May 11, 1997
'You Scratch My Back, I'll Scratch Yours'
By DAVID PAPINEAU
Two books explore why humans are altruistic and why the shy but sexy bonobos are generous and fair
THE ORIGINS OF VIRTUE
Human Instincts and the Evolution of Cooperation.
By Matt Ridley.
295 pp. New York:
The Forgotten Ape.
By Frans de Waal.
Photographs by Frans Lanting.
213 pp. Berkeley:
University of California Press. $39.95.
volution by natural selection is a nasty business. Out there in the wild, animals of all kinds contend fiercely for scarce resources, and the meek leave no descendants to inherit their uncompetitive genes. But how then have we humans ended up so nice? True, we are not all saints, but it is a rare member of the species Homo sapiens who does not feel some impulse to lend a hand to those in need.
One ready answer would be that we are not slaves to our genes. We may indeed be products of biological evolution, separated from our chimpanzee cousins by a mere five million years of natural selection. But we are also creatures of culture, in whom civilization has instilled many characteristics that have nothing to do with animal competition. According to this way of thought, our niceness is just one of the many traits we get from our cultural nurture rather than our biological nature, along with literacy, litigiousness and a liking for rock 'n' roll.
However, the desire to explain human behavior in terms of evolution cannot be so quickly dismissed. The recent history of this idea testifies to its hardiness. Thirty years ago we had the ''naked apes'' and ''territorial imperatives'' of Desmond Morris and Robert Ardrey. Then there was E. O. Wilson and ''sociobiology.'' The last few years have seen the emergence of an influential school of ''evolutionary psychology.'' Whenever the biological approach seems about to collapse under the weight of criticism, it rises again with new strength, like a stubborn boxer whose efforts are only encouraged by each knockdown.
Modern advocates of the evolutionary approach have learned to avoid the mistakes of their predecessors. They no longer seek a direct biological meaning for every human foible, in the way that Desmond Morris would explain home decoration, say, as akin to a wolf marking its lair with its scent. Instead, contemporary ''evolutionary psychologists'' focus on the underlying mental mechanisms we have inherited from our evolutionary past. They accept that these mechanisms give rise to different patterns of behavior in different cultures. But at the same time, they argue, our inherited mentality places limits on what we can and cannot do. Any child can learn languages better than the best computer, but no human can beat a $2 calculator at multiplication. The obvious implication is that evolution has given us a mechanism for language, but none for mental arithmetic. More generally, our biological heritage means that some things come easily to humans, and others are very difficult.
Among the things that come easily to humans is niceness. Children don't have to be taught about good behavior. They catch on to concepts like sharing and playing fair almost before they can speak. But this brings us back to our original puzzle. How could humans possibly have evolved into such altruistic beings? If nice guys always finished last when our ancestors were scrabbling around for food on the African savanna, why does morality come so naturally to us now?
This is the question Matt Ridley aims to answer in ''The Origins of Virtue.'' Or, rather, he aims to provide a battery of answers. The evolution of altruism has been a topic of intense research for more than 20 years. While the biologically minded may still be a minority among social scientists, there are now enough of them to have produced a plethora of competing theories. Mr. Ridley is a distinguished British science journalist who proves an excellent guide to the current debate. Sometimes his eagerness to cover every angle means that different views are not always clearly distinguished, but he is never dull, and he illustrates the intricate logic of natural selection with many parables from ethology, anthropology and game theory.
Perhaps you are wondering why fancy logic is needed to explain altruism. Isn't the answer obvious? Wouldn't cooperative bands among our hunter-gatherer ancestors have fared better than individualists who tried to scratch out a living on their own? But this idea faces a telling objection. Although cooperation is undoubtedly beneficial, it is also evolutionarily unstable. It is open to exploitation by nasty mutants. Once an individual with selfish instincts is born into a hunter-gatherer band, it will take the benefit of any communal food but avoid the risk of catching it. So selfish individuals will leave more descendants, and soon enough the cooperative bands won't be cooperative anymore.
