Bali’s Thieving Monkeys Knowingly Target The Most Lucrative Swag

You better bring the goods if you ever want to see these glasses again. Image credit: Nataly Fortunatova/

Visitors to the Uluwatu Temple in Bali may remember the pickpocketing skills of the cultural landmark’s resident macaques. Light on their feet and ever curious, long-tailed macaques (Macaca fascicularis) are a sacred animal in the eyes of some Buddhist and Hindu temples and it’s easy to see why when you come face to face with these charismatic animals. Also known as crab-eating macaques, they're a dab hand when it comes to cracking things open using their highly dexterous and flexible digits, which aren't enormously dissimilar to our own. Their skills however can turn on the unsuspecting tourist, and they are famous (or infamous, if it’s your stuff they stole) for stealing visitor’s belongings.

The free-ranging population of thieving long-tailed macaques recently became the subject of a new piece of research published in Philosophical Transactions of the Royal Society B. Researchers set out to see if the macaques were using stolen objects as a bartering tool for food rewards, and if they were discerning in what they took. Such economic behavior has never been officially recognized in a free-ranging population of non-human animals, according to the paper, but it was suspected the monkeys’ unique habitat (which they share with humans and their precious phones) may have inspired such devious behavior in these intelligent, perpetually-peckish animals.

The researchers hunkered down for what must’ve been one of the most entertaining observation studies on record, recording thieving events as they unfolded before their eyes. They noted down the macaques’ age, degrees of success, and whether or not the monkeys then used the stolen token as a bartering tool. Statistical analyses of these observations revealed that this bartering behavior was something that had to be learned at a young age if the monkeys were later to become effective thieves-turned-negotiators, with their likelihood of success increasing with age.

The researchers also staged fake robberies where the monkeys were presented with an ideal opportunity to steal from someone carrying medium or high-value items. Examples included shoe versus glasses, or hat versus phone with the former representing the medium value and latter representing the high value in both scenarios. Their results showed older monkeys were better at identifying and stealing high-value items, like phones, glasses, and wallets. They were also more likely to refuse measly offerings and hold out for big-ticket trades, as demonstrated by the glasses-wielding-macaque in the above video.

“This population-specific, prevalent, cross-generational, learned and socially influenced practice may be the first example of a culturally maintained token economy in free-ranging animals,” wrote the study authors in the paper. “Further experimental research on the Uluwatu macaques should make future cross-species comparisons of economic decision-making and symbolic tool use more relevant from an evolutionary perspective and may ultimately lead to a better understanding of the origins of autonomous monetary systems in humans.”


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