Spider monkeys share tips about where to find food by switching social groups, according to new research. The primates were observed frequently changing subgroups of three or more individuals, allowing them to pass on information about the location of fruit trees and the timing of when they would ripen.
The study, published in the journal npj Complexity, found that this behaviour enabled the monkeys to complement each other's knowledge and even combine it to produce new knowledge. For example, one subset might contribute the location of a food source while another provides the timing of its fruiting, together allowing all to exploit the source effectively. The authors described the evidence as a compelling example of collective intelligence in natural conditions.
Researchers from Heriot-Watt University, the University of Edinburgh and the National Autonomous University of Mexico based their findings on seven years of field observations in Mexico's Yucatán peninsula. They tracked individual Geoffroy's spider monkeys and mapped their core ranges, revealing that some forest areas were known to many monkeys while others were known to only a few.
Dr Matthew Silk, an ecologist at the University of Edinburgh, said: "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. By constantly changing their subgroups, monkeys who know different parts of the forest can share information about where fruit is available." Ross Walker, a PhD student at Heriot-Watt, added: "We've shown that there's an optimal middle ground between the monkeys sticking together and spreading out too far. It's best when individuals explore different areas, but still reconnect often enough to pool what they've learned."
Professor Gabriel Ramos-Fernandez from the National Autonomous University of Mexico said: "We have shown that the fluid social dynamics of spider monkeys has an important consequence for their foraging success. By exploring their environment in a distributed fashion and then coming together to share their uniquely obtained information, the group as a whole can know the forest better than a single individual could on its own." The Geoffroy's spider monkey, also known as the Central American or black-handed spider monkey, is considered endangered.
