findings indicate that our primeval predecessors must have been bipedal in the forest. The concept of
the woodland biped has now become, in its turn, the conventional wisdom, and the once ‘supreme’ savannah
hypothesis has been so discreetly dismantled that some of today's students are unaware that it ever existed.”
For roughly half a century, it had been treated as proven by a solid consensus of the scientists specializing in the
study of human origins. But towards the end of the 20 th century doubts about the savannah scenario were
accumulating, and were confirmed when new tools of research enabled scientists to analyse and identify fossilized
pollen in the sites where hominid remains had been found. It meant that at least one of the salient hallmarks of
mankind – bipedalism – must have evolved while our ancestors apparently occupied the same environment as the
other apes.
Replacing the savannah scenario with a woodland one has been treated as a necessary but minor readjustment in the
official story of human evolution. But this re-appraisal involves one major drawback. The strength of the savannah
hypothesis lay in the fact that it offered possible explanations of unique human features such as bipedalism. The
woodland hypothesis made this more difficult. We have a clear extant example of a ground-dwelling African ape:
Adult gorillas walk on all fours in the forest, presumably because it has proved to be the most effective mode of
locomotion in those conditions. Why then would a similar environment among the trees cause just one branch of the
anthropoid apes to evolve along such different lines? The old question, "Why a naked biped?" - now seems further
than ever from a solution in terms of the traditional scenario.
A possible answer had been proposed in 1960, when Professor Alister Hardy enquired whether Man might have
been more aquatic in the past. It was not surprising that scientists initially ignored his article. Their view of the
matter was that the suggestion he made was unnecessary and unheard of: It had not been submitted to a professional
journal in the approved manner, and it was written by a marine biologist with no anthropological qualifications.
In some people's minds, the concept that Man may have been more aquatic in the past is still thought of as an
eccentric fancy, which state-of-the-art scientists could demolish at any time if they thought it was worth the trouble.
One of the main reasons for publishing this book is to help readers to appreciate how much that perception has
changed in fifty years. It should enable them to judge for themselves whether the arguments being advanced here
deserve to be taken seriously or not. They have assembled an impressive list of contributors – most of them with
specialized knowledge, and some who have reached the heights of their profession. That should end any lingering
suspicion that these ideas are exclusively the province of amateurs.
What all contributors to this book have in common is a belief that at least at some point in the past, the lifestyle and
evolutionary development of our ancestors was definitively influenced by the presence of water in their immediate
environment. No contributor takes responsibility for the views voiced by any other contributor. Discussions on these
issues are as animated as were the disputes, in the heyday of savannah hypothesis, over whether the grassland apes
were hunters or scavengers, and whether or not they were pair-bonded. Such debates are now, as they were then,
healthy signs of intellectual work in progress. They generate further questions, and they stimulate research.
There is no reason why this line of thinking should continue to be confined to the kind of academic ghetto,
accurately described by Robert Foley. He commented, in the second edition of Principles of Human Evolution that
supporters and opponents of the aquatic ape hypothesis are still ‘talking past one another’.
Let us look forward to the day when it may be possible for them to talk face to face.
i
Elaine Morgan

ii
PREFACE
This book attempts to provide an explanation for the remarkable observation that the differences between our
species, Homo sapiens, and our nearest relatives, the chimpanzees, are more numerous, more varied and more
radical than between any other two species that are genetically so closely related. In many respects, such as our
nakedness, bipedalism, brain size, profuseness of sweating, strongly increased subcutaneous fat, voluntary breathing
control, a disproportionately large brain, and the power of speech, our species markedly differs, not merely from
other apes, but also from the vast majority of other terrestrial mammals.
Should we explain all of these peculiarities by assuming that our ancestors moved out from the tropical forests to
live on the open plains and become hunters, as we uniformly can read in every textbook and learn from every
television documentary, since decades? Or, are these characteristics more ‘parsimoniously’ explained by assuming
that, rather than striding or running across the grassy plains, our ancestors may have spent one or more periods of
their evolution wading, swimming and diving in shallow waters. Some people find that idea counter-intuitive, and so
did I when Marc Verhaegen first confronted me with it some ten years ago. After all, hadn’t I been terribly afraid of
water until my tenth, learning to swim only at the age of twelve – with much trouble? (As was the case for Marc!, as
he told me recently). According to the ethologist Dirk Meijers, we may have missed a critical imprinting period,
during which swimming for a baby comes natural.
However, as I learned more about the aquatic ape hypothesis (AAH), several of the arguments put forward by its
proponents struck me as intriguing and worth pursuing. But the reception accorded to this suggestion was so
dismissive, ranging from outright hostility to – at best – a deafening silence, that my initial interest in the AAH was
philosophical in the first place, trying to understand this kind of reaction. When the aquatic theory was referred to at
all, the most frequent grounds for rejection consisted not of disputing the arguments put forward, but instead
stressing that they were being advanced by people who were unqualified to express any opinion on the matter. Its
first English proponent, Alister Hardy, was a marine biologist [1], and Elaine Morgan, author of the most persistent
attempts to make it more widely known [2], had been a television scriptwriter (see Chapters 13 and 14). The only
official response addressing the AAH so far [3] (see Chapter 15), in fact also depicted the AAH at the same level of
creationism and of explanations that include invoking aliens from space, and considered the AAH just as “only one
of several ideas rejected by orthodox science that has refused to go away.”
The belief in our savannah past has become so deeply rooted that, even when Phillip V. Tobias, one of its most
eminent former promoters, – as the mental heir of Raymond Dart, who proposed and defended the open plains
theory most explicitly [4], – publicly and explicitly disavowed it, (see Chapter 1), this did very little to shake his
colleagues’ faith in it.
At the end of this book, Tess Williams (Chapter 14) reviews the different reasons that may be at the basis of this
way of reacting by the scientific establishment. My personal understanding is that such neglect and/or hostility can
be regarded as a quite understandable, emotional, response, which can be observed rather often when new ideas pop
up. Indeed, it is often overlooked that new ideas, which contradict established theories, also threaten the lifelong
work and achievements of many individuals, i.e. established scientists.
This occurs whenever a paradigm that has long commanded consensus turns out to be flawed and needs replacing.
Thomas S. Kuhn, in his treatise on The structure of scientific revolutions [5], provided some illuminating examples
of what happens then. The new idea is reviewed by the great and good who have invested a lifetime in upholding
and building on the old idea, which has brought them scientific appreciation, which they have taught for decades to
hundreds of students and on which they have published in highly-valued journals, supported by so many highlyvalued
peers. They speak with one voice in condemning anyone who dares to threaten it. Hence, the new paradigm
can only be promoted by outsiders.
In fact, I would not be too surprised if one day when the AAH has become the established orthodoxy – and the
authors of this book are convinced that that day is not far off – its supporters would close ranks in exactly the same
way against any even newer idea that threatened to supersede it.

The resistance against a partially aquatic past of our ancestors is even more intriguing when we consider the
‘scientific’ basis for the open plain theory of our past. Indeed, the theory that we fell out of the trees and started
walking on our hind legs on the ground is not based on scientific scrutiny, but on the endless repetition of what
looks a straightforward sequence of events, only at first sight. It seems that, if only an idea is repeated numerous
times, it becomes established truth and generally accepted wisdom, which needs no further evidence, and which
becomes almost impossible to tackle. (See also Bender [6] for a description of the history of the ‘savannah’
hypothesis).
So far the philosophy, with the hope that this book finally puts the AAH at the level at which it should have been
treated since decades: as a sound alternative and possibly powerful explanation of many of the peculiar
characteristics of our species. But the content of the AAH and the predictions it may enable to make are even more
intriguing than the philosophical debate of why it encounters so much resistance. Yes, I have become a ‘believer’ in
the meantime, and even more so after reading the diverse contributions to this book.
One of the reasons of why the AAH is worth considering is that it is supported by findings from so many different
lines of research. Breathing physiology research (see Chapter 7), vision research (see Chapters 10 and 11), obstetrics
(see Chapter 9), nephrology (see Chapter 8), brain development research (see Chapters 2, 5 and 12) and skin biology
(see Chapter 2), among many other disciplines, all point to a semi-aquatic past and to the importance of this past still
in our present day lives. This underlines what is one of the greatest strengths of the AAH: Other theories have set
out to account for one or two of the several anomalies that characterize human morphology and physiology, but
none even attempts to find a common thread that could, just conceivably, throw light on many of them
simultaneously.
Moreover, adopting the view that much of our current physiology is explainable as ‘scars’ of an evolution that was
partially aquatic, may contribute to better understanding of several ill-comprised medical problems. Some were
already addressed in the books of Elaine Morgan, in an article by Marc Verhaegen [7], and others are dealt with,
albeit briefly, in this book, e.g. in Chapter 10, with regard to obstetrical problems.
Not only our bodies, but also some of our social behavior may have been strongly influenced by an aquatic past, and
part of our behavior is maybe better understood when viewing ourselves as a pair-bonding, water-adapted and
musical ape, rather than from the present-day Man-the-hunter story.
In summary, it is long overdue to consider the possible influence of aquatic adaptations in our past evolution over
the last 5 million years, since the split with the chimpanzee, not only because this may provide the best explanation
of many of our peculiarities, but also because it may bring us practically useful and important insights in who we are
and in how it affects our present-day health.
Having had the opportunity and the honour of editing the different chapters in this book, it is clear to me that the
burden of proof now rests on the opponents of the aquatic ape hypothesis, or maybe better, semi-aquatic ancestor
hypothesis. After first having progressed from being a sceptic to becoming an interested bystander, I am now
convinced – because of overwhelming support from very different lines of research, all pointing in one direction –
that we need a thorough reappraisal of the events that may have caused us to differ so profoundly from all other
anthropoids, eventually by adopting a wetter view of our ancestry.
The editors thank Christian De Boever for excellent assistance in lay-out.
REFERENCES
iii
Mario Vaneechoutte
[1] Hardy A. Was Man more aquatic in the past? New Sci 1960; 7: 642-5.
[2] Morgan E. The descent of woman. London: Souvenir Press 1972.
[3] Langdon JH. Umbrella hypotheses and parsimony in human evolution: A critique of the aquatic ape hypothesis. J Hum
Evol 1997; 33: 479-94.

iv
[4] Dart RA. Australopithecus africanus: The man-ape of South Africa. Nature 1925; 115: 195-9.
[5] Kuhn TS. The structure of scientific revolutions. Chicago: University of Chicago Press 1962.
[6] Bender, R. Die evolutionsbiologische Grundlage des menschlichen Schwimmens, Tauchens und Watens:
Konvergenzforschung in den Terrestrisierungshypothesen und in der Aquatic Ape Theory. PhD dissertation at the Institut
für Sport und Sportwissenschaft, Universität Bern, Switzerland 1999.
[7] Verhaegen MJB. The aquatic ape theory and some common diseases. Med Hypoth 1987; 24: 293-9.

v
List of Contributors
C. Leigh Broadhurst
Department of Environmental and Civil Engineering, University of Maryland, College Park, Maryland, USA and
USDA, ARS Beltsville, 10300 Baltimore Blvd. Beltsville MD 20705, USA
Wang-Chak Chan
Department of Cognitive Science, Lund University, Kungshuset, Lundagård 222 22 Lund, Sweden
Michael Crawford
Professor, Institute of Brain Chemistry and Human Nutrition, Faculty of Medicine, Imperial College Chelsea and
Westminster Hospital, London SW10 9NH, UK
Richard Ellis
American Museum of Natural History, 42 West 15th Street, New York, NY 10011, USA
Anna Gislén
Department of Cell and Organism Biology, Lund University, Helgonay 3, 223 62 Lund, Sweden
Algis V. Kuliukas
Centre for Forensic Science, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
Elaine Morgan
Mountain Ash, 24 Aberffrwd Road, Glamorgan CF45 4AR, UK
Stephen Munro
School of Archaeology and Anthropology, Australian National University, Canberra 0200, and Curatorial Fellow at
Centre for Historical Research, National Museum of Australia, Canberra, ACT 2600, Australia
Michel Odent
Director, Primal Health Research Centre, 72 Savernake Road, London NW3 2JR, UK
Pierre-François Puech
Institut de Paléontologie Humaine à Paris, Le Zénith 1, 561 avenue Evêché de Maguelone, 34250 Palavas, France
Erika Schagatay
Professor of Animal Physiology, Department of Technology and Sustainable Development and Swedish Winter
Sports Research Center, Mid Sweden University, Akademig 1, 83125 Östersund, Sweden
Phillip V. Tobias
Professor Emeritus, School of Anatomical Sciences, Institute for Human Evolution, University of the
Witwatersrand, Johannesburg, Medical School, 7 York Road, Parktown, Johannesburg 2193, South Africa
Mario Vaneechoutte
Professor of Microbiology, Laboratory for Bacteriology Research, Department of Clinical Chemistry, Microbiology
and Immunology, Faculty of Medicine and Health Sciences, University of Ghent, De Pintelaan 185, 9000 Gent,
Flanders, Belgium

Marc Verhaegen
Study Center for Anthropology, Mechelbaan 338, 2580, Putte, Belgium
Marcel F. Williams
Mu Omega Enterprises, 748 Oakland Avenue 306, Oakland, CA 94611, USA
Tess Williams
Research Services, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
vi

Revisiting Water and Hominin Evolution
Phillip V. Tobias *
Was Man More Aquatic in the Past?, 2011, 3-15 3
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 1
School of Anatomical Sciences, Institute for Human Evolution, University of the Witwatersrand, Johannesburg,
Medical School, 7 York Road, Parktown, Johannesburg 2193, South Africa
Abstract: For many investigators, the rôle of water in the evolution of the Hominini refers to the development of a
number of anatomical and physiological features, which hominins are thought to share with water-adapted animals.
However, in the last dozen years, there has been emphasis on other ways in which water, and the proximity to water,
have been probable influences in hominin evolution. This chapter reviews each of five ways in which water has
influenced or might have affected human evolution. This pentapartite analysis singles out water for drinking, for
keeping cool, for global dispersal, as a basis for aquatic adaptations and for the ingesting of aquatic foods. In contrast
with the heavy, earth-bound view of hominin evolution, which has predominated hitherto, an appeal is made here for
students of hominin evolution to buoy up, lighten and leaven their strategy by adopting a far greater emphasis upon
the rôle of water and waterways in hominin phylogeny, diversification, and dispersal from one water-girt milieu to
others. Some evidence is adduced to show the value and potential of this course of action.
Keywords: Hominin evolution, water, drinking, cooling, migration, aquatic adaptations, aquatic food and brain
development, history of science, paradigm shift.
INTRODUCTION
All of the famous fossil apeman sites in South Africa – like Taung near Kimberley, Sterkfontein, Swartkrans,
Kromdraai and Drimolen near Krugersdorp, and Makapansgat near Polokwane (formerly Pietersburg) – are situated in
what is today the dry hinterland of the subcontinent. Similar conditions apply to the Olduvai Gorge on the Serengeti
Plain of Tanzania, Koobi Fora in North and North East Kenya, and Bahr-el-Gazal, close to the Sahara Desert in the
Chad Republic.
Yet wherever the early members of the human family were evolving, they needed water to drink and to keep cool.
Proximity to water was the most important factor in the location of an evolving group like the early members of the
human family. They must have lived near springs, rivers, lakes and freshwater estuaries. Denied water in a warm,
tropical or subtropical climate, humans quickly become dehydrated and death may follow in days. The same would
have been true of ancient hominin forebears. In other words, water must have been necessary – as it still is – for
survival. Without survival, at least until adolescence, there would be no reproduction, no mutations of the DNA in
spermatozoa and ova, and hence no potential for evolutionary change – because mutations of the genetic material
are the raw materials of evolution.
So water was an essential ingredient in the mixture leading to long-term changes in our ancestors. It was the key to
survival. But that was not the only rôle played by water.
EARLY HOMININS, IN AND OUT OF AFRICA
As a result of discoveries made over the last 80 years, especially in South and East Africa, it is now widely accepted
that hominins – that is, the tribe of mankind – originated in the African continent. Their remains are to be found in
Africa at least 5 to 4 million years earlier than any traces of humanity outside of this continent.
Early signs of humankind out of Africa have been identified near Orce in South East Spain, in Ubeidiya and probably
‘Erq-el-Ahmer in Israel, in Dmanisi in the Georgian Republic of the Caucasus, in Riwat in Pakistan, in Java in Indonesia,
*Address correspondence to Phillip V. Tobias: School of Anatomical Sciences, Institute for Human Evolution, University of the
Witwatersrand, Johannesburg, Medical School, 7 York Road, Parktown, Johannesburg 2193, South Africa; E-mail: Phillip.Tobias@wits.ac.za

4 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Phillip V. Tobias
and in Yuanmou, China. In these areas signs of humanity, either skeletal remains or cultural relics such as stone artefacts,
or both, have been brought to light in deposits dated from about 2.0 Ma (millions of years ago) and onwards. They testify
to the presence of hominins, mostly of the genus Homo, in all of these scattered areas of the Old World.
The out-of-Africa remains are interesting in their own right and a number of investigators have sought to determine
what hominin species and which cultural industries were represented in each area and at what times.
A second important problem and one which is of primary concern in the present context is the route or routes by which
early hominins moved from Africa to Europe and Asia and also, at some periods, in the reverse direction, into Africa.
WATER AND HUMAN DISPERSAL
Water helped in the distribution of humanity across the face of the planet: along seashores, lake margins and river
banks. This would have accounted for the prehistoric peopling of most of the Old World, from Africa to Europe and
mainland Asia. Strolling or swimming along the beach would have been sufficient to carry mankind from the Horn
of Africa to the Peloponnesos, from the Levant to the Korean Peninsula, from Singapore to Siberia. When much
water was bound up on land as glaciers in the Ice Ages, sea levels were lower than they are today, and previously
submerged land-bridges appeared. At such times, it would have been possible to walk dry-shod from Tripoli and
Tunisia to Malta and Sicily, from South Korea to South Japan, and from the Sakhalin Peninsula to Hokkaido, North
Japan, from Malaysia to Sumatra, Java and Bali. These temporary land-bridges helped the spread of humans into
vast new areas of the Earth.
Between Siberia and Alaska there was a broad land-connection known as Beringia: it was more than a ‘bridge’ as it was
over 500 kilometers wide, from its northern to its southern shore. Deepsea corings show that this dry land connection
between Asia and America appeared and disappeared (with falls and rises of the sea level) many times over the last few
hundred thousand years. The southern flank of Beringia must have had a mild and balmy climate, because the landconnection
cut off the icy Arctic current to the North, while the warm Japan current played upon the South coast.
Beachcombers would have had a tolerable life on the southern flank and that was the path they probably took to people
the New World, perhaps originally more than 100 thousands of years ago (ka) and probably on several excursions.
At some stages and in some places, humans learned to cross the water, even without a land-bridge. Java and Bali
were periodically connected to the Asian mainland, so that animals, including humans, could easily gain access to
them. However, the Indonesian island of Flores, part of what was named Wallacia (after Alfred Russel Wallace),
could be reached only by sea crossings, even when the sea level was at its lowest. Yet stone tools and fossil bones
on Flores show that humans (probably Homo erectus) and archaic elephants (Stegodon) must have crossed this deep
oceanic channel 0.9 to 0.8 Ma [1, 2]. We have no evidence to suggest that they knew how to make boats so early.
Either they floated across using tree trunks, rafts of detached vegetation, or logs, or they paddled holding floats, or
they swam. Somehow or other, humans could cross a stretch of water, which, at lowest sea level, was 19-20
kilometers wide nearly a million years ago [3-6]. Morwood et al. [1, 2] have concluded that Homo erectus was
capable of repeated water crossings using water-craft, by the beginning of the middle Pleistocene, 0.7-0.9 Ma.
It is of special interest to consider the movement of people – and transference of proboscideans – into Iberia. Two
important areas have yielded ancient hominin remains. In the North of Spain is the famous site of Sima de Los Huesos –
Gran Dolina, near Burgos. Its wealth of hominin remains, which have been assigned to a proposed new species, Homo
antecessor, are dated to about 0.8 Ma. In the South of Spain, at Venta Micena, Fuente Nueva and elsewhere near Orce
and Murcia, stone objects have been identified as artefacts and manuports [7-9] and some scanty, probably hominin
skeletal remains have been recovered. They have been dated to about 1.5 Ma [10]. Although these remains are still the
subject of discussion, the evidence of cut marks on some of the animal bones, the morphology, fractal analysis and
biochemical analysis of the putative Homo bones, and their own observations have convinced D. Roe of Oxford [9], J.
Lowenstein of San Francisco [11] and the author of this chapter [12] that there is good cause to support the claims of
Gibert and colleagues [7, 8, 13] that hominins were present in the South East of Spain between 1.5 and 1.0 Ma.
For a long time, a critical question has been: how did these earliest Europeans reach the Iberian Peninsula from North
Africa? There are two fairly obvious routes – one, the Levantine Corridor, through the Middle East across Suez and the

Revisiting Water and Hominin Evolution Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 5
Levant, and one from Tunisia, via Malta, Sicily, the Strait of Messina to Calabria, the toe of Italy. A third route, from
Tunisia via Sardinia and then by way of Corsica and Elba to peninsular Italy has recently been proposed [14]. To get to
the South of Spain from any of these three passages would have involved taking a circuitous route from the eastern or
central Mediterranean, and finally crossing the Pyrenees in a southerly direction, or walking along the beach from the
region of Toulon and Marseille, around the Gulf of Lyon, towards Barcelona. Several scholars have been pursuing the
option of a short cut and a more direct passage – the water traverse from Ceuta to Spain.
Earlier investigators, such as Pallary, Obermaier, Pericot, pursued the option of a water traverse from Ceuta and
Morocco in North Africa to Gibraltar and Spain. The idea has been supported more recently by several investigators
including myself [12, 15]. The deep water channel, the Strait of Gibraltar, has a minimum width today of 13-14
kilometers. When the sea levels of the Atlantic and Mediterranean were lower, the distance would have been
smaller. Moreover, a few islands, at present submerged, and a small peninsula joined to the South coast of Iberia,
would have emerged above the water, thus providing stepping-stones between Africa and Europe. The greatest sea
crossing then required, it has been estimated, would have been only 5 km. If people and elephantids were able to
cross 19-20 km of sea to reach Flores just under a million years ago, it is very likely that the smaller water crossing
of the Strait of Gibraltar would have been within the capability of humans and other African mammals just over a
million years ago. Again, floating, rafting on flotsam, the aid of floating vegetation islands, perhaps the use of
rudimentary coracles or canoes or other simple water-craft, possibly swimming or paddling with a float, might have
been early acquisitions in human cultural and behavioral evolution.
PROBOSCIDEANS AND PREHISTORIC HUMAN MOVEMENTS
The earlier reported presence of proboscidean remains in Sardinia/Corsica [16-18] raises the question of elephantids as
markers of large mammal, including human, dispersals. A possibly parallel situation in the western Mediterranean may
be cited.
The mammoth Mammuthus africanavus is a middle to late Pliocene species (3.60-0.78 Ma) found in Algeria,
Tunisia, Morocco and Chad. Coppens et al. [19] have suggested that M. africanavus might have given rise to the
European Mammuthus meridionalis by a trans-Mediterranean expansion during the late Pliocene. Coppens and his
colleagues state, “it cannot be determined whether the North-African early Pleistocene material represents an in situ
evolved stage from africanavus in Africa (and thus a parallel line to the European species), or whether it derived
from a back-invasion from Europe after M. africanavus became extinct in Africa” [19]. The elephantid M.
mammuthus of early Pleistocene Spain (Venta Micena) (2.588-0.781 Ma) was very similar to, if not identical with, a
proboscidean known from early Pleistocene Algeria. It is likely that these early mammoths swam from North Africa
to Iberia, or perhaps from Iberia to North Africa, in the early Pleistocene.
It is known that present-day elephants are excellent swimmers [20-22] and that they swim at speeds of up to 2.7
km/h, while a maximum distance of 48 km has been recorded. Stevenson-Hamilton [20] described how, when
elephants are submerged, their trunks protrude above the surface “like periscopes” [20]. Johnson [21, 22] reports
that they swim in a lunging fashion, as porpoises do, and that they use the trunk as a snorkel. Paul Sondaar often
pointed out that “Elephants have a snorkel” – and that was used as the title of a festschrift in Sondaar’s honor [23]!
Following the construction of the Kariba Dam between Zambia and Zimbabwe and the subsequent flooding of the
Zambezi River valley, elephants have been observed swimming in Lake Kariba.
Reference has already been made to the case of Stegodon having crossed the 19-20 km straits from the Sunda Shelf
to Flores. Darlington [24] concluded that the elephants of the Celebes Islands (Sulawesi), Indonesia, arrived there by
swimming the 40 km barrier of the Makassar Strait during the Pleistocene. Sondaar and Boekschoten [25] similarly
explained the fossil pygmy elephants on Crete. A comparable interesting case is that of the pygmy proboscidean
remains of Mammuthus exilis, which occur abundantly in late Quaternary deposits on the northern Channel Islands
off the coast of California. It had long been assumed that elephants were poor swimmers and that there must have
been land-bridges connecting these islands to the Californian mainland. However, geological evidence for a landbridge
is lacking, while the recent evidence shows that elephants are excellent swimmers and skilled at crossing
water gaps. The Santa Barbara Channel between the Californian mainland and the northern Channel Islands was
only 6 km wide at times of glacially lowered sea levels [21].

