SUMOTO, Hyogo Prefecture--While large groups of humans have been discouraged against eating together during the COVID-19 pandemic, a troop of snow monkeys living here on Awajishima island are under no such restriction. 

Monkeys at the Awajishima Monkey Center in Sumoto, Hyogo Prefecture, were seen huddling up and beginning to eat together as soon as food was laid out on the ground by an employee.

The food was placed by an employee in the shape of katakana characters for “saru,” the Japanese for “monkey,” thereby forming fluffy “monkey letters.”

The population of snow monkeys, also known as Japanese macaques, living on the island has a respect for tolerance, a rare quality among animals of the species that is native to Japan, according to researchers.

“This behavior is, in fact, beyond the abilities of typical snow monkey groups,” said Yu Kaigaishi, 29, a specially appointed researcher of ethology with the Osaka University Graduate School of Human Sciences.

Studies and experiments conducted over the past several years by scholars from Osaka University have revealed unique peculiarities of the monkey society on this island.

One behavior symbolic of the peace-loving nature of the monkeys living here is the habit of eating together.

The Awajishima Monkey Center feeds a population of some 350 wild snow monkeys who come down for food in the morning and go back to the mountains in the evening.

Typically, a troop of snow monkeys has a clearly defined order of ranks. More often than not, low-ranking males who turn up for food end up being chased away or attacked by high-ranking males, so troop members remain scattered about instead of forming the shape of characters.

By contrast, Awajishima’s monkeys can line up in the form of letters as they feed because members of the group with broadly disparate ranks can eat together, said Kaigaishi. 

CAPACITY FOR COOPERATION

Something even more surprising was observed in an experiment undertaken by Kaigaishi, in which monkeys were given an opportunity to snatch food by working as a pair to pull both ends of a rope to bring a food tray closer to them. The contraption does not allow a single monkey alone to get food simply by pulling one end of the rope.

Awajishima’s monkeys successfully worked as a pair to obtain food in 59 percent of the 1,488 trials conducted. Furthermore, they even learned to wait for a partner to arrive, when no potential partner was around, before pulling the rope.

That is in stark contrast to another snow monkey troop from Maniwa, Okayama Prefecture, where the rate of success was only 1 percent in 198 trials. The monkeys in that group could not continue to work together, and the rare cases of success were followed by fights.

“That was the first time it was discovered that snow monkeys have the capabilities to work together with others,” Kaigaishi said. “Tolerance of the entire society is key to cooperative behavior.”

PEACE-LOVING LEADERS

Toshikazu Nobuhara, 67, manager of the Awajishima Monkey Center, emphasizes a tradition of peace-loving leaders that is symbolic of the tolerance of the island’s snow monkey population. A standard was set by Macky, who led a “long-term stable government” for 15 years from 1993 through 2008.

Macky stood out by his tolerance even in this troop, where fights are a rarity. He was a caring individual, and he was often seen coming to a feeding ground holding a weak baby in his arms. He was also popular with females, said Nobuhara.

Macky, in his old age, was succeeded by Itchan, who, however, was a bully who was harsh on the weak. He faced a revolt from three individuals, including Asatsuyu, who replaced him as leader when Itchan fell from power only three months into his reign.

Asatsuyu returned to Macky’s peace-loving line. He was seen, for example, looking after a weakened baby as though it were his own.

UNIQUE EVOLUTION ON ISLAND

Kazunori Yamada, an Osaka University lecturer of ethology, cited two possible factors behind the social tolerance of Awajishima’s snow monkeys, which is reflected in the quality of their leaders. Yamada, 42, who is also from the university’s Graduate School of Human Sciences, has been doing research in Sumoto since 2008.

One of the factors concerns genetics. Some individuals in the Awajishima population have genes for reduced aggressiveness, Yamada said.

The other concerns the habit of sharing food, which has been handed down, in everyday life, from the generation of grandparents through that of parents to the generation of children. Monkeys were seen sharing food as early as in the first years of the Awajishima Monkey Center, which opened in 1967, the researcher said.

“There is a process of social learning that transcends generations, which is about spending time together and learning together,” Yamada said. “That merits the name of ‘culture.’”

No other troop of snow monkeys lives on Awajishima island, which is isolated from the rest of the land by the sea. Those circumstances may have helped the evolution of the unique quality, he added.

“If we are to find out why Awajishima’s monkey population alone was able to build a distinctly tolerant society, that could offer a clue to understanding why we humans have evolved in such a way that we can give consideration to others and empathize with them,” Yamada said.

The Awajishima Monkey Center offers on its website (https://monkey-center.jp/) a live view of the scene on its grounds.