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Do We Need “Evolutionary Medicine”?

3 years ago I wrote an article critical of “evolutionary medicine” as it was presented in a new book.   Recently a correspondent asked me if I thought another book, Why We Get Sick: The New Science of Darwinian Medicine, by Randolph M. Nesse, MD and George C. Williams, PhD, was a more reasonable approach to the subject. It was published in 1994 and got good reviews from respected scientists like Richard Dawkins (“Buy two copies and give one to your doctor.”) and E.O. Wilson (“bringing the evolutionary vision systematically into one of the last unconquered provinces…”).  I was able to obtain a copy through interlibrary loan.

The book was interesting and gave me some things to think about, but it didn’t convince me that “Darwinian medicine” is a new science, that its existence as a separate discipline is justified, or that its unique approach offers any real practical benefits for improving medical care.

Why do we get sick? A simplistic view of evolution holds that it systematically eliminates any factors that decrease fitness for survival. So why does disease persist? Why didn’t we evolve to be “fit” enough to never get sick? Because evolution is not a straightforward process.

Evolution is complicated. There are countless “design flaws” in the human body. For instance, we are subject to choking because of the crossed anatomy of our respiratory and digestive systems. Nesse and Williams point out that it would be more sensible to relocate the nostrils to somewhere on the neck, but that just ain’t gonna happen. Evolution is limited by pre-existing patterns and has to make compromises. Historical accidents result in developments that are far from optimum. A useless or even a harmful gene may be perpetuated because it is linked with a beneficial gene. We are in an arms race with pathogens: we evolve defenses and they evolve ways to overcome those defenses. Natural selection made us fit as small groups of hunter-gatherers on the plains of Africa. We are specifically adapted to Stone Age conditions. We face very different environments today where our evolved traits can be counterproductive.

Who are the fittest? Fitness doesn’t mean fitness for the individual’s welfare, but fitness for propagating the individual’s genes. After the individual has reproduced, diseases of old age don’t affect evolutionary fitness except in minor, indirect ways. (Grandparents past reproductive age can contribute to the survival of descendants by helping with childcare and providing accumulated knowledge and wisdom.)

Nesse and Williams differentiate between proximate and evolutionary explanations: heart attacks are caused by cholesterol deposits in the arteries, but they want to know why evolution shaped us to deposit cholesterol, crave fat, over-eat, etc. I want to know, too; but I’m not so certain that knowing will reduce my chances of a heart attack.

Are evolutionary explanations just pseudoscientific equivalents of Kipling’s Just-So Stories? They argue that they are not. They give the example of morning sickness. It has been hypothesized that the nausea, vomiting, and food aversions of early pregnancy are beneficial because they protect the vulnerable fetus from dietary toxins. This would predict that morning sickness preferentially results in avoidance of foods most likely to harm the fetus. This is a testable prediction and there is some evidence to support it; but there is no way to prove that this is the true explanation or the only one. They suggest that suppressing morning sickness might increase the risk of congenital defects. But there is no evidence for that. They recommend that women “respect their nausea” and remember that it may be beneficial. (It would likely decrease your survival prospects if you said that to your wife while she was throwing up for the umpteenth time!) They admit that relieving suffering is important too, but they recommend that any anti-nausea medicine should be carefully evaluated to make sure it doesn’t cause any harm. Of course, we already do that for all medications used during pregnancy. I fail to see how evolutionary thinking adds anything to the care of pregnant women. In fact, I can see how it might result in unnecessary worry and suffering.

They suggest that sexual reproduction is an advantage because the genetic variations increase survival when a population faces an infection. As supporting evidence, they cite studies showing that asexual reproduction is more frequent in species and habitats with fewer parasites. Maybe. Correlation doesn’t prove causation.

They speculate that schizophrenia must persist in our genomes because it offers some advantage that balances the severe costs. They even have a creative hypothesis about why we sleep.

Most mammals can make their own vitamin C; humans can’t. The authors tell us that when humans switched to a high fruit diet rich in vitamin C, it allowed our biochemical machinery for making it to degenerate. Maybe. If so, nice to know. But so what? We still need exogenous vitamin C.

Even the most plausible evolutionary explanations may or may not be the true story. We can base predictions on them and test those predictions, but that can only provide circumstantial evidence. We can never know for sure whether our Just So Story is true or whether some other accidental factor was responsible.

Should we treat fevers? Fever probably evolved as a defense mechanism: it may do something towards helping fight off the infection. Evolutionary thinking makes us ask why we developed this adaptation and whether it is wise to interfere. But do we need evolutionary thinking for this? Doctors have already questioned the need to lower a fever, recognizing that it is not the fever but the infection that needs to be treated, that fever itself doesn’t do much harm, and that lowering a fever might have adverse effects in some cases. I’ve read many discussions of those points, and nowhere did they mention wondering about why we evolved to have fevers. I don’t see that evolutionary thinking adds anything useful to the discussion. Fever is what it is, and we can study it and deal with it without speculating about how it came to be that way.

Why are wisdom teeth a problem? Modern children frequently need orthodontia and surgery to remove wisdom teeth. They propose a possible explanation: we don’t chew enough. In the Stone Age, food required more jaw exercise. Today softer foods result in deficient use of jaw muscles, which results in poorer development of jawbones so there is less room for all the teeth. They suggest that many dental problems might be avoided if children chewed more gum or engaged in prolonged vigorous biting competitions.

This is nothing but silly, far-fetched speculation. You’ve got to give them credit for imagination; but if this is the kind of thing “Darwinian medicine” produces, we can do without it.

There is a disconnect in their logic. They say

For instance, if we hypothesize that the low iron levels associated with infection are not a cause of the infection but a part of the body’s defenses, we can predict that giving a patient iron may worsen the infection — as indeed it can. Trying to determine the evolutionary origins of disease is much more than a fascinating intellectual pursuit; it is also a vital yet underused tool in our quest to understand, prevent, and treat disease.

We can ask if something acts as a defense. We can ask whether something is a cause or effect. We can ask whether something does more harm or good. We can ask all these questions about how something works without necessarily needing to ask why it evolved to work that way.

Evolutionary thinking is already an integral part of medicine and an essential element of all biology. E. O. Wilson’s description of medicine as “one of the last unconquered provinces” simply is not true. Doctors regularly think about evolution and study its effects. The evolution of drug resistance in bacteria is the best-known example but there are many others. For instance, we think that sickle-cell anemia has persisted because it only affects those who inherit the gene from both parents, while those with only one copy of the gene (heterozygotes) have an increased resistance to malaria.  G6PD deficiency causes hemolytic anemia but also offers protection against malaria.

But consider this: malaria is a credible explanation, but we can’t prove that it is the real one. Some other factor that we have not considered might be the true explanation, and malaria resistance might be a coincidence. And the malaria explanation is intellectually satisfying to those who ask “why” but it has had no practical impact on diagnosis or treatment.

They want anyone faced with a problem of medical importance to ask “what is its evolutionary significance?” But they have not demonstrated to my satisfaction that systematically asking that question improves the progress of modern medicine.

So why do we get sick?

  • We have genes that make us vulnerable. They may be new mutations, or genes that haven’t been eliminated because their effects occur too late in life to affect reproductive fitness, or genes that have unappreciated benefits that outweigh their costs, or genes that only have harmful effects in novel environments.
  • We are exposed to factors that did not exist in the environment in which we evolved.
  • Design compromises.
  • The arms race with pathogens.
  • Unfortunate historical legacies.

They think every discussion of a disease should ask questions based on each of these factors, starting with the question “which manifestations of the disease are actually defenses?” Is the runny nose of a cold a host defense, a means the virus uses to spread itself, or both? That’s a good question, but it can be answered without any need for evolutionary speculations.

They propose special separate funding for studies of evolutionary hypotheses, and they accuse medical science of ignoring evolutionary thinking and even showing an antipathy to it.

Conclusion

I’m sorry, but I just don’t “get it.” Am I missing something? Am I just a contrary curmudgeon? Evolution is already an essential part of all science. Medical scientists already understand evolution and apply its principles appropriately. I didn’t see a single example in their book of any significant practical development in medical care that would not have occurred in the general course of medical science as it is commonly practiced, without any need for a separate discipline of “Darwinian medicine.” Evolutionary explanations, whether true or speculative, may satisfy our wish to understand “why,” but I can’t see that they have much objective usefulness.  Instead, they have produced at least one major annoyance: a movement that preaches to us how we ought to revert to the supposed diet of our ancestors (the Cave Man Diet, etc.).

Posted in: Book & movie reviews, Evolution

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105 thoughts on “Do We Need “Evolutionary Medicine”?

  1. The only book I have read on evolutionary medicine is Evolution in Health and Disease by Stearns and Koella (2nd edition, 2008) and I think that is much less sensationalist and more concerned about motivating the benefit of evolutionary thinking for medicine. It is also more up-to-date than the one from 1994.

  2. Janet Camp says:

    I was thinking of the “paleo-diet” nonsense while reading and then you got to it at the end! Great minds…….

    This kind of thinking is an interesting pastime and we did it all the time when I was an Anthropology undergraduate, but these two seem to be stretching a pastime into something “integrative” in the same way that so many other CAM devotees do.

    It seems to me that to ask, “why do WE get sick?” is the wrong question to begin with. Why does ANY organism get sick? I’d say for the reasons you mentioned and because the “system” isn’t perfect. Evolution doesn’t result in perfection, just effective means of survival. If evolution were perfect, I’m not sure we would have needed to invent gods.

    Thanks for reading this so I don’t have to.

  3. David Gorski says:

    Evolutionary thinking is already an integral part of medicine and an essential element of all biology. E. O. Wilson’s description of medicine as “one of the last unconquered provinces” simply is not true. Doctors regularly think about evolution and study its effects. The evolution of drug resistance in bacteria is the best-known example but there are many others. For instance, we think that sickle-cell anemia has persisted because it only affects those who inherit the gene from both parents, while those with only one copy of the gene (heterozygotes) have an increased resistance to malaria. G6PD deficiency causes hemolytic anemia but also offers protection against malaria.

    I’m going to have to disagree with you strongly here, Harriet. Until pretty recently, evolutionary thinking has never been an “integral part of medicine,” except in distorted forms like eugenics and nonsense like the “paleo diet.” In particular, I would take issue that doctors “regularly think about evolution.” Practicing doctors, in my experience, rarely, if ever, think about evolution with respect to medicine. Although evolutionary considerations have been (and continue to be) important in some areas of research, before the last few years, there were really only two areas in medicine where evolutionary thinking has played a significant role in actual clinical practice. That’s in infectious diseases (the evolution of antibiotic resistance in bacteria) and in medical oncology, where, as I’ve discussed before, the evolution of different subclones in cancer is one of the major hurdles—if not the single most insurmountable hurdle—in designing systemic cancer therapies. I note that the latter of these has only come to the fore in a big way over the last few years. So, while it’s true that evolution undergirds virtually every aspect of the genomics revolution, because evolutionary theory is the very basis we use to compare genes, identify mutations, and infer function, that thinking, sadly, has not filtered down to actual clinical practice very much yet, even now.

    I also have to echo Emil’s comment. Nesse’s book is old. It’s practically ancient. 18 years is an eternity in biomedical research. Back when that book was written, we did not know the sequence of the human genome because the Human Genome Project was in its infancy. Its final results were six years away. In 1994, it was not possible to do whole genome expression profiling, thus analyzing the expression of every gene in the genome simultaneously. Our most recent techniques, next generation sequencing sequencing techniques that allow us to sequence entire genomes and transcriptomes and identify every transcribed sequence, non-coding sequence, and chromosomal alteration were well over a decade away. The sophisticated computer algorithms and bioinformatics approaches that allow us to infer these evolutionary relationships from sequence and proteome data did not exist.

    In other word, Nesse’s book, while prescient, was probably premature. I’d be much more interested in a discussion of much more recent work. In fact, I’d even argue that 2008 is a bit long in the tooth for this discussion, particularly when it’s a textbook we’re talking about given that most textbooks are a couple of years behind the times when they are published. Even four years ago, next generation sequencing techniques were only just starting to become available outside of huge genomics research institutes. These days, this is more what evolutionary medicine looks like:

    http://www.ncbi.nlm.nih.gov/pubmed/19359553
    http://www.ncbi.nlm.nih.gov/pubmed/22271169
    http://www.bmj.com/content/343/bmj.d7671?view=long&pmid=22184558

    And here’s a 2012 article by Nesse himself:

    http://www.springerlink.com/content/c082v076l0m4hhu3/

  4. fledarmus1 says:

    While I enjoyed your review, I note that many of your criticisms of this book, and in general of evolutionary medicine, have to do with the fact that they haven’t improved the practice of medicine. I think this is true in the same way that non-Newtonian physics haven’t improved the practice of architecture. When you are building a structure it doesn’t matter much to you that space is curved by gravity, and when you are treating malaria it doesn’t matter much to you whether the disease selected for sickle-cell anemia in humans or was simply an associated effect. It does, however, provide an interesting basis for study and a means for generating testable hypotheses in a variety of anthropologic and paleontologic areas, which may one day lead to a broader framework of connections and new ways of understanding biological processes.

