What do a vampire bat and a conservative have in common?

This morning David Willetts appeared on Andrew Marr's Start the Week discussing the altruism of vampire bats. Much to Guido's amusement.

But as Guido concedes, the point David was making was a serious one.

A vampire bat that collects more blood than it needs for its own uses will allow others to have some of the blood even if they are not related. The idea is that reciprocity is an evolutionary strategy. It is a deep part of our human nature.

Andrew Marr immediately pipes up that Willetts is taking E.O Wilson's side in his debate with Richard Dawkins. The former argues in favour of group selection - very roughly, that we act in ways to improve the chances of the group breeding - against Dawkins's support for kin selection - the idea that we act for our relatives.

You will be relieved to hear that you will not be required to take a position on this dispute in order to contribute to the political debate. Certainly I am relieved to hear it. Following the debate took me much further into study of the feeding and sexual habits of ants than I felt I was capable of understanding.

Under both group selection and kin selection it is clear that reciprocal altruism can prove a good evolutionary strategy. And this has important implications for conservatism. It means that a philosophy that prides itself on proceeding from human nature has to have a theory of society and not just of the individual.

I rang David and asked him to recommend some reading. He suggests Ken Binmore's Natural Justice.