These Wild Lemurs Sing Just Like Opera Stars, Widening Their Mouths as They Hit the High Notes, Study Suggests

Professional singers are trained to subtly change the shape of their mouths and throats to make their voices louder and more resonant. This technique, known as formant tuning, can be especially useful for hitting very high notes: Sopranos, for example, typically open their mouths wider as they climb a musical scale, a technique that helps them amplify their voices without straining their vocal cords. Now, new research suggests wild lemurs do the exact same thing.

This ability, described in a paper published September 21 in the journal PLOS Computational Biology, likely helps the animals communicate over long distances in their dense forest habitat. The new study focuses on the indri, the only known species of lemur that sings. These primates live in the tropical rainforests of eastern Madagascar, where they use vocalizations primarily to maintain their territorial spacing.

A post shared by The New York Times (@nytimes) “Through singing, they say, ‘Oh, we are here, we are occupying this territory,’” lead author Filippo Carugati, a biologist at the University of Turin in Italy, tells the New York Times’ Taylor Mitchell Brown and Cynthia Silva. And so maybe they can sing for an hour in these long battles. And sometimes it ends with a physical battle.” They also sometimes sing when they’re reunited with their companions, which Carugati likens to our “Marco!

Polo!” call and response. Their haunting songs sound like something between “a wail and a siren,” Carugati tells , with highly structured patterns of rising and falling notes. In the study, researchers analyzed 83 video recordings of 19 wild indris in Madagascar’s Maromizaha forest and Mitsinjo reserve.

They used motion-tracking technology to denote the position of their upper and lower lips frame by frame in the footage, which they then compared with the audio of the creatures singing. The shapes of the animals’ mouths corresponded with their pitches “very robustly,” Carugati tells . More specifically, the researchers found that as the indris sang higher frequencies, they opened their mouths wider—just like professional singers do.

This likely helps amplify the animals’ calls, a helpful adaptation for communicating in an environment filled with thick vegetation. Humans and indris are both primates, but their lineages split from a common ancestor some 74 million years ago. Although the two species may use the same technique today, researchers suspect this adaptation arose independently in each animal, a phenomenon known as convergent evolution.