    The big concern appears to be the misuse of evolutionary medical jargon to avoid the necessity of carrying out the experiment. The “Cave Man Diet” without any outcomes measure is a useful as the perpetuation of quantum effects in water molecules.

  5. BehavEcology says:

    Medical scientists already understand evolution and apply its principles appropriately.

    Medical *scientists* may understand evolution, but I’m not sure how many front-line doctors do. Example: the clinic doctor I was seeing before I left Canada. During a checkup, he asked me what I did, and when I said ‘evolutionary biology’, he launched into a long-winded creationist spiel. ‘It’s just a theory’, he said. I wish I was making that up.

    Luckily, I was leaving the continent, which saved me the hassle of having to find a new doctor.

  6. Ed Whitney says:

    Taking evolution seriously prevents you from trying to transplant a baboon heart into a baby with a hypoplastic left heart. The good doctor at Loma Linda who transplanted Baby Fae in 1984 did not “believe in evolution.” Dr. Leonard Bailey’s religious belief system led to a grotesque experiment whose failure could have been predicted by using an evolutionary frame of reference in considering appropriate transplant sources.

  7. ConspicuousCarl says:

    The next big thing often ends up being the next little thing. Still important, though.

  8. I’m with David Gorski here. What I took from this book was an appreciation of interpretation that has been sorely lacking in the treatment of painful problems during my 40 year career as a physical therapist.

    Shifting our understanding of specific muscular activity from defect to defense is huge.

  9. Harriet Hall says:

    @David Gorski,

    “Until pretty recently, evolutionary thinking has never been an “integral part of medicine,”

    That’s true. I didn’t comment on how recently it became an integral part. Your links support my argument that it is indeed an integral part of medicine today.

    “Practicing doctors, in my experience, rarely, if ever, think about evolution with respect to medicine”

    That’s true. But these authors claimed that doing so would improve office practice. The examples they gave were unconvincing. Do you have any good examples?

    “Nesse’s book is old.”

    I realize that, and I only read it because I was asked to by someone who thought it presented a reasonable case for evolutionary medicine.

    I think “genetics” may be getting confused with “evolution” here. We can understand genetic principles like why baboon hearts don’t work in humans without speculating about why the genetic differences arose.

    My objection is not to understanding evolution and applying its principles, but to accepting speculative explanations that can’t actually be verified. For instance, sickle cell and malaria: it’s possible that the gene arose in a setting where malaria did not occur, and that it survived for some other reason that we can’t go back with a time machine to identify. And even if the malaria link is the true explanation, what difference does it make except to satisfy our idle curiousity? And I don’t see any compelling need for a separate discipline of “evolutionary medicine.” Do you? Doesn’t it make more sense to incorporate it naturally into all medical disciplines?

    @Barrett Dorko,

    “Shifting our understanding of specific muscular activity from defect to defense is huge”

    Huge how? How has it impacted your practice? Do you need an evolutionary explanation to apply the principle that what appears to be a defect may also be a protective mechanism?

  10. David Gorski says:

    That’s true. I didn’t comment on how recently it became an integral part. Your links support my argument that it is indeed an integral part of medicine today.

    In research (and then in only a relatively few types of research), yes. In clinical practice, most definitely not, except for infectious disease and, to a much lesser extent, oncology.

  11. Mark Crislip says:

    Years ago I did a back of the envelope calculation and 50 years of bacterial replication is about on par with 6 million years of human multiplication.

    Makes me wonder if the bacteria of today are the same as the bacteria of yesteryear. Is the S. aureus of 1950 the same same species as the MRSA on 2012? No one has ever compared the genomes, but I wonder if a new species has evolved under our nose; Neanderthal becoming H. Sapiens metaphorically speaking.

    Every time I have asked that of microbiologists and other ID docs they look at me as if I were a loon. Well, perhaps I am, but the question remains.

  12. David Gorski says:

    That is a question that can be answered. There are bacterial stocks from decades ago frozen down and stored around. I can’t believe that at some point some scientist somewhere hasn’t sequenced them and compared them with bacterial stocks from bacteria isolated today. I might have to do a few PubMed searches to find out.

  13. Harriet Hall says:

    @Mark Crislip,

    You bring up an interesting point. A related question: is the Strep of yesteryear, the one that caused so much rheumatic fever, the same organism that hardly ever causes rheumatic fever today?

  14. David Gorski says:

    My objection is not to understanding evolution and applying its principles, but to accepting speculative explanations that can’t actually be verified.

    I’d be a bit careful here, because there will always be some speculative explanations in evolution itself that can’t actually ever truly be verified because we can’t ever go back in time and carefully identify the selective pressures and responses. That doesn’t invalidate evolution.

    And I don’t see any compelling need for a separate discipline of “evolutionary medicine.” Do you? Doesn’t it make more sense to incorporate it naturally into all medical disciplines?

    Actually, I didn’t really see anyone in my more recent readings suggesting a separate discipline of evolutionary medicine. What they suggest is that evolutionary principles should go into the teaching of medicine just as principles of physiology, genetics, biochemistry, etc. do. In other words, evolution should be one of the basic sciences taught in medical school as the basis of disease, just as physiology and biochemistry are. I tend to agree.

  15. David Gorski says:

    A related question: is the Strep of yesteryear, the one that caused so much rheumatic fever, the same organism that hardly ever causes rheumatic fever today?

    Isn’t that more because strep infections are treated and not allowed to progress to rheumatic fever than because strep from 80 years ago is so different from strep today?

  16. Harriet Hall says:

    @David Gorski,

    “In clinical practice, most definitely not [an integral part] ”

    Should “evolutionary medicine” be an integral part of every doctor/patient encounter, as the authors of the book claim? What would it add? Can you think of any examples where it would make a significant difference? The best argument I’ve heard for that is that providing an evolutionary explanation helps the patient accept his disease and cooperate with treatment. Do you think that’s true? Is there any evidence that that approach improves outcomes?

  17. Harriet Hall says:

    “Isn’t that more because strep infections are treated and not allowed to progress to rheumatic fever than because strep from 80 years ago is so different from strep today?”

    I think that’s only part of the explanation. Localized outbreaks of RF continue to occur, perhaps related to specific strains. And I think it can occur even with antibiotic treatment. Mark can correct me if I’m wrong.

  18. Patrick says:

    Hello Dr. Hall:

    Many thanks for writing a review of Dr. Nesse and the late George C. Williams’ book Why We Get Sick on such a short notice. I am a passionate evolutionist and Darwinian to the core and one of the basic claims of evolutionary biologists (e.g. professor Dawkins, professor Ewald, etc.) is that medical doctors are still lagging behind in Darwinian thought despite The Origin of Species being published in 1859. Because I am a Darwinian, I naturally followed people that I admired and believed professor Dawkins, professor Shubin, Dr. Nesse, and others regarding the fundamental soundness of Darwinian medicine. I also firmly believed professor Ewald’s contention that the medical establishment is somewhat reactionary to evolutionary medicine and that the older camp may have to be expunged though time before fresh Darwinian insights could unravel. For instance:

    “… That’s one of the realities of medicine – researchers tend to deny associations. Denial plays a major role as scientists love to hold on to the current dogmatic explanation. This suggests that in order for pathogens to be fully tied to chronic disease we will have to wait until the current powerful people pass away and a sufficient number of young people entering the arena without these vested interests mature into positions of influence, to tip the balance of expert opinion. This is something that Charles Darwin, Max Planck, and Thomas Kuhn all agreed with…”
    ……..
    http://bacteriality.com/2008/02/11/ewald/

    However, now I admire a separate—but closely related camp—of medical doctors representing science-based medicine. I was a little bit concerned that the ideas of evolutionary medicine may clash with the thoughts of the camp at sciencebasedmedicine.org, but it appears that Dr. Gorski and Dr. Novella are Darwin-friendly and warmly welcome evolutionary insights into medicine (1-3). It appears that Dr. Gorski is a staunch evolutionist too (and has managed to annoy the lovely crowd over at uncommondescent). LOL. (4)

    Despite my deep-seated convictions, the scholarship of Dr. Hall has forced me to seriously reconsider my views on Darwinian medicine and perhaps entertain the thought that the lack of attention the medical establishment has given to Darwinian medicine may be a reflection of the fruitlessness of its organizing principles, rather than reactionary sentiment. I do not know yet, that is why I am going to print this review off and read it thoroughly.

    Also, thank you Dr. Gorski for your insights.

    (1) http://www.sciencebasedmedicine.org/index.php/evolution-in-medicine/
    (2) http://www.sciencebasedmedicine.org/index.php/personalized-medicine-vs-evolution/
    (3) http://www.sciencebasedmedicine.org/index.php/personalized-medicine-vs-evolution/
    (4) http://www.uncommondescent.com/evolution/david-h-gorski-do-as-i-say-not-as-i-do/

  19. Amy (T) says:

    Dr. Crislip wrote: “Is the S. aureus of 1950 the same species as the MRSA on 2012?”

    I agree with Dr. Gorski, it’s probably out there, and a search of GenBank might find you the answer. I have a phylogenticist friend who worked at Penn State on MRSA, I wouldn’t be surprised if she compared these herself; I’m pretty sure she was doing phylogenies on more recent strains. I know you all love PubMed (me too), but some of us in research don’t always get funding from NIH for doing micro, virology, etc research and it all doesn’t go to PubMed.

    Dr. Hall wrote: “The evolution of drug resistance in bacteria is the best-known example”

    I always thought the opposite. I felt if doctors had a better understanding of evolution, they could have been more conservative in writing prescriptions for non-bacterial infections. Only when antibiotic resistance showed up did they change their behavior. Seems to me an evolutionary biologists could have (should have?) warned them of the danger and where that will lead.

    Since I was a zoology undergraduate, I was in school with lots of pre-med students. I was so disappointed that evolution was not a requirement for them (or med school- at least the local ones to our area).

    “Should we treat fevers?” I feel like shit when I have a fever, it’s going to take a lot more to convince me not to take an aspirin or Tylenol. Also, I’m pregnant, and read a recent article that fevers in pregnancy correlated with autism- except if you took a fever reducer. If you took something, the chances were equal to that of the non-fever group (which were lower than the fever group). And, of course, the correlations with increased temperatures and birth defects; I don’t find leaving a fever alone in pregnancy to show any benefit, with the evidence today (assuming you don’t have a fever every day, in which case you probably have bigger problems).

  20. Mark Crislip says:

    It is more than antibiotic resistance; that is ubiquitous in the environment. Our abx for the most part are derived from ‘natural’ products. Pick any random chunk of dirt, it will contain abx resistance genes, some of which have yet to be seen clinically.

    It is all the virulence factors and the hospital/ICU environment in which the bugs have lived the past half a century.

    I have looked paper that compares them and yet to find it, perhaps your google-fu is stronger

  21. mousethatroared says:

    Sometimes I wonder if we could use what we know about human evolution, diet and appetite to creat a diet that gives a higher level of satiety for the same amount of daily calories.

    One wouldn’t need to believe in just so stories as with the paleo-diet. The goal, lower cravings, higher satiety is testable. One could just use the knowledge of evolution to generate hypothesis on possible diets to try.

  22. Old_skeptic says:

    Why do people talk as though the evolution of humans ended during the Paleolithic?

    If that were true, none of us would be able to digest dairy products as adults. Lactase persistence didn’t evolve until some groups of humans started to practice dairying, giving people who could continue to digest lactose as adults an advantage over those who could not.

    This is the obvious example of human evolution that occurred after the beginnings of agriculture, but I’m sure it isn’t the only instance. There must be others. Evolution has not stopped.

  23. Harriet Hall says:

    @mousethatroared,

    Isn’t it just common sense that if you can satisfy hunger with fewer calories, it will make it easier to follow a low calorie diet? Do we need evolutionary thinking to figure that out?

  24. mousethatroared says:

    @HH, I think we are misunderstanding each other. I was suggesting that we could use evolutionary medicine (or more accurately evolutionary nutrition) to possibly find out how to satisfy hunger with fewer calories.

    So rather than randomly trying food combinations that might offer better satisfaction, try food combinations based on theories in evolution.

  25. Harriet Hall says:

    @mouse,

    Maybe. I’m having trouble envisioning a specific example of how “evolutionary nutrition” could guide us here. We don’t have a lot of detailed knowledge about what our ancestors really ate, and they probably thrived on a variety of different diets, as the Eskimos and the Maasai do today. Perhaps a more useful way to start would be to look at tribes today and see which diets are associated with lower body weights.

  26. daedalus2u says:

    MTR, no one is trying to find foods that produce satiation more easily. Food manufacturers only make profits when they sell food. Successful food companies will produce foods that require greater consumption to produce satiety, or the food company will not be successful.

  27. icewings27 says:

    @Old-Skeptic Thank you for making the point I was going to make.

    We are NOT Stone Age Humans. We have evolved since then, and if there is a study out there comparing the human genome of today with the human genome 10K years ago I’d like a link to it please. I’m betting there’s enough difference to be statistically significant.

