June 17, 2008

Hugs And Kisses Reduce Stress In Chimps

Researchers have discovered that chimpanzees use hugs and kisses to reduce stress in chimps that were victims of aggression.

"Consolation usually took the form of a kiss or embrace," said Dr. Orlaith N. Fraser of the Research Center in Evolutionary Anthropology and Paleoecology at Liverpool John Moores University in England.

"This is particularly interesting," she said, because this behavior is rarely seen other than after a conflict.

"If a kiss was used, the consoler would press his or her open mouth against the recipient's body, usually on the top of the head or their back. An embrace consisted of the consoler wrapping one or both arms around the recipient."

In Tuesday's edition of Proceedings of the National Academy of Sciences, Fraser and colleagues noted that a warm embrace helped to reduce stress behavior such as scratching or self-grooming.

"This study removes doubt that consolation really does what the term suggests: provide relief to distressed parties after conflict. The evidence is compelling and makes it likely that consolation behavior is an expression of empathy," said Dr. Frans de Waal of the Yerkes Primate Center at Emory University in Atlanta.

What Fraser and colleagues found in their research is "perhaps equivalent to what in human children is called 'sympathetic concern,'" de Waal added.

But while chimps display signs of empathy, monkeys do not. And there is additional evidence to show that some birds and dogs also show lower signs of stress with a gentle touch.

Fraser and colleagues studied a group of chimps at the Chester Zoo in England from January 2005 to September 2006, recording instances of aggression such as a bite, hit, rush, trample, chase or threat.

The results show that "chimpanzees calm distressed recipients of aggression by consoling them with a friendly gesture," Fraser said.

Consolation was most likely to occur between chimpanzees who already had valuable relationships, she added.


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Proceedings of the National Academy of Sciences