Very cool,
snip
...
Indri songs may seem chaotic at first, but University of Turin biologist Chiara De Gregorio says they begin to sound less so the more one hears them. “When you get used to them you can really recognize a pattern in those songs,” she says. “When they start a phrase, you know what to expect, note after note.” In a study published Monday in Current Biology, De Gregorio, Ravignani and their colleagues analyzed recordings of 636 individual indri songs collected from 20 different familial groups to determine whether these booming lemurs do, in fact, possess rhythm.
...