16 Was Man More Aquatic in the Past?, 2011, 16-35
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 2
Littoral Man and Waterside Woman: The Crucial Role of Marine and
Lacustrine Foods and Environmental Resources in the Origin, Migration and
Dominance of Homo sapiens
C. Leigh Broadhurst 1,* , Michael Crawford 2 and Stephen Munro 3
1 Department of Environmental and Civil Engineering, University of Maryland, College Park, MD USA; 2 Institute of
Brain Chemistry and Human Nutrition, Division of Surgery, Oncology, Reproductive Biology and Anaesthetics,
Faculty of Medicine, Imperial College Chelsea and Westminster Hospital, London SW10 9NH, UK and 3 School of
Archaeology and Anthropology, Australian National University, Canberra 0200, Australia; Curatorial Fellow,
Centre for Historical Research, National Museum of Australia, Canberra, ACT 2600, Australia
Abstract: The ability to exploit and thrive on a wide variety of foodstuffs from diverse environments is a
hallmark of Homo sapiens. Humans are particularly well adapted to exploit waterside environments, where they
can forage in areas offering protection from both terrestrial and aquatic predators. Humans are able to walk, run,
climb, wade, swim and dive, and our research indicates that the most parsimonious explanation for this
combination of locomotor traits, and for Man’s current anatomy, physiology, nutritional requirements and unique
intellect is evolution in a littoral environment. This model is consistent with the location and presumed palaeoecologies
of all early Homo fossils and artifacts, and could help explain the rapid dispersal of Homo in the early
Pleistocene (2.56-0.78 million years ago (Ma)), the colonization of Australia and Indonesia in the middle
Pleistocene (0.78-0.13 Ma), and the rapid dispersal of Homo sapiens in the late Pleistocene (0.13-0.012 Ma).
Reliance on the aquatic food chain is also a facile method for providing consistently abundant brain-specific
nutrition for all members of a group or society, thus facilitating the development of the technology and culture
that is uniquely human.
Keywords: Homo sapiens, brain evolution, docosahexaenoic acid (DHA), aquatic food chain, iodine, selenium,
littoral environments.
INTRODUCTION
A long-held assumption of human evolution is that open, semi-arid environments played a key role in the origin of
human locomotion and subsistence patterns [1-3]. Accordingly, terrestrial, open plain or savannah settings form the
basis for a number of palaeo-anthropological models [4, 5]. Human evolutionary discussions often involve speculation
as to how early Homo populations may have found enough food to survive in dry, open landscapes [6, 7], and often the
focus is on how extra meat may have been acquired in terrestrial savannah settings [8-10].
For example, the endurance running model argues that early Homo became adapted to long-distance running in
order to hunt or scavenge large mammals in semi-arid, open landscapes [2, 3]. While we fully agree with occasional
exploitation of large mammals by Homo, we believe there is a significant body of evidence supporting the view that
early Homo populations were waterside generalists, capable not only of terrestrial bipedalism, but also of bipedal
wading, swimming and underwater foraging.
Here, we evaluate and compare the waterside and terrestrial models by focusing on human nutritional requirements,
the anatomy and physiology of humans from a comparative perspective, and palaeo-ecological data from Homo
fossil and archaeological sites.
CEREBRAL EXPANSION REQUIRES LONG-CHAIN POLY-UNSATURATED LIPIDS
The structural, cognitive and visual development of the human brain strictly requires long-chain poly-unsaturated
*
Address correspondence to C. Leigh Broadhurst: Department of Environmental and Civil Engineering, University of Maryland, College
Park, MD, USA; E-mail: Leigh.Broadhurst@ars.usda.gov

Littoral Man and Waterside Woman Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 17
fatty acids (LC-PUFA), and the most important of these is docosahexaenoic acid (DHA) [11]. Excluding water, the
mammalian brain is about 60% lipid. Neuronal membrane phospholipids have a very high percentage of LC-PUFA,
and the central nervous system uses DHA (22:6n-3) and arachidonic acid (AA, 20:4n-6) almost exclusively (Fig. 1)
[12-15]. Membranes rich in LC-PUFA are strictly required to construct tissues such as the brain and retina, which
have high rates of signal transfer and data processing, and LC-PUFA are also necessary for the normal behavior of
cell signalling systems that determine how neurons function [13-16].
Figure 1: Essential fatty acid composition (percentage) of brain ethanolamine phosphoglycerides.
In the human brain, billions of neuronal micro-connections are made between dendrites. These micro-connections
are made of phospholipids rich in DHA and AA [16]. There is substantial evidence linking LC-PUFA deficiencies in
cell membrane phospholipids to attention-deficit/hyperactivity disorder, dyslexia, senile dementia, depression, bipolar
disorder, anxiety, schizophrenia, and other psychiatric and neurological disorders [17-25]. Animal research shows that
these problems increase in severity as successive generations continue to be deficient in LC-PUFA [26-29].
Early brain growth in humans must have a relationship to a shift to diet rich in lipids and high quality, complete
protein [1, 30, 31], and more specifically to a diet rich in DHA [11, 13, 31].
Whereas a number of traditional theories of human evolution speculate that the brains of large savannah mammals
could have provided increased amounts of DHA, it is more likely that this increase came from exploitation of the
littoral zone, in addition to terrestrial scavenging and hunting.
The ultimate source of DHA is marine and freshwater algae and plankton, and therefore primary algae/plankton
consumers such as fish and shell fish quantitatively accumulate DHA in muscle phospholipids. DHA is also
accumulated by algae-eating amphibians and reptiles, and birds and marine mammals, which feed on fish/shell fish.
DHA is not synthesized by terrestrial plants and consequently is far less abundant in muscle tissue of terrestrial
herbivores. The brains of large ruminants are known to contain relatively high levels of DHA [31-34], but the meat and
marrow contain little, because, apart from the brain, the chain elongation and desaturation processes do not reach full
completion in these large, fast-growing herbivores [11]. Although it has been argued that sufficient DHA could have
been synthesized from vegetarian dietary precursors to account for the increased brain growth seen in human evolution
[29, 35-36], the human ability to convert dietary precursors into DHA has been shown to be very weak [37-40]. A
review by Burdge and Calder [41] of stable isotope and long-term feeding studies in humans concluded that, while it
was possible to detect conversion of -linolenic acid (ALNA, 18:3n-3) to eicosapentaenoic acid (EPA, 22:5n-3),
conversion to DHA was barely detectable, though women did have a slightly better ability to convert than men.
Compared to humans, rats are relatively efficient converters of ALNA to DHA, yet in dual labelling studies, stable
isotopes 3 H and 14 C provided during rat brain development showed a 30-fold higher incorporation of preformed
DHA into brain tissue than synthesis from ALNA [12, 42]. In addition, ALNA is known to be oxidized rapidly, and
any excess that reaches the brain is usually used for cholesterol and palmitate synthesis [43]. Since incorporation of

18 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Broadhurst et al.
preformed DHA into brain tissues requires less energy than the synthesis of DHA from dietary precursors,
preformed DHA in the diet offers a significant evolutionary advantage in terms of brain growth and maintenance.
A diet including foods rich in DHA such as fish, shell fish, turtles and sea bird eggs would have been a significant
advantage for early human brain growth and the subsequent development of the complex neuronal networks that
characterize the abstract thought processes that are uniquely human (Tables 1, 2). As reviewed in detail by Cunnane
and Stewart [44], fish remains are common at numerous early Homo archaeological locations including Olduvai
Gorge [45], Turkana Basin [46] and the Middle Awash Valley [47]. Shell fish are common at a number of early
African Homo sites, especially South Africa [48-51], as well as early Homo sites outside of Africa [52-57].
ENDURANCE RUNNING AND SCAVENGING
One way to include preformed LC-PUFA in the diet is to very consistently eat fresh brains, internal organs and bone
marrow (Table 2). The endurance running model [2, 3] argues that the ability to run long distances over sustained
periods evolved in African Homo erectus by about two million years ago (2 Ma) as an adaptation to gain access to
the lipid and protein provided by large terrestrial mammals, and as such, running is seen as a key component in the
evolution of the human body form, including the development of a large human brain.
Endurance running required that hominins run large mammals to exhaustion. First, humans must outrun and
outsmart various carnivores and scavengers that may have been alerted by the situation. Second, supposing animals
are successfully run to exhaustion, then hominins are required to club them to death, because at 2 Ma there is no
evidence for the development of sophisticated weaponry or projectiles. Modern tribal African savannah hunters do
run game to exhaustion, but not on a whim – generally the animal has been mortally wounded by a spear or arrow
(often dipped in poison) and thus there is a blood spoor to follow, and a weakened prey to track.
Table 1: Total Fat Content of Representative Fish and Marine Invertebrates, and of Arachidonic Acid (AA) and
Docosahexaenoic Acid (DHA) in g/100 g Total Lipid. Reproduced from Broadhurst et al. [13]
Fish and Habitat % Fat a AA (g/100 g) DHA (g/100 g lipid)
Lake Malawi African tropical freshwater
Mbelele (catfish) 10.3 4.3 8.6
Njenu (carp) 4.9 1.8 7.8
Mfui (local sp.) 1.1 8.0 19.1
Kambale (local sp.) 1.8 5.9 13.3
Australian tropical freshwater
Bream meat 1.6 5.3 5.6
Bream fat 91 2.0 1.5
Tropical marine
Australian barramundi 0.3 14.5 16.2
Indian halibut 1.7 6.3 10.4
Closed-basin temperate marine (Black and Marmara Seas, Turkey)
Bluefish (immature) 42.9 6.1 12.1
Bluefish (mature) 31.3 4.2 13.8
Horse mackerel 12.8 1.4 6.6
Sardine 11.3 2.6 14.7
Red mullet 8.8 4.6 17.3
Sole 4.7 5.4 16.4
Garfish 4.2 4.6 24.3
Sand smelt 3.8 4.3 24.8
Whiting 2.7 3.5 40.8

36 Was Man More Aquatic in the Past?, 2011, 36-66
A Wading Component in the Origin of Hominin Bipedalism
Algis V. Kuliukas *
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 3
Centre for Forensic Science, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
Abstract: For over 150 years the field of palaeo-anthropology has grappled with several problems of
understanding human evolution, notably those explaining key differences between human beings and our most
closely related species, the African great apes. The first difference to be explained, perhaps in terms of
importance but certainly in terms of chronology, is our bipedality.
This chapter will review the models of hominin bipedal origins published to date, and categorize them, as was
done by Rose [1], by the adaptive mechanism being suggested. In addition, it will propose a new evaluative
framework against which each model may be assessed and compared. In this evaluation, published wading
models appear to be among the strongest although they are among the least well reported in university-level text
books, a discrepancy attributed here to their association with the so-called ‘aquatic ape hypothesis’ (AAH).
Despite their apparent strengths, published wading models do nevertheless contain weaknesses. This chapter
addresses a few of those weaknesses either theoretically or through studies, such as one obtaining new empirical
data comparing the energy efficiency of different bipedal gaits in water. Furthermore, a series of falsifiable
predictions of the wading hypothesis are made about the postcranial anatomy of australopithecines.
The chapter concludes by proposing a specific timescale and ecological niche where such wading behavior could
have provided a stable evolutionary scenario in early hominins that is compatible with the fossil record and other
models of human evolution.
Keywords: Bipedalism, hominin bipedal origins, wading.
CUTTING THROUGH THE TANGLED THICKET OF BIPEDALISM ORIGIN MODELS
To understand human evolution we need to be able to explain, in Darwinian terms, the key differences between us
and the great apes and perhaps the most important of those is our bipedality. Despite a huge intellectual effort,
spanning over 100 years, there is still no consensus among physical anthropologists as to which factors caused the
remarkable divergence that led to one clade moving on land on two legs almost exclusively and the others,
generally, on four. Students of anthropology today are consequently taught a very tentative picture about why only
we, Homo sapiens, are obligate bipeds. This lack of consensus is indicative that, so far, either insufficient
unequivocal evidence has been provided in favor of any particular idea on the matter to make it the generally
accepted one, or that perhaps one of the ideas has been misunderstood.
There is a vast literature on the subject and most of it starts by stating the importance of understanding this problem.
For example, the anthropologist Craig Stanford, in his book Upright makes the point: “The reason that upright
posture and walking arose is the most fundamental question in human evolution [2].” So, considering the problem’s
importance, how have we progressed, since Darwin, in trying to solve it? Rose summed up the status quo in the
early 1990s: “… despite a voluminous literature, our ignorance concerning bipedalization is almost complete” [1].
This situation doesn’t appear to have improved during the last two decades.
Indeed the problem has recently been portrayed as being, if anything, even more uncertain than before. A special
edition of the Journal of Anatomy in 2004, dedicated to the question of human bipedal origins, included a paper by
Harcourt-Smith and Aiello which concluded: “In the light of the richness of recent findings in the hominin fossil
*Address correspondence to Algis V. Kuliukas: Centre for Forensic Science, University of Western Australia, 35 Stirling Highway, Crawley
WA 6009, Australia; E-mail: algis.kuliukas@uwa.edu.au.

A Wading Component in the Origin of Hominin Bipedalism Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 37
record, it is important to ask the question of whether the evolution of bipedalism was a more complex affair than has
previously been suggested” [3]. In 2007, another new idea made the front page of the journal Science with a model
proposing that the ancestors of all great apes practiced “hand-assisted” arboreal bipedalism, as reported in
orangutans [4]. The question as to why one lineage of great ape became an obligate biped, whilst the others did not,
is avoided completely. Apparently, it was assumed that it was possibly just a matter of random genetic drift.
Kevin Hunt perhaps best summed up the situation when he recently gave a talk entitled The tangled thicket of
bipedalism origin hypotheses: Embarrassment of riches or just embarrassment? [5]. This chapter will try to cut
through this tangled thicket, categorize the various models that have been published, compare and evaluate them and
then focus on one of them that appears to have been neglected for all the wrong reasons, the wading hypothesis.
CLASSIFICATION AND EVALUATION OF BIPEDAL ORIGINS HYPOTHESES
The literature discussing ideas on the origin of human bipedalism is so rich it might be helpful to begin by listing
and classifying them. Here, the models will be structured according to an adaptation of Rose’s [1] classification by
suggested adaptive mechanism (Table 1).
Clearly such classifications of models are a matter of opinion. It could easily be argued that some models should be
placed under different or multiple categories. It should also be remembered that few proponents would claim
absolute exclusivity for their model and most would concede that others probably played a part too.
It should also be noted that even the number of models listed here is open to interpretation. For example the differences
between the three arboreal models (the ‘hylobatian’ or brachiator ancestor) model, the ‘upwardly mobile’/vertical
climbing hypothesis and the ‘orangutan-like’ hand assisted bipedalism model) are very minor and the ‘wetland
foraging’ model, ascribed here to both Ellis [53] and Wrangham et al. [54] could easily be split into two separate ones.
Table 1: Published Bipedalism Models, Classified by Mode of Selection
Category Subcategory Code a Specific Idea Original Proponent(s)
Forelimb
pre-emption
(Carrying)
Unspecified 1.0 General freeing of the hands Darwin 1871 [6],
Hooton 1945 [7]
Food carriage 1.1.1 Carrying food back to gallery forest
bases.
Hewes 1961 [8]
1.1.2 Carrying and scavenging Isaac 1978 [9]
1.1.3 Migration-carrying hypotheses Sinclair et al. 1986 [10]
1.1.4 Male provisioning Lovejoy 1981 [11]
Infant carriage 1.2 Female driven infant carrying Etkin 1954 [12], Iwamoto 1985 [13],
Tanner 1981 [14]
Tool/weapon throwing 1.3 Weapon throwing Fifer 1987 [15],
Dunsworth et al. 2003 [16].
Tool carriage 1.4.1 Tool carriage Bartholomew and Birdsell 1953 [17],
Washburn 1960 [18], Marzke 1986
[19]
1.4.2 Weapon wielding Dart 1959 [20],
Kortland 1980 [21]
Social behavior Nuptial gifts 2.1 Nuptial gifts Lovejoy 1981 [11],
Parker 1987 [22]
Aggression (interspecific) 2.2.1 Interspecific threat displays Kortland 1980 [21]
Threat display
(intraspecific)
2.2.2 Intraspecific threat displays Livingston 1962 [23], Wescott 1967
[24], Tanner 1981 [14], Jablonski and
Chaplin 2004 [25]
Evasion/Vigilance 2.3 Sentinel behavior (peering over the
savannah)
Reynolds 1931 [26], Dart 1959 [20],
Day 1977 [27], Ravey 1978 [28],
Walter 2004 [29]

38 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Algis V. Kuliukas
Table 1: cont....
Sexual display 2.4 Phallic display directed at females Tanner 1981 [14]
A new ‘fashion’ 2.5 Copied gimmick idea Dawkins 2005 [30]
Feeding Terrestrial Gathering 3.1.1 Seed eating Jolly 1970 [31]
3.1.2 Terrestrial squat feeding on the
forest floor
Kingdon 2002 [32]
3.1.3 Other gathering Du Brul 1962 [33], Wrangham 1980
[34], Rose 1984 [35]
Postural Feeding 3.2 Postural feeding hypothesis Hunt 1994 [36]
Arboreal Predation 3.3 Arboreal predation Eickhoff 1988 [37]
Terrestrial
3.4.1 Stalking Geist 1978 [38]
Predation/Scavenging
3.4.2 Specific hunting Cartmill 1974 [39],
Carrier 1984 [40]
3.4.3 General scavenging/hunting Szalay 1975 [41], Merker 1984 [42],
Shipman 1986 [43],
Sinclair et al. 1986 [10]
Habitat
compulsion
Efficiency of
Locomotion
Selection for
better
Thermoregulation
Wading 4.1.1 Coastal foraging Hardy 1960 [44],
Morgan 1972 [45], 1982 [46], 1991
[47], 1994 [48], 1997 [49]
4.1.2 ‘Aquarboreal’ model Verhaegen et al. 2002 [50]
4.1.3 Amphibische Generalistentheorie Niemitz 2002 [51]
4.1.4 River apes Kuliukas 2002 [52]
4.1.5 Wetland foraging Ellis 1991 [53],
Wrangham et al. 2009 [34, 54]
Arboreal 4.2.1 Hylobatian (brachiator ancestor)
model
4.2.2 ‘Upwardly mobile’/vertical
climbing hypothesis
4.2.3 Orangutan-like hand assisted
bipedalism
Keith 1923 [55],
Prost 1980 [56]
Tuttle 1975 [57], 1981 [58]
Thorpe et al. 2007 [4]
Other 4.3 Variability selection hypothesis Potts 1998 [59]
Slow, long-distance
walking
Biomechanical
inevitability
Efficiency of moving from
tree to tree.
4.2 Walking on snow or mud Kholer 1959 [60]
5.1 Slow, long-distance walking Rodman and McHenry 1980 [61],
Sockol et al. 2007 [62]
5.2 Biomechanical inevitability Reynolds 1985 [63]
5.3 Efficiency of moving from tree to
tree
Pickford and Senut 2001 [64]
Locomotor “de-coupling” 5.4 Locomotor de-coupling Sylvester 2006 [65]
Exaptation from
‘Endurance running’
5.5 Endurance running Lieberman 2007 [66]
Savannah sweat cooling 6 Thermoregulatory hypothesis Wheeler 1984 [67]
Dietary Factors Iodine deficiency and/or
overly rich Calcium diet
Random Genetic
Factors
(Mutation/Drift)
Combination of
factors
a: Refers to supplementary material.
Mutation in a key gene
involved in vertebral
development
7 Iodine deficiency de la Marett 1936 [68]
8 ‘Evo/devo’ mutation Filler 2007 [69]
Combination of factors 9 Multi-factorial Napier 1964 [70],
Sigmon 1971 [71],
Rose 1984 [35], Day 1986 [72]

