David Friedman's Confusion About Evolution

David Friedman (son of Milton) points out some interesting new reports that, if Mayor Bloomberg were a decent human being, would cause Bloomberg to stop attempting to set the diet for every person that sets foot in Manhattan. Bloomberg is attempting to reduce the salt in take of those in NYC.

Friedman's post suggests this may not be such a good thing:

There is a longstanding argument for reducing the amount of salt modern Americans consume, based on evidence that a high salt diet tends to produce high blood pressure. A recent European statistical study, however, reported just the opposite of what that argument suggests—evidence that lower salt intake was correlated with an increased risk of death from heart disease. Similarly, there is evidence that an increased consumption of omega 3 oils reduces the risk of heart attacks. But it has recently been reported that it also increases the risk of the more serious form of prostate cancer.

After highlighting these important studies, Friedman goes on to make two serious errors about evolution. He writes:

.....evolution is slow. We have had hundreds of thousands of years to optimize our bodies to function in the environment of hunter/gatherers, about ten thousand years to optimize against the environment of agriculturalists, and only a century or so to optimize against an environment where, in the developed world, most people have all the food they want and little need for physical labor. Hence it is not surprising if some of our behavior, and some of our biology, is poorly adapted to our present environment—making possible deliberate improvements in diet or life style

I'm not sure where Friedman gets the idea evolution is slow. I recall reading somewhere that scientists noted the remarkable rapidity in the change of beak size of certain birds, once the environment changed and survival for the birds depended on the new beak size.

Indeed, this type rapid evolutionary change should not be hard to understand. Suppose for some reason all humans died off in their early teens, other than those who had curly hair. It would become obvious that humans would evolve to have curly hair, since they would be the only ones who lived long enough to pass on their genes.

Friedman in his post does recognize the importance of reproduction in evolution, but makes a key mistake. He implies that our bodies over time will optimize to the current environment. This is not completely so. It will optimize to our reproductive years. Since heart attacks and prostate cancer generally occur after child producing years. There is nothing in the evolutionary selection process to weed out those who will suffer from heart attacks and prostate cancer. If a gene carrier for heart attacks or prostate cancer can have children before he suffers from a heart attack or prostate cancer, he is passing on his vulnerability to heart attacks and prostate cancer and there is no natural selection process to weed these diseases out, now or ten thousand years from now.

Friedman is correct in saying that we can deliberately alter our food intake to optimize our health in certain ways, but this has nothing to do with the fact that heart attack genes and prostate cancer genes won't be passed on, as he incorrectly implies. If a heart attack gene carriers and a prostate gene carriers live long enough to have children, those genes will be passed on.