Paul Gauguin/Distributed by DIRECTMEDIA Publishing GmbH

Not enough biologists have taken the time to try to find out what actually happened, and that’s what I’ve done. I’ve shown that we know enough to know what steps led up to [eusociality.] Those steps themselves are very rare, and as a result, only a few come within reach of the power of group selection. Group selection will occur only under very special conditions, which I point out here. It has to do with protecting a nest and foraging out in order to bring food to the young, and that, without known exception, is the final step that was reached in eusocial groups, including humans. When that happens it’s possible for group selection to kick in, and then you can start getting something like authentic altruism among the members of the group.

We share this rare social behavior with certain invertebrates, but in this book, you describe sharing something else with them. While in New Guinea, you took part in the ant-sapsucker partnership by ingesting a droplet of excrement from a scale insect. Did that seal your bond with ants forever?

No. There was no surprise. I was just amused, you know, that I found a scale insect, the insect that ants get the sugary excrement from. I found one big enough, and when I stimulated it, it gave me a drop big enough to taste. It’s a little disconcerting for me to be so closely associated with ants when actually I’m addressing a very important part of fundamental biology.