Such a gene would be passed on to all the offspring instead of to only half the offspring, as happens in ordinary sexual reproduction, therefore such a gene would double in frequency in every generation, and really, in an extremely short space of time, the whole species will be taken over by ameiotic parthenogenesis. Now, this isn't an imaginary scenario, I mean, there are organisms out there that do exactly that, including quite complex organisms. The ones closest to ourselves are lizards. Some lizards are... the whole species consists of a set of genetically identical females, all producing offspring genetically to themselves, no males. And you get these both in Europe and in America. So it's perfectly possible, the problem is, why doesn't it happen? It mean, it's really quite a severe problem that, in the short run, parthenogenesis has this very strong, twofold advantage, and yet the great majority of organisms still do it sexually rather than parthenogenetically. So I think it clearly did present a problem.

[Q] That, of course, presupposes that the parthenogenetic female is capable, economically, of having the same number of offspring as a sexual female would. If the sexual female got a lot of help from her mate and had twice as many offspring, the problem wouldn't arise, would it?

No, that's absolutely right, and that's why I wanted to talk about codfish and not humans, because humans, at least there's the idea that males help to look after their children, I'm not sure that it's really true. But in any species in which the male really contributes as much as the female to feeding and raising the young, then the argument wouldn't apply. It also, it's quite important that it did not apply to the time of the origin of sex, because the first organisms reproducing by producing gametes which then fuse, were what we call isogamous, i.e. equal gametes, there was no differentiation between eggs and sperm, it was just a fusion of two equal sized cells. And if you sit down with a pencil and paper and think about that, there isn't, any longer, a twofold advantage of abandoning sex. So it's really a problem that in the form I presented it, of the maintenance of sexual reproduction, rather than its origin, and it's a problem which applies only to organisms, as you say, in which males don't contribute very much.