Thursday, May 08, 2008

Animal minds: Learning may not pay, but some animals do it anyway

In "Lots of Animals Learn, but Smarter Isn't Better" (May 6, 2008), New York Times science writer Carl Zimmer tackles the question of how learning evolves.

If your science prof told you long ago that learning evolves because animals that learn faster are more likely to survive, forget it. Learning imposes costs of its own, as one experiment showed:
Dr. Kawecki and his colleagues pitted smart fly larvae against a different strain of flies, mixing the insects and giving them a meager supply of yeast to see who would survive. The scientists then ran the same experiment, but with the ordinary relatives of the smart flies competing against the new strain. About half the smart flies survived; 80 percent of the ordinary flies did.

Reversing the experiment showed that being smart does not ensure survival. “We took some population of flies and kept them over 30 generations on really poor food so they adapted so they could develop better on it,” Dr. Kawecki said. “And then we asked what happened to the learning ability. It went down.”

The ability to learn does not just harm the flies in their youth, though. In a paper to be published in the journal Evolution, Dr. Kawecki and his colleagues report that their fast-learning flies live on average 15 percent shorter lives than flies that had not experienced selection on the quinine-spiked jelly. Flies that have undergone selection for long life were up to 40 percent worse at learning than ordinary flies.

Actually, most life forms have not relied on high levels of individual learning to survive (or not, as the case may be). Quick learning is, after all, an alternative to built-in behaviour. Whether it is better or worse depends on the circumstances, I suppose.

The article closes with speculations about human learning. But I don't think the comparison to fly and worm learning really works.

The reality is that we humans must learn. If we don't, we suffer, just as we would if we didn't exercise. Friends who nurse people with Alzheimer and other dementias say that the best defense against the disease is to keep on learning. One Alzheimer nurse recommends learning a new language, for example.

A healthy neuron is a busy neuron? I would love to see a neuroscience study on that!

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