Was Man More Aquatic in the Past?, 2011, 67-81 67
Early Hominoids: Orthograde Aquarboreals in Flooded Forests?
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 4
Marc Verhaegen 1,* , Stephen Munro 2 , Pierre-François Puech 3 and Mario Vaneechoutte 4
1 Study Center for Anthropology, Mechelbaan 338, 2580 Putte, Belgium; 2 School of Archaeology and Anthropology,
Australian National University, Canberra 0200 and Curatorial Fellow, Centre for Historical Research, National
Museum of Australia, Canberra, ACT 2600, Australia; 3 Institut de Paléontologie Humaine à Paris, Le Zénith 1,561
avenue Evêché de Maguelone, 34250 Palavas, France and 4 Laboratory for Bacteriology Research (LBR), Department of
Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, University of Ghent, De
Pintelaan 185, 9000 Gent, Flanders, Belgium
Abstract: The great (orangutans, gorillas and chimpanzees) and lesser apes (siamangs and gibbons) are significantly
different to monkeys, yet the evolution of the apes is rarely discussed in detail, especially from a human evolutionary
perspective. Assuming that the early primates were arboreal and that human ancestors were semi-aquatic, human
predecessors in the intermediary phase must have been aquarboreal, i.e., spent significant time in both trees (Latin
arbor) and water (Latin aqua). Here we describe a number of independent indications that early apes – possibly as
early as 20 Ma (million years ago) – were vertical aquarboreal frugi-omnivores in swamp forests.
Apes differ from monkeys in having a below-branch locomotion, with larger and broader bodies and thoraxes, very
long arms that can easily be extended above the head, and tail loss. Whereas most mammals and monkeys
predominantly move pronogradely (with horizontal spine and trunk), the remarkably humanlike lumbar vertebra of
Morotopithecus suggests that by about 20 Ma the early apes were already orthograde (with a generally vertical
spine). According to the palaeo-environmental data, the fossils of Mio-Pliocene apes typically lay in coastal and
swamp forest sediments around the Tethys Sea (the ancient Mediterranean Sea). The Miocene (23.0 to 5.3 Ma) and
the Pliocene (5.3 to 2.6 Ma) epochs were generally hotter and wetter than the Pleistocene Ice Ages (2.6 to 0.01 Ma).
Recently, the highest population densities of orangutans as well as gorillas have been discovered in extremely hot
and wet swamp forests.
Since all great apes can make and use tools, and most fossil great apes had thick enamel, the ancestral great ape
diet in flooded forests might have included durophagy of hard-shelled foods (e.g., palm nuts or molluscs).
Locomotor requirements for flooded forest dwelling could arguably have included a bigger body with vertical
climbing abilities, including with arms overhead and arm-hanging. Lowland gorillas employ an orthograde
posture and locomotion when they climb, wade through shallow swamps, and sit and feed in shallow water.
Keywords: Aquarboreal, Miocene apes, hominoid evolution, orthogrady, durophagy, Griphopithecus, Oreopithecus,
Dryopithecus, Morotopithecus, Heliopithecus, Saadanius.
INTRODUCTION
A largely neglected aspect of the study of human evolution (including waterside hypotheses) is the evolution of our
nearest relatives, the Hominoidea (apes and humans): the lesser apes and the great apes, especially the African apes (Fig.
1). Apes are different to the other simians or anthropoids, the monkeys: the Old World monkeys (who together with the
apes and humans constitute the narrow-nosed Catarrhini), and the New World monkeys (the broad-nosed Platyrrhini).
In order to reconstruct how human ancestors lived and evolved, it is important to understand how their ancestors, the
Mio-Pliocene hominoids, lived. This chapter gives a brief overview of their environments, including how they might
have moved and fed. Although some general conclusions are clear, detailed reconstructions are as yet impossible.
Note that the Mio-Pliocene apes (23.0-2.6 million years ago (Ma)) were much more abundant and widespread than
the living apes, and considerably more varied in anatomy, diet and locomotion.
According to the biomolecular data, the ancestors of the extant hominoids split into the lesser apes and the great
apes between 18 and 15 Ma. About 15 or 14 Ma, the latter split into the Asian pongids (orangutans today) and the
African hominids (gorillas, chimpanzees and humans today). The hominids then split into gorillas and humanschimpanzees
about 8 to 6 Ma, and Homo and Pan split about 6 to 4 Ma (Figs. 1 and 2) [1].
*Address correspondence to Marc Verhaegen: Study Center for Anthropology, Mechelbaan 338, 2580 Putte, Belgium; E-mail: m_verhaegen@skynet.be

68 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Verhaegen et al.
Strepsirhini (wet-nosed primates): e.g., lemurs, indri, aye-aye, potto, lori
Haplorhini (dry-nosed primates)
Tarsioidea (tarsiers)
Simiae or Anthropoidea (monkeys, apes and humans)
Platyrrhini (New World or broad-nosed monkeys): e.g., marmosets, Cebus, Ateles, Alouatta
Catarrhini (Old World or small-nosed simians)
Cercopithec oidea (Old World monkeys)
Cercopithecinae (omnivorous): e.g., Macaca, Papio, Cercopithecus
Colobinae (folivorous, arboreal): e.g., Nasalis (proboscis and simakobu)
Hominoidea (apes and humans)
Lesser apes: Hylobatidae
Symphalangus, i.e., siamang
Nomascus, i.e., crested gibbons
Brunopithecus, i.e., hoolock gibbon
Hylobates, i.e., about 5 spp. of gibbons
Great apes and humans
Pongidae (orangutans)
Pongo abelii (Sumatra)
Pongo pygmaeus (Borneo)
Hominidae (African apes and humans)
Gorilla gorilla (western gorillas)
Gorilla beringei (mountain gorilla)
Homo sapiens (modern humans)
Pan troglodytes (common chimp)
Pan paniscus (bonobo)
Figure 1: Overview of living primates.
Asia Pongids Lufengpithecus Gigantopithecus SE Asia Pongo
Sivapithecus India
Europe Austriacopithecus Ankarapithecus Anatolia
Griphopithecus C-Europe Rudapithecus Hungary
Arabia Thetys Anatolia Pierolapithecus Dryopithecus Oreopithecus Sardinia worldwide
Heliopithecus Catalonia Anoiapithecus Ouranopithecus Greece Homo
Afropithecus ? Orrorin Africa Australopithecus Pan
Morotopithecus Africa ? Sahelanthropus Ardipithecus Gorilla
Uganda Samburupithecus Hominids
Proconsul Kenya Nakalipithecus Kenya
Ugandapithecus E-Africa Chororapithecus Ethiopia
Early hominoids Equatorius Africa ??
Otavipithecus Namibia
20 15 10 5 0 (Ma)
early Miocene middle Miocene late Pliocene Pleistocene
Figure 2: Overview of fossil Hominoids, after [33].
DIFFERENCES BETWEEN APES AND MONKEYS
Hominoids (apes and humans) differ from monkeys and prosimians in several instances [2-4].
Great hominoids, more so than the lesser apes, are an order of magnitude larger than the average monkey. All
hominoids are remarkably broadly built, broader than the atelid New World monkeys such as spider monkeys Ateles
(below-branch arm-swingers or brachiators, with long grasping-tails), and much broader than all other primates.
The hominoid shoulders and hips are broad, and the thorax is wider in its transverse (latero-lateral) than anteroposterior
diameter. The scapulas (shoulder blades) are broader and have shifted from the sides of the thorax to the
back, so that they can more easily abduct the arms (laterally) and extend them above the head (cranially). The
vertebral column has shifted ventrally towards the sternum (breastbone), so that the vertebral column has a central
rather than dorsal position.

Early Hominoids Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 69
The sternum is conspicuously much wider (hence the old term Latisternalia for Hominoidea) than in monkeys, and
tends to become solidified through fusion of most of its intercostal segments (monkeys generally have about six
unfused rod-like sternal bones). The brachiating atelids have no, or only slightly, broadened sternal bones, much less
than the hominoids including the brachiating gibbons and siamangs. Whereas the width-length proportion of the
sternal body is ~ 11% in cercopithecoids, in hominoids it varies from ~ 24% in chimpanzees (the most quadrupedal
of the apes) to ~ 35% in humans and gibbons, to ~ 45% in gorillas and ~ 57% in orangutans.
In the hominoid spine (vertebral column), the combined number of thoracic and lumbar vertebrae is reduced from an
original general average of 19 in monkeys to about 18 in gibbons, to 17 in siamangs and humans, and even less in
the great apes, especially orangutans. Hominoids have reduced lumbar mobility with less lumbar vertebrae (four or
five instead of about seven) and lower lumbar vertebral length than monkeys. Lumbar length is more than 40% of
the pre-sacral spine in most monkeys, about 32% in humans and 29% in lesser apes, but only about 24% in the great
apes and in the spider monkey Ateles [4], so that the thorax closely approaches the pelvis: “the lumbar region is
usually wedged so far between the greatly lengthened hip-bones that only the upper few lumbar vertebrae can be
freely flexed and the last pair of ribs approaches the pelvic crest extremely closely... there can hardly be any lateral
movement with the stout and broad trunks of the apes, in sharp contrast to the graceful bending of the lumbar region
in the slender, narrow trunks of typical monkeys” [3].
The sacrum bone (the vertebral part of the pelvic ring) consists of three fused sacral vertebrae in most monkeys, but
of usually five to six in recent hominoids (and usually seven in the prosimian pottos and relatives, short-tailed slow
grasp-climbers).
The external tail is lost: the number of caudal vertebrae is reduced from twenty or more elongated and very mobile
tail vertebrae in most primates (including atelids), to three to five diminutive flattened and fused vertebrae in the
hominoid tailbone (coccyx), which is fused to the sacrum and incorporated in the pelvic bottom.
The limbs have become relatively long, especially the arms in lesser apes and orangutans, and the legs in humans.
The encephalization quotient (EQ) of the brain is slightly (apes) or extremely (humans) enlarged in comparison to
most monkeys and especially other arboreal mammals. The great apes regularly or occasionally make and use tools.
Great apes and humans have paranasal air sinuses, whereas most Old World monkeys lack these. Great apes and
siamangs, unlike gibbons and humans, have very large laryngeal air sacs, up to six or seven liters in male orangutans
and gorillas, who – together with viscachas (large, burrowing South-American rodents) – probably have the largest
airsacs per body size [5].
The great hominoids show hair reduction – loss of underfur in great apes and complete fur loss in humans – but
lesser apes and other primates have dense fur, in gibbons even denser than in most Old World monkeys.
Remarkably, seven-month-old chimpanzee (and presumably also other great ape) fetuses are furless except for the
scalp, and after birth regrow body hairs, though no underfur [2, 6].
These hominoid innovations did not evolve simultaneously, but in a mosaic-like way. Some examples. It is thought
that Proconsul (~ 23-17 Ma) had already lost its tail [7], and, with regard to body size, some Proconsul relatives
were almost of gorilla size (Ugandapithecus major). Morotopithecus (~ 20 Ma) is estimated to have weighed
between 40 and 60 kg; its remarkably humanlike lumbar vertebra had a dorsal shift of the transverse processes,
which probably stiffened the lumbar spine and made it stronger in a vertical position, suggesting that
Morotopithecus – and presumably also the closely resembling Afropithecus – had a vertical spine, indicative of an
orthograde posture and locomotion [8, 9]. The extreme lumbar shortening and sacral fusion in the vertebral columns
of African apes possibly took place after they split from human ancestors. Proconsul species had a narrow thorax,
but possibly already a moderately broadened sternum, as well as tail reduction or loss [10, 11]. Afropithecus (~ 17
Ma), in spite of its probable orthogrady, is argued to have moved predominantly above-branch [12]. Arm-hanging
(present in all living hominoids) and a fortiori brachiation (arm-swinging in gibbons, and also in atelids) are thought
to have been absent or underdeveloped until and including the late Miocene (including Sivapithecus) [13, 14].

82 Was Man More Aquatic in the Past?, 2011, 82-105
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 5
Pachyosteosclerosis in Archaic Homo: Heavy Skulls for Diving, Heavy Legs
for Wading?
Stephen Munro 1,* and Marc Verhaegen 2
1 School of Archaeology and Anthropology, Australian National University, Canberra 0200 and Curatorial Fellow,
Centre for Historical Research, National Museum of Australia, Canberra, ACT 2600, Australia and 2 Study Center
for Anthropology, Mechelbaan 338, 2580 Putte, Belgium
Abstract: Compared to the skeletons of all other primates, including Homo sapiens, the crania and postcrania of
Homo erectus were typically massive, displaying extremely thick bones with compact cortices and narrow
medullary canals. Even outside the primate order, examples of animals displaying such massive bones are rare.
Although this feature is sometimes seen as diagnostic of H. erectus, few convincing hypotheses have been put
forward to explain its functional and adaptive significance.
Here, we present data showing that unusually heavy bones were a typical, although not exclusive nor
indispensable, characteristic of H. erectus populations through the early, middle and late Pleistocene in areas of
Asia, Africa and Europe. A comparative review of the occurrence of massive skeletons in other mammals
suggests that they have an important buoyancy control function in shallow diving aquatic and semi-aquatic
species, and are part of a set of adaptations that allow for the more efficient collection of slow, sessile and
immobile foods such as aquatic vegetation and hard-shelled invertebrates. We therefore consider the possibility
that part-time shoreline collection of aquatic foods might have been a typical element of the lifestyle of H. erectus
populations. We discuss the alternative explanations for heavy bones from the literature, as well as apparent
exceptions to the rule, such as thin-boned H. erectus and thick-boned Homo sapiens fossils. A review of the
palaeo-ecological data shows that most, if not all, H. erectus fossils and tools are associated with water-dependent
molluscs and large bodies of permanent water. Since fresh and salt water habitats have different densities, we
hypothesize that in H. erectus as well as in some Homo sapiens populations, there might have been a positive
correlation between massive bones and dwelling along sea or salt lake shores.
Keywords: Pachyostosis, osteosclerosis, medullary stenosis, human evolution, Homo erectus, buoyancy control,
Out of Africa, shallow diving, sessile food, seafood, continental shelves, Pleistocene, semi-aquatic mammals.
INTRODUCTION
“One of the most remarkable characteristics of middle Pleistocene age H. erectus is the presence of thickened bone.
While many observers have mentioned this thickened bone in anecdotal fashion without comparative examples,
other workers have provided fuller documentation of thickened cranial and postcranial bones in this species. In the
H. erectus cranium, it is clear that the increased thickness of the vault bones is due to an increase in tabular rather
than diploic bone. In the femur, the tibia and the ulna the thickened bone is found in the cortical bone of the shaft
walls: the cancellous bone in the metaphyseal and epiphyseal regions does not seem to vary systematically from
anatomically modern H. sapiens in either density or area” [1].
When the Dutch physician Eugène Dubois unearthed in eastern Java in the early 1890s the skull cap and the femur
of what he first named Anthropopithecus and later Pithecanthropus erectus (now the type specimen for Homo
erectus), he was struck by the extraordinarily massive cortical bone tissue, and he interpreted this as a sign of the
primitiveness of these bones. Later researchers, such as Franz Weidenreich, thought the heavy bones suggested that
H. erectus individuals were giant creatures. As more fossils were discovered, however, it became clear that,
although not small, these individuals were no giants, but instead had relatively very compact and thick bones [2, 3],
beyond the range of optimal strength/weight ratio.
Different hypotheses have been put forward to explain this curious feature, but so far there has been no consensus.
*Address correspondence to Stephen Munro: School of Archaeology and Anthropology, Australian National University, Canberra 0200 and
Curatorial Fellow, Centre for Historical Research, National Museum of Australia, Canberra, ACT 2600, Australia; Tel: +61 2 61252023; Fax: +
61 2 6125 2711; E-mail: stephen.munro@anu.edu.au

Pachyosteosclerosis in Archaic Homo Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 83
This paper attempts to help solve this century-old question by comparing thickened bone and other typical bone
characteristics of fossil hominids with other species, and by considering a number of alternative hypotheses.
OSTEOSCLEROSIS, PACHYOSTOSIS, AND MEDULLARY STENOSIS
The terminology on the ‘robustness’or ‘robusticity’ of bones can be confusing, especially since palaeontological and
medical vocabularies differ. In this paper, we follow the palaeontological definitions whenever possible.
Osteosclerosis
Osteosclerosis, literally ‘bone hardening’, means elevation in bone density (compactness, hardness, solidity) through
hyper-mineralization, in medicine normally detected on an X-ray as an area of increased whiteness (calcium). It
occurs in a generalized or localized pattern in a great variety of diseases, in diffuse or focal lesions, often
asymmetrically and affecting various parts of the skeleton (e.g., hyperparathyroidism, sickle cell anaemia, Paget’s
disease, Hodgkin’s disease, leukaemias, metastases, osteomyelitis and osteo-arthritis).
Since fossilization implies re-mineralization and since bone-filling minerals such as calcite can make estimating
densities difficult [4], osteosclerosis is not always easy to discern in fossils, but by comparing relative densities of
fossil bones and by studying their histologies, it does seem possible most of the time to identify which fossil bones
are osteosclerotic [5-7].
The opposite of osteosclerosis is osteoporosis, literally ‘bone porosity’. In human medicine, osteoporosis is a
pathological condition which leads to enhanced risk of bone fractures (e.g., of the thoracolumbar vertebral corpora,
the femoral neck, and the radius 3-4 cm above the wrist joint, especially in short and lean postmenopausal women).
There is an optimal density at which bones are less likely to suffer fractures. Deviation from this optimal density in
either direction increases the risk of fracture [8]: not only do bones that are not dense enough increase the risk of
fracture (osteoporosis), but so too do bones that are too dense (osteosclerosis).
Osteopetrosis, literally ‘rock bone’, in palaeontology is sometimes used as a synonym to osteosclerosis, but in
medicine it means a group of diseases with very dense (calcium-rich on X-rays) and brittle bones (Albers-Schonberg
or marble bone disease). Many mammals have localized very dense, non-pathological bone tissues in the ear region
(os petrosum, see below).
Pachyostosis
Pachyostosis, literally ‘broad-bonedness’, means thick and swollen bones so that the bone's cross-sectional diameter
is inflated relative to the joint surface area regardless of density, e.g., by means of periosteal ossification.
Pachyostotic bone can theoretically be of normal density, or be osteosclerotic, or osteoporotic.
Pachyostosis is a specific form of generalized hyperostosis, literally ‘over-bonedness’. In medicine, hyperostosis
means ossification in places that are normally not ossified. Different hyperostotic lesions, which can be discerned
from the pachyostosis of Homo erectus, have been described in fossil and extant hominids, e.g.,
- Diffuse idiopathic skeletal hyperostosis (DISH), mostly along the thoracic vertebrae, frequently seen in
older people, is probably a form of degenerative osteo-arthitis associated with chronic overload,
comparable to ligament and tendon ossifications and heel spurs. Spinal hyperostosis or spinal
osteophytosis, described in older dogs, horses, whales and other mammals, is presumably also due to
mechanical stresses inducing local osteogenesis [9].
- Endocranial hyperostosis, of uncertain cause, probably identical to hyperostosis frontalis interna and
hyperostosis calvariae interna, is a human anomaly (often in postmenopausal women) involving
thickening of the inner table of the skull and sometimes the diploë, which is radiographically invisible
in early cases. It is remarkably frequent in the frontal squama of H. erectus and Neanderthal skulls
(Sangiran-2, Shanidar-5, and especially Gibraltar-1) but is absent from the Trinil specimen [10].
- Auditory exostoses are local hyperostoses or bony outgrowths in the ear canals of human divers and
surfers after years of chronic maceration and irritation by cold water and wind in marine or freshwater

84 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Munro and Verhaegen
milieus [11,12]. They are often found, usually bilaterally, in older H. heidelbergensis- and H. erectuslike
and especially Neanderthal skulls [13, 14].
- Porotic hyperostosis is a proliferation of bone marrow on the surface of the cranium, typically the
parietal bones and orbital roof (cribra orbitalia), often associated with chronic diarrhea, anaemia, iron
deficiencies and/or parasitic infestations [15, 16]. In incipient aquatic tetrapods with hyperostosis, to
the contrary, all members of the species (although often in varying degrees according to age or sex)
typically show nonpathological bone that is not porotic, but osteosclerotic.
- The thoracic vertebrae of australopithecines (e.g., AL 333-51, AL 288-1, Sts 14), adult chimpanzees,
orangutans, macaques and rarely modern humans can show deposition of a highly vascular bone along
the anterior surface of the vertebral body, under the anterior longitudinal ligament [17]. These lesions
are thought to result from high activity levels, or from trauma.
Medullary Stenosis
Medullary stenosis, literally ‘marrow narrowing’, means narrow medullary cavities, especially of the ribs and long
limb bones, culminating in bones completely lacking medullas and consisting exclusively of compact bone. The
medulla or inner cavity of long bones is normally filled with cancellous (trabecular, spongy) bone, a type of osseous
tissue with a lower density, as opposed to the compact (dense) bone of the cortex.
These three conditions, i.e., osteosclerosis, pachyostosis and medullary stenosis, which frequently occur in
combination in animal species and are often not sharply discerned in descriptions, cause the bones overall to be
heavier. In this chapter, we will use the terms pachyosteosclerosis or generalized hyperostosis for the combination
of these three features. This is not meant to imply that all bones of the skeleton are equally hyperostotic, rather that a
considerable part of the skeleton, in a non-pathological and symmetrical way, is unexpectedly hyperostotic.
Neanderthals are generally less hyperostotic than H. erectus, and some of their bones have been described as more
slender than in present-day humans, notably some skeletal parts on the ventral side: the frontal bone (with large air
sinuses), the clavicles, and the pubic rami [18, 19]. Their skulls, however, especially the occiput, their femora, and
other bones are typically hyperostotic (regional hyperostosis).
While it is possible that H. erectus specimens, like Neanderthals, might also have possessed skeletal parts that were
not particularly dense (e.g., in the proximal and middle femur shaft of the Trinil specimens), most H. erectus fossils
display clear examples of generalized hyperostosis.
PACHYOSTEOSCLEROSIS IN ‘ARCHAIC HOMO’
We use the term ‘archaic Homo’ to refer to Neanderthals, H. erectus and other Pleistocene Homo fossils (i.e., less
than ~ 2.6 Ma), with low, long, flat skulls and heavy supraorbital tori (Tables 1 and 2, Fig. 1). The bones of most
archaic Homo are pachyosteosclerotic, displaying three features that make the bones heavier: unusually thick bones,
compact bone cortices, and narrow medullary canals. These features are present to different degrees in various
archaic Homo fossils, but generally they are most prominent in H. erectus sensu lato [1, 20]. They are mostly absent
from H. sapiens (with rare exceptions, discussed below) and all other primates, extant or fossil, including apes and
australopithecines. With few exceptions (KNM-OL 45500, discussed below), the crania and postcrania of H. erectus
exhibit these three features, although the skull vault might be less thick in juvenile and female crania (e.g., KNM-
WT 15000 and KNM-ER 1808 in Table 1).
Table 1: Fossil Indications for Pachyosteosclerosis and Other ‘Unique’ Skeletal Features in Archaic Homo, especially H. Erectus
Species, site, time Anatomical descriptions
H. erectus (general definition) Heavier and lacking certain refinements of ours [100]
“presence of such thickened bones is extraordinary” [1]
“characterized by a long femoral neck and greatly increased mediolateral relative to
anteroposterior bending strength of the femoral shaft … very thick cortices, especially
medially and laterally, with the medial cortex remaining relatively thick through the
base of the neck” [101]

