This Funny Thing Happens In Monkeys And Humans As They Age

If you think only humans are choosy, then think again. Monkeys are too - at least when it comes to choosing who they interact with as they age. Apparently, this similarity in social selectivity between humans and monkeys could have deeper roots as opposed to the common thought that it stems from a sense of mortality.

According to researchers studying Barbary macaques at the La Forêt des Singes Park in Rocamadour, France, who published their study in the in the Cell Press journal Current Biology on June 23, older monkeys are more picky about who they spend their time with. However, what's truly interesting is that at the same time, the aging Barbary macaques are still interested in what's going on in the society around them.

The scientists claim that the study offers an evolutionary perspective on why humans who are aging behave the way they do. Because monkeys do not know of their limited time on Earth, as noted by Voice of America, the scientists believe that decline in social interaction is inborn in all primates.

For the study, Laura Fischer, who is the head of the Cognitive Ethology Laboratory at the German Primate Center, and her team observed over 100 Barbary macaques while conducting experiments on their interest in new toys as well as social information. As expected, the monkeys' interest in exploring new things decreased as they age, which is credited to loss of motor skills that comes with aging.

Meanwhile, the scientists also witnessed something unexpected with their observations, which was that the aging Barbary macaques are more selective with whom they groomed. With the species, grooming is a form of social interaction, a way of reducing stress, as well as a way of forming group alliances.

In an interview with VOA, Fischer said:

"Some people look at relationships of monkeys just in terms of tit for tat. If I groom you, you have to provide me some support in a future fight. This grooming of these old ladies and old monkey gents means that [younger monkeys] are still attached to them [older monkeys] although they provide no benefits."

What's more interesting is that older monkeys are also interested in social information, or gossip, even as they age.

Fischer explained:

If somebody in their group is having a fight they're still commenting ... as if they were taking part in it emotionally.

Since almost all monkeys have the same social structures as humans, seeing this behavior in the Barbary macaques reflect human social interaction as they age. For a long time, it has been thought that humans become more selective of who they interact with due to recognition of mortality, kind of like make the most of your time here on Earth with the people you enjoy with the most. However, since the monkeys in the new study aren't aware of their mortality, this would imply that the behavior is a trait we share with our primate ancestors. Apparently, humans limited their social interactions first before reasoning out that it's because they are aging.

While this conclusion makes sense, Susan Charles, a professor of Psychology and Social Behavior at the University of California at Irvine, says the results warrants further studies. She said that just because the monkeys are influenced by a feeling of mortality doesn't mean it's correlated to decreased social activity.

There's also the possible reason that "older monkeys... find social interactions increasingly stressful and therefore avoid them," according to Julia Fischer.

Alexandra Freund from the University of Zurich says they will explore the monkeys' cognitive performance.

In any case, it's still pretty cool to learn that we have this similar trait with our animal counterparts. Turns out we're not the only choosy species here on Earth.