Chimps develop fashion trend by shoving grass in their ears — and in their butts

The chimps wear a blade of grass a bit like a fashion accessory. (Image credit: Jake Brooker/Chimfunshi Wildlife Orphanage Trust)

Captive chimpanzees have started dangling grass out of their ears and butts in an unusual fad-like "trend," a new study finds.

The chimps (Pan troglodytes) insert a blade of grass or stick into their ear or rectum and then just let it hang there for a while, researchers reported. The behavior doesn't appear to have any physical or medical purpose, but spreads socially from chimp to chimp.