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Why has the medical profession not taken advantage of the help available from evolutionary biology, a well-developed branch of science with great potential for providing medical insights? One reason is surely the pervasive neglect of this branch of science at all educational levels. Religious and other sorts of opposition have minimized the impact in general education of Darwin's contributions to our understanding of ourselves and the world we live in.Randolph M. Nesse
2
Long before there were effective treatments, physicians dispensed prognoses, hope, and, above all, meaning. When something terrible happens-and serious disease is always terrible-people want to know why. In a pantheistic world, the explanation was simple-one god had caused the problem, another could cure it. In the time since people have been trying to get along with only one God, explaining disease and evil has become more difficult. Generations of theologians have wrestled with the problem of theodicy-how can a good God allow such bad things to happen to good people? Darwinian medicine can't offer a substitute for such explanations. It can't provide a universe in which events are part of a divine plan, much less one in which individual illness reflects individual sins. It can only show us why we are the way we are, why we are vulnerable to certain diseases. A Darwinian view of medicine simultaneously makes disease less and more meaningful. Diseases do not result from random or malevolent forces, they arise ultimately from past natural selection. Paradoxically, the same capacities that make us vulnerable to disease often confer benefits. The capacity for suffering is a useful defense. Autoimmune disease is a price of our remarkable ability to attack invaders. Cancer is the price of tissues that can repair themselves. Menopause may protect the interests of our genes in existing children. Even senescence and death are not random, but compromises struck by natural selection as it inexorably shaped out bodies to maximize the transmission of our genes. In such paradoxical benefits, some may find a gentle satisfaction, even a bit of meaning-at least the sort of meaning Dobzhansky recognized. After all, nothing in medicine makes sense except in the light of evolution.Randolph M. Nesse
3
Even our behavior and emotions seem to have been shaped by a prankster. Why do we crave the very foods that are bad for us but have less desire for pure grains and vegetables? Why do we keep eating when we know we are too fat? And why is our willpower so weak in its attempts to restrain our desires? Why are male and female sexual responses so uncoordinated, instead of being shaped for maximum mutual satisfaction? Why are so many of us constantly anxious, spending our lives, as Mark Twain said, "suffering from tragedies that never occur"? Finally, why do we find happiness so elusive, with the achievement of each long-pursued goal yielding not contentment, but only a new desire for something still less attainable? The design of our bodies is simultaneously extraordinarily precise and unbelievably slipshod. It is as if the best engineers in the universe took every seventh day off and turned the work over to bumbling amateurs.Randolph M. Nesse
4
Chlamydia, today´s most common cause of venereal disease, does the equivalent of hiding in the police station. Schistosomes of the mansoni type go a step further and essentially steal police uniforms. These parasites, a serious cause of liver disease in Asia, pick up blood-group antigens so that they may look to the immune system like our own normal blood cells.Randolph M. Nesse
5
Darwinism gives no moral guidelines about how we should live or how doctors should practice medicine. A Darwinian perspective on medicine can, however, help us to understand the evolutionary origins of disease, and this knowledge will prove profoundly useful in achieving the legitimate goals of medicine.Randolph M. Nesse