Six million years ago, scientists propose, human beings diverged from our closest living relatives, the chimpanzees and the bonobos.

Nobody knows much about our common ancestor. We can, however, look to our two closest relatives, as well as other primates, to help us make sense of human nature and potential.

The vast majority of primates are socially gynocentric. That is, the core of the group is female. The males, less consequential to group survival, but needed for diversifying the gene pool, tend to wander.

Female primates tend to limit the number of males in their group, since males do little to care for the young, and spend too much time fighting with other males and harassing females for sex.

Male human anthropologists have in the past projected their own sexual fantasies and political interests onto primate behavior, calling the gynocentric arrangement a “harem” — as if the females are the sexual servants of the male, and the male is at the center of importance. But it is the females who decide whether an outside male will gain entry into a group. Rhesus macaques limit the group ratio to one male for every six females. Howler monkeys allow only one male for every ten females.

Females bond with other females first and foremost. But intra-female conflict and hierarchies still exist in various degrees, depending on the species. Females fight with each other over food, sexual behavior, and rights of possession of their young. The females also sometimes fight as a group with females of another matriline. But females of diverse matrilines will drop all differences with one another to counteract the threat of male aggression. Females form instant coalitions when a male attacks a female, or insists on sex with an obviously uninterested female, or when a male threatens the safety of an infant.

The females of species with unpredictable female loyalties and high intra-female conflict are, not surprisingly, especially vulnerable to the abuse and harassment of the bored and wandering males.

Female solidarity among bonobos is particularly strong, and among chimpanzees particularly weak. Bonobos construct a sisterhood outside of bloodlines that is highly ritualized, and is effective at keeping male aggression to a minimum. Male murder of infants is a constant threat among many species of mammals, including primates, but is unheard of among the bonobos.

In contrast, female chimpanzees tend to live much more independently of one another, their hierarchies tend to be formed through aggression, and the bonds created are tentative. Female chimpanzees are not dependable in coming to one another’s aid when a male attacks. Sometimes they do, and sometimes they don’t.

Among bonobos, warfare is very rare. Among chimpanzees, the males frequently wage war, sometimes entirely killing off the enemy. Bonobos are mostly vegetarian. Chimps eat meat. Bonobos are famous for their active sex lives. Although promiscuous, chimpanzees do not bond through sex as the bonobos do.

Fossil evidence suggests that the ancient species that led to modern bonobos, chimpanzees, and humans most closely resembles bonobos. That means modern day humans probably didn’t evolve from a chimp-like ancestor. We have simply been trying to imitate the chimpanzees, adopting the worst of their habits, these past few thousand patriarchal years.

— Adriene Sere

(info from Natalie Angier’s book Woman)