    We are still evolving and it is unfortunate that the word “evolve” implies positive change. The fact is most mutations are not useful or helpful to an organism. Only a very few get perpetuated and with modern civilizations growing and changing so rapidly we aren’t very well adapted to our environment.

    I’m going to go finish my latte now, thanks to my European lactose persistence allele.

  28. jmm says:

    I agree with most of this post, despite being an evolutionary biologist by profession. Evolutionary biology rarely, if ever, affects the day to day to decisions of doctors, which we hope are based primarily on clinical trial data. I go further than this though, substituting one term. I also assert that “biochemistry and molecular biology rarely, if ever, affect the day to day to decisions of doctors, which we hope are based primarily on clinical trial data”.

    I see the fight about the status of “evolutionary medicine” as a fight about the status of different disciplines in the undergraduate curriculum, and hence in their power, funding and status. In many universities, ecology & evolutionary biology is a different department from molecular and cell biology, let alone biochemistry. The MCAT and hence the undergrad curriculum is weighted towards the latter, so that is what the students study. More importantly perhaps, reductionism = status in science today, and evolutionary biology is profoundly unreductionist. “Evolutionary medicine” is an attempted power and status grab by evolutionary biologists such as myself.

    In the end, none of this specific biology content knowledge matters too much in the daily practice of medicine, so long as premeds learn the scientific method. I would rather the students had a curriculum heavily loaded with probability and statistics (which they currently study little, but will use every single day as doctors, or indeed even in daily life), and skimp on most of the chemistry and biology. You can teach how to invent hypotheses using proximate causation via molecular biology, or how to invent hypotheses using more distal causation via evolutionary biology. In the end, it is more important that future doctors know how hypotheses get tested than how they get generated.

    That said, if students are to study biology, we should remember that it was evolutionary biologists (Galton, Pearson, and most especially Fisher) who invented statistics, including the randomized controlled trial. Evolutionary biology professors are all comfortable with fairly sophisticated statistics: more molecular folks are not. That, by itself, is a good argument for changes in the biology portion of the premed curriculum.

  29. David Gorski says:

    I have looked paper that compares them and yet to find it, perhaps your google-fu is stronger

    Right here in my own state:

    http://myxo.css.msu.edu/

    This dude is doing some seriously cool science looking at the evolvability of E. coli, and has been doing it for 24 years.

    http://myxo.css.msu.edu/ecoli/celebrate50K.html

    http://www.nytimes.com/2011/03/22/science/22evolve.html

    I realize that it’s not exactly what you’re looking for, but it’s a fascinating experiment related to what you’re looking for.

  30. David Gorski says:

    I’m pretty sure she was doing phylogenies on more recent strains. I know you all love PubMed (me too), but some of us in research don’t always get funding from NIH for doing micro, virology, etc research and it all doesn’t go to PubMed.

    It’s also really hard to find things on PubMed when there are thousands of articles to sift through. Search terms to narrow the information down to just what Mark is looking for are hard to come up with, and I’ve tried on and off today doing some PubMed searches to see if I could find relevant studies.

  31. mousethatroared says:

    HH – specifically, well I guess I imagined it would have something to do with our attraction to fats and sugers…possibly some combination that would notify our body that we have an adquate supply of calories, not being a scientist or a medical person, I don’t know. I just wondered if it was a possibility.

    @daedalus2u
    “MTR, no one is trying to find foods that produce satiation more easily.”

    Ha! (evil laughter) That just means you’d have the market all to yourself, once you figured it out.

    Besides all the big diet companies claim, “loss weight without being hungry.” I’m guessing there’s a market there…the question is whether it’s doable and whether evolutionary theory would be useful.

  32. blu says:

    In the United States, various polls have shown that the majority of doctors do not even believe in human evolution, so I would say that it is not that big a part of the medical thinking. As far as evolutionary explanations being just-so stories, there is a lot of truth to that. Almost all attempts to rationalize the causes of individual adaptations in the distant past are speculative at best. There is no way to know the environment at the time individual mutations occurred, so we cannot really say how adaptive the change was.

    The primary need for evolutionary thinking in medicine is not the past but in planning for the future. What are the evolutionary consequences of this or that treatment. Using this information to inform current decision making. That is what makes it important.

  33. nybgrus says:

    I’m late to the party since I am on night float this week and spent my day sleeping.

    My two cents? That evolutionary principles in medicine should be taught like and treated similarly to embryology in medicine.

    How many times do we applythe principles of embryology in regular clinical practice? Why do medical students hate embryology so much? (basically never, and because they see it as being irrelavent to clinical practice). These days med students get all riled up when they think that what they are learning wont be directly relevant to their clinical practice. Heck, I just commented on a post on reddit about a guy asking how to best get through his clinical rotations. His take? There was no need for critical thinking since that was too time consuming and if he just hammered in algorithms and guidelines that would be much better. I told him go right ahead if he wanted to be a mediocre doctor who was nothing more than a glorified mechanic who will struggle keeping up to date.

    But I digress. The point I am trying to make is that just like embryology, evolutionary biology is a very handy organizing principle for learning things relevant to clinical practice. I remember my anatomy and congential defects much, much better than many of my colleagues because I actually studied embryo in my first two years and they didn’t. I can keep molecular receptors and their varying affinities and actions straight better than my colleagues because when I learned them I did so from an evolutionary perspective. Learning the evolution of the gluccocorticoid receptor from the mineralocorticoid receptor was interesting (to me at least) and also helped me to understand and remember affinities and properties of the physiological responses to activation. Same with βHCG and TSH. You can go on and on.

    So from my perspective I can clearly see what Dr. Hall is saying – yeah, evolutionary principles really don’t actually make a difference in clinical practice. But from that perspective (and you know I respect you greatly, Dr. Hall) this post may as well have gone:

    “Do we need ‘Evolutionary Medicine’?”
    “Micheal Egnor.”
    “QED.”

    But then we have to ask ourselves what do we actually want our physicians to be like? Glorified mechanics who do things without really understanding why? Or actual critical thinkers that can generate hypotheses and better react to the ever changing landscape of their patient population and novel therapeutic modalities? I would argue that the vast majority of medicine can be done without understanding the underlying principles and in fact mid-level practitioners fill in that volume gap quite nicely. The reason we still need physicians is to be able to recognize and deal with the exceptions. Disconnecting ourselves from the basic process that leads us to the understanding and knowledge that we do have limits our ability to do so (and I’ll add makes studies on CAM look more appealing). By further enhancing that basic understanding of the process and not just the outcomes, I would argue that phsyicians will be more capable to accurately and adequately treat even more people. There is a cost-benefit analysis to be done there, and we all recognize there are diminishing returns on eeking out those last few percentage points, but the principle stands.

    A Jiffy Lube mechanic does not need to understand the principles of mechanical and materials engineering to do his job extremely well. Do we want physicians to be Jiffy Lube mechanics for people? What do we want to define the job of a physician as (vs a nurse practitioner or physician’s assistant)? I think that is the ultimate question here.

  34. Harriet Hall says:

    @blu,

    “various polls have shown that the majority of doctors do not even believe in human evolution”

    I haven’t seen any such polls. I’ve seen polls that show just the opposite, for instance http://pandasthumb.org/archives/2007/01/why-do-so-many.html

    And it makes a difference how the question is asked, whether it’s in a religious framework or a medical one.

  35. Harriet Hall says:

    I think we can all agree that it is essential for doctors to understand evolution and that evolutionary principles should be taught in medical school. We need courses in evolution but I’m not convinced we need departments of “evolutionary medicine.” And I’m not convinced that every discussion of a medical reality must necessarily include speculations about “why” that reality came about. We can ask whether a symptom is a defense mechanism with some benefit to the patient without wondering how, when, or why that response evolved. It is equally essential to guard against accepting untested and often untestable evolutionary explanations as if they were facts and against prescribing diets and treatments based on them. And understanding how something evolved seldom changes our management of patients.

  36. nybgrus says:

    I agree with your last comment Dr. Hall. I realize I was not quite explicit in mine – I further agree that a specific branch of medicine called “evo med” or whatever is also rather pointless. For now, at least. I would say that it is premature (well, very premature to be honest).

    It strikes me as similar to Charles Boger trying to do rational drug design in the 80′s with his company Vertex pharmaceuticals. It is a great idea – merely before its time. I think rational drug design is still hindered by a lack of technology and sophisticated understanding. I also think that eventually (I won’t speculate on a timeframe) “evo med” may actually be a viable endeavor somewhat along the vein of what mouse had said.

    However, the point was well made that we certainly have not stopped evolving – so picking some arbitrary point in time to use as a basis for an explanation is inane. However, we could use a deeper understanding and better technological capacity to model evolution in order to make more rationally derived and individually based therapies. The unlocking of systems biology on the genomic, epi-genetic, and proteomic level is the necessary minimum for this kind of endeavor. Now we just have to go out and do it….

  37. nybgrus says:

    I agree with your last comment Dr. Hall. I realize I was not quite explicit in mine – I further agree that a specific branch of medicine called “evo med” or whatever is also rather pointless. For now, at least. I would say that it is premature (well, very premature to be honest).

    It strikes me as similar to Charles Boger trying to do rational drug design in the 80′s with his company Vertex pharmaceuticals. It is a great idea – merely before its time. I think rational drug design is still hindered by a lack of technology and sophisticated understanding. I also think that eventually (I won’t speculate on a timeframe) “evo med” may actually be a viable endeavor somewhat along the vein of what mouse had said.

    However, the point was well made that we certainly have not stopped evolving – so picking some arbitrary point in time to use as a basis for an explanation is inane. However, we could use a deeper understanding and better technological capacity to model evolution in order to make more rationally derived and individually based therapies. The unlocking of systems biology on the genomic, epi-genetic, and proteomic level is the necessary minimum for this kind of endeavor. Now we just have to go out and do it….

  38. Patrick says:

    Dr. Gorski:

    What do you make out of Dr. Paul Ewald’s stringent contention that many chronic diseases—from cancer to heart disease—with unknown etiologies may be the product of infectious microorganisms? His hypothesis is rooted in Darwinian logic: essentially, natural selection would tease out alleles in a population if it made people sick and unable to reproduce. (1) For example:

    “Evolutionary biologists understand that if an allele (a sequence that codes for a gene) were to code for a disease it would slowly get weeded out of the population, particularly since people who are sick are much less likely to reproduce (especially people with a severe disease like schizophrenia).”
    http://bacteriality.com/2008/02/11/ewald/

    Darwinian medicine is quite a broad field and it is not limited to Dr. Nesse and some feedback on these issues, whether positive or negative, is certainly worthwhile.

  39. DavidRLogan says:

    Great comments from the heavy hitters (Dr. G especially…thanks for those awesome links!). Fun read!

    I wonder if we still haven’t heard the case Dr. Hall’s asking for…one where the evolutionary perspective provides the relevant benefit and isn’t vulnerable to what she’s written in her conclusion. I think NYB came closest to such a case (eloquent as always)…but, NYB, I wonder if your experience’s idiosyncratic? Surely there’s someone out there who knows their cell phys as well as you, but hasn’t considered the evolutionary implications (even if you’re not currently in a place with such a person). And I agree with you about embryology, but then embryo is considerably less theoretical than evolutionary bio. What do you think?

    I personally hold an extreme view…strikes me more likely that medicine will shed light on evolution vs. the reverse. For instance, a simple Darwinist picture holds that languages other than DNA/RNA were selected against for many archea, and from there DNA changed mostly via vertical gene transfer (mutated by ionic insults and etc.). However, because of biochemistry, funded by the NIH and evil medical companies ;), we know the importance and pervasiveness of horizontal transfer (viral and other), epigenetics, etc. How do these ideas fit with the traditional picture of vertical transfer and random mutations? However they fit, it’ll be evolutionary theories that need to grapple with the empiricism and constant progress of biochemistry and medical science, not the reverse. Or at least that’s how I see it….love this discussion and can’t wait to read more.

    FWIW…

  40. mdstudent says:

    I think the point Dr Hall is making is that as far as applying evolutionary biology to clinical practice goes we need to be careful not to put too much emphasis on theories for which solid evidence is lacking or would be impossible to get i.e. unfalsifiable speculations. I completely agree.

  41. Tara Smith says:

    I’m surprised you don’t talk more about “stealth infections.” Though I can’t recall how much time Nesse & Williams devoted to it compared to other books that came out about the same time (eg Paul Ewald), I’m an ID epidemiologist and investigating the possible infectious causes/contributions to chronic conditions is a huge area of research, and growing more each day with advances in our understanding of the human microbiome. Indeed, it’s overturning many “just so stories” like stress and ulcers. The evolution of virulence (more Ewald) is another area with important contributions to all kinds of areas, such as rational vaccine design and infectious disease control. Others have already mentioned additional good books and papers, so if you’re really interested in the topic, Ewald’s books are thought-provoking, Steven Stearns is a bit more academic, and even “Good Germs, Bad Germs” takes on the microbiome in a manner relating evolution, chronic disease, and infections.

