Lemurs hum to help protect them from predators and increase their troop's social cohesion, says a new study that could offer clues to the history of human socialisation. Amy Pollock has more.
UPSOT: 'HMM' VOCALIZATION MADE REPEATEDLY AND SQUEAL VOCALIZATION This is the sound of a ring-tailed lemur communicating. And it could hold clues to the way humans' ancestors became socialised. The chatty primates spend their days moving through tree canopy or along the forest floor, making them vulnerable to predators. The University of Toronto Mississauga's Laura Bolt spent five months in southwest Madagascar studying vocalizations in low-ranking male lemurs. She found two specific sounds - a 'moan' and a 'hmm' - they used to keep close to other lemurs. UPSOT And the lemurs made the sounds more often during activities that could lead to separation, like travel or vigilance. Bolt says these "contact calls" could tell us more about how cognition evolved in primates - and humans.