“Joker,” the influential capuchin monkey in Panama

Psychologists and pediatricians say it, letting children be bored is important for their development and creativity. In capuchin monkeys, boredom is also thought to be a factor in creativity. To study these little monkeys closely, researchers from the Max Planck Institute for Animal Behavior (Baden-Württemberg) have 86 cameras and cameras installed in the forest of Jicarón Island, part of Coiba National Park, off the Pacific coast of Panama. The goal is to better understand the use of stones as tools and how this colony of capuchins learns to use them, as their practice is more elaborate than that observed among their counterparts on the continent.

It was while working on these images that a doctoral student, Zoë Goldsborough, was surprised by an incongruous scene: a young male capuchin monkey was carrying on his back a baby of another species, a howler monkey ( Alouatta palliata coibensis ). This behavior had never been observed before by any primatologist in any species.

A painstaking review of eighteen months of recordings taken between January 2022 and July 2023 will uncover a surprising and precise scenario, recounted in a study published by Current Biology . It all began on January 26, 2022, when a white-headed capuchin ( Cebus capucinus imitator ) wandered around, for unknown reasons, carrying a baby howler monkey. Over the next four months, this same juvenile male was seen numerous times in similar unusual company. He carried four different baby howler monkeys for periods ranging from one to nine days. Always for no apparent reason.

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