The Weather Channel reaches over more than 89 million households in the United States, but it might soon find its way to a whole new demographic: monkeys.
In an article published in the June 20th issue of Current Biology, a team of Scottish researchers reveal that monkeys may be able to remember past weather trends and act on this information when searching for food.
A team of researchers from the University of St. Andrews in Scotland monitored a group of gray-cheeked mangabeys (medium-sized monkeys that live in the rainforests of central Africa) over a period of 210 days, as the monkeys traveled from tree to tree in search of fruit.
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A Mangabey's diet is high in figs, which ripen faster when the weather is warm. Since figs ripen intermittently, mangabeys will return to trees that previously held unripe fruit in order check on the fruit's progress.
"There is a lot of competition for fruit, so it would pay to be able to arrive first," said primate researcher Karline Janmaat, the study's lead author.
Janmaat and her fellow researchers discovered that after a period of warm and sunny days, monkeys were more likely to revisit trees where they'd previously found unripened fruit than after a stretch of cool and cloudy days. They also seemed to return sooner to the trees that had the most fruit if the weather since their last visit had been consistently warm.
"I really searched for other explanations, especially because the temperature differences we found were really small, like one degree [Celsius] average difference," said Janmaat, who was able to ruled out many other confounding factors, such as ability to smell or see ripe fruit or increased level of physical activity during warm weather.
So far, the weather explanation looks solid, said Michael Platt, a neurobiologist at Duke University who studies primates. He addeds that the finding provides new evidence for an alternate theory of the origins and function of primate intelligence.
"This would, at the least, require an episodic memory for recent weather patterns and their associated patterns of fruit rewards," said Platt. "This study adds to the very few that suggest a prominent role for foraging behavior in the evolution of primate intelligence."
Traditionally, research has suggested that primates developed large brains to help them negotiate the social world, since primates that live in larger groups have larger brains relative to their body size, Janmaat said. But primates with diets rich in ripe fruit, which is harder to find than many other food sources, such as leaves, gums or insects, also have larger brains.
"It's interesting to find out why fruit-eating animals would need large brains," Janmaat said. "This gives us more insight into what challenges could be influencing intelligent behavior."