Frans de Waal’s Our Inner Ape is a good read. His main point is that people misunderstand both Darwinian evolution and our place among the apes— in both cases emphasizing aggression and violence. Backing up this view are the chimpanzees as we now know them: dominated by powerful males, and not above meat-eating, infanticide, murder, war, and rape.
This isn’t a balanced view of the chimps, but the main contrast de Waal draws is with the bonobos, who are like the Berkeley version of apes. They are matriarchal, relatively peaceful, and jaw-droppingly promiscuous— they use sex as social glue, using it to cement alliances, reconcile after a fight, even to express high spirits on discovering a food source. Both male-male and female-female sex is observed— indeed, the latter is the most frequently observed.
Our natural inheritance, therefore, is not limited to animal aggression; it also includes co-operation, empathy, and reconciliation. We are equally related to chimps and bonobos; yet our nature is not a middle point, but overlaps both ends. We can be more aggressive and warlike than the chimps as well as more pacific and empathetic than the bonobos.
Read enough studies of animal behavior and you may get a very poor impression of males— often brutish, murderous, and frankly caddish with their females. Both in nature and among humans, females can seem to be more peaceful, more level-headed— really the ideal citizens of the future. De Waal offers an observation to balance this picture: among monkeys and apes— including humans— males are much better at reconciliation. Females are peacekeepers: they go out of the way to avoid fights; but once they fight their relationships may be sundered indefinitely. Males are peacemakers: they fight very easily, but also reconcile quickly, restoring wounded relationships.
Another good book for widening one’s perspective: Dr. Tatiana’s Sex Advice to All Creation, by Olivia Judson, a survey of unusual sex practices from all of biology. There are some very strange behaviors out there; few generalizations about males and females hold for even all mammals, much less all animal life.