Still, given that we aren't all nasty nowadays, something must have prevented this outcome. The most popular theory is reciprocal altruism, more familiarly known as ''You scratch my back, I'll scratch yours.'' Suppose that some of our ancestors evolved an instinct to share food only with those who share with them, or, for that matter, to scratch fleas off the backs of only those who scratch theirs. Then they would get the benefits of cooperation but would be immune to exploitation, because they'd simply stop helping those who didn't reciprocate. Mr. Ridley explains how a widely disseminated series of computer models has convinced most theorists that this kind of logrolling instinct can well be favored by natural selection.
However, it seems unlikely that this is the whole story about human niceness. Many humans give to charity without any prospect of a payback. To explain this, Mr. Ridley considers a converse question: Why are humans often so vengeful? What's the point of waging vendettas when they only bring trouble in their train? Well, maybe actually waging vendettas is a bad idea, but to be known for your vindictiveness can be a great advantage, for then people will take care not to cross you. And maybe the surest way of acquiring a reputation for vindictiveness is actually to be vindictive. So perhaps vengeful dispositions evolved not because it is advantageous to be vengeful, but because it is advantageous to be thought so. Similarly with generosity. Even if openhanded generosity is in itself costly, perhaps it is the best way to acquire a reputation for generosity, which will then pay off because it advertises you as someone who can be trusted in a deal.
In his final chapter Mr. Ridley draws some political conclusions from his biological analysis. The state should keep out of human affairs and leave smaller communities of property owners to look after themselves. Our natural inclinations toward trust and mutual aid will insure fairness within communities, but attempts by governments to make us go beyond these inclinations will only breed resistance. As Mr. Ridley puts it, ''We are not so nasty that we need to be tamed by intrusive government, nor so nice that too much government does not bring out the worst in us.''
There is plenty of room, however, to accept Mr. Ridley's style of evolutionary theorizing without embracing his political philosophy. One difficulty with his argument is illustrated by the bonobos, the so-called pygmy chimpanzees that live south of the Congo River. The recent history of this species shows that we can't simply jump from claims about our evolutionary history to conclusions about our current character. The bonobos probably separated from the other chimpanzees only about 1.5 million years ago. Yet their character and social organization are now strikingly different.
The bonobos are best known as the sexy chimpanzees. Their most striking idiosyncrasy is their readiness to use sex as a social lubricant. Any tension within a bonobo group is normally resolved by a quick orgy, in which they all have sex with one another, in all positions and combinations. Yet, as Frans de Waal explains in the elegant photo-essay ''Bonobo: The Forgotten Ape,'' this is just one way in which they diverge markedly from the other chimpanzees.
Mr. de Waal's book is designed more for the coffee table than the research library. The text is spiced with interviews with prominent bonobo experts and illustrated with Frans Lanting's spectacular photographs of bonobos in the wild. But at the same time it does an excellent job of describing what is now known about these elusive primates. Mr. de Waal, a professor of psychology at Emory University and Research Professor at the Yerkes Regional Primate Research Center in Atlanta, is himself a distinguished primatologist, and he explains in detail how a social gulf has arisen between bonobos and their chimpanzee cousins. Where chimpanzee bands are dominated by males and often tainted by infanticide, the bonobos conform far more closely to the model of the cuddly chimp, being female-centered, socially egalitarian and free from any serious violence.
The moral for Matt Ridley's argument is obvious. If such radical changes in chimpanzee psychology can arise within 1.5 million years, there might well be a similar gap between our hunter-gatherer past and modern human psychology. Any psychological traits produced by our evolution on the savanna a few million years ago could easily have been washed out again in the intervening ages.
Apart from this point, there is in any case another, more fundamental objection to Mr. Ridley's political conclusions. He seems to assume that the biologically natural way is necessarily the best way. But this is a mistake. It is arguable that war and philandering are in some sense biologically natural, but this does not make them right. Nor does it make them inevitable. Evolutionary psychologists like Mr. Ridley tend to forget that evolution has blessed humans with one special biological ability.
Unlike most other animals, we aren't just bags of reflexes; we are able to reflect on our circumstances and to figure out the best thing to do. Maybe the right course of action doesn't always come easily, but often we can manage it. When we need to do multiplication, for example, we can make the effort or, better, build a calculator. For all the biological sophistication of Mr. Ridley's ideas, they don't show that we shouldn't make an effort in the political realm too, and build systems of government that can channel our basic moral reflexes in more sophisticated directions.
David Papineau, a professor of philosophy at King's College, London, is the editor of ''The Philosophy of Science.''
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