NOTES ON AN EVOLUTIONARY MEDICINE

Objective: Medicine does not have a comprehensive theory of health, il l-health, and disease. Its explanations of disease are firmly rooted i n pathological anatomy brought about by infection, intoxication, traum a, and mutations in genes. Because medical concepts have been influenc ed mainly by classical physics, it is mechanistic, materialistic, dete rministic, reductionistic, linear-causal, and strongly biased toward p roximate explanations of disease. Of late, many thoughtful persons hav e attempted to provide medicine with a more comprehensive theory that integrates the documented roles of physical, social, environmental, an d psychological factors in the etiology and pathogenesis of ill-health and disease (eg, Refs. 1-3). Method: Until very recently (4), no one has clearly pointed out that such a comprehensive theory should be gui ded by the concepts of evolutionary and organismic biology. Darwin's g reat theory states that evolution is ''driven,'' but not exclusively s o, by natural and sexual selection. Natural selection acts on variants that differ in adaptive capacities. Those capable of adaptation survi ve to reproduce. Failure to adapt reduces reproductive fitness and suc cess, and leads to injury or death. But this formulation could be expa nded to regard ill-health and disease as adaptive failures, whereas he alth usually may be conceived of as equivalent to adaptive success. Ad aptations are determined by many factors-genetic, morphological, physi ological, and behavioral. Selective pressures are many and varied. How ever, social primates are at a selective advantage, and are among the most successful species and varieties. Social behavior leg, support) s eems to enhance the chances of survival and reproductive fitness. Phys iological (immunological, metabolic, cardiovascular) and behavioral ad aptations are geared specifically for interactions with the environmen t. Emotions have evolved as ways of matching physiological responses w ith environmental demands and signaling the organism's state, Results: This study will review aspects of evolutionary theory that would lead to a unified, integrated theory of health, illness, and disease, and to a clearer taxonomy in medicine.