Sunday, May 22, 2011

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. 


  1. Here is the linked article about the prostate cancer study:

    Note in the article that the group of men who received higher amounts of DHA omega-3 did so mainly from actual fish, not from fish oil supplements. It is the fish - especially locally "farmed" fish - that can be high in toxicity, which can contribute to higher rates of cancer.

    Most fish oil supplement makers have been conscientious in their purifying the fish oil, and specify that their fish sources are from cold water, deep sea fish, not locally farmed fish. (After my own research in recent years, I have been getting Nature's Bounty fish oil.)

    The health-conscious consumer needs to make sure that the fish one buys at the grocer or fish market is caught in the cold water deep sea, and isn't locally farmed fish.

  2. Fact #1: You will die.
    Fact #2: You don't know when you will die.
    Fact #3: You don't know how you will die.
    Fact #4: You will get sick from time to time.
    Fact #5: You can get sick (and die) due to no fault of your own.
    Fact #6: Government can't prevent your death.

    Use common sense about how you live your life and treat your body. Don't worry about dying. You will soon enough. To put a proper perspective on life, read the Old Testament book of Ecclestiates.

  3. I'm not this is exactly correct, Mr. Wenzel. The birds and their beaks adapted pretty quickly because those birds who couldn't eat as much effectively died off. But in human societies, we don't allow people to die because they are not perfectly suited to some environment. Others will help them so that as many people as possible can survive. So human adaptations today will probably take a lot longer than a thousand or more years ago

  4. Actually there may some minor forces at play to lower the chances of disease-prone genes to be passed on.

    For example, having grandparents around affects children in multiple ways, including imparting knowledge but also allowing at times the parents to be relieved of their duties.

    The knowledge from the grandparents can help the child to be more successful in reproducing later, and the relief of being able to have your kids looked after by grandparents can cause a higher likelihood of having more kids. Both mechanisms are evolutionarily sound.

    Contrast this with a couple that both parents have died due to a genetic predisposition. No knowledge is being passed to the kids but through the parents, experience, and educational system, and if the strain of child-rearing is higher than if the grandparents were alive, then the parents are less likely to choose to have more kids.

    These mechanisms could manifest over several generations, presumably slowly.

  5. I wanted to add on to my comment about the evolutionary benefit of having grandparents, because it occurred to me that this could be a means for explaining the actual life expectancy.

    Specifically, after grandparents have reached a certain age there is no evolutionary benefit to having them around, and that is where evolution would work over time to cause them to pass away. We can conclude from available evidence that that age is around 70 but in a large range. The large range is an indicator of being of minor evolutionary importance.

  6. Stick to economics dude.

  7. "This is not completely so. It will optimize to our reproductive years."

    NO. In hunter-gatherer society if parents were to die off prematurely, the survival rate of their children (and/or future generations) would also decline. You are over-simplifying.


    This is a great site about the link between evolution and diet, and the harm being done by the modern diet which strays too far from the natural human diet. The guy's not dogmatic, and supports his points. He's also a fan of Murray Rothbard, so you know he's gotta be a pretty good guy.