How spider monkeys team up to track forest’s best fruit

Spider monkeys have been found to share vital information about food sources by constantly changing their social groups, in what scientists describe as a “clever system for sharing insider knowledge”.

Researchers observed that Geoffroy’s spider monkeys regularly split into small subgroups of three or more individuals and then rejoin in new combinations. This fluid social behaviour allows them to exchange information about the location of fruit trees and the timing of when fruit will ripen, improving their foraging success, The Guardian notes. 

The findings, published in the journal njp Complexity, suggest the monkeys are not simply pooling knowledge, but actively combining different pieces of information to generate new insights.

“An example would be if one subset of individuals would contribute the location of a food source and another subset the timing of the fruiting of that source. The resulting, combined knowledge by both subsets of individuals would be synergistic in the sense of allowing all of them to exploit the food source according to its location and timing," the report explained. 

Researchers concluded that this behaviour represents a “compelling example of collective intelligence in natural conditions”.

The seven-year study was conducted in Mexico’s Yucatán peninsula and involved scientists from Heriot-Watt University, the University of Edinburgh and the National Autonomous University of Mexico. Field observations carried out between 2012 and 2017 allowed scientists to track individual monkeys and analyse how their movements and social relationships affected access to food.

“It isn’t random social mingling. It’s a clever system for sharing insider knowledge about where the best fruit trees are located across their forest home.," Dr Matthew Silk, an ecologist at the University of Edinburgh, said. “By constantly changing their subgroups, monkeys who know different parts of the forest can share information about where fruit is available.”

He added: “We tracked individual monkeys’ movements and mapped out their core ranges, or the areas each monkey knows well. Some parts of the forest are known by multiple monkeys, like a town’s most popular restaurant, while others are known by only one or two monkeys, like a hidden gem.”

According to Dr Silk, this balance allows the group to maximise its overall knowledge.

“There’s enough overlap for monkeys to meet and exchange tips, but enough separation that each monkey scouts different parts of the forest. This maximises the whole group’s collective coverage of the best feeding spots.”

Mathematical modelling carried out by Heriot-Watt PhD student Ross Walker showed there is an optimal balance between staying together and spreading out. 

The endangered species, also known as the Central American or black-handed spider monkey, demonstrates how flexible social systems can boost survival. 

By Sabina Mammadli