Monkeys are able to string together a simple “sentence”, according to research that offers the first evidence that animals might be capable of a key feature of language.
British scientists have discovered that the putty-nosed monkey in Nigeria pictured above sometimes communicates by combining sounds into a sequence that has a different meaning from any of its component calls, an ability that was thought to be uniquely human.
Although many animals communicate with one another using calls that have a particular meaning — usually a warning signifying the presence of a certain predator — none has been known to combine these alarm calls into sequences similar to those of human language.
The findings suggest that the rudiments of syntax, a basic component of human language, may be more widespread among primates than is generally thought, and could ultimately shed light on the evolution of this most distinctly human of traits.
The putty-nosed monkeys, Cercopithecus nictitans, of the Gashaka Gumti National Park, have two main alarm call sounds. A sound known onomatopoeically as the “pyow” warns other animals against a lurking leopard, and a cough-like sound that scientists call a “hack” is used when an eagle is hovering near by.
Kate Arnold and Klaus Zuberbühler, of the University of St Andrews, have now observed the monkeys using these sounds in a new way. A particular sequence of pyows and hacks appears to mean something entirely different.
The monkeys live in groups consisting of a single adult male accompanied by several adult females and their young. When the male utters this “sentence”, consisting of up to three pyows followed by up to four hacks, it seems to be a command telling others to move,generally to find safer, less exposed terrain.
They use the signal not only when predators are around, but also during ordinary activities such as foraging. It seems to mean “let’s get out of here”.
The research is published today in the journal Nature. Dr Arnold said: “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 was either produced alone or inserted at certain positions in the call series.