It is fatally easy to read into the animal world what we would like to see in our own, to explain the human condition as an inevitable consequence of our biology. Even Charles Darwin was at fault. Hidden in his unpublished notebooks is the damning passage: ‘Origin of Man now proved – metaphysics must flourish – he who understands baboons will do more towards metaphysics than Locke.’ Darwin, at least, had the excuse of being nearly right nearly all the time. Most of his successors have no such defence. Herbert Spencer – who coined the phrase ‘the survival of the fittest’ – was in favour of arranging society on Darwinian lines. Not surprisingly, his ideas were popular with Andrew Carnegie and his fellow steel magnates. Konrad Lorenz saw humans as ‘killer apes’, which may have explained his own flirtation with the Nazis.
Until recently, the study of animal behaviour was little more than a set of loosely-connected anecdotes. It has been transformed by the rebirth of one of the oldest techniques in biology. Comparative anatomy is what convinced Darwin that we share ancestors with other animals. He was so confident of the evidence of common descent in the physical similarity of men and apes that he dared to say in his second book what he could only hint at in his first: ‘Man still bears in his bodily frame the indelible stamp of his lowly origins.’ Now there is a new science of comparative biology. The study of the order of the bases in the DNA is just anatomy writ small, plus an enormous research grant. Even students of animal behaviour are now using the comparative approach. By dissecting patterns of behaviour in creatures whose affinity is revealed by what genes they share, we can learn a lot about how they, and their way of life, evolved. Thus, primates living in groups tend to be promiscuous, while those that have more lonely lives form faithful pairs. The difference in size between males and females fits well with the extent of polygamy; and what seems in some species to be the disgraceful behaviour of females devouring their own young is in fact a sensible way of dealing with the jealousy of a promiscuous male who would otherwise do the job for them. All this has done a lot to help us understand the living world. The important question is whether it does anything to illuminate ourselves. Is it really the case that, to quote W.S. Gilbert, ‘Darwinian man, though well-behaved, is really but a monkey shaved’? Generally speaking, Jared Diamond believes that it is.
He has a mass of up-to-date and well-presented evidence to support his views. The double helix of DNA is tough stuff. By boiling up together the DNA from different species and allowing the mixture to cool, a hybrid molecule containing one strand of genetic material from each is formed. The stability of this bastard substance depends on how much of the DNA message of the two species is held in common, giving a cheap and easy way of testing how different they might be. For humans and chimps, the results are startling: 98.4 per cent of our instruction manual is identical – only a little less than for chimps and their almost indistinguishable relatives, the pygmy chimps. The chimp-human triangle is what gives the book its title: Diamond suggests that, were it not for anthropocentrism, the two chimpanzees and ourselves would be classified together. Linnaeus, the father of taxonomy, did almost as much when he accepted orangutans into our own family as Homo sylvestris – man of the woods.
The shaved monkey approach certainly gives some insights into the human condition. It provides a hint of what human sexuality might have been before we invented guilt. Our close relatives have very different life-styles. From the human perspective, chimps are deplorable, but gorillas dull. A male chimpanzee copulates hundreds of times with dozens of females each year. The faithful gorilla, on the other hand, has to wait for four years after his partner has given birth before she is ready to mate again. Not surprisingly, there is intense competition among gorilla males for access to females. A successful male may accumulate half a dozen mates – which leaves a number of male gorilla wallflowers out in the cold and anxious to fight for their reproductive rights. This conjugal battle means that male gorillas have evolved to be twice the size of females. The chimpanzee’s more relaxed life-style takes the pressure off sexual aggression, and males and females weigh about the same.
The argument from anatomy suggests that humans, with men just a little bigger than women, have a history of mild polygamy intermediate between chimps and gorillas. If tribal peoples are any guide, polygamy is greater in societies which have invented private property, as women prefer well-endowed mates. When wealth is concentrated into a few hands life may become like the gorilla’s, with a few males monopolising the females. The philoprogenitive Moulay Ismail the Bloodthirsty of Morocco admitted to 888 children, and families of eighty are common among successful males in the Third World (which means, of course, that there is a substantial underclass of men who have no children at all). Fortunately, perhaps, we in the West seem to be evolving in the chimpanzee direction, with most men having at least a chance of finding Miss Right.
