My latest read was Sex at Dawn: The Prehistoric Origins of Modern Sexuality. Very interesting book.
The summary is a bit NSFWish, so here goes:
The authors’ main thesis is that the standard narrative of human sexuality and how it evolved is totally wrong. The standard narrative goes something like this: A woman want to mate with a man who has a lot of resources and is monogamous with her, so when she gives birth the man will help her raise the child. Men want to mate with as many women as possible to spread his genetic material around, and he wants exclusivity with the women to be sure that the children they’re raising are his. This results in a “mixed strategy” of pair-bonding – one man, one woman.
A lot of the book is dedicated to tearing down this narrative. They talk about the “Flintstonization” of prehistory – the tendency to take the culture of today and project it into the past. They also talk about some studies and books that have been written that support the narrative and tear them down a bit.
Of course, it’s a bit hard to say what human culture was like before the advent of agriculture, but we can examine chimpanzees and bonobos (our closest ape ancestors), as well as primitive cultures today. In most models of human nature, chimpanzees are considered to be closest to humans, but bonobos (who were one of the last mammals to be studied in their natural habitat) are just as close. Bonobos and humans are the only species that have nonreproductive sex.
Anyway, I’ll jump to the punchline: their model proposes that our prehistoric hunter-gatherer societies were not monogamous at all, or even polygynous (one male, multiple females), but there was a lot of multimale-multifemale mating. This helped to solidify social relationships within tribes. (no group-living nonhuman primate is monogamous) The parental involvement “problem” wasn’t as much an issue, because if a women has a child and has had sex with a lot of men in the tribe, then they don’t know which one is actually the father and they all feel responsible for raising the child.
Under this model, Darwinian competition for mates is replaced with sperm competition – some of the chemicals in ejaculate seem designed to kill/prevent other sperm from fertilizing the egg.
So their point is that monogamy is certainly possible for humans, but the way we evolved makes it “unnatural” and very hard to do. Which is no huge surprise, given the myriad examples of adultery we hear about.
I always feel like I’m selling a book short a bit when I write a review, and this is especially true in this case. It’s very interesting, and has a surprisingly breezy and entertaining tone. (despite the fact that I knew nothing about evolutionary psychology) Highly recommended!