The way wild Japanese macaque monkeys exchange greetings is different according to their respective regions, a Kyoto University research group has announced.
The group headed by Naofumi Nakagawa, an associate professor of the university, concluded this type of behaviour may relate to social customs rooted in respective monkey groups or the areas in which they live. This is also the case for human beings, who have various ways of greeting depending on countries or areas.
The researchers observed wild adult female Japanese macaques on Yakushima island, Kagoshima Prefecture, and compared the results to those found in macaques on Kinkasan Island, Miyagi Prefecture.
When a female monkey encounters another in both groups, they sit facing each other and put their arms around each other's bodies, Nakagawa explained.
During the embrace, Kinkasan monkeys always face each other, widely rocking each other's bodies back and forth. This differs from the monkeys on Yakushima that sometimes embrace from the back or side, and never engage in body-rocking movement. Furthermore, Yakushima monkeys knead each other's fur by rhythmically opening and closing their palms as they embrace, which tends to take less time when compared to Kinkasan monkeys.
Greeting behaviours of embracing were observed among monkeys in the Shimokita Peninsula, Aomori Prefecture, and the Hakusan mountainous area in Ishikawa Prefecture, while such behaviour was not seen among monkeys in the Arashiyama district in Kyoto Prefecture and the Takasakiyama district in Oita Prefecture.
"Greeting behaviours of embracing are mainly seen on occasions in which antagonistic females almost fight," said Nakagawa. "It is a very cultural behaviour if it corresponds to reducing stress and evading trouble."
The group's article was published in an academic online journal of the University of Chicago Press.