Opera singers and shrieking lemurs share vocalization strategies

With piercing, emergency siren-like calls, the indri (Indri indri) is the world’s only known singing lemur. The primates found in Madagascar’s rainforest swing through the trees, making these sounds that contain a surprisingly human element. To hit those high notes, indris appear to deploy a technique similar to human opera singers. The lemurs coordinate their mouth opening with their songs—the higher the pitch of the song, the wider they open their mouth to sing it. A stu