In the past I have criticized evolutionary medicine for its tendency to rely on unverifiable “Just-So Stories,” but a new book has helped me appreciate what the best kind of evolutionary thinking can contribute to our understanding of medicine. Doves, Diplomats, and Diabetes: A Darwinian Interpretation of Type 2 Diabetes and Related Disorders by Milind Watve investigates diabetes from an evolutionary perspective, suggesting how it might have originated, why it persisted, and how it is related to survival advantages. Watve develops well-reasoned hypotheses that can be tested by examining their expected consequences. He believes it is impossible to understand metabolism without understanding behavioral ecology, and he makes a good case.
A reassessment of the evidence concerning Type II diabetes (T2D) reveals a number of paradoxes. Elevated blood glucose is the defining feature of T2D but controlling it doesn’t prevent all the complications of diabetes, and it doesn’t appear that elevated blood sugar could produce all the pathological changes of diabetes. Insulin resistance is believed to be central to a cluster of deadly diseases in humans, but in other animals it has no adverse effects on health and even increases lifespan. Studying diabetes from an evolutionary perspective can shed light on such paradoxes. (more…)