He found that adult wild long-tailed macaque monkeys were smart enough to understand which items had the greatest value to visitors, such as an electronic item, and would only release it after receiving food that they considered of corresponding value.
The authors said the behavior exhibited “unprecedented economic decision-making processes” among the monkeys observed as part of the study.
An understanding of the economy
Scientists, from the University of Lethbridge, Canada, and Udayana University, Indonesia, noted that in addition to being able to “use objects as symbolic tools to claim specific food rewards,” the monkeys’ ability to successfully trade increased with age. and experience.
The survey, published Monday, was conducted over 273 days from 2015 to 2016, with other observations made in 2019.
Scientists filmed the monkeys while looking at a visitor, approached them discreetly, picked up an object and walked away, waiting for a suitable offering.
Adult monkeys accumulated “multiple food rewards before returning the token”, where the item was of high value, and were “more likely” to accept a “less preferred food reward” in exchange for a lesser item, the study said. .
“Token theft and the exchange of tokens / rewards are cognitively challenging tasks for Uluwatu monkeys, which have revealed unprecedented economic decision-making processes,” said the authors.
“This spontaneous, population-specific, prevalent, intergenerational, learned and socially influenced practice may be the first example of a symbolic economy maintained culturally in wild animals.”