Does Medicine without Evolution Make Sense? (Evolution is irrelevant to medicine in particular)

Citation: MacCallum CJ (2007) Does Medicine without Evolution Make Sense? PLoS Biol 5(4): e112 doi:10.1371/journal.pbio.0050112

Copyright: © 2007 Catriona J. MacCallum. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Catriona J. MacCallum is Senior Editor at PLoS Biology. E-mail: cmaccallum@plos.org

It is curious that Charles Darwin, perhaps medicine's most famous dropout, provided the impetus for a subject that figures so rarely in medical education. Indeed, even the iconic textbook example of evolution—antibiotic resistance—is rarely described as “evolution” in relevant papers published in medical journals [1]. Despite potentially valid reasons for this oversight (e.g., that authors of papers in medical journals would regard the term as too general), it propagates into the popular press when those papers are reported on, feeding the wider perception of evolution's irrelevance in general, and to medicine in particular [1]. Yet an understanding of how natural selection shapes vulnerability to disease can provide fundamental insights into medicine and health and is no less relevant than an understanding of physiology or biochemistry.

One reason that evolution doesn't figure prominently in the medical community is that although it makes sense to have evolution taught as part of medicine, that doesn't make it essential. As explained at a meeting on evolution and medicine I recently attended in York, United Kingdom (the Society for the Study of Human Biology and the Biosocial Society's 2006 symposium, “Medicine and Evolution”), medicine is primarily focused on problem-solving and proximate causation, and ultimate explanations can seem irrelevant to clinical practice. Crudely put, does a mechanic need to understand the origins, history, and technological advances that have gone into the modern motor vehicle in order to fix it?

Randolph Nesse (University of Michigan) and colleagues think otherwise [2], and have been campaigning for evolution to be recognized and taught as a basic science to all medical students (see also the Evolution and Medicine Network, http://www.evolutionandmedicine.org). It has been more than 10 years since he and George Williams published their classic book Why We Get Sick: The New Science of Darwinian Medicine [3]. Other landmark texts linking evolution to health have been written since then, with new editions on the way [4–6], and the research field is blossoming. Still, as Nesse mentioned at the start of the York meeting, there are only a handful of medical schools in the United States and in the United Kingdom with an evolutionary biologist listed as such on the faculty.

The most obvious examples of evolutionary biology's importance to medical understanding are related to infectious disease [7]. As Jon Laman (Erasmus University, The Netherlands) pointed out at the meeting, the immune system provides the perfect platform to explain the medical relevance of the exquisite evolutionary relationships between pathogens and their hosts. Understanding how virulence evolves, for example, can help predict the potential, sometimes counterintuitive (and controversial) negative consequences of imperfect vaccination [8,9]. But evolution can also tell us that the origin of HIV was precipitated by a jump across the primate species barrier [10] and enables us to predict the imminent arrival of avian flu and the mutations most likely to be responsible for that evolutionary leap from birds to humans [11]. Where epidemiological and population genetic processes occur on the same time scale, the emerging field of “phylodyamics” can also inform us about the timing and progression of pathogen adaptation more generally [12].

The relevance of evolution to medicine is, however, much broader. Participants at the York meeting discussed not only how vulnerability to cancer is an inevitable but unfortunate consequence of imperfect human engineering and natural selection (Mel Greaves, Institute of Cancer Research, UK), but how life history theory can potentially explain patterns of pregnancy loss (Virginia Vitzthum, Indiana University), how a comparative approach applied to different human cultures and different primates can improve rates of breastfeeding (Helen Ball, University of Durham), whether clinical depression has an adaptive origin (Lewis Wolpert, University College London), and if suicide attempts are really just evolutionary bargaining chips in intense social disputes (Ed Hagen, Humboldt University).

As with any emerging field, ideas change and the science is challenged. The thrifty gene concept [13]—that some populations (e.g., from Polynesia) are particularly susceptible to type 2 diabetes and heart disease because of past selection pressure specifically during times of famine—no longer enjoys the support it once had [14]. Tessa Pollard (University of Durham, UK) explained that the so-called Syndrome X is now considered to be the result of more general exposure to a rapid change in lifestyle as Western society encroached on these populations during the mid-20th century. The relationship between changing environment, diet, and susceptibility to disease, however, is also far from clear. Many diet-related conditions that typify industrialized populations—e.g., obesity, hypertension, and tooth decay—have been explained as resulting from an evolutionary mismatch between our over-refined, fat-filled contemporary diet and the environment to which humans were once ideally adapted. Sarah Elton (Hull York Medical School, UK) cautioned that while this analogy (the “environment of evolutionary adaptedness”) has been useful as a research tool and has led to public health campaigns for better diets (more seeds, nuts, fish oil, etc.), recreating such a typical “Stone Age diet” as a benchmark can be misleading. Human ecology in the past was at least as variable as human (and other primate) ecology is today.

