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Joseph Leidy studied the anatomy of a wide range of living creatures, as well as creatures long extinct. Among his many publications and achievements, those with the greatest effect on public health may be Leidy’s discovery that the parasite that causes trichinosis is transmitted to humans through undercooked pork, and his studies showing that protozoa and insects such as flies can spread diseases. Leidy is also recognized as a pioneer in paleontology.
As a young man in Philadelphia, Leidy showed a strong interest in natural history and a talent for drawing and anatomy. He earned his medical degree from the University of Pennsylvania in 1844 and began practicing as a physician, but he also continued studying the anatomy of creatures such as sloths, locusts, lemurs, mollusks, snails, and mammalian parasites. Leidy published his research in scientific journals and was invited to join the Boston Society of Natural History and the Academy of Natural Sciences of Philadelphia, which marked a point of departure from therapeutic medicine in his career.
Leidy began teaching and lecturing on anatomy at the University of Pennsylvania, where he was eventually appointed professor of anatomy in 1853. When the university established its Department of Biology in 1884, he became its first director, as well as chair of zoology and comparative anatomy.
Leidy was also a professor of natural history at Swarthmore College, and he accepted the Hershey Professorship at Harvard in 1874. During his 46-year career in science, Leidy authored more than 600 publications on comparative anatomy, vertebrate paleontology, parasitology, zoology, and medicine.