It found that adult wild long-tailed monkeys were intelligent enough to understand which items had the highest value to the visitors, such as an electronic item, and only release it after they received food they thought was of similar value.
The authors said the behavior exhibited “unprecedented economic decision-making processes” among the monkeys observed as part of the study.
An understanding of economics
The 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 request specific food rewards’, the monkeys’ ability to trade successfully increased. and experience.
The study, published Monday, was conducted for 273 days from 2015 to 2016, with further observations in 2019.
The scientists filmed the monkeys as they stared at a visitor, approached them inconspicuously, picked up an object, and then went aside to wait for an appropriate offer.
The adult monkeys collected “different 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 lower value item, the report said. study.
“Token robbing and token / reward swapping are cognitively challenging tasks for the Uluwatu macaques that uncovered unprecedented economic decision-making processes,” the authors said.
“This spontaneous, population-specific, common, cross-generational, learned and socially influenced practice could be the first example of a culturally sustained symbolic economy in free-roaming animals.”