Chimpanzees develop a fashion trend

For the first time, a troop of chimpanzees have been observed participating in a fad, a meme, or actually a fashion statement. The trend is to wear a blade of grass sticking out of one ear. It’s become a tradition among chimps of one troop in Zambia. This behavior was written up by Edwin van Leeuwen of the Max Planck Institute in the Netherlands. It started when a chimp named Julie put grass in one ear. Seven of the 11 chimps in her troop were soon wearing grass in one ear, and continued even after Julie’s death. There is no known advantage to grass in the ear, especially in just one ear.

To figure out if this was really a tradition, and not just chimpanzees sticking grass in their ears at random, van Leeuwen and his colleagues spent a year observing four chimp groups in Chimfunshi Wildlife Orphanage Trust, a sanctuary in Zambia. Only one troop performed the grass-in-ear behavior, although all of the chimps lived in the same grassy territory. There’s no genetic or ecological factors, the scientists believe, that would account for this behavior -- only culture.

Lydia Luncz, a primatologist at the Max Planck Institute in Leipzig, Germany, who was not involved with the research, agrees. This study shows how the chimpanzees who learned to put grass in their ears did so through the “natural transmission” of new behavior, she says.

This is how you do science, folks -a year of watching chimps to see if they stick grass in their ear. Let’s hope they were observing other behaviors as well. Van Leeuwen compares this grass-in-ear fad with human groups that wear earrings or a certain kind of hat.