Monkeys Hug to Head Off Conflict, Study Finds

Mason Inman
for National Geographic News

March 2, 2007

Like Ari "Hug It Out" Gold on HBO's Entourage, spider monkeys reportedly use well-placed embraces to ease group tension.

But unlike Jeremy Piven's slimy superagent, the monkeys use hugs—plus the occasional French-style cheek-to-cheek touch and a bit of mutual armpit sniffing—at the start of a large meeting, presumably to keep things from getting aggressive in the first place.

Spider monkey groups continually split apart into subgroups and then later come together again.

Even among monkeys that know each other, these reunions can be full of tension and uncertainty about what the others will do, and the gatherings sometimes escalate into aggression.

"These embraces are used to try to avoid some of the uncertainty" between the groups and return quickly to everyday activity, said the leader of the study, primatologist Filippo Aureli of Liverpool John Moores University in the United Kingdom.

Although the embraces only last a moment, "they speed up that process," Aureli added.

Aureli and his colleagues noted that the monkeys that hugged rarely became belligerent toward each other or other monkeys during a period of fusion.

The study is based on observations of wild black-handed spider monkeys (Ateles geoffroyi) in a forest on Mexico's Yucatán Peninsula and was published recently in the journal Biology Letters (Mexico map).

(Related: "Monkeys Show Sense Of Fairness, Study Says" [September 17, 2003].)

Who's a Huggy Monkey?

Groups that regularly split apart and come together can be cliquish, and that can often be a cause of conflict at reunions, the study found.

"Individuals can move away to avoid conflicts over resources [such as food] or the decision of where to go," Aureli said.

But eventually the monkeys run into each other in the forest or have to come together to defend the area against invaders.

Often just one pair of monkeys embraces, and this diffuses the situation for both groups, the study says. But it's not clear yet whether certain monkeys tend to take on that role or whether it is more random.

"It could be that you have two ambassadors," Aureli said. "They go and do their thing, and then there's no problems for anybody else."

Insights Into Human Behavior?

Primate-behavior expert Patricia Wright of Stony Brook University in New York State called the project "a great study."

Before this study, "there wasn't a lot of evidence that embracing is a way to diffuse tension and show that they're equals," the anthropologist said.

"I think that's crucial. It seems more like an equal-to-equal, friendly thing."

This kind of work could put human handshakes and hugs in a new light, said Wright, who is a member of the National Geographic Society's Conservation Trust. (National Geographic News is part of the National Geographic Society.)

"There are a lot of methods to alleviate tension, and they vary between species," Wright said.

"The bonobos use sex, for example. We don't see that in any other primates.

"And the hugs are like that too," since they're used only by spider monkeys—and ourselves.

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