  42. niftyblogger says:

    LOOK OUT! Patrick is a Marshall Protocol follower. Trevor Marshall is the definition of medical denialism and oversimplification of some trendy ideas. (Read Mark Crislip’s posts on the MP.)

    I find it really funny that after less than a year working in actual science, rather than just reading Bacteriality and marshallprotocol.com and the “knowledge base” wiki, I have realized that there is no medical industrial complex that I was warned of. The are unscrupulous business practices by pharmaceutical companies, but the problems in the treatment and understanding of disease are incredibly complicated.

    Scientists are not denialists unwilling to accept the “dogma” of their “establishment.” Scientists are unwilling to accept most hypotheses that haven’t been tested relentlessly. The idea that there is an infectious origin to chronic disease is an interesting one, but it is not a question that can be answered easily by one or two people with a few molecular modeling papers and some essays. This would have to span multiple generations of researchers.

    I agree with Harriet Hall that evolutionary medicine has no practical application to modern treatment. I still find it interesting and perhaps it has some value in helping patients regain self worth and motivation to make helpful lifestyle choices after being abused by the “blame the victim” mentality of alternative medicine to realize that they might not have caused their own illness through silly things like one wrong food or one wrong thought.

  43. Patrick says:

    niftyblogger, I would suggest toning down your value-laden response just a tad; you are criticizing me for an argument that I did not even remotely champion or suggest one bit! Your response merely consists of a straw man and putting words in my mouth, which is I why I specifically asked Dr. Gorski for his input, not yours.

    In any event, it is obvious that the scientific consensus can be biased, depending on the circumstances; however, in general, medical bias is quite tame when compared to the literal hysteria and fear mongering presented by HIV-deniers, creationists, and other crackpots. Marshall certainly challenged long-held notions in the scientific community, and he prevailed. Does this fact bestow ammunition to the CAM and other cranks? NO, the fact is that the consensus was changed and molded to mesh novel ideas and experiments is a testament to the contrary. Now how often do creationists, for example, change their mind? NEVER, ever. How about HIV-deniers? I rest my case…

  44. Patrick says:

    “The idea that there is an infectious origin to chronic disease is an interesting one, but it is not a question that can be answered easily by one or two people with a few molecular modeling papers and some essays. This would have to span multiple generations of researchers. ”

    Well, no kidding? Who maintains the contrary? Certainly not professor Ewald. Verbatim:

    “Cancer is really a special case of the problems we have discussed. The same dogma has been driving how the disease is viewed for so long. But if people are able to recognize the dogma for what it is, they can take a better look at definitive evidence about the disease. Taking a look at the track record of cancer researchers is a good way to decide whether the consensus view is right or wrong.

    Back in 1975, mainstream medicine agreed that about 0.1% of human cancer cases were caused by pathogens. When it came to the rest of cases, their view was that they were probably caused by a combination of inherited predispositions and mutagens. Then in 1985, the percentage of cancer cases they tied to pathogens was 3%, and they continued to make the same argument about the remaining cases. In 1995 the percent of pathogen-induced cancer cases was accepted to be around 10%. Now, we’re at 20%. Still, mainstream medicine contends that the other 80% of cases do not have an infectious cause, but the questions is – do you believe them anymore? In this sense, the clarity of hindsight can help a lot. Between evolutionary instinct and plain common sense we can view the issues of pathogens and cancer much more effectively.”

    http://bacteriality.com/2008/02/11/ewald/

  45. David Gorski says:

    Regarding physicians and evolution, there are a couple of things that are very clear based on the evidence. First, religiosity of physicians is as at least as high as that of the general public. Second, a lot of physicians don’t accept evolution to one degree or another:

    http://scienceblogs.com/insolence/2006/04/19/medicine-and-evolution-part-4-1/
    http://scienceblogs.com/insolence/2006/04/20/evolution-and-medicine-part-4a/
    http://scienceblogs.com/insolence/2006/04/26/our-young-earth-creationist/
    http://oracknows.blogspot.com/2005/10/new-england-journal-of-medicine-blows.html

  46. Amy (T) says:

    Dr. Crislip: ” “Is the S. aureus of 1950 the same species as the MRSA on 2012?” &
    “I have looked paper that compares them and yet to find it, perhaps your google-fu is stronger”

    oddly enough, there is a recent article in the NEJM: http://www.nejm.org/doi/full/10.1056/NEJMoa1109910

    press release: http://www.sanger.ac.uk/about/press/2012/120613.html

    Not in the US (is on the UK pubmed), and not comparing MRSA from 50 years ago, but comparing sequences from a recent outbreak. It says they made a phylogeny, but I don’t see it as a figure (nor do I have access to see the figures). I assume they only used the isolates they had for the tree, but I wish I could get the whole article, to see if they put any older strains in it.

    There are a number of MRSA sequences in GenBank, some day, someone may (or may have already), compile them to compare the isolates and see how it’s evolved, if they are from varying isolates over time and geography (too many for me to go through and see when they are from though).

  47. Mark Crislip says:

    There are many interesting articles on short term genetic changes in bacteria, like the NEJM article and another re: the genetic changes in staph that occur shifting the bug from colonizer to invasive.

    The E. coli work I was also aware of, but both are peripheral to my question:

    How, genetically, is a bacterial species defined? How much variation before a new species is declared. And after 50 years has S. aureus, as an example, changed enough to be considered a new species? I had an old guy who had an open fracture as a kid, 60 years ago, that started draining a penicillin G susceptible staph from the fracture site (not even a record), it was like catching a coelacanth. That is what made me wonder if I was seeing a neanderthal thawed from the ice, metaphorically speaking

    Certainly there are organisms like malaria (I think its vivax, I am too lazy tonight to hunt down the reference) where the African and Asian strain look the same, act the same, but are a genetic spectrum across the world and the ones at either end cannot mate, so are different species.

    As another example the cocci of the american SW is genetically different from the s. american enough to warrant their own names. Or the divergent evolution of Histoplasma and Borellia, all of which are the classic divergence due to geographic isolation

    The anti evolutionists are always saying we have never seen one species evolve into another, but I wonder if it has occurred under our nose with common pathogens? I have looked many times for work that meet this criteria, and I cannot find it.

    If someone has done the work, I would have thought it would have been trumpeted as a huge gotcha for the evolutionists. Maybe I should wander outside of the medical literature and ask someone like PJ Meyers. I understand he knows a wee bit about evolution :)

  48. weing says:

    PJ Meyers? The NAIA All-American point guard?

  49. I don’t think the beliefs in religion or evolution are terribly important to medicine. Some of the most evidence-based doctors I know of are highly religious (ie, won’t prescribe birth control for the purpose of birth control unless there are extraordinary circumstances.) Being colleagues and not people who I spend time with outside of the hospital, I don’t really care to go down “that road” of probing what they actually believe in terms of evolution or a god, but I’m pretty sure I wouldn’t agree with most of it. I wonder if there is a link between having a religious-type mindset and the belief in woo. I initially wouldn’t think so, but have no evidence one way or the other. I have lots of anecdotes that don’t support it. Ie, the most religious Pentacostal nurse practitioner telling a patient that water births are absolutely stupid, dangerous, and that she would in no way support that.

  50. Patrick says:

    I just stumbled across Dr. Gorski’s older blog posts a few days ago when, for some reason, I noticed that “uncommondescent.com” would lambaste Dr. Gorski and I could not understand why. Well, it turns out Dr. Gorski is a physician equipped with an understanding of evolutionary biology that rivals the knowledge of any talk.origins veteran.

    Also, I find his statements on physicians and their reluctance to accept evolutionary theory—and even be seduced by intelligent design—very disheartening and even alarming; however, it is very important for Dr. Gorski and the literal mammoth stockpile of science-oriented physicians (e.g., Dr. Hall, Dr. Novella, etc.) to really come out of the woodwork and speak on these issues. Perhaps they will awaken a sleeping giant among the medical community that nobody has seen before.

    It is not fair pick on physicians because, during many of undergraduate classes, I have noticed a variety of professors rebuff evolutionary theory, even with blatant hostility. I notice that even biology professors display general ignorance about evolutionary theory—biology’s organizing principle! So it is not fair to pick on physicians in this regard, and I plan on becoming one in the future.

  51. Patrick says:

    Tara Smith (Dr. Smith!):

    Thank you very much for your sound and informative message, it really is refreshing to see some logic. I am happy to see that evolutionary medicine, in regards to chronic disease, has reached fruition in your niche of epidemiology. I did not know if Dr. Ewald’s research was ever going to gain momentum, but it appears that it has and my ultimate aim in life is to become involved in an infectious disease specialty; my influence was Dr. Ewald’s contention, laid out in Plague Time: The New Germ Theory of Disease, that many chronic diseases are indeed a product of infectious pathogens.

    However, I am a little unsure about his approach to vaccination would come about (i.e., create an environment that favors less virulent strains of a pathogen, rather than the more deadly ones). This hypothesis is a major theme in his work.
    http://www.pbs.org/wgbh/evolution/library/01/6/text_pop/l_016_06.html

  52. Mark Crislip says:

    “I don’t see that evolutionary thinking adds anything useful to the discussion. Fever is what it is, and we can study it and deal with it without speculating about how it came to be that way.”

    But it can be so cool. I happened to come across something I wrote over at Medscape a couple of years ago, so allow me a quick cut and paste re: evolution of fever:

    Insects can be infected with 50,000 different fungi and plants are susceptible to 270,000 fungi. Humans? Many fewer, maybe a couple of dozen pathogenic fungi at best and few that infect normal people. And it may be due to the fact that we are warmer than ambient temperature.

    In a recent JID article they tested the growth characteristics of 4800 fungi at a variety of temperatures from 4 to 45 degrees C, and as the temperature went up, the number of fungi that could grow declined. They found for each increase in temperature of 1 degree C, they “excluded an additional 6% of fungal isolates, implying that fever could significantly increase the thermal exclusion zone.”

    Perhaps not being consumed by fungi helped drive the evolution of increased body temperature.

    “Endothermy is associated with certain metabolic benefits and thermodynamic efficiency, but these benefits come at a high cost since endothermic vertebrates require <10 times more oxygen to support metabolism than do ectothermic vertebrates [8] . Our analysis suggests that part of the cost is mitigated by the creation of a thermal exclusionary zone that can protect against environmental microbes. Given the high metabolic cost of endothermy, the core temperatures of individual mammal and bird species are likely to be a compromise between its benefits and costs. If endothermy was selected for protection against infectious disease, then a case could be made that endothermy preceded homeothermy. Similarly, if one considers fever as a mechanism to extend the thermal exclusionary zone against environmental microbes such as fungi, increases in temperature of only 1-3 degree C can significantly reduce the proportion of such microbes that can inhabit the host."

    Even cooler is they have found a burst in fungal fossils at the Cretaceous-Tertiary boundary when the dinosaurs died off.

    A meteor hits earth, increasing the amount of organic material for fungi to feed on, the fungi proliferate to kill off the surviving dinosaurs, and we mammals remain, resistant to the fungi. It pays to be warm.

    It wasn't the cigarettes after all.

    Rationalization

    Vertebrate Endothermy Restricts Most Fungi as Potential Pathogens. The Journal of Infectious Diseases 2009;200:16236
    Fungal Genet Biol. 2005 Feb;42(2):98-106. Epub 2005 Jan 5. Fungal virulence, vertebrate endothermy, and dinosaur extinction: is there a connection?
    Physiol Biochem Zool. 2004 Nov-Dec;77(6):1019-42. The evolution of endothermy in terrestrial vertebrates: Who? When? Why?

    http://humormedication.wordpress.com/2010/02/24/gary-larson-dinosaurs/

  53. daedalus2u says:

    Patrick, I looked at the interview you linked to, and there is a gigantic blind spot in Ewald’s reasoning. He lists 3 possible causes of disease:

    1. Inherited genes

    2. Parasitic agents (this includes bacteria, viruses, fungi, protozoa

    3. Non-living environmental factors (too much or too little of a particular substance, radiation, exposure to a chemical etc.)

    These are all well and good, but he left out a fourth mechanism.

    4. Loss of beneficial commensal organisms.

    It is #4 that is the major cause of modern diseases, specifically the loss of the commensal ammonia oxidizing bacteria which live on the external skin and metabolize the ammonia in sweat into NO and nitrite. This sets the basal level of NO species, and is a major global control setpoint that regulates essentially all major subsystems.

    http://books.google.com/books?id=a3mwmXzpsjkC&lpg=PP1&pg=PA103#v=onepage&q&f=false

    In terms of chronic inflammation, NO inhibits NFkB and is the normal pathway to reduce inflammation. Low NO potentiates mast cell degranulation, the respiratory burst lowers NO levels and provides for a robust turn-on of the immune system when it is triggered.

    The anecdotes about low dose antibiotics seeming to “work” is artifact. It is the killing of non-resistant bacteria in the gut, those bacteria spill antigens, those antigens produce a Jarisch-Herxheimer reaction, which causes expression of iNOS and transiently increases NO levels which causes transient symptomatic relief of the symptoms that are caused by low NO due to the loss of commensal ammonia oxidizing bacteria.