106 Was Man More Aquatic in the Past?, 2011, 106-119
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 6
Aquatic Scenarios in the Thinking on Human Evolution: What are they and
How do they Compare?
Algis V. Kuliukas 1,* and Elaine Morgan 2
1 Centre for Forensic Science, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
and 2 Mountain Ash, 24 Aberffrwd Road, Glamorgan, CF45 4AR, UK
Abstract: Missing in the literature to date is a concise description of the various scenarios proposing that human
evolution was affected, to some extent, by selection from wading, swimming and diving through water. Most of it
tends to focus on just one such scenario, first proposed by Hardy [1] and promoted by Morgan [2-6], which
suggested that a more aquatic interlude was contemporaneous with, and probably caused, the split between Pan
and Homo, and was followed by a U-turn back to a fully terrestrial life. Although theirs is still the most wellknown,
it is not the only one. Other scenarios, for example that proposed by Verhaegen et al. [7-11], differ quite
markedly in timescale, the proposed degree and mode of aquatic selection, and in terms of the evidence used in
support. This Chapter reports more than ten such ideas and summarizes six aquatic scenarios and clarifies the
differences between them. It also identifies a common thread between them, and uses it to propose a new label
and definition for them.
Keywords: Aquatic scenarios, waterside hypotheses, Hardy, Morgan, Verhaegen.
INTRODUCTION
Discussion of the aquatic ape hypothesis (AAH) in the scientific literature has been for the most part sparse and
dismissive. The one attempted refutation in a first class anthropological journal [12] was largely a critique of
Hardy’s original scenario and Morgan’s promotion of it [1-6], which envisaged an aquatic interlude contemporary
with – and in their opinion causing – the split between chimps and humans. As discussed in Chapter 15, Langdon’s
critique appears to have a number of weaknesses, which greatly damage any claim that it provides a serious rebuttal.
One such weakness is that other ‘more aquatic’ scenarios were not even considered.
Hardy’s and Morgan’s ideas [1-6] have been supplemented, enhanced and sometimes challenged by competing
scenarios of what might have happened, and when, and where. The most highly developed of these is presented by
Marc Verhaegen et al. [7-11] in Chapters 4 and 5 of this volume, but there have also been others before and
since. This chapter seeks to compare and contrast them, and explain where they differ in respect of timing, and
location, and the envisaged life-style of the species they describe.
WATERSIDE IDEAS BEFORE HARDY
Before comparing Hardy’s and Morgan’s scenarios with that of Verhaegen and other ideas that followed, mention
should be made of two other ideas prior to 1960. For a full review of these, see [13].
Sera (1938): ‘Aquatic’ Platyrrhines
Guiseppe L. Sera, an Italian biologist, was probably the first to suggest a possible aquatic phase in primate evolution
[14]. On the face of it, Sera’s contribution has very little relevance to the later ideas of Alister Hardy, since it was
not concerned with humans, or even with apes although it should be remembered that at the time many scientists
believed that our ancestors were primitive. It dealt with the evolutionary history of the Platyrrhini (broad-nosed or
New World monkeys). It foreshadowed Hardy only inasmuch as it was based on anatomical comparisons between
some primate species and some aquatic ones. Features such as the detailed structure of the larynx, nose, ear, female
*Address correspondence to Algis V. Kuliukas: Centre for Forensic Science, University of Western Australia, 35 Stirling Highway, Crawley
WA 6009, Australia; E-mail: algis.kuliukas@uwa.edu.au

Aquatic Scenarios in the Thinking on Human Evolution Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 107
external genitals and the kidneys led Sera to consider the possibility that the platyrrhines might once have occupied
an aquatic habitat. Other parallels with Hardy were the willingness to put forward an idea contrary to contemporary
thinking, and the modest tones in which they were offered. Sera expressed the hope that “such ideas which at first
sound so improbable should at least serve as a stimulus to further research.”
Westenhöfer (1942): Der Eigenweg des Menschen (The Pathway to Mankind)
The most significant predecessor to Hardy in alluding to aquatic factors in human evolution was the German
anatomist Max Westenhöfer (1871-1957) [15]. His attention, like Hardy’s, was drawn to various anatomical traits in
humans, such as lobulated spleens and kidneys, which he believed were somewhat analogous (i.e., had similar
anatomy through convergent evolution) to those present in whales, dolphins, seals, and sea otters. Other such traits
mentioned in his work were hairlessness, bipedalism, subcutaneous fat, reduction of olfaction, face-to-face
copulation, and brain development.
Westenhöfer’s view differed most significantly from Hardy’s in that it did not assume that humans had evolved from
an African great ape stock, but that they descended from, relatively unchanged, a primordial animal so ancient that it
predated even the emergence of primates. The assumption of this primitivity thesis makes any realistic comparison
between Westenhöfer’s and Hardy’s ideas very difficult, especially in terms of time-scale. Even though the two
were partly contemporaneous, neither of them apparently was aware of the other’s thinking.
HARDY / MORGAN: ‘MORE AQUATIC’ U-TURN HYPOTHESIS
This section deals with what most people think of when they hear the term ‘aquatic ape hypothesis’, i.e., Hardy’s
original idea and the promotion of it by Elaine Morgan.
Alister Hardy (1960): Was Man More Aquatic in the Past?
Alister Hardy (1896-1985) was a marine biologist at Oxford University who, in the 1930s, happened to read a
comment by Professor Wood Jones [16] on the puzzling fact that the layer of fat lining the skin of Homo sapiens is
not present in the chimpanzee. Hardy had just returned from an expedition devoted to studying the marine fauna of
Antarctica. Examples of animals and birds that do possess a fat-lined skin instantly sprang to his mind, and he could
not fail to notice that they were all aquatic. Was it possible that Man too was more aquatic in the past?
He had a good idea of the scepticism with which this question would be received, and waited thirty years before
publishing it in New Scientist [1]. Fifty years later, it remains one of the most controversial subjects in palaeoanthropology.
Despite being largely ignored by scientists in that field, interest in it elsewhere has continued to grow.
The reasons for this discrepancy are probably many-fold and complex (see Chapter 14), but one possible explanation
may be, simply, that it has been misunderstood. Clearly, if anyone is going evaluate this idea, let alone reject it, it is
of critical importance that they understand what Hardy was proposing and, perhaps even more importantly, what he
was not proposing.
Hardy was puzzled by several anomalous features of human anatomy. Every species is unique by definition, but the
sheer number and variety of ways in which humans differ from all other primates seemed to him to demand an
explanation. He attempted to account for it by postulating that their ancestors had gone through a “more aquatic”
phase in their evolutionary past. The subcutaneous fat was the feature that first put the idea into his head, but it was
soon followed by others [1, 17].
A key argument in Hardy’s thesis is that most mammalian taxa include at least one species that appears to have
become “more aquatic”, indeed some lineages, leading to entire taxa, have returned to the sea permanently. It
seemed to him quite possible that the Primate Order might also contain such a species, and if so, that Homo sapiens
might be the species in question. Clearly, Hardy argued, since humans today are by no means aquatic, this phase
must have somehow been curtailed and then reversed. This reversal was later characterized as a U-turn, and was
sometimes used as a reason for rejecting the idea. If they had gone into the water, why would they have come out
again? Hardy did not regard that as a serious stumbling-block. Such U-turns are rare, but no means unknown in the
history of life on earth.

108 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Kuliukas and Morgan
When did Hardy propose this phase happened? Hardy’s time-scale was in accordance with what was known from
the fossil record at the time. He proposed that a “more aquatic” phase in human evolution would neatly ‘plug the
gap’ that appeared at the time to exist in the fossil record between Proconsul and Australopithecus, namely about 15
to 10 Ma (million years ago).
Where did it happen? Hardy doesn’t originally propose anything more precise, geographically, than to suggest that
warm tropical coasts would have been ideal for the sort of scenario he envisaged. However, later, he did
enthusiastically endorse the idea of a geologist Leon P. La Lumiere Jr. [18] that the Afar triangle generally, and the
Danakil horst specifically, could have provided an ideal location for the geographical isolation that at the time was
thought to be required for speciation (allopatric speciation).
What was Hardy not proposing? It’s worth briefly noting, considering the controversy that has arisen surrounding
this idea, what Hardy was not proposing. Most significantly, he was not proposing an ‘aquatic ape’, in any real sense
of the word. The phrase ‘aquatic mammal’ has specific connotations about lifestyle and swimming and diving
abilities that go far beyond what Hardy had in mind. Perhaps this is best illustrated by this statement: “It may be
objected that children have to be taught to swim; but the same is true of young otters, and I should regard them as
more aquatic than Man has been” [1: 643].
Hardy, then, clearly set an upper bound for the degree of aquatic adaptation he envisaged. Although some might
counter that an otter is still quite an aquatically adapted mammal, (some might call it semi-aquatic), Hardy is clearly
proposing we were less aquatic than they are. He spelt out, in quite precise terms, how much time he thought our
ancestors might have spent in the water. “I am imagining this happening in the warmer parts of the world, in the
tropical seas where Man could stand being in the water for relatively long periods, that is, several hours at a stretch”
[1]. Several hours might seem a long time for a human, but not for an aquatic mammal. It is certainly not a mermaid
or some kind of ‘primate seal’.
Unfortunately, the response from the field of palaeo-anthropology to Hardy’s idea was muted to say the least.
Despite a ripple of quite positive feedback in the letters pages of New Scientist in the weeks that followed, and an
elegant paper in support by the geography professor C. E. Sauer [17], the idea was all but forgotten until Desmond
Morris, a former student of Hardy, in The Naked Ape [20], mentioned it in a way that would provoke a keen interest
from someone who would become the leading proponent of the idea for some forty years.
Elaine Morgan (1972, 1982, 1990, 1997, 2008): The Aquatic Ape Hypothesis
Elaine Morgan asked Hardy for permission to quote his ideas in a book she was writing. Permission was granted. He
later registered some startlement on learning that the book was to be entitled, The descent of woman [2], but he
welcomed the endorsement of his basic idea and wrote a foreword to her next book [3]. She has written three more
on the subject since.
Morgan’s books [2-6] have been a faithful portrayal of Hardy’s original idea, but she has also made her own
significant and original contributions.
She advanced further examples of the ways in which an aquatic phase might help to explain enigmatic features of
human physiology. Looking at human evolution from the point of view of the woman [2], and then the child [21],
she provided some new insights, from a ‘more aquatic’ context, that Hardy had not seen. For example, she argued
that the fact that human infants are born fat simply makes more sense in a more aquatic environment than elsewhere
[4]. Perhaps most significantly, Morgan picked up Hardy’s almost throw-away comment: that wading in shallow
water might help “our understanding how Man obtained his erect posture” [1] and developed it, over twenty years
into a well-developed hypothesis of bipedal origins though half a dozen chapters containing good evidence and
strong arguments [3-5].
Her main emphasis has always been on the remarkable differences between humans and chimpanzees – animals that
are even more closely related to us than they are to gorillas. Even the most cursory examination of the clade of the
African great apes makes it inescapably clear that Homo is the odd man out. Whatever may have happened in the

120 Was Man More Aquatic in the Past?, 2011, 120-147
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 7
Human Breath-Hold Diving Ability Suggests a Selective Pressure for Diving
During Human Evolution
Erika Schagatay *
Department of Technology and Sustainable Development and Swedish Winter Sports Research Centre, Mid Sweden
University, Akademig 1, 83125 Östersund, Sweden
Abstract: Modern humans are generally considered to be fully terrestrial, yet display a range of activities involving
breath-hold (apneic) diving, including sustained harvest diving, spear-fishing, recreational free-diving and
competitive apnea for duration, distance or depth. Via harvest diving, involving repeated diving with half of the time
submerged for several hours per day, groups in South East Asia obtain a considerable amount of catch. The
physiological basis for such repeated diving involves i) conscious breath control, ii) an efficient diving response,
diverting stored oxygen to the heart and brain, and iii) adequate thermal insulation. Another contribution to the
human diving ability comes from the spleen, which - by ejecting extra red blood cells into circulation - can enhance
blood gas storage and carbon dioxide buffering capacity, a response typically found in seals.
Most striking among human aquatic activities is competitive apnea, with records of a period of 11 min 35 s in
duration, the distance of 265 m in underwater swimming with fins, and a depth of 124 m in deep-diving with fins.
Without fins, the distance of 218 m and depth of 101 m have been achieved, performances in the range of marine
mammals. This requires additional mechanisms to maximize gas storage, minimize energy expenditure, and enhance
conscious tolerance to asphyxia, involving e.g. increase lung volume, baseline hematocrit and spleen volume, and
means to cope with the increased pressure. While it takes both inherent predisposition and training to achieve such
record results, most healthy humans can, after some practice, make voluntary apneas of 3-4 min, swim a distance of
50 m under water and reach depths of 20-30 m, which may be unique among terrestrial mammals.
Human superior harvest diving and competitive diving capacity may suggest a selective pressure for diving
during some time period of human evolution.
Keywords: Apneic diving, diving response, diving reflex, voluntary breath control, spleen contraction, hematocrit,
lung volume, lung packing, diving performance, duration, distance, depth, pressure, metabolism.
INTRODUCTION
Modern humans are generally considered to be land mammals adapted to a fully terrestrial life, yet display a range of
dive-associated activities, involving breath-hold or apneic diving. This chapter reviews the occurrence of and the
physiological background to two basically different aspects of human apneic diving: i) repeated sustained diving, e.g.,
harvest diving for food, which is still being carried out in many parts of the world, and ii) competitive diving for
maximal duration, distance and depth, which is a relatively new sport, emerging in an organized form on the
international scene in the 21 st century. The physiological requirements for repeated diving in order to maximize
productive bottom time for harvesting and fishing, and for extended human diving for single performance of records on
one breath are partly different, and are therefore dealt with separately. The chapter focuses on describing the current
activities and achievements as well as the physiological prerequisites for these two diving activities in humans, and
compares these to the abilities and responses in other animals, with suggestions on how they may have evolved.
HARVEST DIVING
It has been known for long that modern human physiology allows efficient shallow water sea harvesting by diving,
which is a basic activity in some current self sustained economies, e.g., the Ama in Japan, and the Hae Nyo in Korea
*Address correspondence to Erika Schagatay: Department of Technology and Sustainable Development and Swedish Winter Sports Research
Centre, Mid Sweden University, Akademig 1, 83125 Östersund, Sweden; Tel: +46 70 53 214 23; Fax: +46 63 16 57 00; E-mail:
Erika.Schagatay@miun.se

Human Breath-Hold Diving Ability Suggests a Selective Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 121
[1], and the Sea Nomads or Sea Gypsies in Indonesia, Phillipines and Burma [2, 3]. Historical accounts of such
activities in Japan exist since at least two thousand years ago, and of Sea Nomads from at least the 16 th century [4],
but evidence suggests that this form of food gathering has been important since human prehistory. There is evidence
that marine products were a major source of food before agriculture was introduced in Scandinavia, and were used
in the Neolithic period, also after agriculture was adopted [5]. Already with Homo erectus there are traces of marine
products (see Chapter 5). Present-day apneic diving involves submersion during several hours per day, collecting
food with little or no equipment, and the author studied several groups involved in such activities, and economically
or otherwise dependent on them. Field studies, focusing on the diving capabilities of these groups, involved
observations of Suku Laut, Bajau and Malaj divers, all part of the ethnic Sea Gypsy group, in different regions of
Indonesia during 1987-1988 [3, 6], Bajau in Phillipines in 2010 [7], and Ama divers in two different localities in
Japan, in 1991 and 2009 [7, 8].
Sea Nomads of South East Asia
The Sea Nomads traditionally live on house boats and migrate in small family groups between different areas of the
shallow archipelago, where sea harvests are rich. In some areas these groups are settled in villages with huts on
poles above the sea. Such groups were visited in the Riau Archipelago between Singapore and Sumatra (local name
Suku Laut), and in South East Sulawesi (local name Bajau) in Indonesia with the aim of documenting their diving
skills and making physiological measurements. Later, studies were done in Bajau in the Phillipines.
Their lifestyle is completely marine-oriented, with little time spent on land, but much time in the small boats and in
the water. The sea is not only their main source of income but also their living space [9]. Their diving consisted of
collecting seafood, including clams, shell fish and other edible animals, fishing by spear and other means, as well as
collecting sea weed and algae, which were processed for food. They were also diving for coral, sea cucumbers
(Holothuroidea), pearls and mother of pearl for trading or selling. Mother of pearl has been an important source of
income, but this has diminished with the introduction of other materials such as plastic. Sea products, with sea
cucumber tripang as a major ingredient, were dried and traded or sold to Chinese merchants visiting the Riau
Archipelago every month or two. Along with collecting, fishing was done using various methods both from boats
and during diving, using e.g., fish traps (bubu) or spears. Diving was done with wooden goggles as the only
equipment (Fig. 1) and in some areas a modern rubber diving mask, but no fins, suits or weights. Most children were
diving without any visual aids (see also Chapter 10). Men, women and children were all engaged in diving activities
in the fully nomadic populations in Riau, while in the settled groups visited in Sulawesi there was some division of
labor, such that men were more responsible for diving and fishing. In comparison, in Tonga, where marine-oriented
groups still exist, it has been reported that men do the main diving, while women do the collecting in shallow water
[10], whereas in the Ama, women do most of the diving [1].
Figure 1: Diving among the Bajau is done with no other equipment than wooden goggles (Right photograph taken by Erik
Abrahamsson).

122 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Erika Schagatay
At the time (1987-1988), most Suku Laut of Riau were still nomadic, but a settlement program was run by the
government with the aim to make these groups settle in villages. In South East Sulawesi, groups were partly settled
in villages in shallow areas near small islands. However, marine harvesting and fishing from boats or with diving
was the main source of food and income. Fish was caught in fish traps: bubus made of bamboo, placed and retrieved
by diving to depths of up to 15 m. Some spear-fishing and use of small throwing nets also occurred, and in some
areas, nylon nets were being introduced. These were however placed and harvested by divers. The fishing and
collecting for the daily food typically took 2-4 hours per day, with about 50% of the time spent submerged, and
because there was no storage of fish or fish products, this was a daily returning occupation. We observed individual
divers spending up to ten hours in the water, with surface temperatures just below 30 °C, with short pauses for
bringing home the catch [6]. Dive times were usually well within one minute, but some dives were extended beyond
2 min. The longest working dive observed involved swimming for 3 min 10 s when tying a boat to the reef. On
request, some of these divers performed single experimental apneas of up to 4 minutes. While most diving is
shallow, less than 20 m deep, diving for black coral is occasionally done to depths of 30-40 m [Suku Laut, Riao
1988, personal communication].
In a study in a group of Philippine Bajau in Davao during 2010, systematic timing of series of repeated dives and
surface intervals in five male divers (mean age 38 years) was done during spear-fishing at 5-7 m depth. Our study
revealed mean diving times of 28 s (SD 9 s) with recovery pauses of 19 s (SD 8 s) and ~ 60% of the total working
time spent submerged (Fig. 2) [7-11]. The total fishing duration was 2-9 hours per day. The limitation to repeated
harvest diving in humans lies thus not in the total apneic duration produced, but more likely in temperature exposure
and normal energy depletion and exercise fatigue. Such effective harvesting of the seafloor by repeated diving, with
several hours per day working submerged, would be of clear value in an early primate living close to the water.
Figure 2: Graphical representation of mean (SD) durations of 10 subsequent dives and surface intervals in 5 male Bajau divers in
the Phillipines during spear-fishing at 5-7 m depth (After [7]).
An aim with visiting these groups was to study their diving response, i.e., the system of reflexes diverting most of
the available oxygen to the heart and brain during diving, a characteristic typically very pronounced in marine
mammals. Its most evident features are a reduced blood-flow in the peripheral regions such as the skin and inactive
muscles, and a reduction of the heart rate [12] (see also below). The reflex magnitude is most easily estimated by
recording the heart rate to determine its reduction from pre-dive levels, which was done in several groups of the
Indonesian divers during experimental apneas. The diving response was massive in these groups with a mean 45%
reduction of the heart rate from resting levels during experimental simulated dives, twice the response as that
obtained in non-immersed apneas [3, 6].

