Study: Empathy may be hard-wired in apes

ATLANTA, April 8 (UPI) -- A notable lack of aggression in a species of apes may be due to hard-wired brain structure that makes them mellower than other primates, a U.S. study says.

The discovery was made in bonobos, sometimes called pygmy chimpanzees, which are closely related to chimps but are strikingly less aggressive, The Washington Post reported Thursday.

"They are the only ape in our family that does not kill," said Brian Hare, an assistant professor who studies chimpanzees and bonobos at Duke University but was not involved in the study.

In contrast, male chimpanzees have been witnessed killing infants sired by other males and will often also stalk and kill outsider chimps.

Bonobos react to stress in a much more laid-back manner, Hare said, by sharing, playing and engaging in lots of sex.

"It's not like they never have antagonistic interactions," Hare said. "But it's a joke compared to what you see in chimpanzees."

James Rilling of the Yerkes National Primate Research Center, part of Emory University in Atlanta, studied detailed brain images of chimps and bonobos.

Bonobo brains, in comparison to chimp brains, displayed bigger, more developed regions thought to be vital for feeling empathy, perceiving distress in others and feeling anxiety, Rilling said.

One of those regions, the right anterior insula, is involved in generating empathy. People who have suffered damage to this region notably lack the ability to perceive how others are feeling, Rilling said.