They say that human's sexuality is pretty much exactly the same as the bonobos, we've just manufactured the idea that we're supposed to be monogamous and the areas of the world that this hasn't happened human sexuality is pretty similar to the bonobo's.
The lecturer today was just talking about how people think they're special compared to other animals (you know cause we build things etc.), and then mentioned how the chimps and bonobos, the two species closest to humans in terms of genes, run their societies based on violence and sex respectively. Then he said to think of ancient roman society . . . (bi, promiscuous and comparatively very violent)
crying shame this means they can't effectively protect themselves. Lower testosterone and smaller size in Bonobos compared to Chimps means they can't fight off threats like big cats. Good luck asking a leopard to come to your room