Nature, Nurture and Wickedly Smart Bears

By Abraham Verghese

I attended a wonderful presentation a few days ago by Ajit Varki, a physician and scientist at the University of California San Diego and head of the Center for Academic Research and Training in Anthropogeny. That word, "anthropogeny" was a new one for me. It means, 'explaining the origin of humans, or 'the science or study of human generation.' Varki's long standing interest in sialic acid receptors that are plentiful in all our cells led him to discover that we lost one variety of that receptor some time ago when we diverged from our nearest relatives, the apes.  

The work of Varki and his colleagues is particularly helpful in the gene versus environment debate.  A spate of recent articles have pointed out that the human genome project hasn't as yet yielded the treasures that were promised. Our science fiction fantasy was that we'd map your genome, and predict that on a Tuesday in September in 2022, you would wake up with a heart attack or a brain tumor (and presumably there were thing we could to help you avoid that fate). It turns out that even though we now have identified many areas on the human chromosome linked to diseases like diabetes, they simply are not very useful to predict that the patient will get diabetes.

For example, if I see an overweight patient walk into my office, that sight alone is a better predictor of their risk for diabetes than any genetic test I might order.  If a pack of cigarettes shows in his pocket and his finger nail is yellow, I know a lot about his risk of sudden death from heart disease. I must say that as a clinician, this is somewhat reassuring, the notion that you still have to use your eyes and senses and earn the patient's trust to learn the kinds of things that may have put him or her at risk for various illnesses. It also says we have much to learn about the environment and its influences on us.

Dr. Varki's group suggests that even 'nature versus nurture' is too simplistic a debate, and that we as humans evolved because of a dependence on learned behaviors and social interactions that may have been advantageous. It may be that even things like breastfeeding among animals are learned behaviors and are not hard wired! His work makes for fascinating reading and it would be folly to try to summarize.

As I was preparing this piece, I read in the NY Times about a bear named Yellow-Yellow in the Adirondacks who has managed to get past a bear proof food container that stymies all other bears.  Surely this learned behavior will give Yellow-Yellow a survival advantage if that becomes the only source of food available. The big question is can she and will she teach it to her fellow bears, or to her mate and to their progeny?  The fate of the universe rests on such questions.

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