148 Was Man More Aquatic in the Past?, 2011, 148-155
Marine Adaptations in Human Kidneys
Marcel F. Williams *
Mu Omega Enterprises, 748 Oakland Avenue #306, Oakland, CA 94611, USA
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 8
Abstract: Humans possess kidneys that are normally multi-pyramidal in their morphology, a characteristic that is
unique to Homo sapiens amongst primates. While uni-pyramidal kidneys predominate in terrestrial mammals,
kidneys with multiple medullary pyramids are nearly universal in marine mammals. In salt water environments,
renal medullary pyramids appear to function as a means to increases the rate of salt and nitrogenous waste
excretion by increasing the surface area between the cortex and medulla. While renal medullary pyramids seem to
have no functional value in freshwater environments, most freshwater aquatic mammals with renal pyramids can
be phylogenetically traced to either marine ancestors or aquatic ancestors that frequented marine environments.
Terrestrial mammals with multi-pyramidal kidneys such as elephants, bears, and rhinoceroses also appear to have
had semi-aquatic ancestors that frequented marine environments. However, the multi-pyramidal kidneys of the
Bactrian camel and Arabian camel (dromedary) were apparently convergently evolved as adaptations to high salt
consumption in xeric terrestrial environments where camels consume halophytic plants and drink water from
brine pools with natural salinities higher than seawater. The numerous vestiges of aquatic adaptations in the
human body in addition to the abundant distribution of corporeal salt excreting eccrine sweat glands and the
excretion of salt tears in humans, strongly suggest that the multiple medullary pyramids of the human kidneys
probably evolved as an adaptation to a coastal marine ecology rather than to a xeric terrestrial environment.
Keywords: Medullary pyramids, multi-pyramidal kidneys, salt excretion, marine environment.
INTRODUCTION
In mammals, the kidneys function as the principal organ for the excretion of ingested and metabolically produced
water, salts, and nitrogenous waste. Internally, the mammalian kidney is divided into an outer region known as the
cortex, which surrounds and inner region known as the medulla. The filtration of blood plasma occurs in the cortical
region by means of the glomeruli, which allow water, salts, and nitrogenous waste to pass through its glomerular
membrane while selectively excluding larger materials such as blood cells, droplets of fats, and large molecular
proteins. But it is in the medullary region where the kidney increases the concentration of salt originating from the
cortical glomerular filtrate by way of the long loops of Henle. The further the loop of Henle extends into the
medullary region, the higher the kidney's capability to concentrate salts. However, the ability of the kidney to
concentrate salt in the urine only functions under the influence of the antidiuretic hormone (ADH) [1]. However, in
the absence of ADH, kidneys with thick medullary regions still function as efficiently as other kidneys do in
preventing the excretion of too much salt in the urine when diets contain little or no salt resources.
UNI-PYRAMIDAL AND MULTI-PYRAMIDAL KIDNEYS
Most terrestrial mammals have uni- or mono-pyramidal kidneys, lacking medullary pyramids. (Fig. 1). Uni-pyramidal
kidneys are found in most, or all, terrestrial marsupials, insectivores, rodents, rabbits, carnivores, horses, artiodactyls,
and primates. However, most aquatic mammals, have kidneys that are multi-pyramidal in their morphology (Table 1).
It is argued that the simple uni-pyramidal kidney is primitive for mammals, while the more complex multi-pyramidal
kidney morphology is believed to be derived from the simple uni-pyramidal types of kidneys [2-5].
Primates generally have uni-pyramidal kidneys. However, there are two interesting exceptions. While most blackhanded
spider monkeys (Ateles geoffroyi) exhibit uni-pyramidal kidneys, more than 40% of these spider monkeys
exhibit kidneys with multi-pyramidal medullas. However, multi-pyramidal kidneys are universal in the human
*Address correspondence to Marcel F. Williams: Mu Omega Enterprises, 748 Oakland Avenue #306, Oakland, CA 94611, USA; E-mail:
newpapyrus@yahoo.com

Marine Adaptations in Human Kidneys Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 149
species with the human kidney normally exhibiting 8 to 18 medullary pyramids [3]. But humans are not the only
terrestrial mammals with multi-pyramidal kidneys. Multiple medullary pyramids are found in the kidneys of
elephants, bears, camels, rhinoceroses, suids, hippopotamus, tapirs, bovines, the okapi, and the giraffe [2-4, 6].
Figure 1: Longitudinal section of a sheep kidney, displaying the typical uni-pyramidal morphology found in most terrestrial mammals.
Table 1: Mammalian Taxa with Kidneys with Medullas that Are Normally Multi-Pyramidal in their Morphology and their
Closest Phylogenetic Relatives
Taxa with renal medullaryExtant
environment Closest phylogenetic relatives Extant environment
pyramids
of relatives
Cetacea aquatic (M/R) Hippopotamus semi-aquatic (R/L)
Pinnipedia semi-aquatic (M) Ursidae terrestrial/
semi-aquatic (M/L)
Sirenidae aquatic (M/R) Proboscidea terrestrial
Lutrinae semi-aquatic (M/R) Mustela terrestrial
Castor semi-aquatic (R) Sciuridae/
Aplodontidae
Ursidae terrestrial/
semi-aquatic (M/R)
terrestrial
Pinnipedia Semi-aquatic (M)
Proboscidea Terrestrial Sirenidae Aquatic (M/R)
Rhinocerotidae terrestrial/
semi-aquatic (R/S)
Bovini terrestrial/semi-aquatic (R/S) Tragelaphini/
Boselaphini
Tapiridae semi-aquatic (R/S)
Giraffidae Terrestrial Cervidae terrestrial
Suidae Terrestrial Tayassuidae terrestrial
Homo Terrestrial Pan terrestrial
terrestrial/semi-aquatic (R)
L: lacustrine; M: marine; R: riparian; S: swamps.
Aplodontidae: mountain beaver; Boselaphini: bluebuck; Bovini: bison, cattle, water buffalo and zebu; Castor: beavers; Cervidae: deer and
moose; Cetacea: dolphins and whales; Giraffa: giraffe, okapi; Hippopotamidae: hippopotamus, pygmy hippopotamus; Homo: humans; Lutrinae:
otters; Mustela: weasels; Pinnipedia: sea lions, seals and walrus; Pan: bonobo and chimpanzee; Proboscidea: elephants; Rhinocerotidae:
rhinoceroses; Sciuridae: chipmunks, groundhogs, prairie dogs and squirrels; Sirenidae: manatees and Steller’s sea cow only; Suidae: babirusa, pig
and wild boar; Tapiridae: tapirs; Tayassuidae: peccaries; Tragelaphini: bongo, bushbuck, kudu, nyala and sitatunga; Ursidae: bears.
The existence of multi-pyramidal kidneys in mammals have been argued to be an anatomical adaptation to large
body size [7], or a physiological adaptation to deep and prolonged diving in aquatic environments, or a dietary
adaptation to a marine diet [8, 9]. In this chapter, I argue that evolution of renal medullary pyramids in mammals is
an adaptive response to diets with exceptionally high salt contents and that the existence of multiple renal medullary
pyramids in humans was the result of specialized coastal marine adaptations in the human evolutionary past.

150 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Marcel F. Williams
THE ADAPTIVE FUNCTION OF MULTI-PYRAMIDAL KIDNEYS IN MARINE MAMMALS
All marine mammals possess discrete multi-reniculate kidneys [2, 5, 10] with the exception of the dugong (Dugong
dugon), which displays kidneys characterized by transverse medullary lobulation [5, 8]. The kidneys of cetaceans
(whales and dolphins) and pinnipeds (seals, sea lions, and walruses) possess hundreds of medullary pyramids
(reniculi) with some cetaceans possessing thousands of medullary pyramids. And some of the medullary pyramids in
cetaceans and pinnipeds are often subdivided into two or more pyramids in a single reniculi. The West-Indian
manatee (Trichechus manatus) and the West-African manatee (Trichechus senegalensis) possesses kidneys 6-11
medullary pyramids. The now extinct, Steller's sea cow (Hydrodamalis gigas), also possessed multi-pyramidal
kidneys. The smallest marine mammal, the sea otter (Enhydra lutris), also has multi-reniculated kidneys [5].
The diets of cetaceans and pinnipeds tend to be dominated by marine invertebrates and fish with marine birds and
mammals sometimes included, especially in the case of the killer whale (Orcinus orca). While the West-Indian and
the West-African manatee species are known to move between freshwater and marine environments, both manatees
consume seagrasses and other halophytic plant life. Marine algae was the diet of the extinct Steller's sea cows. The
sea otter feeds most only benthic invertebrates, but does include fish in its diet on occasion [10-14].
While marine invertebrates tend to have body fluids that are isotonic with the marine environment, marine vertebrates
tend to have body fluids that are hypotonic relative to the marine environment. So the predation of marine mammals on
marine invertebrates will tend to cause intracellular dehydration since there are no freshwater resources in a marine
environment. And this is probably exacerbated by the incidental ingestion of salt water during predation.
However, the salinity of marine food items is partially compensated by the production of hypotonic metabolic water
from the oxidation of proteins, fats, and carbohydrates. Marine mammals can further compensate for the lack of
freshwater resources by feeding on other marine vertebrates (fish, mammals, birds), which have body fluids that are
hypotonic relative to the marine environment. And, finally, they can compensate for the ingestion of salt water and
saline food items by excreting hypertonic fluids through sweat glands, tear ducts, and their kidneys.
While the kidneys of marine mammals tend to be larger and more lobulated than those of equally sized terrestrial
mammals, there are many terrestrial mammals who have kidneys capable of excreting salt at much higher
concentrations than those of marine mammals. However, increasing the size of the kidney while expanding the
surface area between the cortex and the medulla through medullary lobulation increases the quantity of hypertonic
filtrate that can be immediately processed for the excretion of hypertonic urine. The multi-reniculate kidneys of
marine mammals, therefore, appear to be an adaptation to expedite the processing of ingested hypertonic fluids in
order to avoid intracellular dehydration [9, 15].
This renal adaptation to a marine diet is apparently not restricted to marine mammals. The avian genus Cinclodes,
like all other passerine birds, lacks the functional salt excreting glands that other marine birds utilize to excrete high
loads of salt from their bodies, so, like mammals, they have to utilize their kidneys in order to excrete excess salts.
Similar to marine mammals, the strictly marine passerine Cinclodes nigrofumosus exhibits kidneys that are
relatively larger than more migratory cogeneric species such as C. patagonicus and C. oustaleti, with a higher
proportion of medullary tissue relative to the cortex and nearly twice the number of medullary cones. Similarly,
large numbers of medullary cones are found in the salt-marsh savannah sparrow (Passerculus sandwichensis
beldingi) [16-18].
THE PHYLOGENY OF FRESHWATER SEMI-AQUATIC MAMMALS WITH MULTI-PYRAMIDAL
KIDNEYS
Since multi-pyramidal kidneys are also found in some freshwater aquatic and semi-aquatic mammals such as otters,
beavers, tapirs, and river dolphins (Table 1), how can their existence be explained? As earlier noted, the medullary
region concentrates urine only under the influence of the antidiuretic hormone (ADH), so multi-reniculated kidneys
are still as fully capable as uni-pyramidal kidneys in excreting urine that is relatively isotonic to the intercellular
compartment. This raises the possibility that the multi-pyramidal kidneys of freshwater mammals may have been
inherited from marine ancestors.

156 Was Man More Aquatic in the Past?, 2011, 156-163
Obstetrical Implications of the Aquatic Ape Hypothesis
Michel Odent *
Primal Health Research Centre, 72 Savernake Road, London NW3 2JR, UK
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 9
Abstract: The aquatic ape hypothesis (AAH) offers the possibility to re-interpret several aspects of the human
pre- and perinatal periods. We introduced the concept of birthing pools in the 1970s in order to treat labor pain,
particularly lumbar pain in the middle of cervical dilation associated with failure to progress. We assumed that
immersion in water at body temperature would be a way to reduce the level of stress hormones, facilitating the
release of oxytocin. We first learned that the dilation of the cervix could progress dramatically in an aquatic
environment before water immersion, and that it was associated with behavior suggestive of a reduction in
neocortical control. The release of inhibitors of neocortical control in an aquatic environment was an opportunity
to phrase new questions about the relationship of Homo sapiens with water. We also learned that occasionally
some women did not want nor had the time to get out of the pool for the birth itself. They behaved in a way
suggesting that, while in a particular state of consciousness, they knew that a birth under water was safe for the
baby. The origin of this knowledge, and the strong attraction towards water that some women experience during
labor, should be looked at in the light of the AAH.
By raising questions about the development of the human brain from an evolutionary perspective, the AAH enables
to pose similar questions from an ontogenetic perspective. Today the focus is on the needs in iodine,
docosahexaenoic acid, vitamin D, and other nutrients that are essential for brain development, and that happen to be
abundant in seafood. This led us to reconsider (pre-)eclampsia as a multi-factorial syndrome, related to a maternalfetal
conflict, whereby inadequate maternal nutrition is prioritized as a factor that can independently increase the
probability of conflict, challenging the current belief that reduced utero-placental perfusion is the unique
pathophysiological process in this human pregnancy disease. In other words, we present (pre-)eclampsia as the price
some humans have to pay for having a large brain, while the specific nutritional needs are not ideally satisfied.
Other puzzling and unexplained human particularities in the perinatal period, such as human neonatal vernix
caseosa and of the absence of human maternal placentophagy, can be re-interpreted in the light of the AAH.
Keywords: Birthing pool, eclampsia, pre-eclampsia, nutrition in pregnancy, developing brain, maternal-fetal
conflict, vernix caseosa, placentophagy.
INTRODUCTION: LEARNING FROM BIRTHING POOLS
Health professionals involved in pregnancy and childbirth are in a position to combine fruitful specific perspectives
to study human nature. On the one hand, a renewed theoretical context can influence the practices of obstetrics and
midwifery. On the other hand, the point of view of practitioners can help evaluating the value of new theories.
In the early 1990s, when we became more familiar with the concept of antagonism between oxytocin (the key hormone
in parturition), and the hormones of the adrenaline family (stress hormones, catecholamine), I started to investigate the
management of a common pathological situation in midwifery and obstetrics. It is the ‘failure to progress’ in the middle
of cervical dilation, associated with intense lumbar pain. In this case, the pain appears as an obstacle to cervical
dilation. I was considering non-pharmacological methods of pain relief. This is how I introduced the concept of lumbar
reflexotherapy, based on the gate control theory of pain. Intracutaneous injections of sterile water in a precise zone of
the lumbar region innervated by the posterior branch of the twelfth dorsal nerve can block the visceral pain coming
from the contracting uterus [1]. I also proposed immersion in water at body temperature as a method to relieve pain, to
reduce the level of stress hormones, and thus achieve more effective uterine contractions.
*Address correspondence to Michel Odent: Primal Health Research Centre, 72 Savernake Road, London NW3 2JR, UK; E-mail:
wombecology@aol.com

Obstetrical Implications of the Aquatic Ape Hypothesis Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 157
Taking into account the physiological perspective, and also the strong attraction to water expressed by many laboring
women, I eventually bought a blue inflatable garden wading pool. Thus began the history of birthing pools in hospitals
[2]. As soon as the birthing pool was installed, new strategies became possible. When a woman in hard labor was
demanding painkillers, we had something else to offer than the injection of an analgesic drug (this was before the age
of epidural analgesia). We could introduce the mother-to-be to the aquatic birthing room, so that she could observe and
hear beautiful blue water filling the pool. The room was painted blue, with dolphins on the walls. From that time the
question was no longer: “When will you give me a painkiller?” but rather: “How long does it take to fill the pool?” The
first lesson concerned the importance of the time when the woman in labor is anticipating the bath: the dilation of the
cervix can already progress dramatically before water immersion – if the aquatic environment is associated with
privacy. It is like the sudden release of brakes. We witnessed one of the many magic effects of water on human beings,
a profound power that cannot be easily explained with the language of physiologists [3]. At the time of the plastic pool
(before we installed a solid pool), women were not influenced by the media or by what they read in books about
childbirth. Their behavior was spontaneous, and thus we learned about the genuine effects of a water environment. A
typical scenario (with many possible variations) was the case of a woman entering the pool in hard labor (cervical
opening ~ 5 cm), spending an hour or two in water, and then feeling the need to get out of the pool when the
contractions were becoming less and less effective. This going back to the dry land often induced a short series of
irresistible and powerful contractions so that the baby was born within several minutes.
One day, a mother-to-be had not been in water for long when suddenly she had two irresistible contractions, and the
baby was born before she felt any need to get out of the pool. While giving birth, this woman was really on another
planet. Clearly, in that altered state of consciousness associated with hard labor, she intuitively knew that her baby
could be born safely under water. There was no panic. It is as if a deep-rooted knowing could express itself as soon as
the intellect and its knowledge were set aside. Such births happened again [4]. From that time onwards, many
journalists and photographers were fascinated by babies being born in water. They were indifferent all other aspects of
our unconventional practices. After a short period of surprise and even frustration, I concluded that good journalists are
experts in Human Nature. They know how to attract the attention of their readers or their viewers. They have this
intuitive knowledge that there is a special relationship between human beings and water. By referring to this historical
phase of the use of birthing pools, we offer food for thought in the age of the aquatic ape hypothesis (AAH).
VERNIX CASEOSA: AN INTRIGUING PARTICULARITY OF HUMAN NEONATES
It is commonplace to claim that only the skin of human fetuses and neonates is covered by vernix caseosa (literally
cheesy varnish), the greasy white substance secreted by the baby’s sebaceous glands late in fetal life. In many
cultures, the vernix was denied any rôle and routinely wiped away.
The AAH offers an opportunity to stimulate our interest in this human particularity, since Don Bowen, a marine
biologist from Nova Scotia, Canada, revealed that the pups of seals also have vernix. Interestingly, he noticed that
harbor seals (Phoca viticula), which swim with their mothers within minutes of being born, have more vernix than
other seals, which do not swim for at least 10 days. Although approximately 80% of vernix is water, it still has high
viscosity, suggesting that its water must reside within a highly structured state that is conferred by the abundance of
water-filled fetal corneocytes. These fetal corneocytes act as ‘cellular sponges’ that prevent water from moving
across the skin, whereas sebaceous lipids, including squalene, provide a hydrophobic barrier. Vernix is so rich in
squalene that a measure of its concentration in amniotic fluid had been suggested as a test to detect the effects of
postmaturity [5]. It is noticeable that squalene (an intermediary step in the production of cholesterol from saturated
fatty acids) is released on the skin in less than 5% of mammals (e.g., beaver, otters, kinkajou, human).
By combining these perspectives, we suggest that vernix caseosa might be interpreted as a transitory protection
against immersion in non-isotonic water. We should at least remember that vernix caseosa is a common point
between Homo sapiens and harbor seals, while it is unknown among land mammals.
EATING THE PLACENTA
It seems that in our species placentophagy, i.e., consumption of the placenta by the mother immediately after birth,
as is observed in numerous terrestrial mammals, has never been instinctive. If it had been at any time in the history

158 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Michel Odent
of humanity, we should find traces of this behavior in myths, legends, and reports from preliterate and preagricultural
societies. I know of women who had reached a very instinctive state of consciousness in the perinatal
period, behaving as if ‘on another planet’, and overcoming a great part of their cultural conditioning. Yet none of
them had ever expressed a tendency to bring the placenta toward her mouth. Modern women who occasionally have
eaten pieces of placenta were inspired by theories, such as the theory that it might prevent postnatal depression.
Scientific interest in the placenta has recently inspired such theories leading to a form of human placentophagy
based on rational considerations. For example, the discovery of placental opioid-enhancing factor (POEF), a
placental substance that makes endorphins more effective [6], could be seen as a justification for placentophagy in
our species. However, we should avoid the conclusion that eating placenta is an innate human behavior.
Exploring placentophagy is important since all land mammals eat the placenta. If eating the placenta has never been
instinctive among our ancestors, this would be another common point with sea mammals, including cetaceans and
seals. Interestingly, from this regards, camels are the exceptions among land mammals: they do not eat the placenta.
Camels have another particularity among land mammals: like Homo sapiens and sea mammals they have kidneys
with medullary pyramids (see Chapter 8). Since camels consume highly salty plants, and drink the water of salty
ponds, and since sea mammals also have easy access to hypertonic salty substances, one can suggest that
placentophagy might be correlated with the urgent need in specific nutrients, particularly minerals, in the postpartum
period. It is as if placentophagy and non-pyramidal renal medullas were features shared by mammals that do not
have access to hypertonic salty substances after parturition.
PRENATAL CARE AND SEAFOOD
Since the middle of the 20 th century, there has been a continuous dominant style of antenatal care based on the
detection of pathological conditions and abnormalities through standardized batteries of tests. In an evolving
scientific context, there is a new tendency to enlarge this framework further. An overview of the Primal Health
Research Database (www.primalhealthresearch.com) will convince anyone that our health is to a great extent shaped
in the womb. We can reach similar conclusions via concepts that are becoming familiar in the scientific literature,
especially the concepts of gene expression, gene silencing, and epigenetic modulation: they indicate several phases
of fetal life as critical for gene-environment interaction. In such a context, an increasing number of prenatal
practitioners are gradually developing a new interest in several aspects of maternal lifestyle that can influence fetal
growth and fetal development.
In the early 1980s, I became interested in the specific nutritional needs of the brain revealed by the pioneering work
of Michael Crawford [7] and Stephen Cunnane [8]. They had renewed the AAH by phrasing new questions about
hominid evolution and nutritional influences inducing a spectacular brain development. This evolutionary
perspective helped me realize that brain development is also a priority from an ontogenetic perspective, and that
there is a brain growth spurt during the second half of fetal life. At that time it was unusual, in the context of
antenatal care, to consider the issue of nutrition, and the rare written documents on this matter focussed on calories,
proteins, maternal weight, and birth weight.
In 1991, I started a study in a London hospital (Whipps Cross). The objective was to evaluate the possible effects in
the perinatal period of simply encouraging pregnant women to consume sea fish [9]. A total of 499 pregnant women
having antenatal care before 20 weeks of gestation were offered 20 minutes of nutritional advice. For each woman
interviewed, a corresponding control was established. There was one highly significant difference between the two
groups in the perinatal period: the mean neonatal head circumference was greater in the study group (34.65 cm vs.
34.45 cm; 95% CI 0.01-0.39). It should be noted that, although the statistical power of this observation is low, there
was no eclampsia and no recorded pre-eclamptic toxaemia in the study group, whereas in the control group there
was one case of eclampsia with convulsions and two cases of severe pre-eclamptic toxaemia.
Our Whipps Cross study was replicated and enlarged at Wolverhampton New Cross Hospital [10]. Again, the most
significant difference was related to head circumference at birth. Among the 1,607 cases in the study group, the
mean head circumference was 34.54 cm, vs. 34.32 cm among the 1,078 cases in the control group (95% CI 0.10-
0.35; p < 0.001). The statistical significance remained the same after adjustment for gestational age and sex of the
newborn. The mean body length was significantly increased in the study group after the same adjustments (51.77 vs.

