A team from the University of Lethbridge in Canada spent 273 days at the temple in Bali and recorded over 2,000 interactions between the monkeys and tourists. The team published their findings yesterday, on 11th January 2021, in a paper in a Royal Society science journal, titled “Acquisition of object-robbing and object/food-bartering behaviours: a culturally maintained token economy in free-ranging long-tailed macaques“.

https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0677

The study finds that adult wild long-tailed macaque monkeys at Uluwatu Temple in Bali, Indonesia, learned to steal items from human visitors and negotiate their return for food. The monkeys not only learned to exchange them back for food, but were intelligent enough to comprehend which items had the highest value to the visitors such as mobile phones and wallets, and ensured they received food items with a corresponding value in return.

The monkeys would negotiate for 17 minutes a higher food payout from the humans to get more food before handing back the higher value items, whilst giving way to less food for lower value items.

Typical swag pilfered from tourists included bags, hats, sunglasses, tablets and phones.

The team stated that the monkey’s behaviour displayed “unprecedented economic decision-making processes” among the monkeys observed as part of the study.