From Wired, a report of laboratory monkeys (rhesus macaques, to be specific) that have shown signs of self-recognition (and thus potentially self-awareness):
In the lab of University of Wisconsin neuroscientist Luis Populin, five rhesus macaques seem to recognize their own reflections in a mirror. Monkeys weren’t supposed to do this.
“We thought these subjects didn’t have this ability. The indications are that if you fail the mark test, you’re not self-aware. This opens up a whole field of possibilities,” Populin said.
Populin doesn’t usually study monkey self-awareness. The macaques described in this study, published Sept. 29 in Public Library of Science One, were originally part of his work on attention deficit disorder. But during that experiment, study co-author Abigail Rajala noticed the monkeys using mirrors to study themselves
The article goes on to point out that self-awareness, long thought a unique identifier of human beings, isn’t an all-or-nothing phenomenon:
So-called mirror self-recognition is thought to indicate self-awareness, which is required to understand selfhood in others, and ultimately to be empathic. Researchers measure this with the “mark test.” They paint or ink a mark on unconscious animals, then see if they use mirrors to discover the marks.
It was once thought that only humans could pass the mark test. Then chimpanzees did, followed by dolphins and elephants. These successes challenged the notions that humans were alone on one side of a cognitive divide. Many researchers think the notion of a divide is itself mistaken. Instead, they propose a gradual spectrum of cognitive powers, a spectrum crudely measured by mirrors.
Indeed, macaques — including those in Populin’s study — have repeatedly failed the mark test. But after Rajala called attention to their strange behaviors, the researchers paid closer attention. The highly social monkeys only rarely tried to interact with the reflections. They used mirrors to study otherwise-hidden parts of their bodies, such as their genitals and the implants in their heads. Mark tests not withstanding, they seemed quite self-aware.
I would think that this kind of sliding scale of cognitive abilities is just what evolutionary theory would lead you to expect. After all, it posits a continuity between human beings and other forms of life.
I’d also add that creatures with self-awareness probably shouldn’t be kept in labs and have electrodes stuck in their heads. (Though, ironically, laboratory conditions probably made it more likely that we’d discover their self-awareness.)