Surprisingly, an evolutionary framework to study human variation can be seen as counterproductive. George Ellison (St. George's Medical School, UK) provided an example, although not concerning evolutionary medicine, about a statistically flawed study leading to spurious conclusions about regional variation in IQ (which I won't promulgate here). However, bad papers are published in all subjects and are a failure of scientists and the peer-review system, not the science. These should not provide an excuse to dismiss the relevance of evolution to medicine (or to any other life science). Even at a very basic level, medical students can draw insights from evolution they cannot obtain from other core sciences on their course. Paul O'Higgins (Hull York Medical School) noted that it is much easier for medics to learn the nerves involved in the brachial plexus (the nerves supplying the arm) if they first understand the origin of the pentadactyl limb.

It is not the case, however, that all clinicians fail to see the relevance of evolution. Gillian Bentley (now at University of Durham) conducted a series of interviews with leading biologists and clinicians when she was based at Imperial College London. What was surprising was not the positive endorsement of evolution by the geneticists and evolutionary biologists but the enthusiasm of practicing medical doctors for the topic, whether involved in the active birth movement or dealing with major trauma in intensive care. Indeed, several local clinicians attended the York meeting and helped lead the discussions.

Ironically, the hardest task in adding evolutionary/Darwinian medicine to medical curricula may well be soliciting support from medical students. Although Paul O'Higgins thought a comparison of the brachial plexus to the pentadactyl limb was helpful, not all his students agreed—complaints were lodged that he was forcing evolution on them. That lack of support was also reflected in the participation of only three medical students at the York meeting (albeit enthusiastic ones), despite being widely publicized. It is not clear whether this is because medical students are more overburdened than most or because of a more deep-rooted resistance to the subject, reflecting wider political and religious prejudice against evolution. But evolutionary medicine isn't and shouldn't be controversial, and the best way to challenge prejudice is through education. As the oft-quoted Theodosius Dobzhansky wrote in 1973, “Nothing in biology makes sense except in the light of evolution” [15]. The time has clearly come for medicine to explicitly integrate evolutionary biology into its theoretical and practical underpinnings The medical students of Charles Darwin's day did not have the advantage of such a powerful framework to inform their thinking; we shouldn't deprive today's budding medical talent of the potential insights to be gained at the intersection of these two great disciplines.

1. Antonovics J, Abbate JL, Baker CH, Daley D, Hood ME, et al. (2007) Evolution by any other name: Antibiotic resistance and avoidance of the E-word. PLoS Biol 5: e30 doi: 10.1371/journal.pbio.0050030. Find this article online

2. Nesse RM, Stearns SC, Omenn GS (2006) Medicine needs evolution. Science 311: 1071. Find this article online

3. Nesse RM, Williams GC (1994) Why we get sick: The new science of Darwinian medicine New York: Vintage Books. 290–p p.

4. Ewald P (1994) Evolution of infectious disease Oxford: Oxford University Press. 298–p p.

5. Stearns SC, editor (1998) Evolution in health and disease Oxford: Oxford University Press. 315–p p.

6. Trevathan WR, Smith EO, McKenna JJ, editors (1999) Evolutionary medicine Oxford: Oxford University Press. 480–p p.

7. Frank SA (2002) Immunology and evolution of infectious disease Princeton (New Jersey): Princeton University Press. 348–p p.

8. Gandon S, Mackinnon MJ, Nee S, Read AF (2001) Imperfect vaccines and the evolution of pathogen virulence. Nature 414: 751–756. Find this article online

9. Mackinnon MJ, Read AF (2004) Immunity promotes virulence evolution in a malaria model. PLoS Biol 2: e230 doi: 10.1371/journal.pbio.0020230. Find this article online

10. Keele BF, Van Heuverswyn F, Li Y, Bailes E, Takehisa J, et al. (2006) Chimpanzee reservoirs of pandemic and nonpandemic HIV-1. Science 313: 523–526. Find this article online

11. Nicholls H (2006) Pandemic influenza: The inside story. PLoS Biol 4: e50 doi: 10.1371/journal.pbio.0040050. Find this article online

12. Grenfell BT, Pybus OG, Gog JR, Wood JL, Daly JM, et al. (2004) Unifying the epidemiological and evolutionary dynamics of pathogens. Science 303: 327–303. Find this article online

13. Neel JV (1962) Diabetes mellitus: A “thrifty” genotype rendered detrimental by “progress”? Am J Hum Genet 14: 353. Find this article online

14. Lazar MA (2005) How obesity causes diabetes: Not a tall tale. Science 307: 373–375. Find this article online

15. Dobzhansky T (1973) Nothing in biology makes sense except in the light of evolution. Am Biol Teach 35: 125–129. Find this article online

Comparing what little we know to all that there is to know, I assert that next to nothing in biology makes sense, either in light of, or in spite of, evolution.