    I think that the preoccupation of ID docs with killing bugs (sorry Dr Crislip ;) ) is misplaced. Being killed provides a strong evolutionary pressure to evolve resistance to whatever is doing the killing. Since there always has to be a transition between where the antibacterial agent has a high enough concentration to kill and where it doesn’t, there will always be bacteria exposed to sub-lethal levels. I outline what I think is a better approach here.

    http://daedalus2u.blogspot.com/2008/06/suggestion-to-reduce-antibiotic.html

    Suppressing virulence is just as effective at preventing disease as is killing the infectious agent. If it is not expressing virulence, then it is not virulent. Much of what prevents infection is a microbiome of non-pathogenic organisms that suppress pathogens. Wiping out the commensals in the microbiome leave the equivalent of a clear-cut lifeless moonscape where the “weeds” that grow the fastest come back first, exactly what you don’t want. .

    The advantage of suppressing virulence is that organisms don’t evolve resistance to it. Suppressing virulence is how most eukaryotes suppress biofilms on their surfaces.

  54. nybgrus says:

    @DavidRLogan:

    but, NYB, I wonder if your experience’s idiosyncratic? Surely there’s someone out there who knows their cell phys as well as you, but hasn’t considered the evolutionary implications (even if you’re not currently in a place with such a person).

    Absolutely. And there are people that know anatomy much better than I do who don’t know embryo as well as I do. There are multiple ways to skin a cat – sometimes even just as effectively. I do not think I can argue that an embryological framework for anatomy or an evolutionary framework for molecular medicine is necessarily even the best way to learn it, let alone the only way to learn it. I would argue it is at least one of the best ways. And I would most certainly argue that an active denial of evolution (rather than mere indifference to it) is certainly a negative when it comes to being a physician (or any kind of scientist, for that matter). Not because you may necessarily need evolutionary principles in your work, but because the denial of their existence indicates something about the way you operate and view the world around you which demonstrates a willingness to distort and deny based on ideology (more on that in a bit).

    And I agree with you about embryology, but then embryo is considerably less theoretical than evolutionary bio. What do you think?

    I think that there exists no field of science that is more supported by rigorous, varied, and converging lines of evidence as evolutionary bio. To say that embryo is less theoretical is incorrect.

    However, because of biochemistry, funded by the NIH and evil medical companies , we know the importance and pervasiveness of horizontal transfer (viral and other), epigenetics, etc. How do these ideas fit with the traditional picture of vertical transfer and random mutations? However they fit, it’ll be evolutionary theories that need to grapple with the empiricism and constant progress of biochemistry and medical science, not the reverse.

    I don’t see it as separately as you seem to. Biochemistry research is evo bio research as well. Evo is, after all, the central organizing principle of all biology. Hence my comment that being indifferent probably matters very little – whether your work explicitly mentions evo or not, the work is still applicable in pretty much every case. My argument (which is indeed my own opinion) is that while indifference matters little, and denial is a negative, that active utilization of the evolutionary framework can be a positive.

  55. Patrick says:

    At daedalus2u:

    Thank you for your input, I am reading it right now and I will make sure to put it into my memory bank. After debating HIV-deniers and creationists over the years, it is so refreshing to have such logical responses and debate among skeptics and rational people—even when there are profound disagreements. Cheers!

  56. nybgrus says:

    I don’t think the beliefs in religion or evolution are terribly important to medicine. Some of the most evidence-based doctors I know of are highly religious (ie, won’t prescribe birth control for the purpose of birth control unless there are extraordinary circumstances.)…

    On the surface you are correct SH. It has been my contention around the parts for a while though, that while having a religious ideology doesn’t automatically necessitate that one cannot ever do good science, it does mean that you cannot do good science in a field that abuts your religious ideology. So a Catholic could do evolution research (at least in principle) since the Catholic church has officially agreed that evolution is true (how gracious of them). But doing stem cell research may become a fair bit more problematic.

    The issue is that since religious (or any, really) ideology has no basis in reality it is impossible to predict a priori where an individual’s dogma will be strong enough to overcome scientific rigor. Some people may hold [X] much more dearly than their compatriot who falls under the same ideological moniker. Some people may be more willing to be swayed by evidence than others and thus be willing to amend their view, and some (such as Kurt Wise whom I mention frequently) are able to see the evidence and consciously decide to ignore it in favor of their ideology.

    The point is that these huge spectra of specific beliefs and the strength of their conviction exists. So while religious and evolutionary beliefs don’t necessarily preclude a person from being a good physician, they certainly can and can do so in quite unpredictable ways and to unpredictable extents.

    Of course in my view there is nothing about religious belief or any ideology that has any redeeming quality whatsoever. So in my view, religion is like a weight around your neck as you are trying to be an olympic swimmer. Sure you can cite me an example of someone who was able to swim at that level despite the weight, but my argument is that (s)he would always be better off without the weight.

  57. ^ I whole-heartedly agree. I too have been perplexed on how a very scientifically minded person can believe in most aspects of religion. For some, it must be as you said, that they consciously decide to ignore the evidence in favor of their ideology.

  58. nybgrus says:

    as for the “bacteria are the basis of chronic disease/cancer/etc”….

    my take is that they may be a cause, but certainly not a fundamental cause. We understand reasonably well how oncogenesis occurs and in the cases where virus and bacteria have been succesfully implicated in oncogenesis we find that it is because the infection potentiates the mechanisms already in place. I have yet to see an example of any infectious process yielding a completely unique pathway of oncogensis that isn’t explained by reducing it to already defined and understood principles of cancer biology.

    Specific examples are interesting – such as HPV and cervical cancer. There are two main serotypes of HPV that lead to (or cause, if you prefer) cancer. Why do they do so, but all the other myriad serotypes don’t? Because these two induce the cell to produce proteins which inhibit p53 and Rb – two naturally occurring proteins that guard against deleterious cellular mutations. So does the fact that the virus leads to cancer mean a fundamental change in our understanding of cancer biology? No. It just means we have found yet another way in which already understood oncogenic pathways are activated. (Li-Fraumeni syndrome is an inherited defect in p53 which leads to afflicted persons having myriad varied and early cancers).

    I have no doubt that as we understand the microbiome more fully we will find even more examples of such relationships. We may even find novel oncogenic pathways (though I think this is unlikely it is still very much a possibility I am open to). But I think most of what we will find is the interplay leads to a base background level of oncogenesis. Meaning that once we understand and can accurately map out individual microbiomes we will be better able to assign a background risk of cancer to individuals due to their microbiome. And certain pathogens which impart a significantly higher risk (H. pylori, hepatitis, HPV, etc) will be able to be targeted to bring that risk down.

    As for chronic diseases other than cancer – say Alzheimers or CAD – I am much more skeptical about a specific infectious etiology. Once again, we have a pretty reasonable handle of the genesis of such conditions and while a particular pathogen could accelerate or otherwise potentiate these mechanisms, I am doubtful that we will find a dramatic shift in our understanding such that targeting pathogens will be a primary means to reduce incidence of chronic disease.

  59. I have heard many allegations about the relationship of evolution, our phenotype and practical medicine. The weird one of about why “our” lips are red, the explanation given was that it makes remember vagina. As a result with red lips would succeed in sex and pass the genes to the next generation. It’s seen to be written in a “famous” book aout this subject

    My opinion is that most of people, even in the biology science career, didn’t think or study enough both science philosophy and evolution by natural selection. Skepticism is a every day and every subject practice, not a tool to use in thinks that is not main stream. A true skeptical person would as at least some question about these allegation. Such as : Other hypotheses can explain the same phenomenon, have you enough evidence and so on

    I see that some biologist such as Dawkins (i have read some books) are great to explain evolution, but fault to extrapolate data. Not everything can be explained by evolution, nor follows it’s rules . Although essential to understand biology, thinking ONLY in evolution narrows the way to see the universe. That’s why I recommend the study of classical philosophy and science philosophy (popper) before trying to going to science per se.

    The best idea in my opinion is the competition of ideas (popper) not the theory of evolution. Some people hate religion but uses the same way of thinking to science, I dont see any difference in this aspect.

    Thanks for the post, great idea !

  60. My opinion is that student of biology field should understand the concept of evolution, so that it helps sense of huge amount of data in biology. Genetics, anatomy can be better understood when you think more about evolution in great scale. That dosent meaning that every allegation is correct, quite the opposite.

    I suggest that every student read this book : Your Inner Fish: The Amazing Discovery of Our 375-Million-Year-Old Ancestor
    http://www.amazon.com/gp/product/0141027584/

    What is wanted is not the will to believe, but the desire to find out, which is the exact opposite. (Bertrand Russell)

  61. meghara says:

    This is more of an amusing anecdote than a serious contribution, but it’s something that has stayed with me for a few years now re: religion, evolution, and medical practitioners.

    In the first year of my PhD in Medical Genetics, we often had residents join our classes, particularly if they were foreign and hadn’t had the opportunity to study a particular topic at their medical school. One day our class was discussing the concept of “race” and whether or not it had a genetic component, with a number if journal articles as discussion fodder. One of them was the first comparison study of the complete chimpanzee genome with the complete human genome (this was around 2004).

    There was a Saudi resident in our class that term. She didn’t have the genetics background many of us did, but was invaluable when we had to figure out medical terms! I suspect that she was a practising Muslim, since she wore a headscarf. This particular day she was completely, totally, at a loss. At one point she asked me “what does this chimpanzee study have to do with human races”? I explained to her the idea of the molecular clock, that if we can see how many changes had happened since the split between humans and chimps, and we know approximately how long that took, it helps us to know how quickly changes are happenning, etc, etc. The looked at me blankly for a moment, then said “Oh! You have to believe in evolution!”, and then proceeded to join the discussion of the paper like it was no big deal.

    I was amazed. She had managed to pull a switch inside her head and completely change her way of thinking in an instant. I cn’t imagine what it takes to hold two competing ideas like that in your head at the same time. Major respect to her.

  62. vlprince says:

    Wow- what an interesting thread of comments!

    I’ll admit to being firmly in the camp of evolutionary medicine (I recently gave a brief presentation on my take of evolutionary medicine to my fellow med students), though I don’t deny the perils of ‘just so stories’ when considering this topic. As nybgrus put it so nicely above, the beauty of evolutionary thinking in medicine is that it gives us a paradigm in which to think about medical issues. Trying to think of all medical conditions as isolated circumstances and approaching them with a purely mechanistic interest as we are so apt to do in medicine today makes a complete understanding of the situation much more difficult (it also takes more time and energy, as an evolutionary perspective can often offer a reasonable and appropriate place to base one’s investigations).

    I find the complete disregard for the “paleo diet” to be interesting. The name has become a bit of an anathema, yet the idea that humans could be significantly healthier if they embraced a diet that is evolutionarily appropriate does not seem unreasonable to me. As someone mentioned above, there is likely no single perfect human diet, but combining our knowledge of human evolution with information gleaned for humans still living a traditional lifestyle surely offers us interesting and potentially useful information for thinking about an appropriate human diet. (Indeed, I think that “Ancestral Health” is another aspect that we would do well to consider as we think about the condition of modern humans).

    Other ways that an evolutionary perspective can help guide our approach to human health?
    Explorations of the Hygiene Hypothesis. “Breast is Best”. Realizing that humans have been squatting to defecate for hundreds of thousands of years, and that our modern seated toilets (perhaps in combination with our modern diet) might be responsible for conditions such as diverticulitis and hemorrhoids. The evidence that skin color changed as humans migrated away from the equator is strong evidence for the importance of vitamin D. This is another example where I think combining information from traditionally living populations with an evolutionary perspective is informative… What is the blood level of Vitamin D in a human “in the wild”, and is, perhaps, that a better starting point for studies designed to hash out the “optimal” vitamin D level rather than trying to tease the information out from epidemiological studies of populations that are almost uniformly deficient in vitamin D?

    I’m not suggesting that evolutionary medicine alone can offer many answers to our modern medical questions, but it certainly can offer us a perspective from which to think about a lot of medical conditions. I also don’t necessarily think that “evolutionary medicine” (or Darwinian Medicine, chose your term) should be it’s own specialty. Rather, (stealing a line from one of my recent blog posts) “you can find aspects of each [medical] specialty that would benefit from the keen focus of evolutionary minded individuals who, with careful thought, research, and synthesis of new ideas, could push the standards of medicine to new heights.”

  63. DavidRLogan says:

    Thanks for the response NYBGRUS…good points…yeah I am probably a bit too hasty in some of my generalizations.

    Oh and btw I looked up what you said about the corticoid receptors and found it very interesting…thanks for the tip.

    Have a nice holiday (tho you’re probably not reading this blog right now…jeez I’m a loser with no life).

  64. Mark Hanna says:

    Sorry to take the discussion off-topic, but I noticed earlier in the thread that the “paleo diet” was mentioned. I’ve encountered this before, and thought it sounded less than justified. Does anyone have any recommendations for something I might read on this topic in particular?

