Old monkeys seem to become more isolated as they grow older, similar to how humans select their social groups more wisely as they age.
The Barbary macaques are the subjects of this behavioral study performed by German and Swiss scientists. More than 100 animals were observed to see how they interact depending on their age.
The study involved monitoring social interactions and social experiments. The old monkeys were presented with new toys and information about their friends, in order to test their interest and involvement in social activities.
Scientists discovered that the aged macaques were more attentive in selecting the individuals with whom they would interact. However, they were still interested in social information.
The Experiments
The experimental situations involved showing pictures with babies and playing recorded screams of monkeys from the same group. The macaques reacted with interest towards children, and when their heard friends are calling, they showed their intention to help.
The macaques were also presented with three different types of objects, such as animal toys, a colorful cube and a tube filled with food. Old monkeys were found to be less interested in new things as they might have lost the fine motor skills needed to perform object exploration. However, they were still interested in food.
Gossip and Grooming
Grooming is one of the most productive social activities between macaques. Scientists observed that old monkeys were more selective when they choose their partners. On the contrary, younger monkeys did groom older individuals, despite the fact that it was not always reciprocity in their actions.
The other group members continued to invest in interactions with older monkeys, even though the latter had limited social interest.
Another interesting fact was that old macaques were still participating emotionally in the social interactions in their group. The pictures with babies and the fighting screams obtained reactions from old monkeys as if they were commenting on the actions of other group members.
During the experiments, the macaques not only seemed to keep their interest in their friends and non-friends, but they were more sensitive towards socially important individuals from their group.
Old Monkeys and Humans
Experts believe that humans and monkeys have very similar rules of social interactions, which had been designed to help the individuals perform better in groups and get the needed support from the community.
As the energy level decreases with age, older monkeys seem to find social interactions more stressful. The same behavior was observed in humans, who tend to limit their activities to places they know well and to people whom they are already accustomed to.
Scientists see this change of behavior as an evolutionary pattern linked to how monkeys manage the restrictions imposed by old age.
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