Why We Get Sick

Why We Get Sick: the New Science of Darwinian Medicine
© 1994 Randolph M. Nesse, M.D; George C. Wiliams, Ph.D.
290 pages

Years ago I read an exceptional book on evolution by David Sloan Wilson. I say exceptional because it advocated for freeing evolution from being mere natural history: instead, Wilson argued that we should use it to understand all matters biological, including medicine. He used as his example the case of morning sickness in pregnancies, revealing research that illustrated that far from being a problem to be solved, morning sickness is an adaptive behavior which protects fetuses from foods that might be toxic to them in their highly vulnerable state. This application of evolution floored me, and so you can imagine my delight to discover an entire book on the subject, Why We Get Sick.

For the most part, Why We Get Sick fulfills my anticipation, though its authors are writing mostly to introduce the concept of evolution-informed medicine to the public. Though they share the insights that research with this focus have revealed already,  in any more instances they can only offer speculation, as Darwinian medicine is still quite new. The book covers general health, and explains the science of injuries, nutrition, and sickness. They establish early on that the Darwinian model can help us understand a given disease's ultimate root, and avoid prolonging it in our clumsy efforts to dispels the symptoms. Often symptoms of a disease are actually the products of our own immune system, and if we disrupt those defenses the disease itself is given free reign. Fevers, for instance, are one of our body's ways of disrupting an infection. It doesn't matter to our genes if it makes us uncomfortable: they're more concerned with killing the invaders. But the invaders have their own defenses, and they adapt a lot more quickly than we do -- another reason some diseases to be here to stay, like the flu. The existence of multiple flu strains and our constant attempts to find new ways to kill them are evolution in action, the ongoing biological arms race.  Other physical ailments are hangovers of evolution, like our back problems and heel spurs;  walking upright on two feet is something our bodies are still getting used to. We haven't even started adapting to novel environments, another element of disease: we have bodies accustomed to hardship now living in a world of abundant, cheap food and easy living. Little wonder we struggle with obesity and problems of physical inactivity. And then there are the genetic diseases and strangely adaptive byproducts of mental illnesses...

Why We Get Sick is compact, dense, and brimming with information: the authors are writing to introduce people to the viewpoint,  so there's lot of enticing speculation. If one section doesn't catch your interest, rest assured another will. I for one am quite excited about this novel approach to medicine, and if health or evolution are of any interest to you, this intersection of the two should prove fascinating.

Related:

• American Mania: When More Isn't Enough, Peter Whybrow
• Evolution for Everyone, David Sloan Wilson 
• NPR news article on the "paleo diet" and Darwinian medicine