A new study watching how older monkeys behave has concluded that like humans, they spend less time playing and are less inclined towards social contact.

Grumpy Old Monkeys, Just Like Humans?

100 Barbary macaque monkeys

The study focused on 100 Barbary macaque monkeys and was published on Thursday in Current Biology. The ages of the monkeys ranged from 4 to 29 (29 is equivalent to about 105 for a human), and they were observed in an enclosed 50-acre park in southern France. Their responses were monitored to new toys being introduced, and the number of social interactions, like grooming or fighting in which they participated.

Like the stereotypical crotchety grandpa, it seems as monkeys age, they too are less inclined to spend time ‘monkeying around’ or to go out and interact with others.

Evolutionary Explanation

Dr. Alexandra Freund, a developmental psychologist at the University of Zurich who worked on the study stated, “this clearly tells us that we, as humans, are not unique in the way we age socially but that there might be an evolutionary ‘deep’ root in this pattern.”

Monkeys and humans share a common ancestor, and are separated by approximately 25 million years of evolution, but it appears that we perhaps share this evolutionary trait.

As monkeys hit reproductive age, their interest in toys declines notably. As they reached the ripe age of twenty (the report considers this about the human retirement age), the monkeys being observed had far fewer social interactions and were less likely to go and approach other monkeys.

Dr. Julia Fischer, who studies primate cognition at the German Primate Center in Goettingen, Germany, and worked on the study, noted that the older monkeys were still aware of anything of note occurring, “they are still very much tuned into what’s going on,” she said, adding, “but they don’t want to participate themselves.”

It is unknown why humans generally become more secluded in older age, but the most dominant theory suggests that people are just far pickier with their time. Knowing the end of their life is approaching, they have little interest in doing anything for appearance’s sake.

Yet older monkeys have never given any hint that they are aware of impending death, so perhaps this theory needs to be revisited.

The fact that monkeys and humans have this similar behavior trait suggests, as Dr. Freund stated, “Our behaviors that seem very much the result of our deliberation and choice, might be more similar to our primate ancestors than we might think.”