Evolution and the developmental perspective in medicine: The historical precedent and modern rationale for explaining disorder and normality with evolutionary processes

This is a mostly historical project in which I ask first, what is the origin and nature of evolutionary thought in medicine? The answer is in the late nineteenth century neurosciences, where it helped to explain clinical phenomena that indicated pathology was more an intricate process than an anatomical fact. This view of pathology was grounded in evolutionary theory, and was theoretically elaborated by the philosopher Georges Canguilhem in the mid-twentieth century. He was greatly influenced by the neurologists that preceded him in his perspective, but Canguilhem has a distinctly Darwinian angle.;In the second part of the dissertation, I introduce examples from contemporary Evolutionary-Developmental Biology (Evo-Devo) to argue that a modern definition of disorder that is based on a notion of normality as an implicit 'ideal' proves inadequate given new discoveries about how adaptation and variation are inextricably linked to the developmental phenomena Evo-Devo explores. The historical precedent of thinking about normality and pathology as linked with evolutionary processes proves apt once again, given recent emphasis in evolutionary biology on the relationship between individual development and evolutionary change.;The developmental perspective possesses a significance that is appropriately captured by a diagram most recently elaborated by Randolph Nesse (2000) in which he identifies the nature of biological questions as based on four intersecting elements. The two objects of explanation are the Single Form, and the Developmental/Historical; the two kinds of questions are Proximate and Evolutionary. There is much precedent in medicine for proximate questions about the Single Form object of explanation: how does this (organ, system, part) work, and how can it be described? Nesse himself, and George Williams spearheaded the evolutionary questioning of the Single Form in Darwinian Medicine. The fact that there is another object of explanation (Developmental/Historical) recognized in biology is reason to inquire about its status in medicine. It is the aim of this dissertation to do that. Specifically, I will narrow the topic by looking through the lens of medicine's most visible distinction, that between pathology and normality, to see where and how the developmental perspective gets involved.