Why do we age? Why is congestive heart failure so common? Why do so many of us wear glasses? Why is there a menopause? Why must we sleep? Why do we get febrile when infected?
Medical students, trainees, and physicians are drawn to questions of how the body works, so your likely first response to these intriguing questions is to think about pathophysiologic answers. These proximal, mechanistic explanations form the conceptual and cognitive framework for our learning, practice, and research in medicine.
However, such bodily mechanisms tell only half of the story. To fully understand the complexities of these problems, we must ask evolutionary questions as well. Based on the work of Tinbergen and Mayr, Randolph Nesse developed this Figure describing the four questions that must be answered to provide a full explanation of any biological trait.
The aim of this new Clinical Correlations column is to share fascination with the view of health and illness through an evolutionary lens. Through this lens, the very nature of questions one can ask shifts from proximate “what” questions about mechanism and development in individuals to evolutionary “why” questions about selection forces and phylogenetic development.
Medicine is based on biology, and biology is based on evolution, but medical education and research rarely taps into the elegance and power of evolutionary principles. In fact, in a 2003 survey of North American medical school deans, 48% said evolution is important for physicians. However, not a single medical school teaches evolutionary biology as basic science, no medical school requires evolution as a prerequisite for admission, only 16% had PhD faculty in evolutionary biology, and schools devoted a median of 4 hours of curricular time on core topics in evolution.
Medical Schools are complex institutions and slow to change. Jack Colwill, Professor at University of Missouri, aptly wrote, “We educate tomorrow’s physicians in today’s system while maintaining yesterday’s beliefs.” Curricular time is precious and many valuable fields vie for larger roles in educating physicians. However, Dr. Nesse, Professor of Psychiatry at University of Michigan, argued, “Teaching evolution as a basic science does not add extra facts, it adds a framework on which those facts can be organized and it can make medical education more coherent. It can give students a real feel for the organism…”
In this new series, we hope to explore humanity’s traits and vulnerabilities by asking evolutionary questions. Along the way, we hope to address some core evolutionary concepts and stimulate your interest in learning more about this core basic science. The next column will explore the mystery of aging from an evolutionary perspective.
For a list of web sites, conferences, videos, and books on the interface of medicine and evolution see the attached recommended reading.
Dr. Schwartz is an Associate Professor in the NYU Division of General Internal Medicine.
1. Nesse RM. Tinbergen’s Four Questions Organized, http://nesse.us, 2000.
2. Nesse RM, Schifman JD. Evolutionary Biology in the Medical School Curriculum. BioScience 2003;53:585-587.
3. Colwell J. Primary Care Medicine and the Education of Generalist Physicians. In GeneralistMedicine and the U.S. Health System. Isaacs SL and Knickman JR, Editors. Jossey-Bass, San Francisco, CA 2004.
4. Nesse RM. Evolution: Medicine’s most basic science. Lancet 2008;372:S21-27.