Someone asked me the other day if I wouldn't like to be a woman, just to see what it was like. Sure, I'd love to try it, I said, for a day or two. Imagine seeing the world from the other side, seeing how men assess you and wielding power over them with a glance. Or if you're a woman, imagine being a man, and knowing first hand that we truly are apes, subtler and more complex, to be sure, but unmistakably apes.
Then I read a paper published this week and imagined being both at once.
It might sound weird, but biologists do this sort of thing all the time. For one thing, it cuts to the important questions about sex: whether it is better, in evolutionary terms, to be a female or to be a male. For another thing, biologists just like thinking about sex.