Saturday, November 04, 2006

Self-awareness--it's not just for primates anymore

When I look in the mirror, I am able to discern that the image I see is a reflection of myself. As long as you are not suffering from some sort of debilitating cognitive disorder (in which case you would almost certainly not be reading this), you can do the same. Other species of great apes (and possibly bottle-nosed dolphins) have the brain functions needed to associate their reflections with themselves as well.
Now, according to a new study in the Proceedings of the National Academy of Sciences of the United States of America, elephants show signs of having this ability as well:

Considered an indicator of self-awareness, mirror self-recognition (MSR) has long seemed limited to humans and apes. In both phylogeny and human ontogeny, MSR is thought to correlate with higher forms of empathy and altruistic behavior. Apart from humans and apes, dolphins and elephants are also known for such capacities. After the recent discovery of MSR in dolphins (Tursiops truncatus), elephants thus were the next logical candidate species. We exposed three Asian elephants (Elephas maximus) to a large mirror to investigate their responses. Animals that possess MSR typically progress through four stages of behavior when facing a mirror: (i) social responses, (ii) physical inspection (e.g., looking behind the mirror), (iii) repetitive mirror-testing behavior, and (iv) realization of seeing themselves. Visible marks and invisible sham-marks were applied to the elephants' heads to test whether they would pass the litmus "mark test" for MSR in which an individual spontaneously uses a mirror to touch an otherwise imperceptible mark on its own body. Here, we report a successful MSR elephant study and report striking parallels in the progression of responses to mirrors among apes, dolphins, and elephants. These parallels suggest convergent cognitive evolution most likely related to complex sociality and cooperation.

The Washington Post has more:
Elephants can recognize themselves in a mirror and use their reflections to explore hidden parts of themselves, a measure of subjective self-awareness that until now has been shown definitively only in humans and apes, researchers reported yesterday.

The findings confirm a long-standing suspicion among scientists that elephants, with their big brains, complex societies and reputation for helping ill herdmates, have a sufficiently developed sense of identity to pass the challenging "mirror self-recognition test."

[. . .]

Researchers over the years have provided body-size mirrors to hundreds of animals in zoos and other habitats. Almost always, the animals act as though the image they see is of another.

"Most animals seem incapable of learning that their behavior is the source of the behavior in the mirror," Gallup said. "They are incapable of deciphering that dualism."

By contrast, human babies get it by age 2, as do adult chimpanzees, bonobos and orangutans.

Monkeys, which are more distantly related to humans than are apes, never catch on. Indeed, the only non-ape species to come close to passing until now has been the bottlenose dolphin; it lacks the limbs to touch itself (a key part of the mirror test's final challenge) but can use mirrors to examine hidden parts of its body.

[. . .]

In a series of experiments, the elephants first explored the mirror -- reaching behind it with their trunks, kneeling before it and even trying to climb it -- gathering clues that the mirror image was just that, an image.

That was followed by an eerie sequence in which the animals made slow, rhythmic movements while tracking their reflections. Then, like teenagers, they got hooked.

All three conducted oral self-exams. Maxine, a 35-year-old female, even used the tip of her trunk to get a better look inside her mouth. She also used her trunk to slowly pull her ear in front of the mirror so she could examine it -- "self-directed" behaviors the zookeepers had never seen before.

Moreover, one elephant, Happy, 34, passed the most difficult measure of self-recognition: the mark test. The researchers painted a white X on her left cheek, visible only in the mirror. Later, after moving in and out of view of the mirror, Happy stood directly before the reflective surface and touched the tip of her trunk to the mark repeatedly -- an act that, among other insights, requires an understanding that the mark is not on the mirror but on her body.

The researchers also placed a transparent, "sham" mark that could not be seen in the mirror on Happy's right cheek, to see if the feel of that mark on the skin alone might cause her to touch that spot. It did not.

DeWaal acknowledged that the precise meaning of the test is debatable. In particular, he said, "people who work on animals that don't pass the test get upset" and tend to belittle its meaning.

But he and many others strongly suspect that the rarity of mirror self-recognition -- along with it being more common among animals reported to help other animals in need -- makes the test a good marker for a certain level of consciousness.

"I believe that all animals have some level of self-awareness, but those that pass the mirror test have more of it," de Waal said.

Marc Hauser, a Harvard biologist who has studied self-recognition in cotton-top tamarins, said that the mirror test is valuable but that other tests can also shed light on "what kinds of thoughts animals have about themselves and others."
Not so dumbo is he now, eh?

2 comments:

Dave said...

This post is alternatively titled, "Science news and a criminally bad pun."

Anonymous said...

This is so cool... OK, lame comment, but it is... I've spent the last week studing Hebrew and writing leadership papers. That's the analysis you get.

I have no google ID, and don't really want one, so I'm being anonymous....

-John Reed