Darwinian Medicine and Military History - Evolution News & Views

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Darwinian Medicine and Military History

Several Darwinist bloggers have taken exception to my observation that Darwinian stories about the origin of diseases contribute little of significance to medical education, research, or practice. Orac responds:

...that creationist neurosurgeon with a penchant for laying down hunks o' hunks o' burnin' stupid on a regular basis, that Energizer Bunny of antievolution nonsense, Dr. Michael Egnor has spouted off on evolution again in a way that got my attention. It came in response to a post by PZ about a conference he attended entitled Understanding evolution: the legacy of Darwin, which served as a launching pad for Dr. Egnor to go right down the rabbit hole...The stupid, it burns. It sears. My neurons are crying out in pain. Once again, Dr. Egnor trots out the tired old "Darwin inevitably leads to eugenics" coupled with his usual claims evolution has contributed nothing--or, as Dr. Egnor says it, nothing!--to medicine. Only Dr. Egnor could come up with something so utterly devoid of understanding, so scientifically ignorant, so full of the arrogance of ignorance...

Having gotten that off his chest, Orac, a surgical oncologist who doesn't post under his real name, continues:

[Egnor] tries to dismiss the very real contribution evolutionary biology had to make in understanding why the sickle cell hemoglobin allele is retained in human populations at such a high frequency event though it is so deleterious in homozygotes by attributing the insight to relevant basic sciences, but what led those "relevant basic sciences" to the concept of heterozygote advantage...was evolutionary theory, of course... Ditto bacterial resistance to antibiotics. These are not "just-so" stories. They are instances in which evolutionary theory makes predictions, and, in the case of bacterial resistance and sickle cell disease, biology fits those predictions...

Orac misses my point. I'm not arguing that the Darwinian stories are necessarily untrue. Many of them (e.g. the theory that children hate broccoli because their ancestors gained selective advantage via the avoidance of toxins) certainly seem a bit silly, and most are probably untestable in any way approaching rigor, but perhaps they're true, and perhaps they're false. What I'm arguing is that the truth or falsehood of Darwinian stories is of no tangible value to medicine. Consider the following example.

I would suspect that careful epidemiological studies of the British population would show that the prevalence and incidence of spina bifida increased following World War One. To my knowledge, this has not been investigated, but it would make sense if it were true, for the following reasons:

Britain suffered enormous casualties during the Great War, as did many other European nations. (I'm just using Britain as an example). It has been said, with asperity, that Britain lost a generation of men on the Western Front. Britain suffered 2,300,000 war casualties -- forty four percent of mobilized men, with 703,000 men killed in battle or by disease. On just one day -- July 1,1916 -- 19,240 British soldiers died in the battle of the Somme. The young men who died were the best of their generation -- healthy, and by definition capable of meeting the rigorous physical standards required for military service.

Of course, other British men with debilitating genetic disorders, such as men with spina bifida (which renders the afflicted congenitally paralyzed), were not in the trenches that day, because they were physically unfit for military service, or at least service on the front lines as infantrymen. It's safe to say that military age British men without spinal bifida were at greater risk of death in the war than were military age British men with spina bifida. Whatever the impediments faced by people with spina bifida -- and they face many impediments -- they were not called to serve and die in the trenches.

Spina bifida would then be a fine example of an environmental adaptation; it was protective against "acute lead poisoning" -- protective against being mowed down by German machine gun fire on the Western Front. So, assuming for argument's sake that my hypothesis about the post-war epidemiology of spina bifida is true, the genes that give rise to spina bifida conferred a selective advantage on young British men in the period 1914 to 1918, and the differential survival (and reproduction) of that age cohort would explain a (hypothetical) increase in the incidence and prevalence of spina bifida in England in the post war period.

Interesting vignette, if true. I haven't a clue about its veracity. But here's the crux of my argument: military history, which is the basis for understanding this hypothetical blip in spina bifida in England in the 1920's, is obviously not essential to medical education, research, or practice as relates to spina bifida. Military history may, if my inference is true, offer an explanation for changes in population frequency of the spina bifida genotype and phenotype in post-war England, but it's not in any way essential or even relevant to the medical management or understanding of spinal bifida. It's tangential at best, and such historical vignettes, interesting and perhaps of importance to historians, are of no practical use to physicians or medical scientists.

The analogy between my military history hypothesis and Darwinian theories of the origins of disease is quite close. Darwinian explanations for disease are historical vignettes. Darwinian stories are "military history" hypotheses about the ancient struggle for survival, a characterization long employed by evolutionary biologists, and I think an apt characterization.

I like a good story as much as the next guy, but Darwinian stories, which are orders of magnitude less credible and testable than military history, are, like my spina bifida hypothesis, worthless to modern medical research and practice. I've been educating students and other doctors about spina bifida and treating patients with spina bifida for 23 years, and my most active area of research is on a brain disorder (hydrocephalus) that afflicts most people with spina bifida. I use biochemistry, anatomy, physiology and microbiology in my work. My work is not advanced in any way by stories from military history.

Historical vignettes about differential survival and reproduction, whether from the Great War or the Pleistocene, contribute nothing of relevance to medical science.