The plain fact is that neither statement in any way alters the biological processes themselves, neither alters any man's ability to observe those processes, learn their progression, to understand what happens, and in what order. Whether the man is a humanist, an Islamist, a Moonie, or a Scientologist is entirely irrelevant to the ability to observe, record, and relate the particulars of that which was observed. And it is also irrelevant to the man's ability to identify processes that he does not yet understand, to determine the need for deeper study, and to devise specific methods by which to advance that study.

The theory of evolution is an organizing device. It explains the data better than any other hypothesis (that's why it is classified as a theory).

Heinlein said it best:

Piling up facts is not science--science is facts-and-theories. Facts alone have limited use and lack meaning: a valid theory organizes them into far greater usefulness.
A powerful theory not only embraces old facts and new but also discloses unsuspected facts.
Expanded Universe: The New Worlds of Robert A. Heinlein, 1980, pp. 480-481

To assert that a belief in evolutionary theory would suddenly transform the man from scientific incompetence to Nobel Prize stature is patently absurd.

Nor would I assert such. The converse, rather, is true. Without the knowledge of evolutionary theory, a man of Nobel Prize stature would be reduced to scientific incompetence in any of the fields relying on evolutionary theory. It is an organizing device (as noted above), and without it there is a huge gap in our understanding of biology and several related fields.

The word “evolution” is emotionally charged. It is much more likely to find agreement with the common-sense expression “natural selection”. This can be said, because natural selection is seen around us constantly, in most competitive situations.

Two boxers fight, one wins and one loses. That is natural selection. The better boxer won. The cheetah catches the slowest gazelle in the herd. That is natural selection, too.

It may be fatal, it may give you a better chance to have children with who you want to, it may make your life longer or shorter. It can make you healthier or wealthier. It can even determine if your children are smart or dumb.

All sorts of things come into play with natural selection, and noteworthily, to the religious, there are many, many variables that are not controlled by the participants, and are even invisible. Things that people might call “bad luck”, or “acts of God”, figure just as prominently into natural selection as do the obvious ones. As does free choice. So again, it is a less contentious idea than evolution.

That being said, we can objectively note some of the phenomena of natural selection, things that impact us in our lives.

One I find interesting is the odd phenomenon of grandmothers dying in large numbers when their grandchildren reach some milestone in maturity. The grandchild graduates from high school or college and bam!, grandmother dies. It sticks out in the statistics.

It is very practical to know this. Months before such an event is scheduled to occur, granny should be checked from stem to stern, looking for warning signs of heart attack, stroke, and other quick killers. Then she should be monitored and even be given preventative medical care for a window of time around that event.

People *can* mitigate a lot of the problems associated with natural selection, and we do all the time. Medicine itself is one such mitigation. Christianity as a religion prides itself on defying natural selection to help those who need it.

People under the age of 21-25 or so, often do not have fully matured brains, which translates directly to their judgment. This is why minors can’t sign binding contracts, and shouldn’t be allowed to consume addictive substances, because it is much easier for them to become addicted.

And, of course, they as a rule also have fairly poor judgment about sex and other high-risk activities. Society itself tries to help them not be victims of natural selection.

But everyone is involved to a great extent with natural selection. It is an integral part of all of our lives, and it does determine where we as individuals, and as a people, are going in the future. Some of the choices have little consequence by themselves, but add up; some we can change; some can have tremendous consequences.

Imagine how things would be if we had elected John Kerry instead of George W. Bush? That, too, was natural selection. And a wise choice. And thank God.

This is a political Forum, and there is room for dialogue on a number of subjects, but in the end, it is also a Conservative forum.
You can call people who have alleged relevant backgrounds conservative if you like, but for real, they ain't conservative, and out here they ain't relevant.
I have been around the block, and the so called relevant backgrounders are worse than any mob names that you could ever hurl at FReepers.
Those so called "relevant" types, were in many cases, intolerant, smug, arrogant, and BS artists who have not likely done half the reading that this here particular High School dropout has ever done.

So what you are basically saying is that in order to be conservative, one cannot be a scientist with stronger knowledge of evolution? In all the years I've been here, the crevo threads have been brutal, but the proponents of evolution have consistently had rational, well researched and well cited posts. Creationists, on the other hand, have been caught, multiple times, essentially, and IMHO, "lying for the Lord." Being a creationist is not a requirement for being conservative. Like From Many - One has said, without techical people posting haere anymore, these threads are nothing more than echo chambers so the choir can sing to themselves. It's political masterbation.