  65. @Mark, there is nothing to read on it. There is a single book that supports it, and all the book does is molest and misinterpret the bulk of scientific data in a vain attempt to support the diet. Basically they try to make it sound like saturated fatty acids are great for you, and that they are in no way correlated with high LDLs and therefore do not increase the risk of cardiovascular disease. It’s the classic denial and rationalization that people do when they are living an unhealthy lifestyle.

  66. vlprince says:

    @SkepticalHealth: One book? In the 80′s, maybe…

    @Mark: Boyd Eaton wrote what might arguably be the first “Paleo” book in 1988 when he wrote ‘The Paleolithic Presciption’. I’m not sure when Staffan Lindeberg wrote ‘Food and Western Diseases”, but that is another book that considers health and nutrition from an evolutionary perspective. More recently a number of authors have written books about the “Paleo” diet (though others chose not to focus on the term “Paleo” because of the dislike some people have taken towards the name). The most recent book to be broadly accepted by those with an interest in evolutionary nutrition is “It Starts with Food” which came out last month. These books are generally meant for the lay public, but the recommendations have been seriously vetted by a number of people with strong science backgrounds. Yes there are people that claim “it’s what a caveman did”, but the more reasonable (and scientifically minded) use the concept as a framework on which to base a discussion on nutrition, health, and wellness.

    If you’re looking for some references for the apparent effectiveness of a paleo approach, I can offer these papers:

    1. Jonsson, T., Y. Granfeldt, C. Erlanson-Albertsson, B. Ahren, and S. Lindeberg, A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease. Nutr Metab (Lond). 7: p. 85.
    2. Jonsson, T., Y. Granfeldt, B. Ahren, U.C. Branell, G. Palsson, A. Hansson, M. Soderstrom, and S. Lindeberg, Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study. Cardiovasc Diabetol, 2009. 8: p. 35.
    3. Frassetto, L.A., M. Schloetter, M. Mietus-Synder, R.C. Morris, Jr., and A. Sebastian, Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet. Eur J Clin Nutr, 2009. 63(8): p. 947-55.
    4. Osterdahl, M., T. Kocturk, A. Koochek, and P.E. Wandell, Effects of a short-term intervention with a paleolithic diet in healthy volunteers. Eur J Clin Nutr, 2008. 62(5): p. 682-5.

    There is a lot of research into individual aspects of an evolutionary-appropriate diet, such as the effects of different fatty acids (especially the modern abundance of linoleic acid and the paucity of omega-3s), but the above references look at the “paleo diet” as a whole.

    Honestly- I understand that the term “paleo diet” may rub people the wrong way, but the suggestion to use evolutionary ideas as a foundation from which to build our scientific exploration seems like a reasonable (indeed the only reasonable) place to start.

  67. Look what i found, somethings I agree some don’t. The problem of the discourse is the unscientific allegations, magic cures and preventions. The genotype only changes when the buffer effect of phenotype can’t deal with the new environment. It’s not easy to analyse this two, so that you can predict what is best for the health. In my opinion the best definition for heath is from WHO: social, mental, biological

    TEDxSantaCruz: Rachel Abrams – (R)evolutionary Medicine
    http://www.youtube.com/watch?v=vUP0yt-6ba4

  68. So why do we get sick?

    *We are exposed to factors that did not exist in the environment in which we evolved.

    With this I agree! We are exposed to countless chemicals/toxins in both foods and environment and meds as well.

    That’s why I go organic and natural as much as I can.

  69. nybgrus says:

    @vlprince:

    I find the complete disregard for the “paleo diet” to be interesting. The name has become a bit of an anathema, yet the idea that humans could be significantly healthier if they embraced a diet that is evolutionarily appropriate does not seem unreasonable to me.

    I agree. At which point in our evolution should we define as the point on which to base our diet? When did we stop evolving? Because every actual evolutionary scientist is aware that we are still currently evolving. That is the issue I have with the so-called “paleo diet.”

    Realizing that humans have been squatting to defecate for hundreds of thousands of years, and that our modern seated toilets (perhaps in combination with our modern diet) might be responsible for conditions such as diverticulitis and hemorrhoids.

    A simple study would be possible. Compare the incidence of the conditions in populations that regularly squat to defecate (India, France, for example) and us. In a quick search I could find no such studies. But it was a quick search.

    What is the blood level of Vitamin D in a human “in the wild”, and is, perhaps, that a better starting point for studies designed to hash out the “optimal” vitamin D level rather than trying to tease the information out from epidemiological studies of populations that are almost uniformly deficient in vitamin D

    Besides the fact that we have no way to infer this from a purely evolutionary framework, you must also realize that for any physiological parameter there is no such thing as “the right number.” We have a range in which 95% of the population will fall via statistical analysis. 2.5% will be above and 2.5% will be below and still be normal and healthy. That also (must) factor in time and variance within an individual – what is “normal” for me today is not necessarily “normal” for me tomorrow.

    Furthermore, we must realize that even if the assumption is correct (which I contend it isn’t) that a specific period of our history is when our evolution “stopped” (or at least slowed to the point that we could reasonably focus on that physiology to try and tailor our lifestyle to) there is a second assumption inherent to that goal – that tailoring our lifestyle to those conditions means we would be healthier! Lifespans were incredibly short. Disease and trauma were rampant. The best you could say about an “evolutionarily appropriate diet” is that it would be the one to best achieve fertility and fecundity at an early age. It cannot possibly speak to the “best” diet to get us to and through our 60′s, 70′s, and 80′s.

    So despite being a staunch evolutionist, I do not see utility in using evolutionary biology to attempt to answer these questions… at least not from a historical perspective. Doing so is based on wrong assumptions.

    I’m not suggesting that evolutionary medicine alone can offer many answers to our modern medical questions, but it certainly can offer us a perspective from which to think about a lot of medical conditions.

    I agree with you there. We can use it to predict future outcomes and tailor new lifestyle regimens and drugs to accomodate our current evolution.

  70. nybgrus says:

    @Rafeal:

    The video is… interesting. And wrong on many points (overlapping with my above comment). First off, TED has gone way downhill – used to be an excellent source for new, groundbreaking, interesting, and/or thought provoking stuff. Now with so many spinoffs and so many smaller venues, it has degenerated into anyone who can tell a good yarn. The one about breast imaging via gamma scintigraphy and the one about the kooky physicist who claims to have seen quantum effects on a macroscopic level come to mind. In any event, to address this talk specifically:

    Almost everything about our world has changed in the last 10,000 years except our basic physiology

    This is not only a statement made on pure assumption (does she have a living person from 10,000 years ago to understand his/her physiology?) but also demonstrably wrong. We live longer, reach menarche and puberty later, reproduce later, experience menopause which never existed till just a hundred+ years ago, still maintain lactase production into adulthood, have a different modulation of our immune system (which is even further changing based on current evolutionary pressures like HIV and other infectious diseases), etc. Once again, the assumption that we are not still currently evolving is simply wrong. And it is the most wrong on a molecular level.

    We were created to live in 24 hour cycles of light and dark

    I’ll ignore the usage of the word “created” here. lol. But, this is also demonstrably false. Studies have shown quite nicely that not only do humans actually have a roughly 25 hour circadian rhythm, but that light can and does readily reset that rhythm to conform to changing light/dark cycles. Furthermore, it used to be considered quite normal for people to actually sleep in two separate “cycles” per day. For quite a long time in the middle ages it was absolutely normal to sleep for a few hours, then wake up and read or be otherwise productive for a couple of hours, and then sleep again for another few hours. This was called “second sleep” or “segmented sleep” and it ceased after the industrial revolution. Many argue that this is the “correct” or “best” way to sleep. So who is right?

    To work hard physically on a daily basis for food and shelter…

    Once again, perhaps she is right. But what does that sort of lifestyle (food/work) select for? Would the Stephen Hawkings of the paleolithic era have existed if we had continued that sort of lifestyle?

    When one learns about changing outcomes in complex systems – healthcare for instance – the first premise is that the system is perfectly designed to generate the outcomes that it does. Replacing one cog of a system for another likely won’t affect the outcome. So if you are arguing for a system (lifestyle + diet) that was around during the paleolithic era, you are also arguing for those outcomes – for us to be like our ancestors. I, for one, am quite glad we have evolved far beyond those cavemen ;-)

    …as well as regular exposure to more than 80,000 chemicals we have added to our environment since 1950. BTW, only 10% of those are actually tested for safety. What we do, what we are exposed to, can leaving us feeling tired, depressed, ill, and isolated.

    I can not help seeing this as an appea to the “oh noes, teh toxins!” followed up by an evidence free statement of “fact.” In looking at actual data we find that, on the average, the person living in a modern industrialized nation is better off in all these aspects than our forebears a century or two ago (and even further back)(1). I see a few reasonable explanations for this.

    One is that we simply are actually better in every way and that everything we are doing is a move in the right direction. This has allowed Maslow to speak through his hierarchy. A century ago there were much more immediately pertinent things to complain about than tiredness and depression and isolation. Now, we have it so much better that we have the time to complain about these things. (First world problems, as it were).

    The second would be that we have traded the tiredness, depression, illness, and isolation of rampant disease, death, trauma, and war for the much lower levels of the same from our current lifestyle.

    Either way I see it as an improvement over our ancestors and trying to advocate going back in time to model ourselves after them seems… well, backwards.

    … there is a chasm between the life we and environment that we evolved to thrive in…

    Once again – this is a false appeal. Considering that the total human population never exeeded 50 million worldwide until around the time of the Black Death (at which point roughly 50% of the entire world population died) and that the average life expectancy was somewhere between 20′s and 50′s for the vast majority of our history as a species I would hardly say that such hyperbolic claims are warranted. We did not thrive we scraped out an existence. Now is when we are thriving. We definitely love to romanticize the past – just look at the common motifs for shows of the 1950′s or most movies, shows, and plays about the medieval times. They are usually portrayed as happy times of chivalry and intrigue, simple times when people were happier without all the burdens of modern life. Shows like “Game of Thrones” are a much more accurate depiction.

    …the most shocking example of this is that we will live longer lives longer lives than our children will for the first time in our country…

    This is not an entirely accurate depiction. First off, there is contention as to whether this is actually true or not(2). Secondly, it is primarily an issue of obesity and primarily only in the US. Most other developed nations have longer life expectancies than us and are expected to continue increasing in that life expectancy(3). And lastly, the latest data from the CDC and DHHS states otherwise – that we can continue to expect to see increased life expectancy (albeit at a slower rate of increase than before)(4).

    Life Expectancy in years Figure 1/Table 22
    At birth 76.8 (2000) 77.9 (2007) 78.5 (2009)
    At 65 years 17.6 (2000) 18.6 (2007) 19.2 (2009)

    She then goes on to talk about the diseases of our modern world. Yes – she is correct that people are dying of these things (obesity, diabetes, hypertension, cancer, etc) at much higher rates than ever before. But that is what we have traded for an overall decrease in death from all other causes. There is a great little table in the recent NEJM about how we die differently over the last 200 years(5).

    This is only 2.5 minutes into the 7.5 minute talk (which I did watch in its entirety). She goes on to appeal to emotion (“as a mother of three I find this frightening”) and further hyperbolic statements.

    I have to head off to clinic soon so I will leave it at that (I also reckon most people wouldn’t care to read through this treatise I just wrote anyways).

    TL;DR: I think that the issue with the Paleo diet and other such “evolutionary” considerations is that the focus is misplaced on the past and some (falsely) idealized notion of what our physiology and environment were like back then rather than looking to the future and realizing that we are still currently evolving. That and TED talks have become more sensational with appeals to emotion lacking rigorous evidence to back them up, which I hope I reasonably demonstrated above.

    ***I will include citations below so my comment isn’t held up in limbo***

  71. nybgrus says:

    So my citations comment is held up in moderation because of all the links (which I anticipated but figured that would be better than having three separate comments to get them through immediately).

    In the meantime I notice rustic is back. You asked the question rustic – I’ve already more or less answered it. Just follow the links and try and learn. Though I cannot imagine you actually will.

  72. nybgrus says:

    Sorry almost forgot!

    @DavidRLogan:

    Thanks for the response NYBGRUS…good points…yeah I am probably a bit too hasty in some of my generalizations.

    Oh and btw I looked up what you said about the corticoid receptors and found it very interesting…thanks for the tip.

    Have a nice holiday (tho you’re probably not reading this blog right now…jeez I’m a loser with no life).

    Actually, I sat around watching Battlestar Galactica with the GF all day yesterday. I did read your comment briefly before going to sleep. Glad you found my response interesting and I hope you had a nice holiday as well.

    Best!

  73. DavidRLogan says:

    In my prescientific days I used to like the paleo/caveman view quite a bit…ultimately I had to admit my stats (hormones, pulse, etc.) were worse than ever under that diet :*( I’d strongly discourage those diets unless you want no libido and freezing extremities.

