According to new research, our primate cousins also become more socially selective with age, preferring the companionship of their “friends” to monkeys that are less familiar (or maybe just a drag at parties). The findings also hint at a possible evolutionary explanation for why our social preferences change over the years.
The work, conducted primarily by researchers from the German Primate Center in Göttingen, Germany, was recently published in the journal Current Biology and entailed observing the behaviors of over 100 Barbary macaque monkeys, an out-going, some might say "screechy," species hailing from North Africa. To get a sense of how interest in non-social vs social stimulation changes over the course of their lifetimes, monkeys of varying ages were observed in the presence of both inanimate objects and other monkeys.
They were first presented with three novel objects: animal toys, a see-through cube filled with glitter in a viscous liquid, and a tube baited with food. Those that had reached early adulthood were not interested in the objects without a reward. The younger ones were intrigued by all three. Next the monkeys were shown photos of baby macaques, along with those of "friend” and “non-friend” peers to see which images captured their attention the longest. Their response time to recorded friend and non-friend screams, as well as the duration of their social interactions with one another were also monitored.
The findings in females were clear: the subjects devoted significantly more time and attention to the photos and screams of their friends. They also engaged in fewer total social interactions with age, but maintained a strong interest in interacting with their closest peers, suggesting that the overall decrease in socializing wasn’t due to a general age-related apathy. It seems that the monkeys had grown to prioritize meaningful relationships over the cheaper, fleeting thrills of toys and shiny objects — and also over spending time with less significant acquaintances.
"With increasing age, the monkeys became more selective in their social interactions," said study co-author Laura Almeling in a press release. "They had fewer 'friends' and invested less in social interactions. Interestingly, however, they were still interested in what was going on in their own social world."
As study lead investigator Julia Fischer said in an email, observing “friendship” behavior in male macaques — in whom the results were inconclusive — is complicated by the fact that they only tend to exhibit strong interest in the opposite sex during the mating season (the cads!). Yet she points out that mating partners don't equate with bonding partners. Preliminary data from Fischer and her colleagues strongly suggest that males also develop smaller, more inclusive social networks in their elder years.
As sociologic research has found, and simple self-reflection suggests, it can be harder to make close friends as we age — at least the kind built on those effortless child and young adulthood connections that can endure for decades. (As American poet Sylvia Plath put it, “There is nothing like puking with somebody to make you into old friends.”).
This increasing selectivity is often attributed to our awareness of our own mortality: as the end nears we place increasing value on meaningful relationships and experiences. In psychology speak, this is known as the socioemotional selectivity theory, developed in the early 90s by Stanford psychologist Laura L. Carstensen. Yet presuming that macaques haven’t been gifted (and cursed) with any advanced intel on life’s finite duration, their — and perhaps some of our — narrowing social preferences must be due to other factors.
Still, Fischer doesn’t believe that increasing social pickiness was specifically selected for in primates. Given that in nature macaques don’t typically reach their golden years, there wouldn’t have been an evolutionary advantage to advanced age social selectivity. She instead believes that increasing emphasis on more significant social bonds may be an evolutionary byproduct of establishing important relationships younger in life; specifically, as she puts it, for “something such as risk aversion once they’ve reached reproductive age,” — in other words an evolutionary pressure to keep as many degenerate simians away from their children as possible. Perhaps later in life this awareness of who’s a good friend — of which monkeys can be trusted around their young — manifests as social pickiness.
Fischer and her colleagues hope their research will inspire more collaboration between evolutionary biologists and psychologists to better understand, for example, how primordial primate behaviors could help explain why you're growing increasingly okay with skipping that sure-to-be-dreadful dinner party in favor of drinks with an old pal. To recall another kvetch by Larry David, "If somebody cancels on me? That is a celebration.”
Source: Scientific American