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10/02/2008
Looking in the Mirror
Thinking that my last two columns on mud and dirt were perhaps too easy to understand and write about, I decided to stretch my mind and write about some things that I find hard to fathom, neutrinos and string theory. I’ve said previously that I often write about a subject in an effort to kid myself into believing that I actually understand it. A short News Scan article by Mark Alpert in the September Scientific American spurred my interest. The article discussed work at the Fermi National Accelerator Laboratory in Batavia, Illinois on studies of neutrinos hinting that extra dimensions predicted by string theorists may actually exist. I’ve written before about neutrinos coming in different "flavors" and about the speculated many extra dimensions in string theory.
Well, I made the mistake of going online and tracking down one of the original works discussed by Alpert in his brief article. After an hour or so trying to fathom the exotic mathematics and high-powered theory, I decided my feeble mind was not up to the task. Besides, it was clear that they still hadn’t pinned down the existence or nonexistence of extra dimensions. So, for the time being, I’m content with 3-dimensional space and one dimension of time.
Now, faced with the dilemma of what to write about, I naturally turned to my favorite subject of animals and behaviors indicating a degree of intelligence that we humans are sometimes reluctant to accept. So, let’s turn to magpies and a study brought to my attention by StocksandNews editor Brian Trumbore. I lost the original reference from Brian but believe it was BBC News. However, I found the original work by Helmut Prior, Ariane Schwartz and Orun Gunturkun (umlauts over the "u"s in the last name) published August 19, 2008 in PLoS Biology, Vol.6, No.8, e202. (PLoS is the Public Library of Science, a free and open peer-reviewed set of journals in different fields found on the Web site plosjournals.org.) The article, titled "Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition", was accompanied by Frans B. M. De Waal’s article "The Thief in the Mirror" (ibid., e201}, which helped place the Prior and teammates’ work in context.
The magpie is a member of the corvid family of birds, which includes the crow, raven and scrub jay among its members. In past columns we’ve talked about corvids of one type or another showing distinct signs of intelligence, especially in the use of tools and in the area of stealing and hiding food from other corvids. For example, if one bird notices another bird watching it hiding some food, the first bird is likely to wait for the other bird to leave and then place the food in some other location. This indicates that the food hider knows that in a similar situation, if it were the observer, it would steal the food from the hiding place of the other bird. Could thi mean that the bird possesses some degree of self-recognition?
How to measure self-recognition? One method is to determine whether an animal recognizes that the reflection in a mirror is itself, not some other member of its species. It’s obvious from observing a human using a mirror that he or she has self-recognition. For example, if a person sees some dirt on his or her face, the person flicks off or washes off the dirt. About four decades ago, Gordon Gallup used the same sort of experience to come up with what has become a standard way to see if an animal has self-recognition.
Gallup’s method is the mirror mark test, in which a visible colored dot is marked on a part of an animal’s body that the animal cannot see except with the aid of a mirror. If the animal sees the mark in the mirror, there are at least two scenarios. If the animal doesn’t recognize itself in the mirror it will think it’s another animal’s problem and most likely will ignore the spot. However, if the animal recognizes itself in the mirror, it will want to investigate the spot and probably will want to get rid of it by rubbing or picking it off.
This mirror mark test has been applied to many different animals and, aside from us humans, only some of the great apes, bottlenose dolphins and certain elephants have shown self-recognition by examining and/or trying to get rid of the spot. In an earlier column (11/8/2006), I wrote about Happy, an Asian elephant at the Bronx Zoo, that responded positively to the mirror mark test.
When it comes to birds, until the work of Prior and his colleagues, no positive responses to the mirror mark test have been reported. However, De Waal cites skeptics who point out that some pigeons have been trained to peck at colored dots on themselves while in front of a mirror. Defenders of the mirror mark test will argue that training an animal to do such a specific task doesn’t imply self-recognition but merely trains an animal in a specific task. So far as I know, no untrained pigeon has been reported using a mirror to deal with marks on its body.
OK, let’s get to the magpie. It’s a noisy, quarrelsome bird given to raiding other birds’ nests and enjoys stealing items from humans as well. Prior and colleagues studied five hand-raised adult European magpies named Gerti, Schnatzi, Harvey, Goldie and Lilly. Of the five, Harvey and Lilly showed little or no signs of self-recognition. Harvey especially was quite aggressive and quite agitated, beating his wings and trying to get at the figure in the mirror. The paper contains individual videos of the various birds in action. Harvey was not thrilled with the mirror and the videos show him violently attacking the mirror right up to the end of the experiments.
In the experiments, the birds were first placed in a situation where they could spend their time back and forth between two compartments, one with the mirror and the other without the mirror. Harvey and Lilly preferred to spend most of their time avoiding the mirror, while Gerti and Goldie, and Schnatzi to a lesser extent, preferred to spend most of their time in the mirror compartment. When first presented with the mirror, all the birds responded in a "social" manner, acting as though the figure in the mirror was an intruder. However, especially Goldie and Gerti, and to some extent Schnatzi, soon acted as though they knew something was different and they were obviously curious about this mirror figure. They would walk from side to side watching the figure follow their actions and sometimes would look behind the mirror, presumably to check out the possibility of another bird back there.
After a period of time to allow the birds to acclimate themselves to the mirror, the colored dots in the form of self-adhesive colored stickers were applied and the mirror mark tests begun. Care was taken to apply the stickers in the same manner each time and to make sure the birds were handled in a way that prevented them from seeing the attachment of the dots. In addition to the colored dots, "sham" marks were applied in the form of black stickers placed on black feathers.
Gerti and Goldie quickly detected the colored stickers and responded in most tests by trying to peck or scratch off the dots. With the sham dots, there was typically no response but in some cases, the birds did try to get rid of them. Apparently, in some cases the black-on-black still was visible to the birds. I’ve only given a sketchy account of the experiments and the types of observations. The researchers kept track of self- directed behaviors as well as of the attempts to get rid of the dots. It was clear that the birds who showed interest in the mirror before the mark tests were the ones who performed positively in the mark tests while the birds who avoided the mirror showed little or no indications of self-recognition, Harvey being the prime example.
The number of birds studied wasn’t very large and the authors point out that they deliberately kept the number of trials low so there would be no training effect. You might worry about the fact that only two out of the five birds showed exceptionally positive responses to the mark tests, with Schnatzi a borderline case. However, the researchers point out that the results compare favorably with mirror mark tests on chimpanzees. Chimps would be expected to be a most self-recognizing species given their close kinship to us humans. Even so, in one study only about 75 percent of young adults passed the mark test, while the figures were appreciably lower for young and old chimps.
I like to think that my favorite bird, the late African grey parrot Alex, would have passed the mirror mark test. However, it seems that no African grey has ever passed the test. Oh well, I obviously didn’t pass the test of trying to understand neutrinos and extra dimensions. We all have our limits.
Allen F. Bortrum
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