Older Female Rhesus Monkeys Save Remaining Energy for Family by Ditching Friends, Study Reveals

According to a recent study, female rhesus monkeys become more selective as they age and reserve their energy for close family members or other primates they have known for a long time.

As people get older, they tend to have fewer friends because they become more selective about whom they choose to spend time with.

Other mammals may have smaller social groups as they age, according to research.

Lauren Brent, a University of Exeter professor in the Center for Research in Animal Behavior, said that humans frequently exhibit this pattern of aging-related social network contraction.

Brent said that their research provides the strongest evidence yet that social selectivity is not limited to humans and may therefore have more profound evolutionary roots.

8 Years of Data and 200+ Macaques

An international team of scientists examined eight years' worth of data and observations on more than 200 rhesus macaques (Macaca mulatta) residing on the Puerto Rican island of Cayo Santiago for their research.

Monkeys are very social animals and this population has been very well-studied.

To determine how socially connected the monkeys were, researchers recorded grooming interactions and how close they were to one another physically.

They focused specifically on females between the ages of 10 and 28 because they wanted to examine how social interactions change with age beginning in the prime of adulthood.

The median lifespan for females in these populations is 18 years, with a maximum age of about 30 years, so macaques are regarded as adults at 6 years old.

They recorded whom the monkeys interacted with and how each monkey's social life evolved as they grew older.

Older Female Rhesus Monkeys on Relationships

Researchers discovered that women "actively reduce" their social circle as they get older after ruling out other possible reasons for social behavior changes, such as the loss of a partner.

Four specific changes in their social relationships and interactions were found.

Female monkeys had fewer interactions with other animals as they grew older and were more inclined to have family members in their networks.

They also placed a strong emphasis on partnerships that are stable and connected.

Additionally, female macaques had fewer partners as they aged, indicating that this was a choice made by the aging women.

Older females continued to appeal to other monkeys despite their increased choosiness in mates.

The same number of partners continued to approach them, and the amount of grooming remained constant.

The findings by Brent and her colleagues were published in the journal Proceedings of the National Academy of Sciences.

Read also: Macaques in Yamaguchi Form Aggressive Monkey Gang Responsible for Over 50 Attacks 

From a Different Angle

Erin Siracusa, a researcher also from the University of Exeter, said that age-related social selectivity increases in macaques for a variety of reasons.

The advantages of social interaction, for instance, might alter over time.

A large social group that can aid in the exploration and the discovery of potential mates may be advantageous for young macaques.

However, according to an article published on the University of Exeter website, staying with family and close friends may be simpler and safer for older monkeys due to threats such as disease transmission and conflict.

Siracusa said that although the group observe no decrease in the amount of time spent on socializing, older macaques may conserve mental energy by reducing their network because new relationships will further require more mental effort Treehugger reported.

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