The full programme book (PDF) - Royal Geographical Society

THEME 11: INSIGHTS FROM GENETICS
Insights from genetics – the past and future of ancient DNA research
Ian Barnes
Vertebrates and Anthropology, Department of Earth Sciences, Natural History Museum, Cromwell
Road, London SW7 5BD
After an initial burst of enthusiasm in the late 1980’s, ancient DNA research spent much of
the 1990’s grappling with the technical limitations of the technique, and trying to find a
place for itself within a broader range of relevant subjects: archaeology, palaeontology and
evolutionary biology. While much of the initial enthusiasm for ancient DNA analysis came
from archaeologists, it has been Quaternary palaeontology where some of the most
interesting work has been conducted. Despite the far greater age of the material, it is
possible to find samples with exceptional DNA preservation, due to the availability of longterm
frozen, permafrost-derived specimens. In addition, the types of questions interesting
to palaeontologists have been more readily translated into the language of PCR and
Sanger sequencing than the complexities of culture, gender and status that were of
primary interest to archaeologists at that time.
Throughout much of the 1990’s, the application of ancient DNA to Quaternary material
was focused on a conceptually straightforward problem; the phylogenetic placement of
extinct megafauna. These studies were perhaps most important in maintaining interest in
a technique which was struggling with credibility issues stemming from contamination
problems, and rejecting the increasingly predominant view of ancient DNA as a technical
novelty. By the end of the 1990’s, the importance of permafrost preservation was
becoming increasingly obvious to a number of groups. The ability to work with large
numbers of individuals was further facilitated by improvements in DNA extraction,
amplification and sequencing, and by the wider availability of high-quality radiocarbon
dates.
This approach enabled the first population surveys, or at least surveys of multiple
individuals through time, which enabled us to recognize the exceptionally dynamic nature
of populations during the late Pleistocene. The taxonomic focus has until recently stayed
on the northern Holarctic, extinct, megafauna - although this initial period of big game
hunting seems to be drawing to a close. More recent studies have looked at a broader
range of mammalian species, and there is also an increasing interest in placing results
within the broader context of late Quaternary climate change. Ongoing development of
statistical modeling methods will facilitate this, with the traditional data analysis of choice
for ancient DNA datasets – the Bayesian skyline plot – being continually enhanced, and
now supplemented by coalescent-based hypothesis simulation tools.
The technical requirements of next generation sequencing have driven a renewed interest
in working with well-preserved individual samples, but this is likely to change as better
enrichment methods become available. Beyond this, it is difficult to predict the future of
Quaternary ancient DNA, given the rapidly changing technological basis of DNA
sequencing; however certain features seem highly likely. An increasing awareness of the
complexities of population genomics will drive the need for genomic-level ancient DNA
datasets. At the same time, work on functional genomics in extant species and
populations will provide a basis for studies into the long-term history of selection in
different fauna. Finally, the potential to work with smaller amounts of highly fragmented
DNA may enable us to routinely work with material of much greater age, allowing us to
examine the impact of the earlier warm stages on megafaunal populations.