    @NYB and @VLPrince those are interesting points about squatting to poop. As NYB says it’d be pretty easy to identify their merit, though (I’ll be on the lookout for more info…). I’ve also heard it as a reason for knee issues…knee stabilizers like VMO and glutes are strongly engaged in a full squat and not engaged when sitting on a toilet. But if that’s right why not just full squat (assuming you’re doing so safely/no preexisting issues)? But either way I’ll look more into it…

    @Raphael, Mark Hanna, etc. if you’re also interested in anecdotal evidence there’re the various paleo blogs (like paleohacks)…I think lots of the posters/trolls are pretty honest with their experiences and miseries (impotence, hair loss, wild fluctuations in weight) though some are shameless cheerleaders for the ideas/theory. Gives a more honest appraisel of paleo, tho, vs. some of the gurus with incentives to promote it. FWIW…

    A huge argument about saturated fats is coming, eventually…

  74. @nybgrus nailed it:

    Furthermore, we must realize that even if the assumption is correct (which I contend it isn’t) that a specific period of our history is when our evolution “stopped” (or at least slowed to the point that we could reasonably focus on that physiology to try and tailor our lifestyle to) there is a second assumption inherent to that goal – that tailoring our lifestyle to those conditions means we would be healthier! Lifespans were incredibly short. Disease and trauma were rampant. The best you could say about an “evolutionarily appropriate diet” is that it would be the one to best achieve fertility and fecundity at an early age. It cannot possibly speak to the “best” diet to get us to and through our 60′s, 70′s, and 80′s.

    And, well, his long post nailed it too. Damn, that was some good reading, nybgrus, thank you.

  75. RandyNesse says:

    The timing of this discussion is remarkable since the new Oxford Press journal Evolution, Medicine, and Public Health launched just today. See the press release and website for details. http://www.oxfordjournals.org/news/2012/07/05/evolution-medicine-public-health.html My book with George Williams is indeed dated, but still widely used. Those interested in what is happening in evolutionary medicine can keep at the web journal The Evolution and Medicine Review http://evmedreview.com The issue of how to test these hypotheses is indeed a challenge. My article trying to get people to think critically is Ten questions for evolutionary studies of disease vulnerability, Evol Apps, 2011 http://goo.gl/qlrsT For a review of what doctors do and don’t learn about evolution, and what they need to learn, see a PNAS article in which 12 authors grapple with the question. http://goo.gl/U6YwC Most of my homepage is devoted to articles on evolutionary medicine, for those interested. http://nesse.us

  76. nybgrus says:

    @SH:

    Thanks! Once the links come through that will be nice. The little graph of “how we die” is particularly telling. (Aww, heck I’ll link the screencap here)

    To speak to David’s point:

    ..I’ve also heard it as a reason for knee issues…knee stabilizers like VMO and glutes are strongly engaged in a full squat and not engaged when sitting on a toilet. But if that’s right why not just full squat (assuming you’re doing so safely/no preexisting issues)?…

    The other aspect of this that I didn’t directly touch on relates to the fact that we are indeed still evolving. Why does it make more sense to say that we are better off squatting since that is what we did rather than saying we have been using toilets for hundreds of years now and have adapted to that? I think it is just as plausible to say that if we switched to squatting en masse we would generate a whole host of new problems (and/or se a resurgence of old problems).

  77. daedalus2u says:

    vlprince, vitamin D is not the only photochemical product of sunlight on the skin (there are photochemical NO species too). Photochemical reactions are not the only reason differentially colored skin might have differential benefits. Parasites such as ticks are much easier to see on light colored skin.

    In primates, skin color (and visual receptor number and wavelength sensitivity) is also constrained to make blood flow visible for communication purposes.

    http://171.66.127.192/content/2/2/217.short

    Selection of skin color may reflect the adage, “lucky at cards, unlucky at love”. If facial blood flow is more visible, affect may be more apparent and lead to better romantic relationships (and decreased ability at deception).

    In many individuals skin tone is not uniform, some parts are darker and some are lighter, for example palms are usually lighter. A vitamin D explanation for lighter palms seems implausible.

    Regarding diet, what matters most in terms of evolution is what happens when survival is most difficult, when selection pressure is highest. When food is abundant, its composition doesn’t matter that much. When it is scarce, it matters a great deal. That is probably why humans have no natural evolved defenses against food that is too abundant.

  78. DavidRLogan says:

    @NYB I’m a bit confused (mostly by myself). I agree with you squatting en masse might cause a whole bunch of problems (though possibly for different reasons…explained below), and I agree it makes sense to wonder whether we’ve adapted to some or even many of our present circumstances.

    However I still think there’s something a bit weird going on. What do you mean by “adaptation”? We certainly __change__ because of toilet sitting…(when we sit we get tight hip flexors and other homeostatic stuff…and maybe, should the evidence in question exist, exagerrated lordosis or what VL mentioned would count as a sort of change). And I’d also say because of these changes (say, tight muscles)…squatting suddenly may introduce some new issues. If that’s what you mean by a possible “new problem”, I agree fully.

    However it seems implausible sitting, or many other parts of our life, are something to which we’re “adapted” in the Darwinist/biology-class sense (tho I’m open to hear otherwise). If that’s right, maybe it’s true to say IF we (meaning me and you, people of our generation) started squatting from the beginning of our lives, it would not introduce a new problem. (there were alot of controversial premises in this paragraph that I didn’t explain, including the main controversial one about squatting…but the general idea is here).

    Anyway I think we both dislike the paleo diet view. But I don’t think the more general view (there’re certain aspects of present life to which we haven’t adapted from the immediate past, that we’d be better off without) is as bad in some non-diet cases. I’m reading you as saying you think the more general “paleo” view is almost always a bad view, or at least almost always dubious. Is that right? Since we still don’t have the evidence for the controversial premise, and since you’re a professional, I’ll leave you the last word. Been fun going back and forth….

  79. vlprince says:

    @nybgrus- I don’t think anyone that really “thinks” about evolutionary nutrition would ever say that humans have STOPPED evolving. What we might suggest, however, is that for many people there has been insufficient time and evolutionary pressure for complete adaptation to the products of the agricultural revolution. Even for those that are adapted to some aspects (those with lactase persistence on increased copies of amylase for example), there has surely not been enough passage of time for selection of individuals that thrive on our modern processed diet. There have undoubtedly been epigenetic changes and changes in our gut microbiome- things that are interesting to think about and research.

    Of course I would not suggest there is one magic number that is ideal for Vitamin D. Rather, there is likely a range that is physiologically appropriate. If you study a bunch of people with anemia you might think that a hemoglobin of 8 is pretty darn good, and when compared to someone with a hemoglobin of 5 they’re probably going to look a whole lot better, but unless you look at normal people you may not realize that your HgB of 8 is actually pretty sub optimal compared to those within the true“normal” range.

    @DavidRLogan (& still @nybgrus)- there is limited but interesting research on the effects of squatting on lower GI health. I’m not commenting here to promote my blog, but I did write a post on this (you can just scroll down and look at the references if you don’t want to read it) here: http://principleintopractice.com/2012/04/21/pop-a-squat/

    Oh, and as for the longevity argument. @nybgrus- you said it yourself. People died of trauma and disease- things we have Emergency rooms, trauma surgeons, vaccinations, and antibiotics for today. This is another opportunity to combine ancestral health with evolutionary medicine- look at humans living “in the wild” today… If they make it past childhood, they’re fit and healthy… They’re not dropping dead of heart attacks in their 40s.

  80. Harriet Hall says:

    An orthopedic surgeon once told me hip replacements are seldom needed in cultures where people have a habit of squatting for prolonged periods. Don’t know if it’s true.

    What would be the advantage of thinking of that in evolutionary terms? Would they suggest that we dispense with chairs and toilet seats since our ancestors were not adapted for them? Paleo sitting, like a paleo diet?

  81. DrHall,

    I’d find that hard to believe. Years ago, before medical school, I attended more than half a dozen mission trips to central America where we did total hip and total knee replacements non-stop for a week straight each time. Patients would come from all over the country and hope for a new joint. Each trip we would triage the worst thirty or so. With poor acccess to food, their baseline nutritional status is worse. Also, in those countries they need the arthroplasties, but simple cannot afford them so they cope. They walk with joints we wouldn’t dream of, and when it gets too bad, their surgeons take a surgical steel rod, bend it, put a gunk of surgical cement on it, and use it as the femoral part of a hip prosthesis. (We of course revised that one! I have pics of their homemade prosthesis.)

    Also, this may be stupid, but wouldn’t Wolf’s law of bone remodeling (is that what it’s called? I think?) give you stronger bones by standing upright and stressing the proximal femurs? Seems like squatting would stress the distal femur/proximal tibia?

  82. mousethatroared says:

    HH “An orthopedic surgeon once told me hip replacements are seldom needed in cultures where people have a habit of squatting for prolonged periods. Don’t know if it’s true.”

    Hmm? My first thought was that maybe stronger or more flexible hip/thigh muscles could off-set hip deterioration or pain. Awhile back I was looking to see whether runners experience more hip problems. I came across a study that claimed that runner’s hips seemed to deteriate at the same rate non runner’s hips do., BUT they seem to report less pain for the same level of deteriation. They could determine whether that was due to different perception of pain or some mechanical protective feature of running.

    Ultimately, I would be inclined to go with SkepticalHealth’s explanation, though. Probably people are just putting up with the pain, cause they have no choice.

    Also in countries with lower obesity rates one would expect to see lower knee and hip deteriation rates, Yes?

    I have to say though, I have SI joint issues and when it acts up, squatting or sitting on a low stool feels good, the worse thing is sitting in a chair or car.

  83. nybgrus says:

    @david:

    I was merely commenting that it is possible that instead of spending hundreds of years doing something we are not adapted to handle (sitting instead of squatting) it is also quite plausible that in hundreds of years we are no longer adapted to squat any longer and are better suited to sit.

    The argument was posed that we should go back to squatting since our bodies evolved to do that – all I was saying is “Where is the evidence that we didn’t adapt (evolve) to be sitters in modern times?”

    In my mind though, there is much more to it than musculoskeletal issues. Changes in the size, thickness, and distribution of blood vessels to the rectum and rest of the GI tract might be present to accomodate the “new” way of taking care of business. Different neural responses to varying intra abdominal pressures – both in the enteric and central nervous system – could be present. Different length of time between migratory motor complexes could have evolved.

    This is all speculation of course and I am just listing various physiological parameters. But the point I was trying to make is that it is more complicated than just thinking about hip flexors. And the further consideration is that we may be in a state that is less ideally suited to deal with squatting and not ideally suited for sitting. It could be a wash and if we all start squatting we will merely trade one set of associated problems for another.

    The point is that we can’t infer these sorts of things from an evolutionary framework because there are too many plausible narratives (one has to remember that evolution and adaptation work to the best solution for the current challenge building from the previous state of the organism – thus we cannot infer what “ideal” would mean and often not even what “better” would be since there are many intermediate states of adaptation that an organism can occupy). If we could compare ourselves to our medieval ancestors then we would have a different case. Until then, all if this is speculation at best.

    However it seems implausible sitting, or many other parts of our life, are something to which we’re “adapted” in the Darwinist/biology-class sense (tho I’m open to hear otherwise).

    I don’t see it as particularly implausible – all that evolution is is the placement of an organism of a fitness landscape with many different peaks and valleys and flat space. An organism can move in 3 dimensions on this landscape and adapt in myriad different ways.

    But I don’t think the more general view (there’re certain aspects of present life to which we haven’t adapted from the immediate past, that we’d be better off without) is as bad in some non-diet cases

    Agreed. I also think it is reasonable to say that there are aspects of our diet to which we may not have “adapted” – D2U gave a great example. We haven’t yet fully adapted to a plentiful (essentially unlimited) diet. Hence obesity. But some of us have since there are people who are still thin and fit without having to think too much about it, despite others of us being quite obese or having to work very hard at staying fit (just as an example).

    I’m reading you as saying you think the more general “paleo” view is almost always a bad view, or at least almost always dubious. Is that right?

    I would say generally always dubious. The problem being that we simply cannot infer and have no direct way of saying how, exactly, our biological state has differed from any point in the past. However, evidence shows us that we have indeed changed. And even if that is only a partial change (i.e. arguably not “fully” adapted to modern times – whatever that may mean) it is still a different state from the past and thus trying to argue that living/eating as our ancestors still just doesn’t make sense to me. That is, of course, assuming we can fully describe and have available to us what our ancestors actually ate.

    Since we still don’t have the evidence for the controversial premise, and since you’re a professional, I’ll leave you the last word. Been fun going back and forth….

    Indeed, it has been. And you are too kind. I am just sussing out ideas and finding the argument of trying to re-create living conditions of our ancestors for health benefits to be highly dubious at best.

    (PS – hope this all made sense. I had some trouble sleeping last night and am a bit foggy over my coffee this morning, plus trying to get this out quickly since I have lecture to attend shortly)

  84. mousethatroared says:

    Also, can I just add that it’s surprising how seldom activity levels come up in discussions of specific vitamins, diet, squatting vs sitting, etc. Comparing an Asian country where large parts of the population work in agriculture or strenuous factory jobs to a country were large parts of the population work in sedatary jobs…hmmm.

