Grandmother monkeys have been witnessed helping to raise their grandchildren in Japan.
Two wild Japanese macaques living in Katsuyama have been seen taking an active role in caring for the children of their offspring. It is the first time such behaviour has been unmistakably recognised in a non-human primate.
When one mother went missing from the troop unexpectedly, the ‘grandmother monkey’ took responsibility for care of the abandoned infant until the return of its mother six days later. The infant was groomed and encouraged to suckle by the grandmother.
Another grandmother was seen to intervene in the parental duties of her daughter when a younger, more vulnerable infant demanded more care than her other offspring. The grandmother provided the older infant with care for five months whilst the mother nursed the newborn monkey.
The observations, made by Japanese scientists at Osaka University, support an idea known to ethologists as ‘The Grandmother Hypothesis’. It suggests that animals who can no longer reproduce look after younger family members to increase their chances of survival and the likelihood that their genes are passed on to the next generation.
Japanese macaques have been studied extensively in the wild and can survive freezing temperatures in snowy habitats. The Japanese snow monkeys have previously made the news with the discovery that they enjoy taking baths in hot springs and that they can learn skills from each other, such as washing potatoes in the springs before eating.
