Rhesus monkeys are not inherently able to recognize themselves when they look in a mirror, but a group of researchers have successfully shown that they can be taught to do so. This was accomplished using the ‘mark test’ which has been used on a number of other animals, including elephants. This is the first time self-recognition has been identified in these monkeys. Liangtang Chang of the Chinese Academy of Sciences is lead author of the paper, which was published in the journal Current Biology. 

Though human infants often enjoy looking in mirrors, they don’t fully understand that they are seeing a reflection of themselves until they are about almost 2 years old. Sure, they might enjoy what they see in the mirror long before that, but it takes some time for them to understand what is going on. Rhesus monkeys, on the other hand, have never before been shown to self-recognize in mirrors.

"Our findings suggest that the monkey brain has the basic 'hardware' [for mirror self-recognition], but they need appropriate training to acquire the 'software' to achieve self-recognition," senior author Neng Gong of the Chinese Academy of Sciences said in a press release.

Other studies involving rhesus monkeys and mirrors have indicated that they understand the nature of a reflection and used it as a tool for other applications, but did not show signs of self-awareness when looking at themselves. Even if the scientist marked the monkey’s face, they did not appear to realize there was something on their face.

In the new study, the researchers taught the monkeys how to complete the mark test. This involved shining a beam of light from a laser on the monkey’s face as it sat in front of a mirror. Though the light was harmless, it was meant to be rather annoying. Over several weeks, five of the seven monkeys appeared to have learned to identify themselves in a mirror, while a control group of untrained monkeys did not.

When these test monkeys looked in the mirror and saw the mark on their face, they touched the spot on their head with their hand, and then smelled their fingers to explore what the mark may have been. Beyond that, the monkeys further demonstrated self-awareness by using the mirror to examine other body parts they are not normally able to see very well.

The ability to teach self-recognition may be good news for those who are not able to due to various neurological conditions such as autism, Alzheimer’s, or head trauma.

"Although the impairment of self-recognition in patients implies the existence of cognitive/neurological deficits in self-processing brain mechanisms, our finding raised the possibility that such deficits might be remedied via training," the authors explained. "Even partial restoration of self-recognition ability could be desirable.”

However, this might not be a slam dunk quite yet. Live Science reports that Gordon Gallup Jr., the evolutionary psychologist who invented the mark test, dismissed the findings. He chalked the results up to learning to touch their face as the researchers had taught them, but not actually participating in learned self-awareness.