Long-tailed macaques living near an Indonesian temple have figured out how to run a ransom racket on visiting tourists. These sly macaques grab glasses, cameras and even wadges of cash which they run off with until they’ve got what they want.
This cultural behaviour is only found at the Uluwatu Temple in Bali and researchers believe these monkeys – although extremely annoying – have developed amazing cognitive abilities similar to humans, as quoted from Daily Mail.
‘The monkeys were always trying to steal my hat, my pen, even my research data’, said primatologist Fany Brotcorne from the University of Liège in Belgium who led the study.
Dr Brotcorne spent four months watching macaques that lived near the temple and found the group that spend the most time with tourists were the most badly-behaved and regularly stole.
Although observed by tourists for a few years, this study is the first evidence ever that this is a cultural practice passed down generations.
Dr Brotcorne also noticed that groups of monkeys who move into the area then learn this behaviour too – showing that these primates are able to learn from watching one another.
Groups with young males in were also more likely to have learnt this adaptation, writes New Scientist.
“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”, researchers said in their paper, published in Primates.
“In line with the environmental opportunity hypothesis, we found a positive qualitative relation at the group level between time spent in tourist zones and RB [robbing and bartering] frequency or prevalence”, researchers said.
“For two of the four groups, RB events were significantly more frequent when humans were more present in the environment.”
Dr Brotcorne believes this study gives us insight into the psychology of primates and how much they learn from each other as well as their ability to plan for the future.
“Bartering and trading skills are not well known in animals. They are usually defined as exclusive to humans,” she said.
The paper shows that robbing and bartering could be considered a behavioural tradition among this species.
“This preliminary study showed that RB is a spontaneous, customary (in some groups), and enduring population-specific practice characterized by intergroup variation in Balinese macaques”, researchers said.