Monkey business

Scientists have discovered Africa’s wild putty-nosed monkeys can talk — and they use syntax, writes Steve Connor

The African monkeys use different sounds in response to different threats
The African monkeys use different sounds in response to different threats

A study of wild putty-nosed monkeys in Africa has found that they can mix different alarm calls to communicate new meanings to fellow members of a troop.

Scientists found that the two basic sounds—"pyows" and hacks— which are used to warn against different predators, can be combined to mean something quite different. The monkeys call out "pyows" to warn against a loitering leopard and "hacks" are used to warn about hovering eagles overhead. However, combining pyow and hack means something like "let’s go", according to scientists from the University of St Andrew’s.

"To our knowledge, this is the first good evidence of syntax-like natural communication system in a non-human species," said Klaus Zuberbuhler, one of the researchers.

The putty-nosed monkeys in the study live in the Gashaka Gumti National Park in Nigeria and were frequently heard using different sounds in response to different threats. Kate Arnold, the other member of the team, said that she became aware that the monkeys used several "pyows" followed by a few "hacks" as a way of telling a group to move away to safer terrain.

"These calls were not produced randomly and a number of distinct patterns emerged. One of these patterns was what we have termed a "pyow-hack sequence". This sequence was either produced alone or inserted at certain positions in the call series," Dr Arnold said.

"Observationally and experimentally we have demonstrated that this call sequence serves to elicit group movement in both predatory contexts and during normal day-to-day activities such as finding food sources," she said.

The scientists demonstrated in a study published in Nature that they would imitate the communication syntax of the monkeys by playing recorded calls to the wild troop living in the forest.

"The pyow-hack sequence means something like ‘let’s go’ whereas the pyows by themselves have multiple functions and the hacks are generally used as alarm calls," Dr Arnold said.

"Previously, animal communication systems were considered to lack examples in which call combinations carried meanings that were different to the sum of the meanings of the constituent elements," she said.

"This is the first good example of calls being combined in meaningful ways. The implications of this research are that primates, at least, may be able to ignore the usual relationship between an individual call and any meaning that it might convey under certain circumstances," Dr Arnold added.

— By arrangement with The Independent