164 Was Man More Aquatic in the Past?, 2011, 164-172
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 10
Superior Underwater Vision Shows Unexpected Adaptability of the Human Eye
Anna Gislén 1 and Erika Schagatay 2,*
1 Department of Cell and Organism Biology, Lund University, Helgonav 3, 223 62 Lund, Sweden and 2 Department of
Technology and Sustainable Development and Swedish Winter Sports Research Centr, Mid Sweden University,
Akademig 1, 83125, Östersund, Sweden
Abstract: Adaptability of the eye is a key feature in a semi-aquatic mammal and several optical and
physiological strategies can be used to allow functioning of the eye in the two media, i.e., air and water. Human
eyes are considered to be adapted to vision in air as more than two-thirds of the refractive power is derived from
the curved cornea, an effect that is lost under water. It was observed that children of Sea Nomad groups in South
East Asia appeared to have much better underwater vision than expected, allowing efficient collection of small
shells from a non-contrasting background without visual aids. Studies on the visual acuity of such groups were
carried out, followed by studies to reveal how the observed adaptability of the eye was achieved. Standardized
optical methods were adopted to field conditions and used to reveal how the Sea Nomad children see under water.
Results showed a high adaptability of the human eye to the underwater environment, with the visual acuity of the
Sea Nomad children being twice that found in a European control group. Training in non-diving children was
found to evoke the same adaptive responses as those observed in Sea Nomads. The mechanisms responsible for
this superior underwater vision were heavy accommodation and concurrent pupil constriction, features previously
observed in semi-aquatic mammals and birds. This may be an interesting example of convergent evolution. The
human eye proved to be flexible and adaptable enough to function under water with an uncompromised function
in air. An explanation for this surprising adaptation in a terrestrial mammal could be that it has evolved during a
phase with selective pressure for foraging under water.
Keywords: Underwater vision, pupil constriction, aquatic, terrestrial, adaptability.
INTRODUCTION
Most Mammals
Rely heavily on vision for their survival and have thus developed eyes with the necessary properties to ensure e.g.,
food retrieval, finding possible sex partners, or avoiding predators. However, different environments require
different adaptations, and animals that return to an aquatic or semi-aquatic life after having evolved efficient vision
on land, have to change their eyes dramatically to achieve functional vision under water. Semi-aquatic animals
inhabit both air and water, and these amphibious animals need adaptations to see well in both media – something not
easily achieved. The most radical example of air and water vision may be the four-eyed fish (Anableps) that lives at
the water surface and has functionally two pairs of eyes, one above the water, and the other below [1].
Human Vision
Is normally extremely poor under water. This could be a major argument against a semi-aquatic phase in human
evolutionary history. However, during travels to South East Asia to study human diving adaptations, especially the
human diving response [2], one of the authors (ES) encountered a tribe of Sea Nomads in Indonesia, nomadic people
who live a more marine-oriented life than any other group studied [3, 4]. In this ethnic group, the children start
swimming before they can walk, and children aged 4-10 years were observed to collect small shells from a noncontrasting
background with high precision (ES, unpublished observations). It was realized by the author that, unlike
herself, they could see these shells despite not wearing goggles. This initiated detailed studies by an animal vision
research group at Lund University [5-8]. Human underwater vision was an unexplored area at that time, and the first
question was whether South-East-Asian Sea Nomads had a better underwater vision than humans in general. If such
qualities were discovered, the next question would be how these were achieved.
* Address correspondence to Erika Schagatay: Professor of Animal Physiology, Department of Technology and Sustainable Development,
Akademigatan 1, Mid Sweden University, 83125 Östersund, Sweden; Tel: +46 70 53 214 23; Fax: +46 63 16 57 00; E-mail:
Erika.Schagatay@miun.se

Superior Underwater Vision Shows Unexpected Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 165
Human eyes are generally considered to be adapted to air, not water, and the idea that humans could develop a better
underwater vision sounded at first very implausible. Still the young Sea Nomads in South East Asia did seem to see
rather well under water without using visual aids, and would clearly benefit from having improved underwater
vision. A superior underwater vision would point to an amazing adaptability of the human eye, and show a
flexibility beyond that typically associated with a structure adapted to air alone.
Vision in Air and in Water
Eyes are structures designed to detect light, and most likely have evolved independently several times during the
history of animal life [9]. What we call light is electromagnetic waves, with the right amount of energy to be visible
to the human eye. Specialized cells in our eyes react when hit by these energy packets, and their responses are
interpreted in the brain as different colors, depending on their energy content. It should be noted that many animals
have the ability to see colors that we humans cannot, e.g., UV-light. A mammalian eye can be compared to a
camera, with optics that focus the light and a light-sensitive area on which the image is projected, the retina. Two
elements focus the light in order to create a clear image, i.e., the curved outer cornea, and the internal lens (Fig. 1).
Figure 1: A human eye in cross-section. The curved outer cornea functions as a refractive interface between the air outside and
the water-like substance (aqueous humor) on the inside. The internal lens can change its shape when we accommodate to see
things at close distance, thus refracting the light more. In a relaxed eye, the cornea is responsible for about two- thirds of the total
refractive power of the eye and the internal lens almost a third.
In a human eye, about two-thirds of the refractive power comes from the cornea and only a third from the internal
lens. The internal lens, however, is able to change its shape, to accommodate, and thereby change the extent to
which light is refracted. When we, for instance, read at close distance, the lens becomes rounder, refracting light
more. In a terrestrial eye, the cornea refracts light because there is air outside of it. Air has a different density than
the liquid inside the eye, and this density difference makes light refract at the surface of the cornea [10]. The
curvature of the cornea is important as only a curved cornea can produce a focused image. When we dive, air
outside the cornea is replaced with water. As the refractive index of water and that of the contents of the eye are
almost the same, there will be no refraction at the corneal surface. The image will no longer be in focus on the
retina, causing everything we see to become blurred and unfocused (Fig. 2). If we use a diving mask under water,
we restore the air-water interface in front of our eyes, and the image becomes focused again. Semi-aquatic spiders
are known to use the same strategy, holding a bubble of air over the corneal surface when they dive, through which
they can get a clear image under water [11].
Figure 2: Focal plane in air and under water. a) In air, the image is focused on the retina at the back of the eye. b) When we
dive, the cornea no longer refracts the light and the focal plane of the eye lies behind the retina, causing a blurred image.
The physiological requirements for vision under and above water are thus quite different, and amphibious animals
need adaptations to adjust their eyes to cope with both media. In addition to the strategy of covering the eyes with

166 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Gislén and Schagatay
air when under water (cf. semi-aquatic spiders), this problem can be dealt with in basically two different ways. The
first is to make the cornea flat so it does not matter which medium lies on the outside of the eye: a flat surface does
not focus light, unlike a curved one. Animals with flat corneas instead need to rely on the focusing power of the
internal lens, which can be accomplished by making it more spherical. A flat cornea is used by fish that live in
intertidal waters or mudflats [12], and many amphibious birds have slightly flattened corneas, including penguins
[13, 14], albatrosses [15], dippers (Cinclus spp.) [16] and Manx shearwaters (Puffinus puffinus) [17].
The other solution is to make it possible to accommodate to such an extent that it compensates for the loss of
refractive power when going from air to water. The change of lens shape is usually accomplished by the ciliary
muscles attached to the lens. This strategy is commonly used by terrestrial animals that forage in water. The extent
to which these animals can accommodate is remarkable. Accommodation is measured in diopters (D or m -1 ), and a
young human being can accommodate up to 18 D, after which the ability diminishes with age. For comparison,
diving ducks are known to be able to accommodate up to 80 D [18] and cormorants up to about 40 D [19]. Birds
accomplish this extensive accommodation by squeezing parts of the lens with muscles in the iris [20, 21], a strategy
probably also used by turtles [22].
Seals have flattened corneas and rather spherical lenses [23, 24], suggesting that they have optically adapted more to
an aquatic life than to a terrestrial life. The vertical slit pupil of these animals on land has been suggested to be an
adaptation to terrestrial life as the pupil is circular under water [20]. Otters have an extraordinarily large
accommodative range, i.e., 40-60 D [25], as do walruses and sea lions [26]. These amphibious animals have
developed stronger ciliary muscles to allow for this extensive accommodation [26]. Thus, we find several solutions
to the problems of amphibious vision. This leaves the question whether humans can use any of these solutions to
achieve a better underwater vision.
DO SEA PEOPLE SEE BETTER UNDER WATER?
The Sea Nomads or Sea Gypsies are nomadic boat people who live in many areas of South East Asia. The first
records of them are from the 16 th century [27], but they probably lived in the area for thousands of years [28].
Traditionally, each family owns one main boat on which they spend most of their life, moving around to collect food
from the shallow ocean. Large part of this gathering is done by diving, with no or little equipment (Fig. 3). These
people traditionally live on and in the water, and may even give birth in water [28, 29]. Many groups are now settled
at least part of the year by on-sea or near-sea villages, while other groups are still fully nomadic (Fig. 4 and 5) [30].
For the vision study, a village of settled Sea Nomads was contacted, located on Ko Surin in Thailand, a group of
small islands just near the border of Myanmar. This ethnic group call themselves Moken (sometimes spelled
Mawken) and live by the beach in houses on stilts – as the tide comes in, the houses are surrounded by water. The
children were very adept in water and used no visual aids when diving. A group of 17 children (age 7-13 yrs) were
recruited to participate in diving experiments.
Figure 3: Sea Nomad children diving. Two children from the Bajau tribe dive without any equipment.

Human Aquatic Color Vision
Wang-Chak Chan *
Department of Cognitive Sciences, Lund University, Sweden
Was Man More Aquatic in the Past?, 2011, 173-180 173
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 11
Abstract: Many human physiological and behavioral features could possibly be explained as semi-aquatic
adaptations in the remote past. However, aspects of human perception and cognition have rarely been considered
in this light. In this chapter, human color vision will be discussed at two levels.
At the physiological level, visual pigments of retinal cone/rod cells, being essential to color vision, are compared
among humans, their closest primate relatives, and terrestrial as well as aquatic mammals. Also the cause of
human color blindness is discussed.
At the cultural level, the mystery of ‘fuzzy’ color terms like grue (green-or-blue) in many world languages is discussed,
and we propose a new model based on two arguments: each color term actually corresponds to a naturally occurring
color, and the ‘fuzzy’ terms were produced in a semi-aquatic primitive life since the dawn of human language.
Keywords: Human evolution, aquatic adaptations, color vision, color blindness, linguistic color terms.
INTRODUCTION
Since the proposal by Alister Hardy [1] and its popularization by Elaine Morgan [2], the aquatic ape hypothesis
(AAH) remains controversial in the scientific community. The hypothesis states that human ancestors have been
dwelling in a waterside habitat and started to adapt to the new environment - an adaptational process responsible for
many of our special characteristics, especially when compared to chimpanzees and other apes. Besides increasingly
convincing fossil evidence of a semi-aquatic environment (see Chapters 2, 4 and 5), there is behavioral,
biochemical, physiological and anatomical evidence in favor of the AAH, e.g., wading bipedalism [3] (see Chapter
3), infant diving reflexes [4] (see Chapter 7), an essentially marine diet [5] (see Chapter 2) and a multi-pyramidal
kidney structure [6] (see Chapter 8). Since the AAH claims that a semi-aquatic environment had a pervasive effect
on human evolution, it should manifest itself in various, even unexpected, aspects. One of them may be human color
vision [7]. Indeed, Newman and Robinson [8] state: “It has long been hypothesized that the visual systems of
animals are evolutionarily adapted to their visual environment.”
Here I propose that several peculiar characteristics of human color vision, just like other human features discussed
elsewhere in this volume, might be best explained in the context of a more aquatic past of our species. The
arguments include: (1) the blue shift of the human S-cone visual pigment in analogy to (semi-)aquatic mammals, (2)
human color blindness in analogy to S-cone loss in aquatic mammals, and (3) the lack of green-blue or yellow-red
color distinction in many languages. I will propose these characteristics as cornerstones of a new model of human
aquatic color vision (HACV), suggesting that the evolution of our color vision was profoundly influenced by aquatic
habitats, and left unmistakable traces in our physiology, cognition and culture.
HUMAN AQUATIC COLOR VISION AT THE PHYSIOLOGICAL LEVEL
Comparative Studies
A large body of evidence, indicating that human color vision is adapted to some degree to an aquatic environment,
comes from comparing the color sensitivity of the human retina to that of primates and of aquatic mammals.
Color vision at daytime is made possible by cones (cone-shaped photoreceptor cells) in the retina, and at nighttime
monochrome vision is mediated by rods. Most mammals and primates are dichromatic (two-channel color vision)
with two types of cone cells, i.e., S-cones and L-cones, while the Old World primates (i.e., Old World monkeys,
*Address correspondence to Wang-Chak Chan: Department of Cognitive Sciences, Lund University, Sweden; E-mail: azul.chan@gmail.com

174 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Wang-Chak Chan
great apes and humans) have evolved an additional M-cone and became trichromatic (three-channel color vision).
Each cell type (rod/S-/M-/L-cone) has its own kind of visual pigment, i.e., a protein responsible for light absorption,
and the visual pigment’s wavelength specificities (light sensitivity) may differ among species.
Table 1 and Fig. 1 list the peak sensitivity of the cone/rod pigments in various mammalian species, including data
for primates like human (Homo sapiens, with or without color deficiency), common chimpanzee (Pan troglodytes),
Old World monkeys (catarrhines), New World monkeys (platyrrhines); land mammals like cow (Bos taurus), sheep
(Ovis aries), pig (Sus scrofa); aquatic mammals like West-Indian manatee (Trichechus manatus), harbor seal (Phoca
vitulina), bottlenose dolphin (Tursiops truncates), and long-finned pilot whale (Globicephala melas).
Table 1: Wavelength Specificity (nm) of Visual Pigments in Different Species and Cone/Rod Types. Data from [7-15].
Species Color vision type Wavelength specificity (nm)
L-cone M-cone S-cone Rod
Human Tri 561 [11]
530 [11]
414 [7]
Human (color deficient) Di 561 [11] X
Di X 530 [11]
Tri (Poly) 554~ 548 [13]
537~ 532 [13]
498 [9]
Common chimpanzee Tri 563 [11] 530 [11] 430 [11] 500 [15]
Old World monkeys Tri ~ 560 [14] ~ 530 [14] ~ 430 [14] ~ 500 [15]
New World monkeys Di/Tri (Poly) 562~ 535 [14] ~ 430 [14] ~ 500 [15]
Cow Di 555 [12] - 451 [12] 499 [9]
Sheep Di 552 [12] - 445 [12] ~ 500 [15]
Pig Di 557 [12] - 441 [12] ~ 500 [15]
Manatee Di 556 [8] - 414 [8] 502 [10]
Harbor seal Mono 548 [8] - X [8] 501 [10]
Bottlenose dolphin Mono 524 [8] - X [8] 489 [9]
Pilot whale Mono 531 [8] - X [8] 488 [10]
-: not evolved, X: degenerated, Mono: monochromatic, Di: dichromatic, Tri: trichromatic, Poly: gene polymorphism.
Bold: significant deviations, that are discussed in the text.
Figure 1: Graphical representation of data from Table 1: Legend: Human (Poly): Gene polymorphism in human visual
pigments.

Human Aquatic Color Vision Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 175
Blue Shift in Human S-Cone Visual Pigments
As an adaptation to the underwater environment, aquatic mammals (e.g., dolphins, seals, manatees) often have the
light sensitivity of their cone/rod pigments shifted to the blue side of the color spectrum, compared to terrestrial
mammals. Dolphins and whales have their L-cone and rod pigments blue-shifted [9], and manatees have their Scone
pigment blue-shifted [8] (marked bold in Table 1).
Curiously, humans also have an S-cone pigment blue shift compared to chimpanzees (our closest relatives) and
indeed all other great apes and Old World monkeys [7, 11, 14]. No adequate explanation is given in the literature for
this unexpected but significant shift. However, this blue shift could be easily and straightforwardly explained as an
adaptation to an underwater environment, similar to aquatic mammals.
Human Color Blindness
Color blindness (a more accurate term would be color deficiency) affects about 7-8% of the human population. It is
caused by mutation in the visual pigment genes, mostly of the L- and M-cone genes located on the X chromosome.
A side-effect is that males with only one copy of X chromosome are more prone to color blindness than females
(prevalence 7-8% and 0.5%, respectively).
There are two types of color blindness: people with dichromacy lost one type of cone pigment (usually the M- or Lcone),
so they can only identify two principle colors (e.g., blue and yellow), while people with anomalous
trichromacy have mutated cone pigments (caused by gene polymorphism) with shifted sensitivity (usually the Mcone,
rarely the L-cone), so, though retaining trichromatism, their ability to distinguish colors (hue discrimination) is
weakened (Table 1, marked bold). Remarkably, both types of color blindness are extremely rare in chimpanzees and
other Old World primates [16]. While L/M-cone pigment gene polymorphism (causing anomalous trichromacy in
humans) also occurs in New World monkeys, it was evolved separately.
These conditions are classically explained by a relaxed selective pressure in human modern societies, where color
vision is less critical to survival [17]. However, the civilization argument is contradicted by the presence of color
blindness in different populations [16], which in addition suggests an early origin. On the other hand, some have
suggested that the gene polymorphism (anomalous trichromacy) could have been caused by gene level modulation
and not necessarily adaptive evolution [18], but a recent genetic research, which compared extensively the L-cone
pigment genes in humans and common chimpanzees, provided evidence for the adaptation hypothesis [19].
Comparative physiology indicates that similar deterioration of color vision typically occurs in aquatic mammals. For
deep sea-foraging species like dolphins, whales and seals, their S-cone pigment has been totally lost in the course of
evolution (Table 1, marked with X), making them completely color-blind [8, 9]. This is best explained by a relaxed
selective pressure in the dark underwater environment, where S-cone based vision is rendered useless and could
even be disadvantageous by causing chromatic aberration [8]. Human color blindness could be explained using the
same line of reasoning, whereby the nearly monochromatic underwater scenery makes the trichromatic vision,
useful to a terrestrial or arboreal diurnal animal, redundant. In fact, all types of color blindness (loss of L-cone, loss
of M-cone, mutation of L-cone towards M-cone, and vice versa) may well point to a single outcome, i.e., adaptation
towards dichromacy with only one L/M visual pigment left. Thus, human color blindness could be seen not as a
defect, but as a possible adaptation to a shallow-diving habitat in progress.
Convergence with Manatees
Another notable observation is the convergence of human color vision with that of the manatee (Table 1), a shallow
water dwelling mammal. From Table 1, it can easily be imagined how the ongoing progress of human color
blindness would let converge our color vision with that of the manatee: dichromatic vision, S-cone pigment peak
sensitivity shifted to 414 nm, single type of M/L-cone pigment with peak sensitivity around 530-560 nm, and rod
peak sensitivity remaining at about 500 nm. This convergent evolution strongly suggests that human color vision
until relatively recently was adapted to shallow water, like that of manatees, although not as extreme as the
adaptations in deep sea-dwelling mammals.

Seafood, Diving, Song and Speech
Was Man More Aquatic in the Past?, 2011, 181-189 181
Mario Vaneechoutte 1 , Stephen Munro 2 and Marc Verhaegen 3,*
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 12
1 Laboratory for Bacteriology Research (LBR), Department of Clinical Chemistry, Microbiology and Immunology,
Faculty of Medicine and Health Sciences, University of Ghent, De Pintelaan 185, 9000 Gent, Flanders, Belgium;
2 School of Archaeology and Anthropology, Australian National University, Canberra 0200 and Curatorial Fellow,
Centre for Historical Research, National Museum of Australia, Canberra, ACT 2600, Australia and 3 Study Center
for Anthropology, Mechelbaan 338, 2580 Putte, Belgium
Abstract: In this paper we present comparative data, suggesting that the various elements of human speech evolved
at different times, and originally had different functions. Recent work by Nishimura [1-6] shows that what is
commonly known as the laryngeal descent actually evolved in a mosaic way in minimally two steps: (a) a descent of
the thyroid cartilage (Adam’s apple) relative to the hyoid (tongue bone), a descent which is also seen in non-human
hominoids, and (b) a descent of the hyoid bone relative to the palate, which is less obvious in non-human hominoids,
and which is accentuated by the absence of prognathism in the short and flat human face. Comparisons with other
animals suggest that (a) the first descent might be associated with loud and/or varied sound production, and that (b)
the second might be part of an adaptation to eating seafoods such as shell fish, which can be sucked into the mouth
and swallowed without chewing, even under water. We argue that the origin of human speech is based on different
pre-adaptations that were present in human ancestors, such as (a) sound production adaptations related to the descent
of the thyroid cartilage associated with the territorial calls of apes, (b) transformation of the oral and dentitional
anatomy including the descent of the hyoid, associated with reduced biting and chewing, and (c) diving adaptations,
leading to voluntary control of the airway entrances and voluntary breath control. Whereas chimpanzee ancestors
became frugivores in tropical forests after they split from human ancestors about 5 Ma (million years ago), human
ancestors became littoral omnivores. This might help explain why chimpanzees did not evolve language skills, why
human language is a relatively recent phenomenon, and why it is so strongly dependent upon the availability of
voluntary breath control, not seen in other hominoids, but clearly present in diving mammals.
Keywords: Speech origins, language evolution, laryngeal descent, hyoid bone, thyroid cartilage, hominid diet,
hominoid evolution, diving abilities, seafood, suction feeding, consonants, Homo erectus, song, musical abilities,
comparative biology.
INTRODUCTION
The evolutionary origins of human language are still heavily debated. Here we attempt to explore some of the preadaptations
that might have contributed to the origin of human speech. We use a comparative analytical approach,
which is based on the assumption that most of the ‘unique’ features of a species (in casu, human speech) consist of
more elementary features, which are less unique (in casu, breath control, laryngeal sound production, sound
modification by the pharynx, and the specific morphology of e.g., the palate, the tongue and the lips, and our extreme
musicality). We argue that since these features are inherited largely independently, and have or had specific and often
overlapping and evolving functions, they provide information on present or recent past lifestyles through comparisons
with other species with similar features. Even in those cases where we do not know the exact functions of certain
features, comparisons with other animals with similar features can provide information on past lifestyles. Using this
method, we attempt to reconstruct the different evolutionary pathways of human phonation abilities, especially after
human ancestors split from the last common ancestors shared with the chimpanzees, about 5 Ma [7, 8].
Humans have several remarkable differences when compared to chimpanzees and other primates, not only in the nasal,
oral, pharyngeal and laryngeal anatomy (Fig. 1, Table 1), but also in the neurological control of these structures (Figs. 2
and 3, Table 1). Because the nasal and dental differences are probably less important in speech production, we focus
mainly on the oropharyngeal (mouth and throat) adaptations that distinguish humans from the apes.
*Address correspondence to Dr. Marc Verhaegen: Study Center for Anthropology, Mechelbaan 338, 2580 Putte, Belgium; E-mail:
m_verhaegen@skynet.be

182 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Vaneechoutte et al.
Figure 1: Midsagittal sections through chimpanzee (left) and human (right) head. Note the external nose, the absence of oral
prognathism, the globular tongue, the short, vaulted, smooth palate, and the lowered hyoid in humans. In chimpanzees, air and
food passages are separated in rest (not during e.g., hooting and panting). In humans older than about four months, they overlap,
probably due to the shortened oral cavity and the hyoidal descent (which the comparative data suggest might have been an
adaptation for suction and/or underwater feeding). This overlap of air and food passages allowed the laryngeal sounds, generated
by the vocal chords, to be permanently modified through mouth and tongue movements – a precondition to human speech.
Table 1: Unique features of human air and food passage entrances and their neurological control – possible convergences and functions
Characteristic Pan: often the original
situation?
INTERNAL NOSE
Homo: mostly
innovations?
References on
Homo/Pan
differences [11-14]
Examples of possible
convergences in other
animals
Possible functions (not
mutually exclusive)
Olfaction Rather poor Very poor [43] Aquatic mammals Atrophy: useless in water
Nasal passage More direct Long, inverted U Fig. 1 Easier closure, keeping
water out?
Plexus cavernosus
on inferior concha
nasalis
EXTERNAL NOSE
Absent: no erectile
vascular tissue
Well-developed, nasal
cycle 90 seconds
Size Small Large cartilages (esp.
cartilago alaris maior)
[44] Diving cycle of sea
otter
Elephant, tapir,
proboscis monkey,
bladdernose seal
Shallow diving
Semi-aquaticness e.g.,
snorkel? Sound
modification? Sexual
selection?
Nostril form Rounder More slit-like Easier closure
Nostril direction Forwards Downwards Sea otter Easier closure, keeping
water out
Philtrum in upper
lip
MOUTH OPENING
Absent Fitting with septum
between nostrils
[45] Closure, see Fig. 6 of
Chapter 7
Lips Less visible mucosa Everted (red mucosa) (Watertight?) fitting
together. Kissing?
Opening size
DENTITION
Normal, wide Small [10] Globicephalines Suction feeding, prepared
foods?
Front teeth Prognathism Flat face, vertical
incisors
Canines Large + diastemata Incisor-like, only
slightly projecting
Tooth row Parallel cheek teeth Parabolic, closed tooth
row
Enamel thickness Thinner: reduced? (very
thick in australopiths)
Occlusal relief Higher relief Bunodont (rounded
cusps on cheek teeth)
Biting/chewing
force
Stronger temporalis and
masseter muscles
Dusky titi,
globicephalines
Dusky titi, parabolic
tooth rows in aquatic
mammals
Thick Capuchin, orangutan,
sea otter
Weak (MYH16
inactivation)
Unerupted teeth Rare Frequent in archaic
Homo, M3 frequent in
H. sapiens
Less biting, suction feeding
Larger cutting edge, e.g., for
frugivory? Tooth row
closure, e.g., for suction?
Suction feeding of slippery
foods, e.g., fruits, seafoods
Durophagy, e.g., feeding on
nuts and/or shells
Suids, sea otter Harder food items: cracking
rather than slicing foods?
[15] Less biting: suction
feeding?
[46] Very frequent in e.g.,
Globicephalines
Atrophy, e.g., for suction
feeding?

