Ever since Koko the gorilla learned a rudimentary form of sign language years ago, our concept of animal consciousness has expanded. Putting aside for a moment the debate over whether animal communication can ever constitute actual language itself–whatever you call it, it’s still pretty amazing. When Koko coined new signs such as “drink fruit” for watermelon, or asked for a replacement pet cat when hers died, it’s hard to imagine that there wasn’t something quite advanced happening in that construct we would almost have to refer to as her mind.

And then there’s the topic of mirrors, which can be used to measure an animal’s consciousness of self, or self-consciousness. According to this NY Times article, humans, apes, and perhaps dolphins have the ability to recognize their own images in a mirror, and now there is new evidence that monkeys may have some capacity to do so, too.

Dr. Frans de Waal of the Yerkes National Primate Research Center in Atlanta has done research that challenges the idea that capuchin monkeys only see strangers when they look in a mirror. The behavior of the capuchins indicated some awareness that the image was not a stranger, although it stopped short of showing a sense of self. The monkeys’ behavior front of the mirror varied according to their gender (I suppose that shouldn’t surprise us too much):

The female capuchins, the researchers found, avoided eye contact with a strange monkey while also making friendly overtures. But in front of a mirror their behavior was different. They looked often at their image, almost as if trying to flirt with it. The male capuchins, in contrast, were seriously bothered by their image. Unlike Narcissus, they “appeared confused and distraught by their reflections” and often tried to escape from the testing room, the Yerkes team reports.

Theories about what might cause these differences aren’t all that convincing:

The male capuchins, particularly the high-ranking ones, may be discomfited by their reflection because it fails to play by the rules of the monkey hierarchy and show them due deference. On the other hand, this realization might be expected to build up gradually in the minds of the male monkeys, making it hard to explain why they instantly perceive that the image is not a stranger…Male capuchins probably react differently from females because they take their mirror image more seriously and don’t know how to handle it, Dr. de Waal said.

But female chimpanzees, members of the ape rather than the monkey family, have no such problems. Far from being discomfited or distraught, they react to mirrors as though they’ve been waiting for one all their lives:

Give a female chimp a mirror, and one can have no doubt she knows just what it is for. The chimp will look at the two important parts of her body that she can usually never see, Dr. de Waal said. One is the inside of her mouth; the other is her rear end.

Apparently, beauty is in the eye of the beholder.