Research into the behaviour of female macaque monkeys shows that ‘girl gangs’ are not just a phenomenon in the human world. When united against a common enemy, such as a female monkey higher up in the social ranks, studies show that subordinate females can achieve a coup and overthrow their leader. With the moral support of other less powerful female macaques, these primates can achieve better social mobility that they would be unable to achieve alone.

The scientists selected rhesus macaques as the test subjects to carry out their experiment on, due to the rigid hierarchies of female power in their society. The team studied 357 adult females in captivity over two-years and observed in the region of 11,000 power conflicts.

When a low-ranked rhesus monkey encounters a more senior monkey, they have to grovel by bearing their teeth. Darcy Hannibal, at the University of California, described this signal as important in communicating social rank, similar to the human equivalent of bowing.

To maintain or increase social rank, females will recruit allies in the form of friends or family. The primary advantage in having additional support is ease when competing with dominant monkeys for resources. The scientists working on the project discovered that lower-ranked monkeys that are older, heavier (by at least 7 kilograms than their opponent), had more followers, or had their mothers amongst those in their support group were more likely to rebel. Interestingly, the number of followers possessed by a dominant monkey did not put off or encourage inferior monkeys to committing acts of insubordination.

Dario Maestripieri at the University of Chicago has suggested that the team’s definition of rebellion may have been too broad and that primate examples of entire families revolting against and killing their chiefs is actually very uncommon.

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