Next time I visit Kyoto, it’s not the temples I’ll want to see — it’s the monkeys.

On the slopes of Mount Arashiyama in Kyoto Prefecture is Iwatayama Monkey Park, home to some 150 wild Japanese macaques. The park also plays host to scientists from the renowned Primate Research Institute at Kyoto University.

Jean-Baptiste Leca is one of those researchers. He was watching a group of the monkeys at Iwatayama last year when he noticed a 14-year-old female perform an unusual behavior — she pulled hair out of her own back and used it to floss her teeth.

Other species of monkey have been seen collecting stray human hairs and twining them into a string in order to floss, but the behavior had not been reported in the wild until then, and never in Japanese macaques.

“Our study is one of the rare reports on the spontaneous appearance of tool-use behaviour in Japanese macaques under natural conditions,” Leca told me in a recent e-mail.

“Just like the use of twigs as ‘toothpicks’ by chimpanzees, bonobos and orangutans, the use of hair as dental floss can be considered tool-use in a hygiene context. It’s health maintenance, which is a form of self-medicative behavior.”

There have previously been reports that chimps and other apes may “self- medicate,” that is eat certain “medicinal” plants when they are sick with gut parasites. There has also been some excitement around the idea that further study of this behavior may help us find new drugs. And inevitably, the discovery of self-medication in apes has been discussed by scientists in terms of the evolution of medicine in human societies.

Leca and his colleagues argue that flossing in macaques is a form of medication. Unlike chimps that swallow leaves to flush out parasites, however, no other monkeys at Iwatayama have started flossing.

The Kyoto University team under Leca recently published their report on flossing in the journal Primates, and it got me thinking. Japanese macaques are fastidious about hygiene, washing sweet potatoes in sea water before eating them, and famously bathing in hot springs. Both behaviors fit well with the popular image of Japan being ultrahygienic and clean.

What else can they do? Atsushi Iriki, of the Saitama Prefecture-based Brain Science Institute of RIKEN [Rikagaku Kenkyusho, a huge natural sciences research institute founded in 1917 that is almost entirely government funded] argues that macaques have a sense of self. They can also learn to use tools.

I suppose it’s going too far to suggest that monkeys are familiar with the precepts of Confucianism — but oddly enough, it wouldn’t be the first time nonhuman primates have been spoken of as “religious.”

I was talking to geneticist Steve Jones, from University College London, at a party earlier this year, and I asked him if chimps had religion. It was fairly late in the evening and there had been a lot of free alcohol at the party, but luckily Jones didn’t think I was a raving maniac.

He told me of an incredible behavior that one individual has been seen doing in a chimp sanctuary in Spain. The animal, named Marco, dances with abandon during thunderstorms. The world-famous primatologist Jane Goodall has also reported seeing chimps dancing in front of waterfalls, and hurling rocks.

Now here’s some serious anthropomorphizing: the waterfall dance and the thunderstorm dance could be some kind of primitive display of awe at what to them is an incomprehensible natural phenomenon. They appear to “marvel” at their surroundings. Chimps seem to have it in them to acknowledge a higher power. Forget evolution of medicine — this is evolution of religion.

I wonder if the chimps “get” anything from doing this. I can imagine that people who pray feel consoled if they think a higher power is watching over them, and people such as priests who interpret what supposed higher powers mean gain certain status in society. What do chimps get from the waterfall dance? Perhaps simply joy.

Just down the road from Kyoto in another of Japan’s ancient capitals, Nara, where I saw something almost like this.

Nara Park is famously home to more than 1,000 sika deer that roam the 600-odd-hectare grounds freely. I remember finding a tiny shrine in a wooded, hilly part of the park, where a few deer loitered, foraging. Nara deer are designated National Treasures, but it was only after World War II that they received that protection. Until then they were considered divine and sacred, as in Shinto they are regarded as messengers of the gods.

I had spent a meditative, restorative afternoon cycling gently around the park. Seeing the deer and the tiny shrine I fancied that I could understand how people once thought them divine animals. (I thought the same thing about foxes when visiting the magical Inari Shrine just outside Kyoto, the “headquarters” of all fox spirits in Japan.)

The scene — deer peacefully hanging out at a shrine — might have suggested animal divinity, but the deer themselves were of course clueless. They might as well have been foraging around a vending machine for all they cared.

Primates, chimps at least, seem to be different. With the amount the Kyoto researchers are learning about macaques, however, I wonder if it’s only a matter of time before we get a “spiritual” insight into their lives. And what an insight that would give us into ours.

Perhaps I should be content with what we’re already learning about the complexities of Japanese macaques. But let me restate what I want to do next time I’m in Kyoto: The ideal visit would combine both monkeys and temples.

The second volume of Natural Selections columns translated into Japanese is published by Shinchosha at ¥1,500. The title is “Hito wa Ima mo Shinka Shiteru (The Evolving Human: How New Biology Explains Your Journey Through Life).”

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