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Joseph Leidy: The Last Man Who Knew Everything By Leonard Warren (review)

How do you remain a well-recognized medical biologic scientist a century after your career has ended? Not by being broadly knowledgeable in chemistry, geology, unicellular living creatures, botany, worms (especially parasitic forms), insects, mollusks, crustaceans, and all vertebrates with a strong emphasis on paleontology and human anatomy. Nor by adding to this the role of a leading early microscopist and public health expert. And certainly do not add to this immense knowledge base a very strong work ethic, being a nice, kindly person and a great lecturer, or helping to put American biology on the map when European science was much more advanced. This is the lesson to be learned from this thorough, generous presentation of the life of Joseph Leidy, a physician-anatomist-naturalist who was born, lived, and worked in Philadelphia from 1823 to 1891, but whose reputation as the "last man who knew everything" has faded from popular memory. It was a wonderful age in America when the study of biology moved from the amateur Jefferson-like patrician statesman or businessmen who studied biology part-time to full-time academic biologists who focused on specific areas and reported their findings. Medicine similarly was going from a time when doctors treated patients symptomatically, dealing with spirits and ill humors that disorganized body functions, to thinking more about pathogenesis of disease with identifiable symptoms and organized effective treatments. The new-age physician-naturalists fell into two groups: those who became observational descriptive naturalists and those who became experimentalists. Both were exceedingly curious, dedicated scientists, but they took fundamentally different approaches in answering the questions at hand. Both were necessary to move biological knowledge ahead. This is the setting entered by the youngJoseph Leidy. His ancestry was Schwabian German farmers who had come to northeastern Pennsylvania. (A distant German relative was Leydig, of testicular androgen-secreting Leydig cell fame.) His father had left the farm and moved to Philadelphia, where he became a successful hatter. As a child, Leidy walked the countryside around Philadelphia, observing all aspects of nature and learning to record his observations in sketchbooks. His stepmother recognized his intellectual capabilities and encouraged him, while his authoritarian father pushed him to learn a trade to support himself. After high school, Leidy matriculated at the University of Pennsylvania medical school, where he particularly enjoyed anatomy. Three years later, at age 21, he graduated after writing a thesis on the comparative anatomy of the eye in vertebrates. He had already been recognized by professors Goddard and Horner as a dedicated future anatomist. In 1844 he set himself up in private practice in Philadelphia, but his heart was not in it, and he helped teach chemistry to premedicai students and actively worked as a