Seafood, Diving, Song and Speech Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 183
Table 1: cont....
ORAL CAVITY: TONGUE AND PALATE
Palate length Long Short Cf. hyoidal descent?
Palate form Flatter Vaulted Dusky titi Fitting tongue form, e.g., for
suction feeding?
Palate ridges
(rugae)
5-15 2-8, restricted to the
front, smooth palate
Tongue form Flat, long Globular, short, fitting
in palate and tooth row
THROAT: HYOID AND LARYNX
Hyoid bone
localization
Larynx position in
rest
Aquatic mammals Slippery foods, suction
feeding
Versatile for suction
feeding? For speech?
Undescended Descended vs. mandible [4, 22, 47] Sea cows Suction feeding?
Connected to the nasal
passage
Descended vs. hyoid:
Adam’s apple in adults
Larynx size Normal Well-developed, very
muscular vocal folds
Laryngeal airsacs Very large (liters) Absent (vestigial
laryngocele): atrophy?
CEREBRAL CONTROL: BRODMANN’S AREA 4
Hand, finger and
thumb
representation
Mouth and tongue
representation
Larynx
representation
Representation of
breathing muscles
Rather large, equally
large as foot
representation
Very large, many times
Larger than (reduced)
foot representation
Rather large Very large, coordinated
by Broca’s area
Small Present, coordinated by
Broca’s area
Small or absent Present, coordinated by
Broca’s area
[48-50] Phonation? Suction?
[49] Singing, calling, speech
[22, 47], Chapter 4 Cf. absence (reduced?)
in gibbons
[7, 8], Fig. 2 and 3 Fine hand movements,
e.g., in sea otters and
raccoons
Breathing control in
diving mammals
Hindrance to diving,
especially in salt water?
Hindrance to singing?
Fine manipulation of foods
and/or tools
Singing? Airway closure?
Suction feeding?
Hyperventilation? Speech?
Singing? Airway closure?
Speech?
Singing? Diving? Speech?
Most human differences with chimpanzees and other primates are obvious (e.g., red lips, external nose) or described in Schultz [11] and Ankel-
Simons [12]. Additional references are given in the fourth column. Not all items are discussed in this paper: see also our earlier publications [7, 8].
Differences between extant humans and chimpanzees-bonobos could evolve in the Homo or the Pan ancestral lineages at different times between ~ 5
and 0 Ma (if Homo and Pan split ~ 5 Ma), so that, for instance, thick enamel originally does not contradict enamel reduction in chimpanzees’
ancestors (e.g., for more herbivory?) and on the other hand masticatory muscle atrophy in human ancestors (e.g., for more suction feeding?).
Figure 2: Sideview of a) chimpanzee cerebral cortex [Available at: http://ahsmail.uwaterloo.ca/~aktse/Brodmann.gif. Cited 2010
October 24]; b) human cerebral cortex, with Areas of Brodmann indicated on human cortex [Available at:
http://commons.wikimedia.org/wiki/File:1911_EB_Chimpanzee_Brain.png. Cited 2010 October 24].

190 Was Man More Aquatic in the Past?, 2011, 190-198
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 13
Aquagenesis: Alister Hardy, Elaine Morgan and the Aquatic Ape Hypothesis
Richard Ellis *
42 West 15 th Street, New York, NY 10011. American Museum of Natural History, New York, USA
Abstract: This paper gives an overview of the beginnings and the scientific acceptance of the so-called aquatic
ape hypothesis of human evolution (AAH), especially the work of Alister Hardy and Elaine Morgan. In 1960,
marine biologist Sir Alister Hardy, in a notorious article in The New Scientist, entitled Was Man more aquatic in
the past?, suggested that “a branch of the primitive ape-stock was forced by competition from life in the trees to
feed on the sea shores, and to hunt for food, shell fish, sea urchins, etc., in the shallow waters off the coast … ”,
and that “these semiaquatic creatures were soon wading into deeper water, and eventually began to swim and dive
for food at even greater depths.” [1]. His hypothesis was based on observations such as human swimming and
diving skills, our furlessness and subcutaneous fat tissues, and our streamlined shape “compared with the clumsy
form of the ape.” Hardy’s littoral hypothesis was brought into the attention of the great public by the books and
papers of tv writer Elaine Morgan, beginning with her bestseller The descent of woman [2], and followed by The
aquatic ape [3], The scars of evolution [4] and The aquatic ape hypothesis [5], in which she discussed the
waterside theory in much greater detail, e.g., with regard to the origin of human bipedality and laryngeal descent
and in which she made comparisons to the fossil swamp ape Oreopithecus and to living animals such as the
mangrove-dwelling proboscis monkeys (Nasalis larvatus) and the arguably ex-aquatic elephants. This paper
further discusses relevant work of Desmond Morris and Christian de Muizon, as well as diverse reactions of
palaeo-anthropologists, such as professor Phillip Tobias’s dismissal of the savannah hypothesis.
Keywords: Aquatic ape hypothesis (AAH), Alister Hardy, Desmond Morris, Elaine Morgan, littoral hypothesis,
Oreopithecus, palaeo-anthropological reactions, Thalassocnus.
SIR ALISTER HARDY
In the 1930s, professor Alister Hardy, marine biologist at Oxford, argued that humans, millions of years ago, must
have had littoral ancestors who found part of their diet wading and diving in coastal waters. He was afraid of the
possible consternation it would cause and only reported his idea many years later, on 5 March 1960 after he had
become a respected academic in a speech to the British Sub-Aqua Club in Brighton, not expecting any attention, but
it was reported in a national newspaper. This generated immediate controversy in the field of palaeo-anthropology.
Consequently, Hardy published the theory. In an article in New Scientist on 17 March 1960, Was Man more aquatic
in the past?, he described his theory in more detail: “My thesis is that a branch of this primitive ape-stock was
forced by competition from life in the trees to feed on the sea shores and to hunt for food such as shell fish and sea
urchins in the shallow waters off the coast. I suppose that they were forced into the water just as we have seen
happen in so many other groups of terrestrial animals. I am imagining this happening in the warmer parts of the
world, in the tropical seas where Man could stand being in the water for relatively long periods, that is, several hours
at a stretch” [1]. In the article, he asked, if ichthyosaurs, plesiosaurs, turtles, water-snakes, whales, dolphins,
dugongs and manatees, seals, sea lions, polar bears, otters, shrews, and the platypus “were forced back into the water
to make a living” why could not the same thing have happened to the primate now known as Homo sapiens?
In this hypothetical scenario, he suggested that these semi-aquatic creatures were soon wading into deeper water,
and eventually began to swim and dive for food at even greater depths. His hypothesis is based on certain
observations: humans, he says, are excellent swimmers, which “indicates to my mind that there must have been a
long period of natural selection improving Man’s qualities for such feats.” Our enjoyment of the seaside is another
factor, and “does not the vogue of the aqua-lung indicate a latent urge in Man to swim below the surface?” Then
there is the business of hairlessness. Since Man has lost almost all of his hair except that on the top of his head,
*Address correspondence to Richard Ellis: 42 West 15 th Street, New York, NY 10011. American Museum of Natural History, New York,
USA; E-mails: rellis@amnh.org; richellis@nyc.rr.com

Aquagenesis Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 191
perhaps he needs hair only to protect his head from the sun’s rays while swimming. Hardy also commented on the
graceful streamlined shape of Man “compared with the clumsy form of the ape,” and concluded that “all the curves
of the human body have the beauty of a well-designed boat.” In the “tentacle-like fingers” of the human hand, Hardy
sees great possibilities for exploring the sea bed and capturing crabs and other crustaceans, and for “turning over
stones to find worms and other creatures sheltering underneath.” And to him, the fat beneath the skin so resembles
the blubber layers of whales, seals, and penguins, that he at once thought “perhaps Man had been aquatic too.”
MAX WESTENHÖFER
For completeness, it should be noted that similar ideas had been formulated completely independently. In 1926, Max
Westenhöfer, professor of pathological anatomy in the Berlin University, declared before the Anthropological
Congress at Salzburg that Man, based on anatomical features of the human kidneys, spleen and other organs, must
have gone through an amphibious stage in his evolution [6]. In 1942, Westenhöfer wrote: "The postulation of an
aquatic mode of life during an early stage of human evolution is a tenable hypothesis, for which further inquiry may
produce additional supporting evidence. Primitive surviving features from an aquatic phase are preserved in Man's
anatomy today, such as the appendix, the lobulations of kidneys, and the indentation of the spleen and formation of
additional spleens [7]. The last two characteristics are now typically found in water mammals (see Chapter 8), and
so Westenhöfer explained that the predecessors of modern Man must have been more aquatic.
ELAINE MORGAN
Elaine Morgan was more than willing to pick up where Hardy left off in his article about an early aquatic hominid.
Born in Wales and educated at Oxford, she started as a writer for television, working on shows like Dr Finlay’s
casebook and Z-cars, broadcast on the BBC between 1962 and 1971. In 1972, enraged by the omission of women in
almost all discussions of human evolutionary theory, she wrote, The descent of woman [2], which was a
revolutionary work about the unrecognized rôle of women in human evolution. Traditional anthropologists (who she
calls ‘Tarzanists’) emphasized the idea of ‘Man-the-hunter’, based on his rôle as breadwinner – or more accurately,
meat winner – while the women were relegated to a footnote, passively cooking and raising the babies. She wrote:
“Most of the books forget about her for most of the time. They drag her onstage rather suddenly for the obligatory
chapter in Sex and Reproduction, and then say, “All right, love, you can go now,” while they deal with the real
meaty stuff about the mighty hunter with his lovely new weapons and his lovely new straight legs racing along the
Pleistocene plains.” Afterward, inspired by Hardy’s article, she began to formulate the notion that the traditional
ideas about the descent of Man (that is, Homo sapiens, not just the guys), were also unsatisfactory, and began
writing articles for The New Scientist, and eventually The descent of woman [2], The aquatic ape [3], The scars of
evolution [4] and The aquatic ape hypothesis [5]. The ‘scars’ are the price we have to pay for having achieved
various evolutionary enhancements such as the power of speech and an upright stance: “the propensity to suffer
from lower back pains, obesity, enlarged adenoids, acne, varicose veins, cot deaths, sunburn, sleep apnoea,
gynaecological and sexual malfunctions, dandruff, inguinal hernia, hemorrhoids.”
She regards the 1982 The aquatic ape [3] as “a bit out of date now” [personal communication, 2000], so I have relied
for my quotes on the 1990 edition of The scars of evolution [4] and the 1997 The aquatic ape hypothesis [5]. At first,
“aquatic ape hypothesis” sounds as if it might be a weird riff on water as a healing medium, or the importance of
drinking eight glasses of the stuff every day, but it is far from a trivial book. Although conservative anthropologists
may not accept her hypothesis, many of her propositions make considerably more sense than the accepted ones. She
has been asked to speak at Oxford, Cambridge, Harvard, and Tufts University, and in 1998, she was invited to
participate in the International Association for the Study of Human Paleontology in South Africa. A television film of
The aquatic ape was made by the BBC, and shown also in the US on the Discovery Channel in 1999.
There are many things about the accepted hominid evolutionary theory that Elaine Morgan dislikes. For example, if
our ancestors inhabited the African plains, along with zebras, antelopes, lions and baboons, why are we the only
ones without fur? For that matter, why are we the only primates without fur? Why do we have more body fat than
any other primates? Why is it that along with the penguins, Homo sapiens is the only animal that walks with a
perpendicular, bipedal gait? Why would a primate that previously had a hairy coat, move to the plains – scorchingly
hot by day, and uncomfortably cold at night – and then lose its protective covering? Also, humans and other aquatic

192 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Richard Ellis
mammals (whales, seals, manatees and dugongs) breathe consciously, i.e., we take in the appropriate amount of air
for the activity we are about to perform, while all other primates and indeed, all other mammals – except cetaceans
and sirenians – breathe involuntarily. We developed a big brain, up to 1/40 of our body weight, but such a
development would have been just as advantageous for a chimpanzee. Why us?
Morgan explains these discrepancies in a simple manner: humans are not descended from terrestrial hominids, like
Australopithecus, but from aquatic apes. In the past 5 million years, humans have lost many of the aquatic traits but
the vestiges remain. Hairlessness, she writes, had evolved long before humans moved from the forests to the
savannahs: they had become hairless when they were semi-aquatic. The only hairless mammals are those that live
underground, like naked mole rats, or (ex)aquatic ones, like whales, dolphins, manatees, elephants and hippos. The
argument that humans became hairless to prevent overheating does not make much sense when considering that
many animals that live in the hottest climates. Camels, e.g., still have a full hairy coat.
Bipedalism (walking upright on two legs) now occurs only in humans and penguins. Walking on two legs – although not
necessarily vertically – was also commonplace among dinosaurs, and of course, birds – direct descendants of the dinosaurs
– also walk on two legs, but except for the penguins, their spine is inclined towards the horizontal. Certain other mammals,
such as chimpanzees, gorillas, orangs, and bears, are capable of standing up on their hind legs and walking for a while, but
the natural gait of gorillas and chimps is quadrupedal knuckle-walking. Australopithecus anamensis and A. afarensis
fossils also show specialized wrist morphology associated with knuckle-walking [8]. Meerkats, and many rodents, like
chipmunks, squirrels, and prairie dogs also assume a vertical posture – usually when looking for predators – but when the
time comes to escape, they dash off on all fours. Kangaroos are among the only other mammals that move faster on two
legs than four, but their two-legged hopping gait is completely different from that of other mammals, and besides, it is
counterbalanced by the weight of a heavy tail. Kangaroos cannot move by putting one hind foot in front of the other – in
other words, they cannot actually walk – so they swing their hind legs forward while leaning over with their weight on
their forelegs. Because the idea of a quadruped rising up on its hind legs and deciding to become a biped is so
preposterous, Elaine Morgan asks us to imagine what it must have been like for the first humans to stand up on their hind
legs and walk: “… millions of years ago a population of apes on the savannah chose to walk on two limbs, instead of
running rapidly and easily on four, like a baboon or a chimpanzee. They stood up. With their unmodified pelves, their
inappropriate single-arched spines, their absurdly under-muscled thighs and buttocks, and their heads stuck on at the
wrong angle, they doggedly shuffled along on the sides of their long-toed, ill-adapted feet.”
An already semi-aquatic primate is the proboscis monkey, a long-nosed creature that lives in and around the mangrove
swamps of Borneo. Morgan cites many instances of these monkeys walking through the water (see Chapters 3 and 4)
and states that wild proboscis monkeys, “having acquired their bipedal gait in water, are seen calmly walking on the
ground in single file.” While some other primates, baboons for example, have a protruding muzzle, none but proboscis
monkeys and humans have a protruding nose. Not surprisingly, Morgan sees this as yet another aquatic adaptation: “If
a gorilla attempted to dive or to swim under water, the water would be forced into her nasal cavities and cause her the
most acute discomfort. A seal avoids this by having nostrils, that it can open and close at will, something some people
can do as well to different degrees. Still others can close their nostrils with their upper lip, whereby the vertical groove
on the upper lip, i.e., the philtrum, fits the nose septum [5] see Chapter 7, Fig. 6), and which must have been easier in
archaic Homo, who had a more protruding face (prognathism). The aquatic ape avoided it just as efficiently by
modifying the shape of her face so that the water would be deflected by a splendid new streamlined structure and her
sinuses would be safe.” In the developmental history of baleen whales, the nostrils migrated to the top of the head and
are now facing tail-ward, making it possible for the whale to surface and inhale while moving forward without getting
water in its nose. The breathing apparatus of baleen whales – called a ‘blowhole’ although it actually consists of paired
nostrils – closely resembles a human infant’s nose.
According to Morgan’s thesis, there was a period where early hominids lived a semi-aquatic existence – they were
never aquatic the way cetaceans are, but rather went in and out of the water frequently, like pinnipeds. In 1997 [5],
she wrote: “Whales and dolphins have been aquatic for about 70 million years and seals for between 25 and 30
million years. For most of these periods the cetaceans have been fully aquatic – never returning to land, and the seals
need to go ashore only to breed. The hypothetical aquatic phases of the ancestral apes during the fossil gap would
have been brief, a matter of two or three million years. Nobody has suggested that they turned into mermen or
mermaids. They would have been water-adapted apes in the same sense that an otter is a water-adapted mustelid.”

Was Man More Aquatic in the Past?, 2011, 199-212 199
Just Add Water: The Aquatic Ape Story in Science
Tess Williams *
Research Services, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 14
Abstract: Science theory argues that all ideas are contextualized in their disciplines and also reflect historical and
current cultural and social values. This chapter looks at the origins of the aquatic ape hypothesis (AAH) and its
development over fifty years, focusing on the particular contributions of Elaine Morgan. The hypothesis had its
genesis in a gendered debate on human difference and has connections with anthropology, primatology, palaeontology
and other disciplines. More radically, it has a complex relationship with scientific method, gene-centered neo-
Darwinism and theories that advocate multiple agents of biological change. Analysis of the AAH reveals much about
the history of various genres in science writing, and constructions of scientific authority and knowledge.
Keywords: Human evolution, feminist science theory, cultural studies, genre.
INTRODUCTION
“This idea of ‘Ecological and Evolutionary Cascades’ (EEC’s) is not entirely speculative. For example, the dietary
shift by the Koshima troop of Japanese macaques to digging for peanuts buried on the beach, led to juveniles
bathing, swimming and even diving for seaweed. One individual swam to a nearby island…. By a small extension in
dietary habits, the troop had grated (sic) an additional way of life on to their previous mode. They were on the
borderline of becoming partially marine organisms. Not only would this open up a whole new set of ecological
opportunities it would also expose the troop to a new series of physical pressures (i.e., the different mechanical
requirements of swimming).” Russell D. Gray [1]
Science theorists in the humanities and social sciences present diverse attempts to understand science. They examine
the position of science in culture and its relationship to nature. They track historical relationships between scientific
ideas and cultural movements, between cultural and scientific representations of nature, and between science and
society. Analyses of particular cultural and science sites can include considerations of material processes, historical
change, the interplay between different scientific discourses, central figures and the language of the field. These
investigations of science also consider authority, power and how representations of nature in the scientific processes
connect to broader cultural ideas. Such examinations often also explore resistances to dominant notions in particular
disciplines. This chapter follows this methodology to explore the aquatic ape hypothesis (AAH).
The AAH, originally entitled the ‘aquatic ape theory’, is a cultural site constructed over a fifty-year period. It is a
site of complex and multiple authorship, that argues an alternative view of human evolution. It resists savannah and
‘Man-the-hunter’ narratives of biological and cultural change that have dominated popular understanding and much
scientific interpretation of human origins since the early 20 th century. Initially proposed by a distinguished scientist,
the hypothesis was ignored for a decade before being written up as popular science. The AAH then transformed into
a story-telling critique of science, challenging the narrative elements of human evolution stories with its own
narrative. In the 1970s, the AAH introduced important questions about disciplinary and gendered constructions of
scientific knowledge. During the next twenty years the hypothesis struggled to gain a foothold within the field of
human evolutionary theory, but in the last ten years it has made some significant connections to mainstream science
in unexpected ways. This chapter particularly addresses Elaine Morgan’s writings around semi-aquatic stories of
human origins, as she has been the main proponent and developer of the theory.
In 1960, Sir Alister Hardy published a paper in New Scientist, entitled Was Man more aquatic in the past? [2]. His
thesis was that “a branch of … primitive ape-stock was forced by competition from life in the trees to feed on the
*Address correspondence to Tess Williams: Research Services, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009,
Australia; E-mail: tess.williams@uwa.edu.au

200 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Tess Williams
sea shores and to hunt for food, shell fish, sea urchins etc., in the shallow waters of the coast.” His arguments for
assuming a semi-aquatic detour in human prehistory included human grace and endurance when swimming,
hairlessness, the unusual layer of subcutaneous fat found in humans, and our upright posture, which Hardy believed
could have come from wading. He also contended that the potential for tool use may have occurred when the
proposed human ancestors needed to access water line food sources such as oysters and crabs. Hardy’s thesis was
not entirely novel as F. Wood Jones, a comparative anatomist, had previously likened human subcutaneous fat and
hair loss to features of aquatic animals [3]. However, Hardy’s analysis was the most comprehensive to date.
Ten years later, this germinal idea was further developed by Elaine Morgan in her book, The descent of woman [4].
Her approach in this book is interdisciplinary, argued through functional morphology and social anthropology,
supplemented with an analysis of convergent aquatic features in humans. Her primary contention is that the story of
Man-the-hunter cannot explain the considerable biological differences between humans and other primates. Morgan
claims that the needs of females for food and protection, the vulnerability of the offspring, and a probable change in
environment drove human evolution at least as much as male dominance, territoriality and reproductive urges. She
went on to write five more books on the topic.
The AAH is generally situated as a popular science site, lacking in academic rigor, and is often dismissed because of
the feminist polemic in Morgan’s first book. However, closer readings of the cultural site reveal a layered politic to
the continuing relationship of the hypothesis with science and science writing. Over time, the AAH has destabilized
scientific notions of authority in evolutionary narratives of palaeontology and palaeo-anthropology, and has
provided a context for significant scientific findings about the prehistoric diet and brain development. The AAH, as
it has been developed, also models the tensions that exist between neo-Darwinist evolutionary thinking and the
gene-driven new synthesis, and resistant theories such as punctuated equilibrium and epigenetics, which consider
environmental pressures to be a significant key to evolutionary change.
SITUATING THE AQUATIC APE HYPOTHESIS
Although there were prior incursions into the field, anthropological extrapolation from human fossils are generally
considered to have originated with Raymond Dart. Dart found the fossilized skull of the South-African Taung child
in 1925 [5]. The skull was significant because it had a larger brain than any known primate, and the foramen
magnum (the hole in the skull for the spinal cord) indicated the child walked upright. Dart proposed in his original
paper that this was a species that had come out of the jungle to the savannah, to an environment that “sharpened the
wits, and quickened the higher manifestations of intellect in direct response to keen competition and the swiftness
and stealth” of prey and predators [5]. In the 1930s, following fossilized australopithecine finds lying together with
cracked and broken gazelle bones, Dart suggested this was evidence of Man as a ‘killer ape’, a prehistoric predator,
and he wrote journal articles to that effect [6, 7]. Dart’s story telling was not well received by some scientists at the
time, but it eventually made a deep impression on the field and in the culture.
According to Adrienne Zihlman, anthropologist at the University of California, Santa Cruz, Dart’s killer ape stories
dominated the field for at least two decades and notions of more complex social group formation and potential
cultural developments in pre-hominids did not enter Palaeolithic stories until the early 1950s. Zihlman [8] states
that, by the mid-sixties, ethnographic information and popular texts had simultaneously “formalized the concept of
Man-the-hunter and provided a means to challenge it”. Science theorist Donna Haraway, in her landmark text,
Primate Visions [9], mentions Robert Ardrey, Desmond Morris, Lionel Tiger, Robin Fox, Konrad Lorenz, Steven
Goldberg and Irven deVore among those that promoted the hunting hypotheses, but lists only Jane Goodall, Evelyn
Reed and Elaine Morgan as writers with a different vision. Although their backgrounds were very dissimilar, these
women primarily argued in the public forum that the hunting hypothesis gave primacy to aggression, xenophobia
and territoriality in humans and that there were alternative readings to human prehistory and culture.
While the work of all three women attracted a degree of controversy, Goodall was a primatologist, and Reed was an
anthropologist. This gave them enough cachet in the scientific community to ensure academic dialogue, but Morgan
had little of that. Morgan was born into a poor Welsh mining community. At Oxford University, she developed a
strong interest in socialism, and married a returned soldier who had fought in Spain against Franco’s dictatorship.
She began writing when the mother of young children, and was a scriptwriter with the BBC for many years [10].

