How being stressed helps monkeys in Costa Rica survive severe droughts

Being stressed-out is not always bad, at least not for wild animals, a recent study finds.

Using long-term stress hormone data collected from wild white-faced capuchins, a monkey native to Costa Rica, researchers were able to measure how strong each monkeys’ stress response was whenever a drought occurred.

They then looked at the relationship between the strength of an individual’s stress response to previous droughts and whether they survived a very severe El Niño drought.

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They found that monkeys who had higher levels of stress hormones in previous droughts were more likely to survive the severe drought. “These results suggest that the rise in stress hormones during a drought may be what helps these monkeys survive,” Dr Susan Perry, co-author of the study, tells BBC Wildlife.

This is the first study from a wild primate that shows the beneficial side of the stress response. But it’s important to note that it is not the stress itself that’s beneficial, rather – as Dr Jacinta Beehner, co-author, clarifies – “it’s the ability to respond to stress in an adaptive way.”

Do these results mean more stressed-out humans might have some sort of advantage, too?

“The stress response in humans today is mismatched with our current stressors, for example mortgages, traffic jams, interpersonal relations. It doesn’t help us escape these, yet it accumulates damage in our bodies,” Dr Sofia Carrera, lead author, says. “However, wild animals are – mostly – still dealing with challenges where a reactive stress response helps them survive better.”

So in modern humans, at least, a strong stress response is probably not such a good thing. Once, though, it would have been beneficial for us to mount strong stress responses in the face of danger. And in wild animals, a strong stress response may mean the difference between life and death – especially in a world where extreme weather events are becoming more common.

Main image: 24-yr-old adult female white-faced capuchin chewing on sticks in search of insects/Susan Perry, Lomas Barbudal Monkey Project

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