April 4 2018 | By Sarah Gibbens for National Geographic
Famous Japanese Macaques Take Baths To Lower Stress
(Above: Japanese macaques, also called snow monkeys, soak in a hot spring in Jigokudani, Japan. PHOTOGRAPH BY JASPER DOEST, MINDEN PICTURES/NATIONAL GEOGRAPHIC CREATIVE)
There’s a reason macaques look so serene in their photos. Submerged up to their cheeks in steamy water with snow drifting onto their furry heads—they look almost meditative.
Researchers always suspected the monkeys used the hot springs to stay warm in the winter, and a new study published in the journal Primates confirms this. While the researchers suspected this was the case, the finding could still illuminate how the monkeys cope with stress.
A COLD NORTH
Of all the primates in the world, Japanese macaques live the farthest north. For decades, they’ve been observed taking baths in Jigokudani Monkey Park in Japan. Their behavior has become so endearing to people that thousands of tourists often trek north to take a peek at the snow monkeys’ bath time.
In the mountainous regions of Japan, winters can be harsh. While the monkeys are lounging in a calm pool of water, they’re often subjected to intense snowfall and freezing temperatures. (Read more about the world’s snowiest place.)
To see exactly what kind of benefit the macaques got from their baths, a group of researchers from Japan’s Kyoto University tracked 12 females. Their behavior was observed in two different seasons: their birth season, from April to June, and their winter season, from October to December. The scientists looked at which monkeys bathed the most often and for how long.
They then measured the amount of a hormone called glucocorticoid from the monkeys’ fecal samples. Glucocorticoids come from a family of steroid hormones and are produced when the monkeys undergo stress—often from trying to maintain a body temperature that’s not too cold and not too hot.
Read more about it on National Geographic.
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