The Meme Machine

THE BIG BRAIN 79
skills. But the heuristics for choosing what to imitate are only rough-and-ready
guidelines and the memes are beginning to proliferate beyond purely survivalrelated
skills. For example, as memes for singing appeared, the best imitators
would begin to sing best, singing would be perceived as important, and so
copying singing would come to have survival value. In this way, the specific
nature of the memes of the time would determine which genes were more
successful. The memes began to force the hand of the genes.
There is a fourth and final step that might increase the process again – though
it is not necessary to the explanation. We can call this ‘sexual selection for
imitation’. Sexual selection, first described by Darwin and much argued about
ever since, is a well-recognised, if controversial, process in biology (see Cronin
1991 for a review and Fisher 1930). Particularly interesting cases involve
runaway sexual selection, in which elaborate but otherwise useless structures,
such as the peacock’s fantastic tail, are selected for by generations of peahens
choosing males with fancier tails. Once the process has begun it can incur
enormous costs for the male but it works for the following reason. A female
who chooses a male with a good tail will have sons with good tails who will
attract mates with choices like hers. She will therefore have more grandchildren.
The reason it is the females who do the selecting is the imbalance between the
sexes in parental investment. Male birds can potentially have vast numbers of
offspring but females are constrained to producing only a few eggs a year or, in
the case of humans, a few children in a lifetime. So females cannot greatly
increase the number of children they have. They can, however, increase the
number of their descendants in future generations by choosing mates who will
give them ‘sexy sons’ who will have many offspring. With lots of females all
going for the same males, this process rapidly escalates until the costs become
too great.
The big brain certainly looks like a runaway phenomenon and I am not the
first to suggest a role for sexual selection in brain size. But previous theorists
have not explained why sexual selection should pick on brain size (e.g. Deacon
1997; Miller 1993). My answer comes directly from the power of the memes.
The way memes can exploit the process of sexual selection is unique.
Whatever is deemed ‘in’ can change as fast as the memes change – and that is
much faster than genes can produce longer tails or an innate ability to build a
fancy nest. If you follow the heuristic ‘mate with the man with the most memes’
you will soon find yourself mating with the one with the best hairdo or the best
song (as well as the ability to imitate). If other females start going for good
songs then it becomes advantageous to have male children who can pick up a