Professor of Anthropology Richard W. Wrangham signed bananas and books last night at a reception promoting his latest book, Demonic Males: Apes and the Origins of Human Violence.
The signing gathered some 180 anthropology students and others at the Harvard Museum of Cultural and Natural History.
Wrangham, one of the world's leading authorities on primate behavior, spoke about his field research on the great apes of Uganda and the latest theories of human evolution, suggesting that human violence has an evolutionary origin.
The two species most closely related to humans, chimpanzees and bonobos, are respectively the most and least violent of all mammals.
Male chimpanzees have been observed to exhibit a pattern of deliberate, vicious violence against their own species.
Wrangham's examples included rape and a behavior he terms "lethal raiding."
Male chimpanzees habitually leave the main community in groups, in order to sit on the end of the community territory and call out into the neighboring range.
If several chimpanzees from the adjoining community reply, the first group does nothing. But if they hear only one call, they will converge on their victim and beat them to death.
Chimpanzees, Wrangham said, will not attack unless the danger to themselves is negligible, and they become wildly excited during the attack.
This is significant, Wrangham said, because "humans and chimpanzees are the only two mammals that launch raids into other groups with the intent to harm the other group," Wrangham said.
Wrangham suggested that lethal raiding might be related to hunting. In other words, nature selects in favor of the violent chimpanzee because that animal would be a more successful hunter. It might be possible, then, to substitute a rival of the same species for prey in the mind of the chimpanzee.
Next to the chimpanzee, Wrangham places its sibling species, the pacifistic bonobo.
Male bonobos have not been observed to engage in lethal raiding, and incidents of violence against females are few.
Wrangham suggests that several factors contribute to the bonobos' relative pacifism.
First of all, bonobos live in larger and more stable groups. There is a better balance of power, and males are less likely to try to challenge the leaders.
Large groups also allow the bonobos to develop strong female-to-female alliances so that they can defend themselves against males when solicitations of sex become violent.
In addition, female bonobos conceal their ovulation so that males are less likely to fight over them.
"Chimpanzee females reveal their ovulation, and the result is mayhem," Wrangham said. Male chimpanzees know when females are fertile and often become violent.
And although bonobos, like chimpanzees, eat meat, they are almost never observed to hunt.
Although Wrangham declined to draw conclusions about humans based on his research among the great apes, he said he believes the similarities are important.
Wrangham suggested that there might be parallels between human war and violence against women and chimpanzee lethal raiding and rape.
"The deep lesson here is that the similarities we see in apes force us to see similarities in ourselves," he said
"Like chimps," said Wrangham, "we are ourselves a chimeric species. You can look in the face of a chimp and see both hostility and sympathy."
Yet like bonobos, human beings live in large groups and the females conceal ovulation.
"I don't want to suggest that we are bonobos any more than we are chimps," Wrangham said.
"It is simply that [looking at these apes] starts to give you a sense of how violence could possibly relate to chance in evolution," Wrangham continued.
"Patterns of violence come from deep within our brains, and we need to be aware of that."
According to David Pilbeam, Ford professor of the social sciences and the dean for undergraduate education, Wrangham's book is "well done and full of insights and provocative argument."
"I would like to see it form the basis of a rational, civil discussion on the interaction of 'biology' and 'culture,'" Pilbeam said.
Demonic Males: Apes and the Origins of Human Violence was co-authored by Dale Peterson.