In the contemporary imagination kindness is a puzzle requiring a solution. Looking after Number One makes sense: looking after everybody else for anything other than purely selfish gain is unimaginable. To the cynic, altruism must be just one more move in the great game of life.

There is a fine line between cynicism and neo-Darwinism. Darwinians have always been more than puzzled by altruism. To them, it makes even less sense. If evolution through natural selection is the fundamental truth of biology, how could such a disadvantageous strategy have arisen? Since altruism requires sacrifice, there does not seem, on the face of it, to be anything in it for the individual.

Because we have minds, you might say, we can free ourselves from our biological destiny. But the problem does not arise, initially, from humans. Animals from amoebae to elephants exhibit behaviour that can only be described as altruistic. Monkeys shriek and gazelles leap to warn of the presence