Monkey 'mafia' in Bali bartering stolen items for food

Monkeys outside an Indonesian temple are running a ransom racket on visiting tourists by stealing valuables such as glasses, hats, cameras or even cash to exchange them for food, researchers have found.
The macaques grab valuable items and then wait for tourists and staff to offer them food before dropping their ill-gotten gains and dashing off with the prize.
"It is a unique behaviour. The Uluwatu Temple is the only place in Bali where it is found, which suggests it is learned rather than being an innate ability," said Fany Brotcorne, a primatologist at the University of Liege in Belgium.

Researchers spent months observing four different groups of the monkeys that live near the temple.
The two groups that spent the most time around tourists had the highest rates of robbery and bartering, supporting the idea that they were learning the behaviour by watching each other, researchers said.
They found that groups with more young males, who are more prone to risky behaviour, also had higher rates than other groups, 'New Scientist' reported.

Although the study is based on a small sample, Brotcorne believes it provides the first evidence that the behaviour is cultural, transmitted across generations as monkeys learn from each other.

"Bartering and trading skills are usually defined as exclusive to humans. Seeing them in macaques could help us learn how early the behaviour might have arisen in the human lineage," Brotcorne said.
The research was published in the journal Primates.