A Blog Around The Clock

Comments

  1. #1 TheBrummell
    January 30, 2009

    I saw Dr. Nesse give a presentation at the University where I did my M.Sc. several years ago. This video shows him in a similar way, which is good because he’s actually a very interesting speaker and has some great things to say.

    Unfortunately, there are some weaknesses, too. First, this video includes the presentation of the extreme adaptationist position: they both agree that any feature must be good simply because we see it. This is wrong. Some features of organisms are certainly adaptive, but many are certainly not, and are simply neutral, or even mildly deleterious but selection has not eliminated them. Why selection would not remove some negative feature of an organism could be for any of several reasons, including limited population size or time since this feature appeared in the population, genetic and phenotypic links and tradeoffs between features, the process of development, selection-mutation balance, and other considerations most importantly of which is Genetic Drift, a process at least as significant in evolution as Natural Selection.

    Second, of the list of disease symptoms that Dr. Hesse briefly presents, only three (coughing, fever, and pain) are discussed in some detail. Of those three, the obvious and extreme example given of people without the ability to feel pain is perhaps the least convincing. The extremes of any spectrum are always going to be rare and associated with other extremes (like early death). What does this mean for the rest of us? What are the fitness effects of a reduced (but not absent) or increased (but not all-pervasive) sense of pain? Do people with high pain tolerance have lower survival than the rest of us? Do people who go to great lengths to avoid ALL pain have higher survival or more children?

    The other examples are poorly supported. When I talked with Dr. Hesse after his presentation years ago, I asked him if he had specific examples of the benefits of fever. He mentioned the studies on lizards, as he does in this video. But I disputed then I and still dispute today the relevance of these observations. Yes, increases in temperature can inhibit pathogenic bacteria. Is there a threshold of effect for this – must you raise your temperature by at least 5 degrees to see any benefit? Lizard cells are presumably capable of functioning over a wider range of temperatures than mammalian cells, does this have any bearing on a raised body temperature and an infection? Very little is said about coughing, which just leaves that issue wide open.

    Overall, I think Dr. Hesse is doing a good job at something important: convincing the medical profession that evolutionary biology has something important to say about health and disease. But I wish he’d put some more concrete data into his message.

  2. #2 Coturnix
    January 30, 2009

    Good points – Larry Moran on Sandwalk said something similar. As you may know, I met Randolph last year in Berlin and he’s just the nicest guy ever. The ultra-adaptationism bothers me in general, but on the other hand, it is simplistic and easier to persuade with, so using it on physicians is sorta OK in my book. Sophistication can come later.

  3. #3 The Science Pundit
    January 30, 2009

    Interesting.

  4. #4 Randolph Nesse
    January 31, 2009

    Thanks for the posting and your encouragement. Your questions are good, but a TV interview is not a good place to provide detailed answers. Answers are readily available, however, in articles on my website http://nessse.us and at http://evmedreview.com

    I cannot see how anyone could conclude that Darwinian medicine is an “extreme adaptationist position.”. The program begins with an explanation of why the ulna and radius are too thin to protect against breakage. Natural selection could not do better because of a tradeoff. We went on to talk about really lousy aspects of the body, such as lower spine, and why the eye has a blind spot, and why the coronary arteries and the birth canal are too narrow. Most Darwinian medicine is about aspects of the body that are ill-suited to their purposes in ways that leave us vulnerable to disease. See, for instance, my article in the Quarterly Review of Biology, “Maladaptation and Natural Selection.” My writing offers dozens of examples of ways in which the body is poorly adapted. Drift is the least important and least interesting reason. There are five others.

    About pain, see Congenital insensitivity to pain—review and report of a case with dental implications Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, Volume 101, Issue 1, Pages 58-62 by J. Butler, P. Fleming, D. Webb for a review of the several different kinds of congenital pain deficits and their clinical correlates. An evolutionary view suggests that individuals who experience much more or much less pain than others will be at a disadvantage in the natural environment. Which is pretty much what you say above.

    About fever, instead of disputing it, why not look it up?. Kluger’s studies on the role of fever in lizards are a scientific classic. For a simple review, see Fever and survival, MJ Kluger, DH Ringler, MR Anver – Science, 1975, or some of the 200 articles that cite it, or his book. Studies on the adaptive value of fever in human infections are sadly lacking. There are some, but if you have influenza, will you get better faster or slower if you take something to reduce your fever? We don’t know. We do know, however, that the capacity for fever was shaped by selection because it is useful. For several reasons why, see my articles and books. I have, however, always been mystified by exactly how fever is useful. After all, you would not think that bacteria would be much bothered by an increase of a degree or so of body temperature. Finally, I found with a satisfying answer, one that exemplifies the role of Darwinian medicine in demonstrating why many aspects of the body are very poorly “designed” indeed! See http://skepticaladapatationist.com for the answer.

    And, it is Nesse, not Hesse.

  5. #5 Coturnix
    January 31, 2009

    While I dislike panadaptationism, I did not think that either this interview or writings fall into that category. And of course, talking to the ur-panadaptationist, Dawkins, in person, and trying to get one’s point across is probably not the best time to argue about adaptationism.

  6. #6 TheBrummell
    February 6, 2009

    Please accept my apologies for misspelling your name. People do that to me all the time, and it is aggravating. Sorry!

    Your responses are excellent; thank you, I will look up your papers and books when I have some spare time.

    I remain unconvinced about the value of fever in endotherms, but I haven’t studied the relevant literature, yet. A mechanism would be nice to see described, even in speculation.

    And I disagree that Drift isn’t interesting!

The site is currently under maintenance and will be back shortly. New comments have been disabled during this time, please check back soon.