Just Add Water Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 201
The Descent of Woman was produced because Morgan became ‘fearfully cross’ with masculine-centred stories of
evolution [11]. Sir Alister Hardy was an academic progenitor of sorts, but he gave her no formal tuition or
institutional connection. In fact, in an upset of conventional pedagogical authority, Morgan claims she approached
Hardy and simply told him that, with or without his permission, she was going to explore his ideas further [12].
Although he was initially ‘shocked’ at the idea, he encouraged her, and even wrote the foreword for The aquatic
ape: A theory of human evolution in 1982.
By way of contrast, Haraway speaks about the influence at the same time of Sherman Washburn on the generation
of American women primatologists who were telling stories of primate troupes and developing changing views of
primate, and therefore human, behavior [9]. Washburn was not an isolated force of cultural production in their
training, rather he fostered those ‘daughters of Man-the-hunter’ through his own protégés, his training in physical
anthropology, Professorial positions at Columbia and UCLA, grants from the Wenner-Gren Foundation, and the
baboon archetypes he used to synthesize stories of early human bodies and behavior for over thirty years [9].
Washburn’s contributions to both primatology and the eventual production of feminist resistances to aggression
models of human social behavior in post-war primatology were timely. Alister Hardy’s ‘aquatic ape’ contribution,
on the other hand, was not. Occurring to Hardy much earlier in his scientific career, he did not formally present the
hypothesis until he had achieved his goals of Professorship at Oxford and become a Fellow of the Royal Society.
Morgan contends he was advised against advancing the idea and, when he did finally present it, it was viewed as a
late career eccentricity rather than a viable research topic [12]. Haraway points out that Washburn’s prehistoric
hunter was closely related to Dart’s killer ape. Hardy’s ideas just didn’t have the same cultural weight. Washburn’s
feminist science re-‘sisters’ formed a significant disciplinary group and began unraveling patriarchal assumptions
and beliefs in primatology through postgraduate field research and academic publications [13], while Morgan
occupied the lonely and ironic position of ‘Hardy’s bulldog’, with no science background, but with excellent and
versatile communication skills.
Morgan was also a solitary ground breaker in other respects. Seventeen years prior to Haraway’s Primate Visions,
and nearly two decades before Misia Landau’s Narratives of Human Evolution [14], Morgan prepared the general
science reader to understand that stories from ethology, biology, primatology and evolution are partially mythmaking
activities and they can contain unexpected biases. Immediately, she ironically positions Darwin next to
Genesis in her introduction to The Descent of Woman [4]. In a few short words, she defuses the polarity of the
creationism/science argument and puts her readers on notice about a third option for human evolution that focuses
on the culturally, socially and environmentally repressed. Where, she asks, are the women, the children and the
environment in the savannah and Man-the-hunter scenarios?
In Kuhnian terms, Washburn’s feminist students expose the anomalies and the politics of the ‘normal’ science of
evolutionary theorizing, but stay within recognized paradigms, whereas Morgan is an outsider, who comes into a
discipline, perceives the field in a very different way from trained science practitioners, and offers that revolutionary
“switch in visual gestalt” that Kuhn talks of in his discussion of scientific process [15]. Thus, this particular
evolutionary story – while it has an early focus on gender – is very different in its inception and initial development
from other stories produced by women scientists within traditional disciplinary boundaries.
Analysis of Morgan’s story-telling process in science also reveals that she anticipates a socialist science process, as
articulated nearly two decades after her initial publication by the October 29 th Group from Wisconsin University
[16]. This science project proposes an ideal science model including, among other things, veracity above the
pressure to publish, a democratic and communal social structure in science, community participation, and thoughtful
rather than fashionable choices of research topics. This open model is literally very close to Morgan’s praxis, a
praxis that reflects her other activities such as campaigning as a student against Franco’s dictatorship. The AAH is
unusually democratic in that it regularly demonstrates a loss of the divide between scientist and non-scientist
through Morgan’s person and through its supporters.
Thanks to Morgan’s approach, the AAH makes institutionalized certification an ambiguous marker of knowledge
with regard to sociobiology, popular science and even evolutionary theory. While the AAH has been developed and
championed by her, and she is significantly identified with the discourse, this site is one that perplexes western

Was Man More Aquatic in the Past?, 2011, 213-225 213
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers
CHAPTER 15
Langdon’s Critique of the Aquatic Ape Hypothesis: It’s Final Refutation, or
Just Another Misunderstanding?
Algis V. Kuliukas *
Centre for Forensic Science, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
Abstract: Thus far, there has been no challenge to Langdon’s 1997 critique [1]of the aquatic ape hypothesis (AAH),
despite its having a number of weaknesses. The paper lacks scholarliness as it does not draw upon the one published
scientific investigation into the plausibility of the AAH in the literature, i.e., that byRoede et al. [2]. Langdon’s
summary of “anatomical evidence for the AAH” seems to have been directed against an exaggerated interpretation
of Alister Hardy’s hypothesis that humans were “more aquatic in the past” [3]. Most of the critique was based on
cursory and superficial comparisons with fully aquatic mammals, such as cetaceans, rather than considering whether
human ancestors could have been more aquatic than those of apes. Even on this basis, Langdon considered eleven
out of twenty-six traits to be “possible aquatic adaptations” or “consistent with the AAH”.
It is argued here that none of the specific hypotheses of the AAH have yet been refuted. Instead, what appears to have
happened, is that individuals have been left to interpret certain ambiguities in arguments put forward by proponents of
the hypothesis in their own way and then reject, or accept it on that basis. More than a decade later, significant new
evidence has emerged, and other AAH-based models have been published, which demand serious reconsideration.
Keywords: Langdon, AAH critique, rejection, parsimony.
INTRODUCTION
In 1991, Vernon Reynolds stated: “Overall, it will be clear that I do not think it would be correct to designate our
early hominid as ‘aquatic’. But at the same time there does seem to be evidence that not only did they take to the
water from time to time but that the water (and by this I mean inland lakes and rivers) was a habitat that provided
enough extra food to count as an agency for selection.” [4].
That paragraph, taken from Reynolds’ concluding editorial section of the Valkenberg symposium [4], which
specifically considered the so-called aquatic ape hypothesis (AAH), signals that the author believed that the hypothesis,
although probably wrong in its extreme (and, perhaps, most commonly interpreted) form, deserved consideration in
some revised, moderate reconstruction. The idea that moving through water for food might have acted as an agent of
selection in human evolution has, however, remained more the target of ridicule than of research in the field of palaeoanthropology.
This state of affairs has remained to this day, possibly in part because of the critique of the AAH by
Langdon [1], the only paper published in a palaeo-anthropological journal that considered, and rejected it.
Langdon justified his critique by arguing that “the aquatic ape hypothesis continues to be encountered by puzzled
students who wonder why mainstream palaeo-anthropologists overlook it [1]. If only because of this last audience, it
should not be ignored.” Langdon makes a good point. In my experience, students and lay people who hear about the
AAH for the first time tend to be open to it: “That makes sense” is a common reaction. Indeed, the negative reaction
to the AAH from the field of palaeo-anthropology might be seen as interesting as the hypothesis itself, and has been
the subject of a number of scholarly articles in the literature [e.g., 5].
Whatever the reasons for the lack of serious attention afforded to the AAH by palaeo-anthropologists in the past, be they
some kind of “perceived ‘outsidership’ of Elaine Morgan” [5], or be it simply bad timing, arguing for the importance of
water in 1960 when the general consensus was more focused on aridity, Langdon was right to address the issue.
*Address correspondence to Algis V. Kuliukas: Centre for Forensic Science,University of Western Australia, 35 Stirling Highway,Crawley
WA 6009, Australia; E-mail: algis.kuliukas@uwa.edu.au

214 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Algis V. Kuliukas
The interest by new students and the interested lay public in the AAH appears to be as real today as it was in 1997: It
has remained by far the most popular topic of discussion on internet newsgroups about palaeo-anthropology for years
(e.g., science.anthropology.paleo). However, a student of human evolution, familiar with the literature today, might be
forgiven for concluding that Langdon’s critique was the final refutation of AAH, as no reply has been published since.
This might also explain why so few prospective Ph.D. students have chosen AAH-related subject areas in which to
conduct their research, or why most students have probably been persuaded not to waste their time looking into it.
With that audience in mind, this counter-critique has been written. Weaknesses in Langdon’s paper deserve to be
challenged, pro-AAH arguments not covered should be heard, and alternative interpretations of the AAH not considered by
Langdon’s critique should be aired for scientific scrutiny. It also aims to respond to a recent plea from Phillip V. Tobias “to
re-examine these claims, much as Langdon (1997) has done” [6]. Tobias has been one of the few palaeo-anthropologists in
the past few years, calling for his peers to reconsider the rôle that water has played in human evolution [7].
This chapter mirrors the structure of Langdon’s original publication. It critiques his arguments, and outlines
additional AAH-related ideas.
LANGDON’S INTERPRETATION OF THE AQUATIC APE HYPOTHESIS (AAH)
Langdon introduced the hypothesis thus: “The AAH in its present form was first articulated by Alister Hardy in
1960 in an issue of New Scientist magazine, featuring the relationship of Man and the sea, past present and future”
[1]. Most AAH-proponents probably take Hardy’s paper [3] as their starting point. It should be noted however, that
the AAH, like any model of human evolution, is under constant revision, in response to criticisms and as new
evidence is gathered. Therefore, its present form today is not the same as the one Langdon dismissed in 1997. There
are now several AAH variants, differing in their proposed timescales, aquatic habits and habitats (see Chapter 6),
and human traits suggested as evidence. It should also be noted that Hardy’s ideas are not the only (or indeed the
first) to be articulated in the literature (see Chapter 6).
Most importantly perhaps, Langdon overlooked Hardy’s rather modest title: “Was Man more aquatic in the past?”
(my emphasis). This, in my opinion, is the most common misunderstanding of the hypothesis. On first hearing the
term ‘aquatic ape’, reviewers could be forgiven for understanding that the hypothesis postulates that humans
evolved from a truly aquatic ape, in the sense that whales and sea cows are aquatic mammals. A series of
publications [8-30] never made such an extreme claim.
At most, some of them have argued that a move into more littoral habitats shaped a distinct phase of human
evolution, in a similar way to that which, it is postulated, must have happened in the earliest stages of the evolution
of Cetacea, Sirenia and Pinnipedia. Almost every mammalian order contains at least one or two genera or species
that appear to have taken advantage of, at some time in their evolution, more aquatic habitats, and human traits such
as nakedness and increased subcutaneous fat, which seem to be rather unique in the primates, have analogues in
more aquatic mammals [e.g., 2, 10].
Both Hardy and Morgan apparently were not arguing for anything more than a semi-aquatic or littoral stage in
human evolution. For example, Hardy wrote: “It may be objected that children have to be taught to swim; but the
same is true of young otters, and I should regard them as more aquatic than Man has been” [2]. And Morgan: “At
the highest point of their period of aquatic adaptation the ancestral hominids, though never as fully marine as the
dolphins or sirenians, would probably have been capable of crossing wide stretches of water under their own steam;
and without postulating that at such an early stage of their evolution they became boat builders, it is highly possible
that they would have been aware of some of the uses of a floating log.” [9]. It would appear that it was exactly how
these ideas were personally interpreted that determined how well they were received. If one interpreted them as
meaning that humans went through some kind of ‘primate seal’ or ‘merman’ phase, they were rejected. If one
interpreted them as merely arguing that ancestors of ours included more aquatic foods in their diet and/or did more
swimming and diving than we (or our ape cousins) do today, it was difficult to see what the fuss was all about.
Although Langdon began his paper by referring to Hardy’s original paper, ignoring the earlier work of Max
Westenhöfer [31], almost all of it subsequently appraises the work of a single proponent of the AAH, Elaine

Langdon’s Critique of the Aquatic Ape Hypothesis Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 215
Morgan. Morgan is certainly the most prolific proponent, but she is not the only one. Unfortunately, Langdon’s
critique was published in the same year as Morgan’s The aquatic ape hypothesis [13], and could not take into
account the answers to a number of weaknesses pointed out by Langdon, but already addressed by Morgan in The
aquatic ape hypothesis.
ANATOMICAL EVIDENCE FOR THE AAH
About half of Langdon’s critique discussed modern human anatomical traits which AAH proponents have suggested
as evidence of a more aquatic past. Twenty-six such traits were paraded, as if for ridicule, and most were dismissed
after a very cursory treatment. No attempt was made to emphasize the more important of these traits, an approach
very much at odds with Morgan’s, who, for example, wrote six chapters on just three of them in The aquatic ape
hypothesis [13].
Langdon placed the traits into six categories [1]:
1. Primary evidence - possible aquatic adaptations
2. Parallelisms inadequately explained by the aquatic hypothesis
3. Traits consistent with the AAH
4. Primitive traits
5. Hypothetical reconstructions of past events
6. Secondary developments.
Even Langdon [1] categorized four traits as “possible aquatic adaptations” (voluntary-breath holding, enlarged
pharynx, thermoregulatory strategy, and absence of salt hunger) and seven as “consistent with the AAH”
(bipedalism, speech, protruding nose, paranasal sinuses, long scalp hair, sebaceous gland distribution and apocrine
gland distribution). However, throughout the table, and the review generally, he repeatedly appears to be critiquing
an extreme interpretation of the hypothesis. His one-line rebuttal “not typical of aquatic animals” was used several
times, as if the AAH was arguing that human ancestors had been aquatic.
Bipedalism
In the first paragraph, Langdon discussed just one of Morgan’s many arguments for a wading origin for bipedalism,
i.e., that medical disorders associated with bipedalism, such as increased risk of lumbar disk herniations, and
vascular problems such as fainting and varicose veins, would have been reduced in water [11]. In the second
paragraph, this argument was refuted on the grounds that “authors who wish to recite the many disadvantages of
bipedalism commonly do so by comparing humans to medium-sized terrestrial quadrupedal mammals” [1]. No such
authors were cited, but it was implied that this was Morgan’s reasoning. Morgan, in fact, only compared humans to
apes. Even if one assumes that she meant a medium-sized terrestrial, knuckle-walking ancestor, this is not a
remarkable position to hold as many prominent palaeo-anthropologists [28] also advocated such models at the time.
Langdon then went on to suggest that climbing and suspensory specialization and the resulting increased use of
bipedal posture and gait in hominids is a more likely explanation of bipedal origins. He misrepresents Morgan by
arguing that she “wrongly dismisses these specializations on the grounds that brachiation is irrelevant” [1], when she
only said that “as far as the spine is concerned, brachiating is at the opposite end of the spectrum to bipedalism. For
the ape, the weight of the body and legs tends to stretch the spine and minimize pressure on the disks of cartilage
between the vertebrae.” [11].
His concluding comment on this (“the climbing/suspensory complex both removes our ancestry from conventional
terrestrial quadrupedalism and helps to bridge the gap towards human bipedalism” [1]) merely backs the
brachiationist model of bipedal origins, which is only one of many. As there are more than twelve other such models
[33], arguably as many as thirty (see Chapters 3 and 6), and very little consensus exists in the field about them,
Langdon’s argument hardly acts as a rebuttal to the aquatic argument for bipedal origins. Indeed, he even
categorized bipedality in his table as “Traits consistent with the AAH”.

226 Was Man More Aquatic in the Past?, 2011, 226-244
A
Index
AAH, AAT (Aquatic ape hypothesis, theory) i-iii, 7-10, 12-13, 36, 40, 47-50, 62, 78-79, 106-118, 156-158, 160,
173, 179, 190-197, 199-207, 213-223
Abalone (awabi, Haliotes) 123
Abdur, Eritrea 96
Acidosis 125, 131, 137
Adam’s apple 181, 183-184, see also Larynx
ADH 148, 151
Adipocyte 193
Adipose tissue 19, 23, 78, 89-90, 111, 132, see also Adipocyte, Fat, Subcutaneous
Adrenaline 156
Afar (triangle) 24, 108-109, 114-115, 117, 209, see also AL
Afropithecus 68-71, 75-76, 110
Aïn Hanech, Algeria 6, 98
Air sinus see Sinus
Airsac 69, 72, 74, 77, 79, 183
AL 288-1 (Lucy, Afar Locality, A. afarensis) i, 60, 77, 84, 219
AL 333-51 (A. afarensis) 84
Albatross 166
Albers-Schonberg disease 83
Ama divers 121, 123-124, 126-128, 130-133, 135, 137, 140, 142
Ambledon 194
Ambulocetus 88
Amphibische Generalistentheorie 38, 40, 44, 115
Anableps 164
Anapithecus 56
Andaman Islanders 97
Ankarapithecus 68, 71, 75
Anthracobune 151
Anthropopithecus erectus 82
Antidiuretic hormone see ADH
Aonyx capensis 151, see also Otter
Ape see Hominoid
Aplodontidae 149
Apneic diving 120-121, 132-134, 136, 138, 141-142
Aquarboreal 38, 44, 46, 67, 71, 73, 75-79, 109-110, 114, see also Flooded forest, Mangrove
Aquatic ape hypothesis, Aquatic ape theory see AAH, AAT
Arachidonic acid 11, 17-18, 161
Archaeocetes 88
Ardipithecus ramidus 8, 56, 68, 75, 114, 219
Area 4 183-184, 186-187
Area 41 187
Asphyxia 120, 125, 131, 133, 135, 137
Atelectasis 140
Ateles geoffroyi (spider monkey) 68-69, 148
Auditory cortex 185, 187
Auditory exostose 78, 83, 111
Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds)
All rights reserved - © 2011 Bentham Science Publishers

Index Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution 227
Australopithecus 7-8, 11, 50, 56-57, 68, 71, 74, 76, 85-86, 98, 108, 116-117, 192, 218-219, see also Gracile, Robust
australopith
Australopithecus afarensis 56-57, 60, 74, 116, 192, see also AL, Dikika, Lucy
Australopithecus africanus 11, 86, see also Sts 14
Australopithecus anamensis 192, 219
Australopithecus boisei 77, 98
Australopithecus robustus 98
Austriacopithecus 68, 71, 75-76
Awabi see Abalone
Aye-aye 68, 75
B
Babbling 185
Baboon marker 209, see also Retroviral
Baby swimming 126, 131
Babirusa, Babyrousa 152
Bactrian camel (Camelus bactrianus) see Camel
Bahr-el-Gazal, Chad 3
Baleen whale 192 see also Cetacea
Bamford, Marian 8
Basal metabolic rate 125, 127, 129, 132-133, 137-138
Basic color 176, see also Color vision
Basilosaurus 88
Bear (Ursus) 6, 54, 75, 88, 92, 149, 151, 186
Bearder, Simon 197
Beaver (Castor) 72, 88, 129-130, 142, 413, 149-151, 157, 196
Bee brood 96, 99
Bel Hacel, Algeria 6
Bender, Renato and Nicole iii, 117
Bent hip bent knee see BHBK
Benveniste, R. E. 209
Bering Strait 193
Beringia 4, 6
BHBK (bent-hip-bent-knee) 57-59, 61
Biorhythm 204
Biped, Bipedality i-ii, 7-10, 12, 16, 21, 23, 29-30, 36-63, 56, 71-73, 77-79, 91, 94, 107-108, 111, 115-116, 153, 173,
190-194, 196-7, 204, 215-217, 221-222
Birthing pool 156-157
Bladdernose seal 182
Blaffer Hrdy, Sarah 204-205
Blombos Cave, South Africa 27, 96
Bodo, Ethiopia 85
Bone tissue 82-99, 160
Boselaphini 149
Bottom-feeding 78, 88, 90, 93-94, 120, 123, 127, 133, 135
Bottom-walking 88, 90, 93
Bovine 149, 151-152
Boxgrove, England 78, 85, 92-94
Brachiating, Brachiator 37-38, 40, 49, 68-70, 72-73, 215
Brain case (skull) 23, 76, 85
Brain centres 183-187

228 Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Vaneechoutte et al.
Brain learning (plasticity, vision) 165, 169-170
Brain oxygen 120, 122, 127-129, 131, 133, 137-139, 143
Brain size, growth, nutrients ii-iii, 8, 10-12, 16-21, 29-30, 39, 46, 69-70, 72, 74, 76-79, 90-92, 94, 99, 107, 111-112,
156, 158, 160-161, 192, 194, 196-197, 200, 202, 204-206, 217, see also Iodine, DHA
Brain stem 186-187, 223
Brain tissue density 90
Bramble, D. 23
Breast 204, 217, sea also Lactation
Breast bone 68-70, 72, 76, 79
Breathing ii, iii, 9, 29-30, 45, 49, 74, 94, 99, 120, 124-128, 131-134, 136-143, 181, 183, 185-187, 192-193, 215,
217, 222-223
Brittle bone 83, 87, 90-91, see also Osteoporosis, Osteosclerosis
Broadhurst, C. Leigh v, 10-11, 16, 18-19, 206, 210
Brodmann’s Area 183-184, 186-187
Broom, Robert 7
Brul, Lloyd du 38
Buia, Ethiopia 96
Bulla tympanica 90
Bunodont 21, 75, 77, 182
Buoyancy 3, 13, 23, 59, 82, 87-89, 94, 99, 112, 115, 127, 137, 139, 193, 204, 218
C
Cadman, Ann 8
Calcium 38, 83, 90, 160-161
Calvariae interna, Calvarial bones 83, 85
Camel (Camelus, Camelidae) 95, 148-149, 151-152, 154, 158, 192, 216
Cameron, David W. 55, 109
Cancellous bone 82, 84, 87, 90
Canine teeth 71, 182, 184
Cape clawless otter see Aonyx capensis
Carentonosaurus 89
Carey, T. S. 57-58
Carrier, David 38
Carrying hypothesis 37, 39, 41, 44-47, 51, 59, 73, 91
Cartmill, Matt 38
Castor see Beaver
Catecholamine 156
Celebes, Indonesia 5, 121-122, 170
Cerebral 16, 20, 183, 223, see also Brain
Cerebral palsy 160-161
Cervidae (deer) 90, 149
Cervical, obstetrics 156-157
Cervical, vertebra 195
Cetacea (whales) 20, 22, 26-27, 72, 83, 87-90, 93-94, 96, 107, 125, 127, 138, 142, 149-150, 158, 174-175, 187, 190-
196, 208, 213-214, 216, see also Dolphin
Chan, Wang-Chak v, 173
Cheek bone see Mandible, Maxilla
Cheek tooth see Molar
Chemeron, Kenya 78, 95
Chemoreceptor 173
Chest breathing 187