Evolution has no clinical relevance, and there simply isn't room in the curriculum to replace medically relevant subjects with Darwinism.

I agree with you here

I think a lot of universities are shoving Darwinism down the throats of medical students.

However, Darwinism is largely irrelevant to medical schools today and perhaps even in the past.

I am not sure if Darwin has added anything valuable to our understanding medical science.

In fact, if you read the article carefully, it demonstrates exactly what is implied --- which is this --- Darwinism is useless in medicine.

Medicine has been getting along very nicely without Darwin and medical students are smart enough to see that adding Darwinism to the curriculum is a waste of time.

My read of the article tells me that the author is perhaps unwittingly admitting how Darwinism has little utility to the practice of medicine.

I find it ironical that while the author is saying Darwinism is fundamental to medical science, medical doctors in practice today find it irrelevant.

Let's mine the article for the hidden gem of a quote :

One reason that evolution doesn’t figure prominently in the medical community is that although it makes sense to have evolution taught as part of medicine, that doesn’t make it essential. As explained at a meeting on evolution and medicine I recently attended in York, United Kingdom (the Society for the Study of Human Biology and the Biosocial Society’s 2006 symposium, “Medicine and Evolution”), medicine is primarily focused on problem-solving and proximate causation . . . .

There ya go...

Medical schools have been training doctors since before Darwin was born and after that without actually REQUIRING the teaching of Darwinism.

Medical science has progressed greatly with few doctors being required to learn about Darwinism other than the basic ideas of Natural Selection plus random mutation.

Now suddenly, just because dogmatic evolutionary biology is being seriously challenged, we have people DEMANDING that medical students be forced to take it as REQUIRED instead of as an elective course.

I see little difference between this and forced indoctrination.

Let me just say I have practiced Medicine for 22 years and never in my practice of caring for patients has evolution popped into my head while deciding what to do to save a life at 0300, while delivering a baby, prescribing medicine etc. What you do not want is your physician who is treating you thinking “Now what would evolution tell me about how much lasix or dopamine this patient needs who is in acute CHF and in shock?” I really tells you NOTHING. I have never used the theory directly. I am dealing in Medical Science not evolution. I am treatin ill human beings not wondering how the human being exists at all. Guys evolution is not the “knowledge that MUST be known” to do most anything. Unless you are a research scientist doing specific research in a very limited slice of science is it even necessary to know. A physician would be better served by a class in world religions so they can relate to their patients human needs.

"So what you are basically saying is that in order to be conservative, one cannot be a scientist with stronger knowledge of evolution? "

I am not saying that.

I have taken Microbiology courses, A & P, Biology, and a few others. I believe that I have some grasp of the debate positions

If I have to express a position then I will say that their Theory of Evolution is a "Scientific Theory." That is, it is not the word "theory" as defined by most people.

It is a poor description of an explanation of a vast collection of works that are intended to describe just what the cause, course, and processes of biological life forms are about.

Evolutionists, in the debate club, are coming from a position of presumed authority which is contrary to the "scientific method" and additionally they are it seems to me preset in their opinions on the matter.

They want it both ways. Darwin did not intend to explain "the origin of life" despite the fact that he titled his big work "On the Origin of Species."

OK, ,,,probably non sequitor, but still, the Crevo threads were full of know-it-alls who really after all (IMHO) never really were open minded, and on the other side a bunch of folks who could not argue coherently about the real aspects of TOE because among other reasons, they did not know what they were talking about.

The Bible states that God created Heaven and the Earth. It does not take more than a single page to get to that fundamental claim.

When people choose to debate things then consideration ought to be given to just exactly what the other position is, and where the adherents are coming from.

Do you mean to imply that the Evos were not largely condescending and arrogant out here?

If folks want to discuss the cellular structure of Prokaryotes, Eukaryotes, DNA, RNA, Mitochondria, hydrophils, Golgi Complexes, reticular this or that then there is no real conflict.

When folks are intent on undermining fundamental beliefs and principles, then they have crossed a line.

The Evos may all be bright people, but they certainly have proved that they have no place in a forum that is intended for discussion of issues based on common sense and reasonable positions.

As far as I am concerned, the Evos can all get together in their little lab coats at some convention someplace with their nerdy little note pads and play with each other.

They are no better than the folks who claim that a third trimester baby is still just a mass of cells or as they euphemistically like to put it "fetal tissue."

I know a little bit about a few things, and as I have been accused of, I do not mind thumping my chest every once in a while, if that is what it takes to make a point out here.

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