To the untrained ear monkeys of a certain species may all sound the same, but Japanese researchers have found that, like human beings, they actually have an accent depending on where they live.
The finding, the first of its kind, will appear in the December edition of a German scientific journal Ethology to be published on December 5, the primate researchers said on Tuesday.
"Differences between chattering by monkeys are like dialects of human beings," said Nobuo Masataka, professor of ethology at Kyoto University's Primate Research Institute.
The research team analysed voice tones of two groups of the same species of primates, the Japanese Yakushima macaque also known as Macaca fuscata yakui, between 1990 and 2000.
One group was formed by 23 monkeys living on the southern Japanese island of Yakushima, and the other group comprised 30 descendants from the same tribe moved from the island to Mount Ohira, central Japan, in 1956.
The result showed that the island group had a tone about 110 hertz higher on average than the one taken to central Japan.
Monkeys on Yakushima Island have an accent with a higher tone because tall trees on the island tend to block their voice, Masataka said.
"On the other hand, monkeys on Mount Ohira do not have to gibber with a high tone as trees there are low," he said.
"Each group adopted their own accent depending upon their environment."
This suggests differences in voice tones are not caused by genes, Masataka said, adding the results "may lead to a clue to the origin of human language."