A Smithsonian Q & A with E. O. Wilson

E.-O.-WilsonFrom Carl Zimmer's interview with E.O. Wilson, over at the Loom:

Q: Just to take one example that the critics raised, they talked about how inclusive fitness theory makes a prediction about sex allocation, about the investment in different sexes in the offspring. And they say this is something that inclusive fitness predicts and we’ve gone out and we’ve done a lot of tests to see if that’s true and they find these ratios in lots of animals as predicted by that theory. When they make that sort of argument, what’s your response?

A: It’s a little bit like Ptolemaic astronomy: epicycles will always give the exact results if you’re willing to add them. And in this case–I have pointed this out as well–there’s a flaw in the reasoning about the studies of investment, particularly in whether you invest more in males or females in the social insect societies.

If you have only one female who is queen in the colony, and if that queen has mated only once so that her offspring are that close, then you should see because of the implications of haploid/diploid, the way sex is determined in ants, bees, wasps. You should see a favoring of investment in new queens, over investment in males as measured by the amount of biomass. And that inequality does exist and it should be three to one investment in the weight. And that has been what is thought to be a very powerful argument.

However, this I believe has a major flaw in the reasoning. The colony wishes to make an investment in males versus females in numbers that would be most advantageous in having a female successfully mated, when they leave the nest to get mated, bees, ants, wasps. And therefore, the colony should be trying to get something closer to a one-to-one investment.

And since females are much bigger–they have to have all that fats and ovary and so on–and males are much smaller because in most of these social insects. All they have to do is find a female, deliver their sperm, and die. So the males are much smaller.

This means then that getting a one-to-one ratio in sex that is the same as you see throughout the rest of the animal kingdom, means that you will be having to invest much more in the females when you invest in males. And actually when you make that hypothesis, use that principle, which is the obvious one, then that comes closer to the actual figures we have in the biomass investment.

They [Wilson’s critics] may dispute that, but my point is that they did not by any means find a testing ground on which the old theory could stand or fall. It’s in my view a much simpler and more precise explanation to use the argument of one to one ratios of male and female.