Why is it that Hamilton, having had the sort of central notion, really ran with it, really made it an important part of our biological understanding. Whereas Haldane had the notion and did nothing with it, I understood the notion and did nothing with it. And I do think, I have to put it down, to some extent, to political and ideological commitment. Hamilton had the advantage over us, in a sense... a) that he was passionately interested in social insects and knew something about them and wanted to explain them. He saw them as a problem to be explained. And he had, clearly, no reluctance in his mind about the idea that notions about the evolution of altruism in social insects, might possibly have a relevance to humans. Neither Haldane nor I knew anything much about social insects at that time, though Haldane did become interested in them later. But more importantly, we, at that time, and we're now talking about '56, '57, I suppose when we were discussing this idea, if you look at it in the context of where Haldane publishes it, in an article in New Biology, it's very much in the context of trying to understand human behaviour and human altruism, and people going out and winning the VC or joining monasteries or what you will. And neither he nor I at that stage were at all willing to entertain the notion that such behaviour would be anything other than culturally determined and influenced. We were, I think, very reluctant, as Marxists would be, to admit that anything genetic might influence human behaviour. And I think that we didn't say consciously to ourselves that this would be un-Marxist so we won't do it, that's not the way that the mind works; but I think it was a path that our minds were not, so to speak, prepared to go down, in a quite almost unconscious sense, whereas Bill was very prepared to go down it. And he also had the natural history background and knowledge to enable him to go down it, which we both lacked. And so what I'm really try to say is that to make big breaks in science, which Hamilton did, it's not enough to have the technical understanding of some technical point, you've got to have the - it's got to fit in with your world view that you should pursue this road, and I don't think it did for Haldane and myself at that time. It would have done later.