Not many animals will use lethal aggression towards those in their own species, but two groups do - humans, and chimpanzees.
In this River to River segment, host Ben Kieffer talks with Iowa State University primatologist and anthropologist, Jill Pruetz. Pruetz was one of 30 international researchers who contributed to a story published in Nature that focuses on chimpanzees and aggression. The study analyzed 18 chimpanzee and four bonobo communities over five decades throughout Africa. Their main question: is aggression in primates caused by human interference or is it instinctual?
"I think it is something that is a natural behavior in chimpanzees; it really depends on the context, " she says. "I personally think that the rates are low."
Jill says that predicting aggression can be done by looking at density of primates and the number of males within the group (she has a large number of males at her site.) While she says that lethal aggression in chimps is often overstated, he has witnessed chimpanzee aggression and studied killing firsthand. While confident in the study's results, Pruetz is doubtful the origin of chimp aggression is officially settled.
"It's hard to say how humans have affected chimps historically," she says. "[The study is] a good move in that direction, [but] it doesn't seem to me...that it has settled the argument."