Researchers Believe Chimps Have Secret Handshakes

By Kelli Bender Aug 30th 2012

Handshakes aren't just for humans anymore. According to Live Science, the hand-holding behavior seen in chimpanzees during grooming is the animals' form of a secret handshake, and it changes among different groups of chimps.



Researchers have noticed that how these primates hold hands varies from group to group. No genetic or environmental factors have been found that could be responsible for the change, leaving cultural expression as a possible explanation.

The behavior being studied is called a hand-clasp. It's the action of two chimps grabbing onto each other's arm and raising them in the air in unison while they groom each other with their free hands. Groups of chimps approach the hand-clasp in different ways, changing where the hand is placed.

Scientists have also observed that the hand-clasp behavior of a certain group of chimps stays consistent through generations, suggesting that the "handshake" is passed down and learned by new members.

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"By following the chimpanzees over time, we were able to show that 20 young chimpanzees gradually developed the hand-clasp behavior over the course of the five-year study," Mark Bodamer, of Gonzaga University told the (U.K.) Daily Mail. "The first hand-clasps by young individuals were mostly in partnership with their mothers."

This behavior is not seen in all chimp groups. Many of them groom partners without the hand-clasping behavior. Hand-clasping was first seen in a Tanzania group of primates, and was also found in 15 other groups.

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Researchers studied the differences in hand-clasping behavior by observing chimps at the Chimfunshi Wildlife Orphanage Trust in Zambia. The Trust proved an ideal setting for research, because groups of chimps were separated from each other and included a mix of wild animals and those born in captivity. Even with these differences inside the groups, each group showed their own unique hand-clasping behavior, which all members shared and passed on.

"The indication might be that chimpanzees have the capacity at least to respond to their environment with more flexibility," Edwin van Leeuwen, a doctoral student at the Max Planck Institute for Psycholinguistics told Live Science. "It's social flexibility and that's of course what we definitely see in humans."

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