How did the transition happen?
We have this group, and there is a strong dominance hierarchy in it. There is that alpha male who can beat up everybody and chase away all males. He is not going to give up his power. Males on the bottom of the hierarchy cannot do much alone against this alpha guy, but they might be willing to try a different strategy.
It is well known that what occasionally happens with chimpanzees is provisioning females and exchanging food for a mating opportunity. The males start doing that, but it is not enough, because females can just take food and still mate with the alpha male. So we need something else. That something else that I included in the model was the idea of mutual choice.
In a sense, the whole species gets “self-domesticated” by the following process. Males are selecting females who are more and more faithful to them. And, simultaneously, females are selecting males who are better providers. We have this process known in biology as co-evolution, when changes are happening in two different groups.
You call this “the most important sexual revolution for our species.” Why?
For humans, the development of human offspring is very long. Chimpanzees, I think, become independent and able to live on their own by the age of three or four. In humans, it takes three or maybe four times longer. So, help is necessary. Males are the obvious source of this help.
Cooperation at all levels has been extremely important in human society. The easiest way to establish genes for cooperation and altruism is if these traits are directed toward your relatives. To do that, you need to know who they are. So, by establishing this pair bonding, it is not just that males help, but also the knowledge of the kinship networks allows for cooperative behavior.
What is your next big question?
I am always interested in what I view as the ultimate speciation event, the origin of our own species. There were a lot of social and behavioral changes, and not just genetic, physiological or developmental changes.
I have one very exciting project that I am trying to publish now that could explain the origin of our moral values and then also the origin of social complexity and the origins of chiefdoms, states and empires. Basically, I am looking at different things happening just before and soon after that transition from apes to humans.