Chimps teach each other to ‘shake hands’

Chimpanzees engage in social traditions which they pass on to the next generation, new research shows.

Researchers at the Gonzaga University and the Max Planck Institute focused on the ‘grooming handclasp’, whereby two chimpanzees clasp one another’s arms, hold them in the air and groom each other with their free arm.

Only some groups of chimpanzees do this, and it wasn’t known whether it was instinctive or learned behavior. Even amongst those that do use the grooming handclasp, there are differences in style: one group grasps each other’s hands during the grooming, while another folds their wrists together.

“We don’t know what mechanisms account for these differences. But our study at least reveals that these chimpanzee communities formed and maintained their own local grooming traditions over the last five years,” says Edwin van Leeuwen of the Max Planck Institute.

“Our observations may also indicate that chimpanzees can overcome their innate predispositions, potentially allowing them to manipulate their environment based on social constructs rather than on mere instincts.”

The study’s shown, though, that the handclasp is transmitted to the next generation, with 20 young chimpanzees gradually developing the behavior over the course of five years.

“The first handclasps by young individuals were mostly in partnership with their mothers,” says Mark Bodamer of Gonzaga University. “These observations support the conclusion that these chimpanzees socially learn their local tradition, and that this might be evidence of social culture.”