Gorillas sing and hum when eating, a discovery that could help shed light on how language evolved in early humans.
Singing seems to be a way for gorillas to express contentment with their meal, as well as for the head of the family to communicate to others that it is dinner time.
Food-related calls have been documented in many animals, including chimpanzees and bonobos, but aside from anecdotal reports from zoos, there was no evidence of it in gorillas.
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To see if they make these noises in the wild, , a primatologist at the Max Planck Institute for Ornithology in Seewiesen, Germany, observed two groups of wild western lowland gorillas in the Republic of the Congo.
Luef identified two different types of sound that the gorillas sometimes made when eating. One of them was humming 鈥� a steady low-frequency tone that sounds a bit like a sigh of contentment (listen to clip below).
The other was singing 鈥� a series of short, differently pitched notes that sounds a little like someone humming a random melody (listen to clip below).
鈥淭hey don鈥檛 sing the same song over and over,鈥� says Luef. 鈥淚t seems like they are composing their little food songs.鈥�
, who looks after gorillas at Toronto Zoo in Canada, says humming and singing is a frequent part of mealtimes there. 鈥淓ach gorilla has its own voice: you can really tell who鈥檚 singing,鈥� she says. 鈥淎nd if it鈥檚 their favourite food, they sing louder.鈥�
Singing for supper
But although every individual in the zoo sings for its supper, Luef found that in the wild it was generally only dominant silverback males that sang and hummed while eating.
This suggests that as well as possibly signalling contentment or pleasure with the food 鈥� a sort of gorilla version of 鈥渙m nom nom鈥� 鈥� the activity might be the silverback鈥檚 way of informing the group that mealtime is continuing and it is not yet time to move on.聽鈥淗e鈥檚 the one making the collective decisions for the group,鈥� Luef聽says. 鈥淲e think he uses this vocalisation to inform the others 鈥極K, now we鈥檙e eating鈥�.鈥�
, a psychologist at the University of Birmingham in the UK, who has studied communication in bonobos, says it is interesting how food calls in different species reflect the different social structures of the great apes.
鈥淲e think food calls are a very social signal; it鈥檚 about coordinating feeding events with others,鈥� she says. 鈥淪o in gorillas you get the dominant male producing the calls, because he has to keep hold of all the females in his group.鈥�
In the much more fluid chimpanzee and bonobo societies, in which individuals constantly make decisions about who they want to hang out with, they all get involved in dinner-time conversations.
Because there is so much variation in calls both between individuals and species, food calls provide a good way to study the origin of language, says Clay.聽鈥淚t gives a good insight into the origin of meaning in animal signals, and also the social pressures that might drive the flexibility we see in language,鈥� she says.
Journal reference: PLOS One, DOI:
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