As people get older they become more selective on whom they meet and spend time with.
According to new study published in the Cell Press journal Current Biology Barbary macaques also becomes selective who they hang out with as they get older.
"An important psychological theory suggests that humans become more socially selective when they know that their remaining life time is limited, such as in old age," says Laura Almeling of the German Primate Center in Göttingen, Germany. "We assume that monkeys are not aware of their own limited future time. Therefore, if they show similar motivational changes in old age, their selectivity cannot be attributed to their knowledge about a limited future time. Instead, we should entertain the possibility that similar physiological changes in aging monkeys and humans contribute to increased selectivity."
Researchers have watched closely more than 100 Barbary macaques during social interactions. Researchers also have also did experiments that examined monkeys’ interest in new stuff and social information with their friends.
From the experiments the researchers realized that monkeys’ interest in exploring new things dropped with age. But they did show interest if it was related food.
The researchers also realized that as the Barbary macaques aged, they became much more selective with whom they groomed but they were still groomed by younger monkeys. Grooming is considered to be a prolific method of social interaction in the monkeys.
"With increasing age, the monkeys became more selective in their social interactions," Almeling said. "They had fewer 'friends' and invested less in social interactions. Interestingly, however, they were still interested in what was going on in their social world."
"Older females continued to respond particularly strongly to hearing a scream for help from their best friend," Almeling explained. "Older males still looked preferentially at pictures of the newborns", she says, noting that Barbary macaque males use infants as status symbols."
It is not known why humans usually become more selective in older age, but the most popular theory tells that people are just far selective with their time knowing the end of their life they don't have much time to live and want to spend the time more preciously.
Yet monkeys have never given clue that they are aware of remaining future time, so perhaps this theory needs to be reassed.
Alexandra Freund, Fischer's colleague, says the discovery of the study precisely tell us that we are not distinctive in how we grow into old age.
"There might be an evolutionary 'deep' root in this pattern," says Freund.
Almeling and her colleagues wants to push further to rule out the possibility that older monkeys avoid social interactions as they age due to the stress they cause.
