May 25 2012

Understanding Evolution and Being a Good Doctor

I need to dip into the topic suggestions more often. Here is a good recent question:

Hi Dr. Novella,

Over at Why Evolution is True Jerry Coyne wrote about Ben Carson, the creationists doctor at Johns Hopkins, saying some bizarre stuff about evolution. In the comments a couple people have made the point that they don’t think understanding evolution is directly relevant to being a doctor (especially a surgeon, ENT, or oncologists). One commenter even said he thought oncologists “have precisely and exactly zero need to understand evolutionary theory.”

I tried to argue that understanding the foundational principle of biology was directly relevant to physicians, in a variety of areas. I am very interesting in your views on the subject. Does understanding evolution help a doctor be better as her/his job? Is understanding evolution going above and beyond as a doctor, or something that should be expected of physicians?

Here’s the link to the main comment I had in mind (#30) and a couple responses, including mine:


In my opinion there are two basic questions here: how relevant is evolution to the science of medicine, and how does understanding the science of medicine impact the practice of medicine?

Evolution in Medicine

The topic of evolution in medicine has been discussed many times before, mainly the context of a creationist challenge to the relevance of evolutionary principles in medicine. Their argument is that evolution is of no practical use, because it’s wrong. Legitimate science, they argue, always has a practical use. While I think there is a kernel of legitimacy to this premise – that valid science has utility – it is not always true and it is not a litmus test for legitimate science. There does not need to be an immediate practical application of dark matter, for example, in order to consider the evidence for dark matter compelling. A claim, however, that has an obvious practical application, like ESP, does raise skepticism when it cannot be used for the purpose to which it is so obviously suited (if it existed). Creationists, therefore, are misapplying this notion, or perhaps overapplying it. Evolution can be completely true without having direct application to the science of medicine.

Their other premise, however – that evolution is of no practical use to medicine, is also false. (Here is a website dedicated to the issue.) Evolutionary principles are important in understanding antibiotic resistance, genetic illness, and the natural history and response of cancers to treatment, to name the most obvious examples. It is also critical to understanding any animal model of biology or human disease. A great deal of the basic science on which science-based-medicine depends requires an evolutionary perspective in order to interpret it properly.

The creationist claim, therefore, is based upon two false premises.

Evolution and the Practice of Medicine

The second question is whether or not an individual doctor needs to understand evolutionary principles in order to be a competent physician. This is really part of a broader question – do doctors need to understand scientific principles in order to be a competent physician?  I think the answer is yes, but with a significant caveat.

Within medicine there is a standard of care that is developed by the medical community, but mostly driven by the recognized experts in their field synthesizing available evidence and experience. For the average physician in private practice, in order to be minimally competent they need to understand clinical decision-making and the current standard of care as it applies to their specialty. For procedure-based specialties, like surgeons, they also need to be technically competent. None of this requires an understanding of the science behind medicine.

Physicians who practice in this manner are essentially behaving like technicians, not scientists. They have the requisite fund of knowledge and know what practices are required in given situations. The more procedure-based a practice is, the more a physician can get away with this level of practice, as their technical skills comprise a larger portion of their daily practice.

However, while I think you can get to a level of minimal competence practicing in this fashion (cook-book style, following standards of care without necessarily understanding how they came about), this level of practice results in a mediocre clinician. This is because it is essential to understand scientific principles in order to be a fully functional clinician. Again I will break this down into two areas.

The first reason that understanding the science of medicine is important to the practice of medicine is making sense of the science itself. While there are many practice guidelines and published standards available, they are not comprehensive, and cannot account for every unique patient situation. Further, science is always rapidly changing and practice guidelines take time to put together so there is always a lag. Practitioners therefore often have to rely upon their reading of the latest published evidence.

It is also not uncommon for there to be controversies within the standard of care. You may remember the controversy that arose over the new guidelines for screening mammography in women. Different groups disagreed on what those guidelines should be. There was recently a similar controversy over the use of PSA in screening for prostate cancer. There are also emerging therapies, like the liberation procedure for alleged CCSVI in multiple sclerosis. The MS community claims that CCSVI and its treatment are far fetched and not legitimate, but there is a vocal minority claiming significant results and demanding research. What should a physician say when asked about this procedure by their patient?

It is increasingly common, in fact, for patients to ask their physicians to help them make sense of the scientific evidence with regard to a specific disease or treatment. There may not be a published guideline available, or the evidence may all be preliminary and ambiguous. There are also increasingly treatments that are on the fringe of science, and some that are outright fraudulent, and a good clinicians needs to be able to navigate all this scientific complexity with and for their patients.

The second reason that understanding scientific principles is helpful to being a good clinician is that they are directly applicable to clinical decision making. Understanding the nature of placebo effects, confirmation bias, the limitations of human memory, and other cognitive biases is critical to making sense of a patient’s history, their diagnosis, and their response to treatment. Each interaction with a patient is a mini-scientific investigation, and thinking scientifically (and skeptically) is critical to doing that well.

Understanding evolution is therefore important to clinical practice to the same degree that it is important to the science of medicine, as I briefly outlined above.

The final question is this – what implication does being a creationist have on the ability to think scientifically in general. I have serious concerns about the scientific literacy of anyone who can deny the science of evolution. On the other hand, however, people do have the ability to compartmentalize. It is reasonable to argue that denial of evolution requires a certain lack of critical thinking skills and/or factual information about biology and the evidence for evolution, but people seem to be able to function scientifically in one area, but then function completely irrationally in another area that has special ideological significance. They may not even see the conflict between the two, or they find some way to rationalize them away.


In summary, I think that the science of evolution has very clear implications for the science of medicine. The ability to think critically and scientifically is very important to being a competent clinician. However, individuals can get by following published standards and compartmentalizing their personal unscientific beliefs.

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