The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [170]
The idea is hard to grasp at first, so a thought experiment may help. Imagine two primeval women, one of whom develops at the normal rate and the other of whom has an extra neoteny gene, so that she has a hairless body and is large brained, small jawed, late maturing and long lived. At the age of twenty-five, both are widowed; each has had one child by their first husband. The men in the tribe have a preference for young women and twenty-five is not young, so neither stands much chance of getting a second husband. But there is one man who cannot find a wife. Given the alternatives, he chooses the younger-looking woman. She goes on to have three more children, while her rival barely manages to rear the one she already had.
The details of the story do not matter. The point is that, once males prefer youth, a gene for delaying the signs of ageing would generally prosper at the expense of a normal gene, and a neoteny gene does exactly that. The gene would probably make the woman’s sons appear neotenized as well as her daughters for there is no reason that it should be specific to the female sex in its effects. The whole species would be driven into neoteny.
Christopher Badcock of the London School of Economics, who unusually combines an interest in evolution and an interest in Freud, has proposed a similar idea. He suggested that neotenous (or, as he calls it, paedomorphic) traits were favoured by female choice, rather than male choice. Younger males, he suggests, made more co-operative hunters and therefore females that wanted meat picked younger-looking men. The principle is the same: neotenous development is a consequence of a preference for it in one sex.59
This is not to deny that bigger brains themselves brought advantages in Machiavellian intelligence or language or seductiveness. Indeed, once these advantages became clear, men who were especially fussy about picking youthful-looking women would be most successful because they would sometimes be picking neotenous, big-brained women and therefore would have more intelligent children. But it does suggest an escape from the question: why did it not happen to baboons?
However, Miller’s sexual selection idea suffers from a near-fatal flaw. Remember it presupposes sexual choosiness by one or other sex. But what caused that choosiness? Presumably, the cause was the fact that men took part in parental care, which gave women an incentive to confine probable paternity to one man and gave men an incentive to enter into a long-term relationship so long as they could be certain of paternity. Why then did men take part in parental care? Because by doing so they could increase the chances of rearing a child more than by trying to seek new partners. The reason for this was that children, unusual for ape infants, took a long time to mature and men could help their wives during child-rearing by hunting meat for them. Why did they take a long time to mature? Because they had big heads! The argument is circular.
That may not be fatal to it. Some of the best arguments, like Fisher’s theory of runaway sexual selection, are circular. The relationship between chickens and eggs is circular. Miller is actually rather proud of the theory’s circularity, because he believes that we have learnt from computer simulation that evolution is a process that pulls itself up by its bootstraps. There is no single cause and effect, because effects can reinforce causes. If a bird finds itself to be good at cracking seeds, then it specializes in cracking seeds, which puts further pressure on its seed-cracking ability to evolve. Evolution is circular.
Stalemate
It is a disquieting thought that our heads contain a neurological version of a peacock’s tail – an ornament designed for sexual display, whose virtuosity at everything from calculus to sculpture is perhaps just a side-effect of the ability to