New research shows that female rhesus macaques “actively shrink” their social networks and prioritize friends and family as they get older.
Having fewer friends later in life is considered harmful, including among humans.
But a new study shows that female macaques are becoming increasingly selective, focusing more on kin and long-standing friendships.
The results show that women are not shunned later in life – changes are made by women themselves.
The study – by the University of Exeter, Arizona State University, New York University and the University of Pennsylvania – was conducted on Cayo Santiago, also known as Monkey Island, off Puerto Rico.
“This pattern of narrowing of social networks with age is common in humans,” said Professor Lauren Brent of the Exeter Center for Animal Behavior Research.
“Our study offers the most compelling evidence to date that social selectivity is not unique to humans, and therefore may have deeper evolutionary bases.”
The study used data from more than 200 macaques over eight years to see how each individual’s social life changed.
After ruling out other explanations, such as the death of partners, the researchers found clear evidence of social selectivity among women.
“There are many possible reasons why macaques become more socially selective with age,” said Dr Erin Siracusa, also from the University of Exeter.
“For example, preferences for social interactions may change over time. Young macaques can benefit from a large social group that can help them explore and find potential mates.
“It may be easier and safer for older macaques—in terms of everything from conflict to disease transmission—to stay with family and existing friends.
“New relationships also require more mental effort, so while we don’t see a decrease in time spent socializing, older macaques may be saving mental energy by reducing their network.”
Long-term monitoring of macaques on Cayo Santiago was made possible by the Caribbean Primate Research Center, and this research was funded by the National Institutes of Health.