As people age, it is common for their social connections and sense of cohesion to decrease. This can happen for a variety of reasons, including physical limitations that make it harder to engage in social activities, changes in living arrangements (such as moving to a nursing home or losing a spouse), and changes in relationships with family and friends.
According to a new study of one of humanity’s closest relatives, social cohesion and connection are declining in an aging population. Researchers have been studying rhesus macaques on Cayo Santiago (also known as “Monkey Island”) in Puerto Rico for decades.
Female macaques “actively reduce” the size of their social networks and prioritize existing connections as they age, according to new research. The new study, led by the University of Exeter, looks at how this affects the overall cohesion and connection of the groups of older monkeys.
While the observed macaque populations (which had no more than 20% “old” individuals) were not affected at group level, computer simulations showed higher proportions of old macaques would reduce cohesion and connection.
Focusing on close friends and family in later life may bring a variety of benefits for both humans and macaques. Our research sought to determine the impact that individual age-related changes have on the overall connectivity of a society.
Dr. Erin Siracusa
“Focusing on close friends and family in later life may bring a variety of benefits for both humans and macaques,” said Dr. Erin Siracusa of Exeter’s Centre for Research in Animal Behaviour.
“Our research sought to determine the impact that individual age-related changes have on the overall connectivity of a society. We had data on six monkey groups gathered over an eight-year period, totaling 19 social networks. The first thing we discovered is that older female macaques are poor influencers. Because older females have fewer friends, they are less able to transmit knowledge and experience outside of their immediate social circles.”
The researchers investigated whether monkey networks with a higher proportion of elderly females (over the age of 18) were less cohesive and connected. They found no difference between networks that were older and those that had a higher proportion of young adults in the macaque populations studied.
In any given group, however, no more than 20% of the monkeys were old. Even older networks were still vulnerable. As a result, the researchers developed a computer model that simulated the effect of higher proportions of old macaques and discovered a decrease in network cohesiveness and connectedness.
“We found really substantial consequences for network structure, which could affect useful things like information transmission and cooperation, and could also limit the spread of disease,” said Professor Lauren Brent, also from the University of Exeter. In humans, population ageing is poised to be one of the most significant social transformations of the 21st Century. Our findings suggest this could have far-reaching effects on the structure of our societies and the way they function.”
With the global over-60s population expected to double by 2050, the findings suggest that social structures, cohesion, and connectedness may all change significantly.
While the human population is getting older, some animal populations are getting younger on average, which could have serious consequences. For example, older male elephants are frequently targeted by trophy hunters for their large tusks – and a 2021 University of Exeter study discovered that when there are fewer older male elephants present, male elephants are more aggressive to things like tourist vehicles.
