Macaque monkeys got on better with others in their social groups after a devastating hurricane, according to researchers.
Researchers studied the impacts of a hurricane on a population of Rhesus macaques on an island off Puerto Rico.
Temperatures are often around 40C so shade is a precious resource for macaques, since tree cover is still far below pre-hurricane levels.
Macaques, who are known for being aggressive and competitive, have become more tolerant of one another to get access to scarce shade.
“It’s extremely hot, it’s not just uncomfortable, but actually dangerous for one’s health if you don’t manage to lower your body temperature,” said Dr Camille Testard, a neuroscience research fellow at Harvard.
In 2017 Hurricane Maria hit Puerto Rico, killing more than 3,000 people and destroying 63% of the vegetation on Cayo Santiago.
The island is also known as Monkey Island and is home to the macaques studied by the researchers.
The study, which was led by the universities of Pennsylvania and Exeter and published in the journal Science, found that storm damage changed the evolutionary benefits of sharing shade and tolerating others.
“We expected that after the disaster in a more competitive landscape with less shade resources, you would have perhaps more aggression. But actually, that’s really not what we found. We found the opposite pattern,” said Dr Testard.
Using data collected before and after the hurricane, the researchers examined the strength and number of social ties among macaques.
Whether it’s food or shade, macaques aren’t known for being very good at sharing resources.
Due to the increased tolerance, more macaques were able to access scarce shade, which is crucial to their survival.
“There’s still competition within your groups the way it was before, but the rules of the game have changed since then. What really seems to be important, are the risks of not living, heat, stress and getting access to shade,” said Professor Lauren Brent, from the University of Exeter.
Researchers found that the macaques’ increased tolerance spilled over into other aspects of their daily lives.
Macaques that had been sharing shade were also spending time together in the mornings, before the heat forced them to seek shade.
In effect, the hurricane changed the rules of the game in the monkeys’ society.