  85. nybgrus says:

    @vlprince:

    I don’t think anyone that really “thinks” about evolutionary nutrition would ever say that humans have STOPPED evolving. What we might suggest, however, is that for many people there has been insufficient time and evolutionary pressure for complete adaptation to the products of the agricultural revolution

    The highlighted part is a very, very reasonable argument. One that I (indirectly) addressed previously:

    Furthermore, we must realize that even if the assumption is correct (which I contend it isn’t) that a specific period of our history is when our evolution “stopped” (or at least slowed to the point that we could reasonably focus on that physiology to try and tailor our lifestyle to)…

    The inherent and necessary assumption in my bolded part is that the selective pressure on us remitted sufficiently to be a reasonable focus for when to use as our model of health behaviours/foods. The remainder of what I said took into account that as being true and still found fault with it.

    Furthermore, you said it yourself: complete adaptation. My argument does not in any way require complete adaptation. However yours (well, the argument for returning to “evolutionarily appropriate lifestyles”) does require that we haven’t evolved/adapted at all.

    Because even if we only partly adapted that still means an “evolutionarily appropriate lifestyle” makes no sense. You could argue (and I would be hard pressed to disagree) that we aren’t well adapted to our current lifestyle. But the argument you (and Rachel Abrams of the TED talk) need to be making in order to convince me is that we are still best adapted for a historical lifestyle. And I can’t see how that argument can be made – especially since nobody can give any good rationale for picking a specific timeframe to point at as “best.” Should we be looking pre- or post-industrial revolution? During the feudal times? Roman Empire? Greek? Before Common Era? Even further back? When did the selective pressure remit enough that you can say “Yes, that is the timeframe to which we are still best adapted”

    The point is that we have evolved and still currently are. So it makes very little sense to me to try and go back in time to model how we should eat and live. We may not be ideally suited to modern lifestyles, but I would argue that we are still currently best suited for it (or at least as ideally suited as we would be for an ancient lifestyle, whichever one you wish to pick). Best case scenario then, is that one is then forced to say something like, “We are still mostly adapted for [X] timeframe but with [Y] and [Z] changes” which then becomes a conversation about our current state. Of course, we can’t even infer X, Y, or Z to begin with so it is entirely a moot point.

    If you study a bunch of people with anemia you might think that a hemoglobin of 8 is pretty darn good, and when compared to someone with a hemoglobin of 5 they’re probably going to look a whole lot better, but unless you look at normal people you may not realize that your HgB of 8 is actually pretty sub optimal compared to those within the true“normal” range.

    Indeed. And the part I neglected to include in my comment was that we look at “normal” populations – i.e. asymptomatic individuals since defining “normal” to begin with is not as straighforward as one might imagine. And that was my point – different populations have different “normal.” Men have different cutoffs for anemia than women and pregnant women different still. And we may diagnose anemia but never treat it since the person is asymptomatic. From an evolutionary standpoint anything that doesn’t decrease your fertility and fecundity is still “normal” so using that to infer “correct” physiological states is also impossible.

    Which brings me right back to the original point I made in the passage where I quoted myself above – looking back in time to try and make an evolutionary fit (even if it were possible) can only speak to re-creating the conditions and states of that time. Perhaps a vitamin D level of [X] is evolutionarily “normal.” I would argue that we don’t actually necessarily want to be evolutionarily “normal.” Aubrey de Grey says it well when he talks about aging. Right now, we consider it great if grandpa is walking without assistance, mentating clearly, and able to live on his own at 80 or 90. Is it unreasonable to think we could reach a state where grandpa should still be running sub-7 minute miles and a marathon or two? Evolution would not select for that ability – especially in modern times. Yet I would love to see people living that healthily to that late an age as the norm.

    We are in a unique position to go past our evolution and to make our own selective pressures for future evolution. I just find the concept of trying to go back to ancestral states of living as pointless in addition to nonsensical.

    Oh, and as for the longevity argument. @nybgrus- you said it yourself. People died of trauma and disease- things we have Emergency rooms, trauma surgeons, vaccinations, and antibiotics for today.

    Indeed. And those changes have completely changed the selective pressure on our species.

    This is another opportunity to combine ancestral health with evolutionary medicine- look at humans living “in the wild” today… If they make it past childhood, they’re fit and healthy… They’re not dropping dead of heart attacks in their 40s.

    Well, first off we aren’t dropping dead of heart attacks in our 40′s these days either. But the notion that “wild” populations of people (which typically refer to things like Amazonian and African tribes still living in thatch huts and living as hunter-gatherers) are quite healthy if they live past childhood is simply incorrect. There is no evidence support that claim and plenty to demonstrate that they still suffer from chronic diseases, arthralgias, cancers, heart attacks, etc. The indidence and prevalence tend to be lower since they don’t live as long and because they tend not to be diagnosed and treated.

    Heck even the ancient Egyptians had coronary artery disease. One of my old mentors (whom I’ll be having brunch with in a week) actually went to Egypt and did scans on the vessels of mummies in the museums. They definitely had coronary artery and peripheral vascular disease. And these were ancient people who were also young and had extensive atherosclerosis. So yes, these ancient “wild” folks probably would have been “dropping dead of heart attacks in their 40′s”

    I simply don’t see a good argument for any particular benefits of trying to implement ancient lifestyles to address modern human health problems.

  86. nybgrus says:

    @SH:

    Yes, it is Wolff’s law. Though I never actually learned it as that. The more contemporary understanding demonstrates to us that the calcium hydroxyapatite crystal matrix acts as a piezo electric network. When you place stress on the bone, that frees electrons from the crystalline matrix and creates a local charge difference. Osteoblasts are attracted to and activated by this charge which prompts them to strengthen and remodel bone that is under stress. (This mechanism of generating electricity is the same used in those “click” BBQ lighters – there is actually a crystal under the activator button that deforms and releases electrons to spark the butane fuel).

  87. daedalus2u says:

    nybgrus, I think the mechanism is not so much piezoelectric but rather the strain of bones causes fluid flow in the crevices and shear of the fluid flowing in those crevices activates nitric oxide synthase and it is NO that regulates osteoclasts and osteoblasts.

  88. @nybgrus

    Thanks for the answer, this blog is a really a good place to discuss real science and skepticism. I have noticed the same thing, TED talks have slip in many branches and as result lower it’s quality and relevance. The presentation about breast imaging via gamma scintigraphy was interesting, but lacked to show the sensitivity and specificity of the test. What do you thing about that specific presentation ? It would be interesting to have a blog post about it

    “but that light can and does readily reset that rhythm to conform to changing light/dark cycles””

    That is probably right, many workers can really deal the overnight working hours, while sleeping during the day. It’s only a matter to give time to the body to adapt to this new “day cycle”. Otherwise physician would have a miserable life, wouldn’t they ? I will study more about the “second sleep” but seems that in Spain/Italy it’s a still common practice , it’s called siesta. http://en.wikipedia.org/wiki/Siesta

    “Now, we have it so much better that we have the time to complain about these things. (First world problems, as it were).”

    Totally agree with you, I would add that now we report more diseases because we got a better system do perform this task. We got better doctors, better diagnosing tools, better data analyses (computer plus internet) and so on. People usually wrong correlate cancer with chemicals and new life style. Nobody(few) think that their parents haven’t lived enough to have a common (now) cancer

    “They are usually portrayed as happy times of chivalry and intrigue, simple times when people were happier without all the burdens of modern life. Shows like “Game of Thrones” are a much more accurate depiction.”

    The problem here is that student don’t learn any thing about medieval era, at least in my country (Brazil). The majority don’t really imagine that at that time people eat with their hands and toilet didn’t exist. The statement about “Game of Thrones”is both hilarious and true. Damm Hollyhood movies !

    “primarily an issue of obesity and primarily only in the US”

    The problem is that reality is becoming more and more common in other countries, mainly in developing countries, such as Brazil, India and China. People are replacing the tradicional food and replacing with packed , grease and with lot of sugar food. The point is that our nature will always “force” us to use the escalator, the only way out is a better education and a better urbanization. Now it’s clear that “the amercian way of life” is not healthy…

    Ps: sorry for my grammar, english is not my first language

  89. Justin says:

    I was surprised nobody has mentioned the college level text that was published in 2010 by Oxford Press entitled “Principles of Evolutionary Medicine.” This text is designed for the medical student as a supplement to normal medical school, to help teach the underpinnings of evolutionary medicine. Great book, and well organized, although, I haven’t read every chapter I have learned quite a bit from the chapters I have read.
    I think one of the key points that I have learned is the concept of mismatch. This is the idea that the genome or the developmental programming of the epigenome can be mismatched with the individual’s ultimate environment.

    A quick example would be the Dutch babies born during a famine period of WWII. These babies underwent a developmental programming that took into account a lack of food, and their physiology was altered in a way to deal with this. But as they grew up there was no lack of food, and therefore a statistically significant number of these children suffered from obesity. There was a mismatch between their developmental environment and their ultimate environment.

    WRT to the concept of evolutionary diet, I think this is a reasonable and plausible avenue to explore. 99.99% of human evolution has occurred with a diet solely based on whole unprocessed foods. In such a short time (evolutionarily speaking) have humans adopted a diet high in processed foods, there is no way that the genome could possibly change this quickly to adapt to these massive changes in diet, evolution happens on a much longer time scale. Now, that is not to say that there is some magical “paleo-diet” that will match your genome to your current environment, but it is highly likely that you will be more healthy if you consume a diet solely based on whole foods, which I don’t see anyone arguing against.

    One other example I remember reading in some pubmed papers on paleo diet is the change in consumption of Potassium compared to Sodium. Whereas, the majority of human existence was dominated by a consumption of roughly 100:1 times more Potassium than Sodium, now, the ratio is flip flopped and the modern human consumes roughly 100 times more Sodium than Potassium. This is another mismatch that the human genome is dealing with and has difficult to quantify implications for modern human health and disease.

    One of the other difficult to quantify changes that has been ushered in due to changing diet and lifestyle is the changing human microbiome. The microbes that reside in our gut feed off of the food we eat, and therefore it is logical to expect this resident flora to also change when the diet changes substantially. What are the implications of this mismatched microbiome and metabalome on the development of the human immune system? As D2U brought up, the skin flora has undergone massive changes in an evolutionary blink of an eye due to changing hygiene. What are the implications of this on human physiology?

    Evolutionary medicine doesn’t need to be used as an afterthought to explain something, but it does provide a great framework for developing testable hypotheses that will accelerate the optimization of medicine.
    Interesting conversation!

  90. nybgrus says:

    @D2u:

    Actually it is pretty well accepted to be a piezo electric effect:

    http://www.ncbi.nlm.nih.gov/pubmed?term=piezoelectric%20bone%20remodeling

    and an effect that is currently being explored to stimulate bone growth

    http://www.ncbi.nlm.nih.gov/pubmed/22084058

  91. nybgrus says:

    @rafeal science:

    no apologies – your English is great.

    I also agree that obesity is rapidly becoming a problem beyond America. That is indeed something to address in public health circles.

  92. nybgrus says:

    @Justin:

    I actually have not read or heard of that book. Shame – it sounds quite good.

    WRT to the concept of evolutionary diet, I think this is a reasonable and plausible avenue to explore. 99.99% of human evolution has occurred with a diet solely based on whole unprocessed foods. In such a short time (evolutionarily speaking) have humans adopted a diet high in processed foods, there is no way that the genome could possibly change this quickly to adapt to these massive changes in diet, evolution happens on a much longer time scale.

    First off I would be hesitant to say there is no way it possibly could. Indeed it could. Epigenetic factors can act quite rapidly without changes in population level allelic frequencies. Did it? I agree probably not

    But the issue you bring up is more related to behavioral aspects of having access to inordinately calorie dense foods in unlimited quanities, not some aspect of physiological/phenotypical change as a factor of the genome… which is what the paleo diet argument is based on – that our physiology is best suited to those kinds of food. Not that our behavioral factors haven’t adapted to a new mode of eating.

    The other thing to consider is that just because evolutionary pressures have been stable for a very long time does not mean that it will take an equally long time to change once selective pressures change.

    The comments re: K and Na as well as microbiota are indeed interesting though. We may not be best suited for our environment – the question is how do we address that? My contention is that looking at past states to try and infer best current states is not straighforward (like paleo diet believers and the TED talk would have you believe). At best it can help infer some guideposts to go from in testing strategies – but cannot directly suggest the strategy wholesale.

  93. Patrick says:

    So the question still remains: does medicine fit within a Darwinian framework? I think a preliminary question is this: how many people even understand evolutionary theory and its contention that all organisms, from bacteria to baboons, stem from a single universal population and are thus completely related in a manner akin cousin relationships? This explains why scientists have been able to use flies and worms to elucidate the nature of genetic diseases in humans. Common descent has also blessed all organisms with not just a “similar” genetic code, but a code that is (identical) among all known organisms (with a few exceptions). This has made recombinant DNA technology possible for molecular biologists to even work with. It is beyond dispute that evolutionary theory will exert tremendous influence over medicine, and it will only gain momentum over time—even if it is just indirect pressure.

    http://www.talkorigins.org/faqs/comdesc/

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