According to a study in the journal Animal Cognition, chimpanzee’s do something that seems altogether arbitrary: ear accoutrements.
“Our observation is quite unique in the sense that nothing seems to be communicated by it,” says study author Edwin van Leeuwen, a primate expert at the Max Planck Institute in The Netherlands.
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.
There’s no genetic or ecological factors, the scientists believe, that would account for this behavior — only culture.
Chimpanzees putting grass in their ears is like us wearing earrings.
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