The Radio West program hosted Vanessa Woods, a researcher who studies bonobos. Most people who are familiar with bonobos know about them because they're very promiscuous. As in, sex is about as common among bonobos as a handshake is among humans and serves much of the same social function (kind of, anyway).
The sex aspect isn't actually why she find bonobos interesting. It turns out they're also matriarchal and don't fight. When stresses threaten to erupt, bonobos have sex with each other to diffuse the situation. It's a completely different behavioral and chemical response to fighting, where instead of stress leading to an increase in testosterone and aggression, stress leads to an increase in cortisol and sexual behavior. Female bonobos stick up for one another, chasing out overly aggressive males. It's hypothesized this very different response to stress and very different group structure came about because bonobos evolved in a very productive region where food was plentiful and it wasn't possible, or even necessary, for males to monopolize resources.
These are our closest primate relatives, so it's hard not to think about the human implications of bonobo behavior. Humans are very different, obviously, in that we're monogamous and our response to stress is more like the chimpanzee in that we increase testosterone and aggression. Humans evolved in a less fertile, more challenging environment (which may have helped encourage the development of big brains) in which resources were monopolized by male-dominated groups. Still, the thinking about evolution in a situation where women are able to control resources is intriguing. We westerners live in a world of plenty, where women control their own resources. We women don't stick up for one another to the point of creating a matriarchal society, but we do strive for an egalitarian society with some of the characteristics of the matriarchal society (like no bullying). Assuming we can figure out how to maintain our standard of living, will the situation of plenty and security promote matriarchy, or simply egalitarianism?