A recently published study has shown that monkeys with similar personalities are more likely to have better relationships than those with very different personality traits. Some of the key indicators that were connected with how strong their relationships were linked to their levels of openess and sociability.
In order to determine the monkeys’ individual personality differences the researchers used a 54 trait personality questionnaire that the zookeepers completed for each monkey. Then to determine the quality of their relationships they conducted behaviour observations.
The behaviour study included noting how much time the monkeys would spend together, as well as what they were doing when they were together (e.g. aggression, food sharing, grooming etc).
In addition puzzle feeders were added into the enclosure to see if the monkey pairs showed symmetry in their behaviour to use the device or avoid it.
While watching the monkeys Dr Morton noted high levels of affiliative behaviour between Popeye and Penelope (pictured above), as well as high levels of symmetry in their behaviours around the puzzle feeder. Interestingly, these two monkeys also had similar personality traits appearing in their scores from the keeper surveys.
The results remained true even when other factors such as sex, age and rank were controlled for. These findings mean that their personalities may play a role in the quality of their relationships beyond that of status and kinship.
Morton, F.B., Weiss, A. Buchanan-Smith, and Lee, P.C (2015). Capuchin monkeys with similar personalities have higher quality relationships independent of age, sex, kinship and rank. Animal Behaviour.105, pp. 163 -171.