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By Root 438 0

people are cleverer than chimpanzees, which is no great surprise, but it starkly poses the question: why? If Figan had had a bigger brain he might have seen what was coming. So the evolutionary pressure that Nick Humphrey identified – to get better and better at solving social puzzles, reading minds and predicting reactions – is all there in the chimpanzees and baboons, too. As Geoffrey Miller, a psychologist at the University of Stanford, has put it, ‘All apes and monkeys show complex behavior replete with communication, manipulation, deception and long-term relationships; selection for Machiavellian intelligence based on such social complexities should again predict much larger brains in other apes and monkeys than we observe.’48

There have been several answers to this puzzle, none of which entirely convinces. The first is Humphrey’s own answer, which is that human society is more complex than ape society because it needs a ‘polytechnic school’ in which young people can learn the practical skills of their species. This seems to me merely a retreat to the toolmaker theory. The second is the suggestion that alliance building among unrelated individuals is a key to success in human beings and that this complication vastly increases the rewards of intellect, which prompts the question: what about dolphins? There is growing evidence that dolphin society is based on shifting alliances of males and of females, so that, for example, Richard Connor observed a pair of males which came across a small group of other males that had kidnapped a fertile female from her group. Instead of fighting them for the female, the pair went away and found some allies, came back and, with superior numbers, stole the female from the first group.49 Even in chimpanzees, the rise of a male to the alpha position and his tenure there is determined by his ability to command the loyalty of allies.50 So the alliance theory once more seems too general to explain the sudden increase in human intelligence. Moreover, like most of these theories, it explains language, tactical thinking, social exchange and the like but it does not explain some of the things to which human beings devote much of their mental energy: music and humour, for example.

Wittiness and Sexiness

At least the Machiavelli theory proposes an adversary for the human brain that is its equal, however clever it gets. Few of my readers will need reminding of the ruthlessness that human beings can show when in pursuit of self-interest. There is no such thing as being clever enough just as there is no such thing as being good enough at chess. Either you win or you do not. If winning pits you against a better opponent, as it does in the evolutionary tournament generation after generation, then the pressure to get better and better never lets up. The way the brains of human beings have got bigger at an accelerating pace implies that some such within-species arms race is at work.

This is just what Geoffrey Miller argues. After laying bare the inadequacies of the conventional theories about intelligence, he takes a surprising turn.

I suggest that the neocortex is not primarily or exclusively a device for tool-making, bipedal walking, fire-using, warfare, hunting, gathering, or avoiding savanna predators. None of these postulated functions alone can explain its explosive development in our lineage and not in other closely related species … The neocortex is largely a courtship device to attract and retain sexual mates: its specific evolutionary function is to stimulate and entertain other people, and to assess the stimulation attempts of others.51

The only way, he suggests, that sufficient evolutionary pressure could suddenly and capriciously be sustained in one species to enlarge an organ far beyond its normal size is sexual selection. ‘Just as the peahen is satisfied with nothing less than a visually brilliant display of peacock plumage, I postulate that hominid males and females became satisfied with nothing less than psychologically brilliant, fascinating, articulate, entertaining companions.