Monkeys keep chatter 'short and sweet'

Monkeys avoid long-winded chatter, preferring to keep it brief, a new study suggests.

Scientists found that macaques use short calls far more often than lengthier vocalisations.

Humans also do this: the words that we use most often, such as "a", "of" and "the", do not take long to say.

The fact that we both share this vocal trait could shed more light on the origin of human language, the team writes in the journal Biology Letters.

The relationship between the length of a word and how often it is used is described by the "law of brevity".

Dr Stuart Semple, an author of the paper from Roehampton University, UK, said: "The law of brevity states that the words we use very often are very short and the words we use very rarely are long.

"If the words we used most frequently were very long, our conversations would go on forever, because you use them hundreds of times each day.

"This makes communication more efficient and this seems to hold across all languages," he added.

To find out if the urge to "keep it brief" occurred elsewhere in the animal kingdom, the researchers looked at Formosan macaque monkeys (Macaca cyclopsis) living on Mount Longevity, Taiwan.

Dr Semple said: "We know these macaques rely a great deal on vocal communication, but nobody had looked to answer this particular question."

Screams and whines

These primates have a repertoire of 35 different calls - although their precise meanings are yet to be determined - and the researchers studied the relationship between the call duration and the rate of its utterance.

Dr Semple said: "The calls they used most often - greetings, grunts and coos - are really short. This is their everyday chatter, if you like. They keep it short and sweet.

"The ones that you hear very rarely - the screams and whines - are very long.

"This is the first time we have seen this in a non-human vocal communication."

The researchers say that doing this not only saves time and energy for the macaques, but it also helps to avoid drawing too much unwanted attention from potential predators.

The similarity between humans and macaques suggested that our common ancestor could also have employed this "law of brevity", helping to reveal more about why we communicate as we do.

The next stage for the researchers is to see if any other species, including non-primates, also make these vocal short-cuts.