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.