Chimpanzees Wear Grass as Earrings?

In a classic case of “monkey-see, monkey-do”, chimpanzees copy a very human-like behavior in their own culture.

Julie, a chimp in Zambia’s Chimfunshi Wildlife Orphanage Trust sanctuary 
sets the newest trend for chimps in 2010 by wearing grass in her ear.
(Photo courtesy of Liz Simon / National Geographic)

Most people know that the chimpanzee is one of the most closely related animals to humans, but now there are new findings to show that this is truer than ever before. Chimpanzees have different adaptive cultures in their communities, similar to fads or trends in fashion. The “grass-in-ear behavior,” as scientists have termed it, serves no apparent purpose. The blades of grass appear to be ornamental like jewelry or fashion.

Observations

In 2010, Edwinvan Leeuwen began his study on a group of Zambian chimpanzees. van Leeuwen is a primate expert at the Max Planck Institute in The Netherlands. His team studied 700 hours of video footage to understand how the ‘grass-in-ear’ trend developed in four groups of chimps.

Julie, a chimp in Zambia’s Chimfunshi Wildlife Orphanage Trust sanctuary, was the first observed chimp to repeatedly put a stiff, straw-like blade of grass for no apparent reason in one or both of her ears. On subsequent visits, van Leeuwen saw that other chimpanzees in her group had started to do the same. Eight of the 12 chimpanzees in Julie’s group copied her behavior. The first to copy her was her son, Jack, followed by others she hung out with often.

van Leeuwen said, “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’. The observations show that there’s nothing random about individual chimpanzees sticking grass into their ears.”

Two of the chimpanzees kept up the custom even after Julie, the original inventor of this behavior, died. Watch the primates creating their own culture. 

Explanations

The scientists conclude that there are no genetic or ecological factors that influenced this behavior. Therefore, the only thing that would account for it is culture. The grass shows artistic conceptualization, pre-planning, tool-use and culture. It is as if the grass identifies chimps as members of a team or a social club.

van Leeuwen said, “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.”

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.

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