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Capuchin monkeys learn best-payoff ways to open fruit from others

University of California - Davis

Wild capuchin monkeys readily learn skills from each other -- but that social learning is driven home by the payoff of learning a useful new skill. It's the first demonstration of "payoff bias" learning in a wild animal, and could inform whether and how animals can adapt to rapidly changing conditions, for example due to climate change or reintroduction of species from captive breeding.

"When animals learn, they can learn very quickly," said Brendan Barrett, a graduate student in animal behavior at the University of California, Davis, who led the study, published June 7 in the journal Proceedings of the Royal Society B. "What are the psychological mechanisms animals use to learn?"


"They explore their world, harvesting food from it," Barrett said. That includes coming up with new ways to open and harvest hard-to-access fruits and seeds. Unusually for monkeys, capuchins will tolerate other monkeys watching them as they open fruit.




High payoff, rapid learning

The researchers found that overall, most monkeys adopted the most efficient technique for opening the fruit -- the method with the highest payoff.

"We found that the most efficient technique could spread very quickly through the group, in as little as two weeks," he said. Even older monkeys that had already mastered one opening technique would pick up another that was more efficient by watching others, Barrett said.


Some monkeys settled on their own technique, even if it wasn't quite as efficient, but the options they tried were still guided by watching other monkeys.

The study shows that "payoff-bias" learning -- guided by which technique is more efficient -- may be more widespread in wild animals than previously thought, Barrett said. Understanding how animals learn skills could be important, for example, when considering how to reintroduce captive-bred animals to the wild, or moving a population into a new habitat.


Co-authors on the paper are Susan Perry, UCLA; and Richard McElreath, UC Davis Department of Anthropology and Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. The work was supported by the National Science Foundation, the American Society of Primatologists, the ARCS Foundation and the Max Planck Institute.
