The parasite theory, I think its main proponent has been Bill Hamilton, though I don't think he was, by any means, the first person to say it. And the more general sort of Red Queen notion; that's to say, that the reason why species have to evolve is because of the other species that are there competing with or feeding on, or being fed on by [them], or their parasites. I mean, the basic notion that we evolve because of other species evolving, the so-called Red Queen Model, on the basis that... it's a quotation from Alice, when the Red Queen says, 'Here, we have to run as fast as we can to stay in the same place.' That theory was given its name by Leigh van Valen, but it's been around for longer than that, actually, I mean, it's an old idea. But the specific parasite notion I think is primarily...

[Q] It's clearly in Fisher, I think, the...

Yes. The Mutation Theory, in one of its forms it goes back to HJ Muller. And Muller, I never met him, but he must have been the most gifted and original guy, of all the sort of colleagues of Morgan who developed the chromosome theory of heredity, Muller does seem to me to be the one who really did have bright and original ideas. One keeps on coming across ideas. And he formulated one mutation - sex is good for getting rid of mutations model. The person who I think, at the moment, is its main proponent and has done some very elegant formal mathematics to investigate it, is Alex Kondrashov. I'm rather happy about Alex, apart from the fact that he's a nice guy anyway. He... he was a Russian working in Russia at a time when you couldn't really do genetics very well, not evolutionary genetics, because it was still unpopular. And he was working in a department of cybernetics, apparently, he was meant to be a computer scientist. And his boss - I'm not sure of his name - somehow had got hold of a copy of my sex book, The Evolution of Sex. Alex says, 'I took it from him because I didn't think he was able to understand it and I thought I would.' He assures me that it was really my book that got him interested in sex. That makes me feel very pleased, you know, it's nice to know that you've been a spark to start somebody thinking. Alex is now... has a permanent job in America. But he, I think, has developed the formalism for what has to be the case, if one is to maintain sex on the mutation... getting rid of mutations argument. And it's largely as a result of his calculations that I was being rather definite in saying that I thought the load of mutations had to be very high. He, himself, thinks that it may be very high, and he's even doing experiments to try to show that it is. And other people are also trying quite hard to measure the load of mutations, it's not... not a trivial thing to measure.