Sex at Dawn: The Prehistoric Origins of Modern Sexuality

In the field of evolutionary psychology, there's a basic proposition that seems to be taken as a fundamental tenet. In any male-female pair bond, the two halves have diametrically opposed interests. Men, in an effort to spread their DNA as widely as possible, are interested in multiple casual affairs, and are most threatened by physical infidelity, because it might mean they are duped into spending their resources on what are actually the offspring of other men. Women, on the other hand, have to invest heavily in each of their children because the energy-intensive gestation and feeding of infants falls to them. They want relationships that last so that they're able to ensure the best environment for their kids, and are most threatened by emotional infidelity, because it might lure away their partner for good. In Sex at Dawn, Christopher Ryan and his co-author, Cacilda Jetha, critically examine these ideas by looking at the behavior of our nearest animal relatives to come to an entirely different conclusion.

The way Ryan and Jetha see it, humans are naturally polyamorous and best served in a group where sex is exchanged frequently and without possession or jealousy. They make the point that while researchers searching for the roots of human behavior often compare humans to chimpanzees because of the closeness of the genetic relationship, we're equally as closely related to bonobos, who have much different social structures. They look to these and other members of the ape family as they compare and contrast things like vaginal position, common copulatory positions, size and shape of the male reproductive organs, and female vocalizations during intercourse (and more) in an effort to determine how human sexuality has actually evolved over time and what it means for society today.

This book was a bit of a mixed bag for me. I thought they made some good arguments, but the language often got a little jokey informal trying-to-be-cool. Either you're trying to make a serious argument or you're trying to write a book aiming at a pretty low common denominator to get more sales, and this seemed like it was trying to be both. It's possible to write about important concepts in an accessible way, I just wrote about how well Silent Spring did that exact thing, but this doesn't hit the mark. I also thought they came off a little one-sided in their highlighting of the few examples of cultures that don't subscribe to the monogamous or polygamous models, portraying them as nearly utopian. The reality is that for most people in most cultures in modern history, marriages are between one man and one woman with the expectation of exclusivity. That hasn't always worked well in practice, but it's likely that even members of cultures that don't follow the mainstream experience unhappiness and strife in their personal relationships. More frustratingly, they don't really present a solution beyond “burn it all down and start over”. It's an interesting look at the other side of evolutionary psychology, if you enjoy that sort of thing, but I wouldn't recommend it widely or whole-heartedly.