Matt Ridley

equivalent to a day and a half in the life of bacteria. Moreover, until very recently the life of a European was essentially the same as that of an African. Both hunted meat and gathered plants. Both lived in social groups: Both had children dependent on their parents until their late teens: Both used stone, bone, wood, and fiber to make tools: Both passed wisdom down with complex language. Such evolutionary novelties as agriculture, metal, and writing arrived less than three hundred generations ago, far too recently to have left much imprint on my mind.

There is, therefore, such a thing as a universal human nature, common to all peoples: If there were descendants of Homo erectus still living in China, as there were a million years ago, and those people were as intelligent as we are, then truly they could be said to have different but still human natures.' They might perhaps have no lasting pair bonds of the kind we call marriage, no concept of romantic love, and no involvement of fathers in parental care.

We could have some very interesting discussions with them about such matters. But there are no such people: We are all one close family, one small race of the modern Homo sapiens people who lived in Africa until 100,000 years ago, and we all share the nature of that beast.

Just as human nature is the same everywhere, so it is recognizably the same as it was in the past: A Shakespeare play is about motives and predicaments and feelings and personalities that are instantly familiar. Falstaff 's bombast, Iago 's cunning, Leontes ' s HUMAN NATURE

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jealousy, Rosalind 's strength, and Malvolio ' s embarrassment have not changed in four hundred years. Shakespeare was writing about the same human nature that we know today. Only his vocabulary (which is nurture, not nature) has aged. When I watch Anthony and Cleopatra, I am seeing a four-hundred-year-old interpretation of a two-thousand-year-old history. Yet it never even occurs to me that love was any different then from what it is now: It is not necessary to explain to me why Anthony falls under the spell of a beautiful woman. Across time just as much as across space, the fundamentals of our nature are universally and idiosyncratically human.

THE INDIVIDUAL IN SOCIETY

Having argued that all human beings are the same, that this book is about their shared human nature, I shall now seem to argue the opposite. But I am not being inconsistent.

Human beings are individuals. All individuals are slightly different. Societies that treat their constituent members as identical pawns soon run into trouble. Economists and sociologists who believe that individuals will usually act in their collective rather than their particular interests ( 'From each according to his ability, to each according to his needs ' ' versus 'Devil take the hindmost') are soon confounded: Society is composed of competing individuals as surely as markets are composed of competing merchants; the focus of economic and social theory is, and must be, the individual.

Just as genes are the only things that replicate, so individuals, not societies, are the vehicles for genes. And the most formidable threats to reproductive destiny that a human individual faces come from other human individuals.

It is one of the remarkable things about the human race that no two people are identical. No father is exactly recast in his son; no daughter is exactly like her mother; no man is his brother 's double, and no woman is a carbon copy of her sister—unless they are that rarity, a pair of identical twins. Every idiot can be father or mother to a genius—and vice versa. Every face and every set of fin-

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gerprints is effectively unique: Indeed, this uniqueness goes further in human beings than in any other animal. Whereas every deer or every sparrow is self-reliant and does everything every other deer or sparrow does, the same is not true of a man or a woman, and has not been for thousands of years. Every individual is a specialist of some sort, whether he or she is a welder, a housewife, a playwright, or a prostitute: In behavior, as in appearance, every human individual is unique.

How can this be? How can there be a universal, species-specific human nature when every human being is unique? The solution to this paradox lies in the process known as sex. For it is sex that mixes together the genes of two people and discards half of the mixture, thereby ensuring that no child is exactly like either of its parents: And it is also sex that causes all genes to be contributed eventually to the pool of the whole species by such mixing. Sex causes the differences between individuals but ensures that those differences never diverge far from a golden mean for the whole species.

A simple calculation will clarify the point: Every human being has two parents, four grandparents, eight great- grandparents, sixteen great-great-grandparents, and so on: A mere thirty generations back—in, roughly, A.D. 1066—you had more than a billion direct ancestors in the same generation (2 to the power of 30): Since there were fewer than a billion people alive at that time in the whole world, many of them were your ancestors two or three times over. If, like me, you are of British descent, the chances are that almost all of the few million Britons alive in 1066, including King Harold, William the Conqueror, a random serving wench, and the meanest vassal (but excluding all well-behaved monks and nuns), are your direct ancestors: This makes you a distant cousin many times over of every other Briton alive today except the children of recent immigrants: All Britons are descended from the same set of people a mere thirty generations ago. No wonder there is a certain uniformity about the human (and every other sexual) species. Sex imposes it by its perpetual insistence on the sharing of genes.

If you go back further still, the different human races soon HUMAN NATURE

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merge. Little more than three thousand generations back, all of our ancestors lived in Africa, a few million simple hunter-gatherers, completely modern in physiology and psychology.' As a result, the genetic differences between the average members of different races are actually tiny and are mostly confined to a few genes that affect skin color, physiognomy, or physique. Yet the differences between any two individuals, of the same race or of different races, can still be large. According to one estimate, only 7 percent of the genetic differences between two individuals can be attributed to the fact that they are of different race; 85 percent of the genetic differences are attributable to mere individual variation, and the rest is tribal or national. In the words of one pair of scientists: 'What this means is that the average genetic difference between one Peruvian farmer and his neighbor, or one Swiss villager and his neighbor, is twelve times greater than the difference between the 'average genotype ' of the Swiss population and the 'average genotype ' of the Peruvian population: ''

It is no harder to explain than a game of cards. There are aces and kings and twos and threes in any deck of cards. A lucky player is dealt a high-scoring hand, but none of his cards is unique: Elsewhere in the room are others with the same kinds of cards in their hands. But even with just thirteen kinds of cards, every hand is different and some are spectacularly better than others: Sex is merely the dealer, generating unique hands from the same