Monkeys Coordinate Movements with Peers Just Like Humans

Researchers from Japan have found that monkeys synchronize their body movements with peers, just like humans do.

Humans are known to coordinate their movements with others - like adapting their pace to walk in step or clapping in unison. But researchers from the RIKEN Brain Science Institute, Japan, have reported that pairs of macaque monkeys synchronize their movements without any conscious effort.

For their study, the research team tested pairs of Japanese macaque monkeys to find out if they were able to synchronize a simple push-button movement. The monkeys were trained to push a button repeatedly using one hand before the experiment began. During the first experiment, the monkeys were paired and placed facing each other and their push-button movements were recorded.

In the second experiment, each monkey was shown a video of another monkey pushing a button at varying speeds controlled by the researchers. In the last experiment, the macaques were not allowed to either see or hear their video-partner.

The research team found that the macaques were able to synchronize the speed of their button-pushing tasks with both the real and video partners. They modified (either increased or decreased) the speed of their push-button movements to be in tune with their partners. The monkeys coordinated much better when they could both see and hear their partners. But different pairs of monkeys synchronized differently and reached different speeds.

This kind of synchronizing behavior could not have been learned by the monkeys during the experiment, as previous research has shown that it is difficult for monkeys to learn intentional synchronization, said the researchers. It is not clear as to why these monkeys show behavioral synchronization, but researchers suspect that it could be linked to similar adaptive behaviors that are significant for survival in the wild.

They hope the study could shed light into human behavioral dysfunctions such as autism, echopraxia and echolalia.

The findings of the study appear in the journal Nature Scientific Reports.