Lemur songs are similar to human music says new research reported in The New Scientist magazine on 25 October 2021.
Research scientists from the University of Turin in Italy are studying the Indri Lemur (Indri indri) in the lowland rainforest in eastern Madagascar.
Their research suggests that the primate’s calls have a great deal in common with human music.
The Indri Lemur sings to communicate with other family groups, or to locate and reunite with family members, says Chiara De Gregorio, the research leader. The Indri Lemur is a large, black and white lemur in the Indriidae family.
The researchers recorded songs from 20 different Indri Lemur groups over 12 years in Madagascar’s rainforests and analysed the timing of the notes.
They found that the Indri Lemur uses two distinct rhythm categories: 1:1, where the notes are evenly spaced like a metronome, and 1:2, where the gap between one note is twice as long as the previous one. Such rhythm categories – or “categorical rhythms” – are universal in human music.
“This is the first evidence of the presence of a typical trait of human music in another mammal,” says De Gregorio. She adds that just two bird species – thrush nightingales (Luscinia luscinia) and zebra finches (Taeniopygia guttata) – are known to show this trait when they sing, but they only have one categorical rhythm. “Instead, the Indri shares with human music two different rhythms, which makes their songs quite complex and articulated,” she says.
Considering that lemurs and humans last shared a common ancestor about 77 million years ago, categorical rhythms could have evolved independently twice among primates.
However, the research focused only on the timing properties of the calls, and therefore the significance of the rhythms for communication is unclear. But the researchers think that these rhythms may generally play a role in song coordination and social bonding.
Simon Townsend, from the University of Zurich in Switzerland, who wasn’t involved with this research, says the research “beautifully illustrates” the value of using comparisons with other species to find out what features of music and rhythm are, and are not, unique to humans.
Alexandre Celma-Miralles, at Aarhus University in Denmark, would like to see similar research on gibbons, because these primate apes also sing.
De Gregorio and her research team plan to investigate whether the Indri Lemur is born using the rhythm categories or if they learn them from their parents and families. The Indri Lemur is facing a bleak future, De Gregorio says. “Every attempt to build captive populations has failed and their habitat is vanishing at a very fast rate,” she says.
Journal reference: Current Biology, DOI: 10.1016/j.cub.2021.09.032
Photographer: Martina Nicolls
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