Diamond points to other skirmishes in the battle of the sexes, some of which suggest a more salacious past for humankind. One way for a male to displace another is simply to flood out his predecessor’s contribution with sperm of his own. Chimpanzees, the Lotharios of the primate world, have enormous testes, while gorillas, in spite of rumours to the contrary, are far less well endowed. Humans, surprisingly enough, are not too different from chimps in this respect – which may say some startling things about our past. In penis size, man stands alone, but why we should be so well equipped is a mystery. Diamond has some remarkable stories about phallocarps, the formal attire of the well-dressed Papuan.
The evolutionary pressure of sex may (perhaps) explain a lot more about the way we behave, and Jared Diamond does not hesitate to roam on the wilder shores of sexual speculation. Darwin suggested that human races look so different for the same reason as peacocks have long tails: not because they have evolved to fit the place in which they live, but because of arbitrary choices by women, who prefer the looks of one man over another, so that his genes prevail. Women’s sense of male beauty is capricious and varies from place to place, so that, in time, the peoples of the world diverge. Diamond makes much of women’s choosing men like themselves in intelligence, colour and – strongest of all – length of the middle finger, but, like Darwin, is less successful in the case he makes for their importance in our evolution.
Sexual enthusiasts make much of the currently fashionable ‘handicap principle’: that males evolve cripplingly expensive ornaments to demonstrate to potential spouses that their genes are good enough to bear the cost. Diamond takes it further. Handicapping, he suggests, explains drug abuse. Men take alcohol, tobacco or heroin to demonstrate to women how tough they are, how their constitutions can manage mistreatment and how they might make excellent fathers as a result. One of his Indonesian field helpers, a fitness freak, took refreshing draughts of kerosene to prove his desirability. Jared Diamond uses this ingenious theory to explain one of the most baffling findings of modern anthropology: the discovery of small tubes in the tombs of Maya Indians. These, he suggests, were used for ritual enemas of toxic drugs that would guarantee instant intoxication and a widely admired statement of sexual prowess.
An obsession with sex is universal among animals. There are, of course, many attributes which are uniquely human, but Diamond traces many of these to animal roots as well. No non-human can speak; but many can transmit messages. Vervet monkeys even have a vocabulary, with distinct calls to warn their troop of different dangers – big cats, or eagles. The idea of teaching chimpanzees to speak, or at least to use symbols, is one of the great blind alleys of behavioural research. Samuel Butler warned of the problem. Hearing of a Victorian attempt to teach a dog sign language, he commented: ‘If I was his dog, and he taught me, the first thing 1 should tell him is that he is a damned fool!’ Diamond takes a more lenient view. He points out, too, that although art might seem unique to ourselves, several species of animal have exhibited and sold their work. William de Kooning, having been fooled into praising an abstract by an elephant, retorted: ‘That’s a damned talented elephant!’
The last third of the book moves away from the excesses of our evolutionary past, and lakes a more sober view of recent history and of what it might hint about the future. Economic progress does not always lead to contentment. The beginning of agriculture ten millennia ago led to a fall in the standard of living of most of those involved: so much so that the mean height of the ancient Greeks dropped by several inches immediately after they took up the new economic system. Agriculture may also have marked the beginning of another uniquely human trait: social class and the inheritance of wealth. Skeletons of the first farmers from as far apart as Mycenaea and Indiana show that the wealthy were healthier and, probably, happier than the mass of the people: a situation which has not changed.
The concentration of resources into a few hands soon led to another distinctively human attribute, nationalism. At least in Diamond’s view, this has within it the unavoidable seeds of genocide. He describes the destruction of the Tasmanians and the Armenians, and contrasts this with the relative mildness of even the most murderous among other primates. Perhaps our technology has outstripped our evolved ability to deal with its consequences.
The Third Chimpanzee is literate, informative and impassioned: it well deserves the Science Book Prize. Its central message, however – that humans are constrained by their evolutionary past – is surely less startling than the author makes out. The big shock was in 1859, when The Origin really did change our views of the human condition. The nature of humanity is not coded in our genes: as Jared Diamond’s book so brilliantly demonstrates, the attributes which distinguish us from chimpanzees (or from potatoes) have to do with knowing our history and speculating about our future – and there are no genes for these.