Nature's Role in Disease, Bigger Than We Thought

Continual fear and danger of violent death; and the life of man, solitary, poor, nasty, brutish, and short”

Thomas Hobbes

http://www.sciencenews.org/view/generic/id/69610/title/Adaptive_no_more
http://www.ajcn.org/content/early/2011/02/02/ajcn.110.001909.abstract

Most plants grow well here in California, but we are too close to the coast to grow tulips. When the environment changes, the tulip's adaptations for one set of circumstances limit it's ability to grow in a different ecology. It turns out that people are no different. The epidemic of “diseases of modern life”, obesity, diabetes, heart disease and asthma, appear to be the unintended consequences of evolutionary mechanisms designed to combat famine, chronic infections, and other afflictions of pre-industrial life.

The popular wisdom, return to nature advocates, and our educational system do not appreciate, as Hobbes did, how brutal and difficult life was a few hundred generations ago. Primitive societies(see my article from 7/6/10), have a violent death rate of 6%, 50% childhood mortality, are prone to prolonged periods of famine, and carry a huge burden of acute and chronic infectious disease.

The articles referenced today discusses how human physiology evolved to cope with some of these challenges. In periods of famine, low blood sugar may result in death of the unborn child. The tendency for diabetes may therefore be a substantial advantage for the pregnant woman. Chronic tuberculosis, endemic in many societies, results in loss of body mass and wasting. The tendency to store fat might keep individuals alive long enough to reproduce. A hyper-stimulated immune system would keep chronic bone and tooth infections from spreading throughout the body.

Of course,modern society, addressing famine and infections has caused these survival mechanism to backfire. Elevated sugar levels lead to diabetes, tendencies to store fat leads to obesity, and hyper-stimulated immune systems lead to asthma or rheumatoid arthritis. Thousands of generations of evolution, with strong genetic and physiologic imperatives, are constantly working against the efforts of healthcare providers. Understanding these processes may eventually contribute to treatments, but in the meantime we are left with what we have.

It is important to remember that defects in one environment might be beneficial in another. Sociopaths, who lack feelings for others, thrive in times or war. Those prone to diabetes or obesity will do better following some upcoming climate/nuclear/zombie apocalypse. Human diversity encompasses more than ethnicity. We must remember that evolution works for the survival of the species, not for the individual. Nature is efficient, but is also heartless and doesn't care much for the good intentions of Obamacare.