I have often wondered what chimpanzees can teach us about protohuman behavior in our own
distant past. “Lucy” and her kind, and even older human ancestors had brains roughly the size of
modern chimpanzees, and may have behaved in similar ways. Now researchers are studying a
peculiar chimpanzee social behavior that may hold clues to our ancestors’ development of
simple forms of social culture. It seems that a few groups of chimps have developed handshakes
as part of their grooming habits.
Chimps have been observed holding hands, raising them over their heads while they groom one
another with their free hands. Grooming has long been understood to be a way for the animals
to bond with one another as well as a way to remove insects and other matter from their fur. The
hand holding may be an extension of the bonding process.
Not all chimpanzee groups practice handshaking. Some groups hold hands while individuals in
other groups grasp one another’s wrists. These local variations seem to indicate that each chimp
group has developed its own method of handholding, which suggests that genetic or
environmental conditions are not involved in developing the behavior.
Handshaking, or hand holding, was first observed in a group of chimps in Tanzania, and has now
been observed in at least fifteen other groups. The behavior is not confined to Tanzania,
however. For example, four different groups of semi-wild, rescued chimpanzees live at the
Chimfunshi Wildlife Orphanage Trust in Zambia.
Edwin van Leeuwen and his colleagues from the Max Planck Institute for Psycholinguists
watched the Chimfunshi Wildlife groups between 2010 and 2012. They found that two of the
four groups practiced handholding while the other two did not. Interestingly, one of the two
handholding groups held hands while the other group used the wrist-grasping method.
Interviews with workers at the sanctuary indicate that this behavior has been occurring for at
least nine years.
The handholding behavior is passed down to young chimpanzees, who usually begin by
practicing the handholding behavior with their mothers. In this way, the behavior is being
passed down from generation to generation.
There’s more information on the possible ramifications of this behavior, and pictures showing the
chimps engaging in hand holding, here