Monkeys are notorious yet adorable creatures that we must love from afar. There have been several instances which have shown how smart they really are and now, a new study has shed light on yet another astonishing aspect of monkeys.
Researchers have discovered that the monkeys from the Uluwatu Temple in Bali, Indonesia steal items that are more valued by humans to derive the highest bounty in exchange for it.
The study was conducted by researchers from the University of Lethbridge in Canada and Udayana University in Indonesia and according to researchers, this could be the first example of a culturally maintained token economy in free-ranging animals.
They analysed 333 free-ranging monkeys for 273 days from September 2015 to August 2016. It analysed another set of 15 monkeys in December 2019. They collected data by video recording the monkeys who looked at human targets and got within five metres of them. Human targets were either temple visitors wearing or carrying at least one inedible object which according to the researchers was ‘more or less likely’ to be bartered for food if stolen.
They categorised the inedible items in six categories — empty containers including phone cases, camera bags etc, accessories like key rings, hairpins, hats or caps, shoes, glasses and electronics like phones, cameras etc.
They then categorised them as low-value tokens, medium value tokens and high valued tokens, depending on how often humans bartered with monkeys to retrieve them back.
Researchers found that low-valued tokens including empty containers and accessories were rarely bartered by humans. Medium value tokens including hats, shoes were often bartered whereas high value tokens like glasses, electronics were almost always bartered.
Researchers discovered that age was a big factor in the robbing activities with older monkeys stealing items more valued by humans, with researchers referring to them as the most skilled robbers. Subadult monkeys were more successful than younglings while adults were most successful.
However, while stealing is half of the game, getting properly rewarded for the stolen item was something only adults and some subadults managed to thrive. Adult monkeys recognised high-value items vs low-value items and targeted the former, whereas juveniles didn’t really care what they stole as long as they got their hands on it.
Authors explained, “These more skilful and selective individuals appeared to make economic decisions, as evidenced by clear behavioural associations between value-based token possession and quantity or quality of food rewards rejected and accepted.”
Dr Jean-Baptiste Leca, the lead author of the study and associate professor of psychology at the University of Lethbridge, said in a conversation with the Guardian that such robbing and bounty retrieving tactics by the monkeys is actually a sign of cultural intelligence from the monkeys.
“These behaviours are socially learned and have been maintained across generations of monkeys for at least 30 years in this population.”