Macaca fascicularis at Ngarai Sianok, Bukittinggi, West Sumatra. Image: Wikimedia Commons

Sopranos superfans will be glad to know that the mafia is still alive and well—sort of. A temple in Bali, Indonesia has apparently been overrun by mafioso macaques that have been stealing tourists’ items in exchange for food. New research suggests the unusual phenomenon is a learned behavior, and goddamn is it a good one.

In 2010, a team of researchers spent four months observing four groups of long-tailed macaques (Macaca fascicularis) near the temple. In total, the team logged 201 instances of robbing and bartering events—unsurprisingly, the two monkey clans that spent the most time around tourists had the highest recorded incidences of this behavior. According to New Scientist, in recent years, a fifth group has joined in on the scheme.

“Robbing and bartering (RB) is a behavioral practice anecdotally reported in free-ranging commensal macaques,” the researchers wrote in their study, recently published in the journal Primate. “It usually occurs in two steps: after taking inedible objects (e.g., glasses) from humans, the macaques appear to use them as tokens, returning them to humans in exchange for food.”

The researchers suggest that the urge to rob and barter—behavior typically viewed as exclusive to humans—is passed down from generations, rather than something innate or compulsive.

Advertisement

“It’s a unique behavior,” Fanny Brotcorne, primatologist at the University of Liège and lead author on the study, told New Scientist. “The Uluwatu Temple is the only place in Bali where it’s found.” Apparently, Brotcorne was robbed by the monkeys several times.

Hopefully, this research can give us new insight into primate psychology. It’s no surprise, however, that snacks are a language that’s universally understood.

[Primates, New Scientist]