Studying brain metabolism, scientists investigate how macaque reshus treats sounds. Like humans, when macaque hears people's calls, it increases the activity of the left hemisphere of the brain. According to the researchers, this slows down the activity of the right hemisphere. Moreover, any other sound does not produce the same response in the monkeys' brains.
Scientists have begun to speculate on the possibility that this activity is representative of the ability to speak, in short, something similar happens in humans. However, researchers have also raised the reverse idea that the study of macaque reshus can help to understand human evolution.