n of small populations from larger ones can accelerate evolutionary change, because a small population's average characteristics are likely to differ from those of the larger group from which it is drawn. Like much evolutionary theory, this is just applied common sense. But only recently has such common sense been applied systematically to areas of anthropology that have traditionally ignored it and sometimes resisted it. The result, when combined with new techniques of genetic analysis, has been a revolution in the understanding of humanity's past.
And anthropology is not the only human science to have been infused with evolutionary theory. Psychology, too, is undergoing a makeover and the result is a second revolution, this time in the understanding of humanity's present. Such understanding has been of two types, which often get confused. One is the realisation that many human activities, not all of them savoury, happen for exactly the same reasons as in other species. For example, altruistic behaviour towards relatives, infidelity, rape and murder are all widespread in the animal kingdom. All have their own evolutionary logic. No one argues that they are anything other than evolutionarily driven in species other than man. Yet it would be extraordinary if they were not so driven in man, because it would mean that natural selection had somehow contrived to wipe out their genetic underpinnings, only for them to re-emerge as culturally determined phenomena.
Understanding this shared evolutionary history with other species is important; much foolishness has flowed from its denial. But what is far more intriguing is the progress made in understanding what makes humanity different from other species: friendship with non-relatives; the ability to conceive of what others are thinking, and act accordingly; the creation of an almost unimaginably diverse range of artefacts, some useful, some merely decorative; and perhaps most importantly, the use of language, which allows collaboration on a scale denied to other creatures.
There are, of course, gaps in both sets of explanations. And this field of research being a self-examination, there are also many controversies, not all driven by strictly scientific motives. But the outlines of a science of human evolution that can explain humanity's success, and also its continuing failings, are now in place. It is just a question of filling in the canvas—or the cave wall.
The proper study of mankind human evolution
This article appeared in the Special report section of the print edition under the headline "The proper study of mankind"