Chimps as Fashionistas: Jewelry in the Primate World

African Chimpanzees show off their grass "jewelry" in an interesting

encounter (video courtesy of Barry Gordemer).

A group of Zambian chimpanzees are sticking a blade of grass in their ears. Are chimps experiencing their first “fad”?

In a recent study published in the Journal Animal Cognition, lead researcher Edwin van Leeuwen, a primate expert at the Max Planck Institute in the Netherlands said that “The grass-in-ear behavior is not far removed from a human fad. I’d say this could be the equivalent of people wearing earrings or certain kinds of hats.”

Doctor Leeuwen describes his goals as unearthing “the circumstances under which chimpanzees learn (socially), the conformist bias and the suggested conservative nature of their behavioral choices.”

Jewelry for Chimps?

The grass serves as a social symbol for some primates, Van
Leeuwen says. (Photo Courtesy of Barry Gordemer).

This “grass-in-ear behavior” is like jewelry or fashion. The research team studied 700 hours of video footage to understand how the ‘grass-in-ear’ trend developed in four groups of chimps.

The scientists found that there were no genetic or ecological factors that influenced this behavior, therefore, culture is the only thing that would account for the behavior. It is as if the grass identifies chimps as members of a team or a social club.

Van Leeuwen suggests that those animals that find a specific behavior somehow rewarding will continue to do so on their own, even if the chimpanzee they have learned it from is no longer around.  “The fact that these behaviors can be arbitrary and outlast the originator speaks to the cultural potential of chimpanzees.”

The Anthropology of Chimpanzees

Van Leeuwen says that when we look at these chimps who decided to make ear adornments part of their culture, what we are also seeing is one of the profound steps that our own ancestors took. It’s animal anthology at its finest. 

Although a blade of grass in the ear seems rather insignificant, we would not have modern society or any of the comforts that we have created for ourselves, without one of our ancestors having the idea of fashion, culture, and hitting things with rocks and sticks. 

“Monkey See, Monkey Do”

In 2010, van Leeuwen first noticed that the chimps repeatedly put a stiff, straw-like blade of grass for no apparent reason in one or both of her ears. The chimp, Julie, is in Zambia’s Chimfunshi Wildlife Orphanage Trust sanctuary. On subsequent visits, van Leeuwen saw that other chimpanzees in her group had started to do the same. “They spontaneously copied the arbitrary behavior from a group member. Chimpanzees have a tendency to learn from one another – clearly a case of ‘monkey see, monkey do’ in fact.”

Van Leeuwen says that “the observations show that there’s nothing random about individual chimpanzees sticking grass into their ears.”