Great apes, alongside humans, have long been known to be self aware. Chimpanzees, for instance, are famous for their individuality and remarkably human-like behavior, even playing dress-up in front of mirrors and referring to themselves in sign language. However, a new study shows that "lesser" monkeys can learn the concept of "self" as well, even using mirrors to become familiar with their own bodies.
That's at least according to a study recently published in the journal Current Biology, which details how rhesus monkeys developed apparent self-awareness after spending two to five weeks training with a mirror.
According to the study, this training consisted of sessions in which researchers shined a mildly irritating laser on a monkey's face. Investigators looked for clues that the monkey understood that the monkey he was seeing in the mirror - the one with a laser dot on his face - was himself. The researchers explained in a Cell Press release that they were looking for a "hey, what's that on my face?" kind of response.
Past research has shown that when offered mirrors of various sizes from a young age, lesser monkey species like these rhesus monkeys would quickly learn to use them as tools, even angling them for better perspectives - a sign that they understood that mirrors reflect images. However, they never showed any of the signs of self recognition that great apes do.
After this new mirror training, however, these signs finally became apparent. Specifically, five of the seven trained monkeys eventually started touching their face where the laser was being shown, sometimes smelling their hand as if to investigate how that strange red or green dot got there.
"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," Neng Gong of the Chinese Academy of Sciences explained in the release.
Soon after this self-recognition was achieved, the monkeys also began to investigate their own bodies using mirrors in unprompted ways, showing a complex understanding of "self" and how mirrors function.
Gong and his colleagues added that this is also great news for Alzheimer's treatment research, as it offers the possibility that people who are unable to recognize themselves in the mirror due to brain disorders can be trained to remedy this problem.
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