As people get older, they become choosier about how they spend their time and with whom they spend it.
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It turns out that’s a similar story with Barbary macaques which has led European researchers to suggest it’s a stage of life which could be deeply ingrained in primate evolution.
Since nearly all monkeys have the same social structures as humans, seeing this behavior in the Barbary macaques reflect human social interaction as they age. They analyzed monkeys’ reaction to physical objects such as novel toys and tubes with food, social interactions such as fighting and grooming friends and new social information, such as calls and photos of friends and strangers.
Yet older monkeys have never given any hint that they are aware of impending death, so perhaps this theory needs to be revisited.
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”. However, monkeys of other age groups continued to interact with aging monkeys despite their avoidance. This phenomena was once thought to be due to our own awareness of our limited future time – we are aware of our finite lifespan and choose to spend our little time left with only a select few. Therefore, if they show similar motivational changes in old age, their selectivity can not be attributed to their knowledge about a limited future time.
What’s more interesting is that older monkeys are also interested in social information, or gossip, even as they age.
Another hypothesis is that monkeys socialise only with carefully selected individuals because they find social interactions increasingly stressful and therefore avoid them if they are not essential.
From the experiments the researchers realized that monkeys’ interest in exploring new things dropped with age.
The researchers investigated Barbary macaques’ selectivity regarding their interest in the nonsocial and social environment in a large sample of more than 100 monkeys of different ages kept in the enclosure “La Forêt des Singes” in Rocamadour. So if monkeys and humans are acting the same way, it may just be a natural behavior with biological roots, principal investigator Julia Fischer told the New York Times. “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”.
The Barbary macaques are the subjects of this behavioral study performed by German and Swiss scientists. Sadly, a lot of those friends turned out to be fair-weather friends, and as I continue aging, I tend to become more and more selective when it comes to the people I spend my free time with. The findings offer an evolutionary perspective on why aging humans behave as they do, according to the researchers. “Interestingly, however, they were still interested in what was going on in their social world”.
“SST does describe and accurately predict human behaviour”, says Fischer. She says they will explore these issues and changes in the monkeys’ cognitive performance in future studies. Scientists found that older monkeys still hissed to others during fights and still responded to photos of others.
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A very old male Barbary macaque eats at ‘La Forêt des Singes, ‘ a monkey reserve in Rocamadour, France.
