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Books, Journals, New Media
January 5, 2000

Biography: Joseph Leidy: The Last Man Who Knew Everything

Author Affiliations

Harriet S.MeyerMD, Contributing EditorJonathan D.EldredgeMLS, PhD, Journal Review EditorRobertHoganMD, adviser for new media


Not Available

JAMA. 2000;283(1):122-123. doi:10.1001/jama.283.1.122-JBK0500-3-1

When William Osler came to Philadelphia in 1884 to begin his American career, the young physician's rising star crossed the orbit of Joseph Leidy, then at its zenith. Leidy—medical doctor, anatomist, parasitologist, paleontologist, and consultant to the Smithsonian Institution—was quite possibly the most illustrious natural scientist in America. Osler could write, "It was my privilege to know well one of the greatest naturalists of this country, Joseph Leidy. . . ." But a century later, Leidy's name has lapsed into total obscurity. Indeed, this Ozymandian fall from fame provided the impetus for the present volume. When Leonard Warren, professor emeritus at the University of Pennsylvania, came to Philadelphia he found Leidy's name attached to a university building, a public school, an avenue, and a named professorship of anatomy. Who was his predecessor at the university, and what did he do? The present book is the result of Warren's inquiry.

Joseph Leidy, the third-born but first surviving child of a Philadelphia hat-maker, came from a long line of German forebears including the histologist Franz von Leydig (the original of "Leidy"). His mother died in childbirth when he was two years old, and he was raised by a devoted and intellectually agile stepmother. A lackadaisical student at William Mann's Classical School, young Joseph showed native talent in drawing and a deep curiosity about the details of the world around him. When the time came to choose a trade, his father proposed that he take up sign painting, but Joseph and his stepmother prevailed in their choice of medicine. He obtained an MD at Penn in 1844. A foray into medical practice was short lived, in part because of a lack of bedside manner and in part because of the attraction of science. The microscope was just becoming commonplace, and Leidy mastered its use. In 1846, he discovered the larvae of Trichina spiralis in pig muscle and, recognizing the public health significance, advocated thorough cooking before eating pork products.

He soon moved beyond endoparasites. In 1847, he began the identification and classification of prehistoric fossils sent to him by explorers of the American west. Leidy correctly identified the remains of extinct native horses, camels, and dinosaurs. Warren never divulges how Leidy became not only adept at this work but indeed became the first real expert paleontologist in the New World. His childhood education made him a bit of an autodidact, but I would have liked to know how on earth he became so good at so many things, and all without formal training. He did read, and he published, and he corresponded with many of the scientific notables of the day, but he rarely left Philadelphia, and he worked largely alone. To illustrate his manuscripts and books, he burnished his skills as a draftsman. The artistic merit of his Fresh Water Rhizopods of North America was so great that Osler asked for—and got—an original drawing ("Could you not steal me one of the original sketches of the rhizopods? You see what a greedy devil I am!").

Given the recognized depth and breadth of his learning during his lifetime, why do we know so little of Leidy today? Warren hints at this when he repeatedly points out that, at a time when the biological world was turning to experimentalism, Leidy was an observer and a cataloguer, not a theorizer or explainer. He bent to the microscope, seeing clearly and drawing accurately what he saw, but it was Darwin (whom Leidy admired and cited in his lectures) who provided the rationale for the fossil forms Leidy described and Pasteur who opened the doors to the great experimental foray that has unveiled so much of the world of biology.

There are shortcomings to the book. Much of it seems repetitious, in part because the multiple threads of Leidy's career require tracing the same time frames more than once. And Leidy himself, for all his encyclopedic understanding, lived a very conventional, mundane, humdrum—dare I say dull—life. That makes this book seem a longer read than it is.