OUR INNER APE
by Frans de Waal
Granta £17.99 pp272

“It is a truth universally acknowledged,” wrote Jane Austen, “that a single man in possession of a good fortune, must be in want of a wife.” The truism holds good among behavioural psychologists, albeit ploddingly bereft of Austen’s irony. A decade ago, the American psychologist David Buss canvassed 10,000 people in 40 cultures of the world to conclude that, naturally, it is the single woman who is in want of a single man of good fortune. Men, on the other hand, he claimed, are in want of youth, good skin and lustrous hair. Buss took this to mean that men are programmed to seek breeding potential, while women are after breadwinners. But the significance of bonding traits has ever been problematic, especially when the evolutionary biologists get to speculate.

Biologist Robert Sapolsky’s Monkeyluv has a fund of fascinating behaviours to report. We learn, for example, that the female olive baboon favours males that, in a fit of “displacement”, beat up other females and not their mates when they are angry. And there are female baboons that lure a pushy stud they don’t find attractive into the path of his worst male rival, giving the females the chance to sneak into the bushes and mate with the male they really fancy. But the interest of Sapolsky’s book is how his colleagues can flirt promiscuously with so many simultaneous explanations for human bonding.

What does a female want? A set of good genes? The contention was invariably illustrated by that old standby the peacock, strutting before the pea hen, or the stag showing off his big antlers. But Ronald Fisher, the British geneticist, long ago challenged the display argument by objecting that if the male has squandered so much on exotic plumage he can hardly have spent sufficient on keeping his immune system in good nick. He’s a bad bet.

Fisher has been in and out of favour over the years. But he recently received a boost from two Australian biologists who argued that females of some species look for fancy colour patterns in their males because, obviously, they desire attractive offspring. They subsequently discovered that sons of these attractive males are less likely to survive infancy than the plainer ones. The early mortality, moreover, had nothing to do with flashy types being a target of predators. High mortality rates occurred before growth of their finery. We were back to the significant cost of ornamentation. So, what is the ornamentation about?

Sapolsky sets forth the proliferating current explanations. One team of Swedish experts avers that it is a question of fashion. If the females of a species flock around a male with a green plume, then it simply catches on, like wearing baseball caps back-to-front. The female naturally wants her offspring to get the green plume. And so it goes on: ostentatious markings, argues another academic team, indicate freedom from parasites — good superficial health. Yet another team contends that females “have evolved to be able to differentiate between ornamentation that genuinely reflects good genes and the kind that suggests bad genes, or merely an acquired trait”. Like the woman who prefers the genuinely tall fellow to the titch in cuban heels.

Have the experts come up with anything truly profound about the human condition? David Buss claims that the most neglected aspect of sexual attraction in his human investigation was a woman’s need for kindness in a man. Frans de Waal’s Our Inner Ape supports this contention in a new and intriguing way. De Waal, a leading primatologist, has worked with chimpanzees, which are famously aggressive, and with bonobos, which are given to empathy. Both these primates possess DNA that is nearly identical to that of humans, and de Waal argues that homo sapiens inherits genetically both the violent competitive traits and the gentle ones. Bonobos greet colonies outside their own and spend their time grooming, playing games and having sex. De Waal is convinced that when we come to understand the evolutionary pressures that shaped bonobo society we will begin to comprehend how they managed to escape “what many people consider the worst scourge of humanity: our xenophobia and our tendency to discount the lives of our enemies”.

Animal behaviour as a guide to human behaviour, Sapolsky demonstrates, is an inexact science, and there are alternative explanations for our occasional capacity for peace and, more typically, for war. Richard Dawkins argued in The Selfish Gene that human beings have language and imagination, endowing us with the freedom to turn our genetic selfishness on its head. The last sentence of his book asserts: “We, alone on earth, can rebel against the tyranny of the selfish replicators.”

De Waal is unhappy with a scenario that describes our human inheritance as one of self-centred aggression masked by a thin and fragile crust of civilisation. He has, accordingly, put new life into a debate that appeared to be running out of steam. The wonder is that evolutionary biologists can still offer such disparate theories despite the impression they like to give that science speaks with a single and unerring voice.

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