Karl Gegenbaur (21 August 1826 – 14 June 1903) was a German anatomist and professor who demonstrated that the field of comparative anatomy offers important evidence supporting of the theory of evolution. As a professor of anatomy at the University of Jena (1855–1873) and at the University of Heidelberg (1873–1903), Karl Gegenbaur was a strong supporter of Charles Darwin's theory of organic evolution, having taught and worked, beginning in 1858, with Ernst Haeckel, eight years his junior. Gegenbaur's book Grundzüge der vergleichenden Anatomie (1859; English translation Elements of Comparative Anatomy by Francis Jeffrey Bell, 1878) became the standard textbook, at the time, of evolutionary morphology, emphasizing that structural similarities among various animals provide clues to their evolutionary history. Karl Gegenbaur noted that the most reliable clue to evolutionary history is homology, the comparison of anatomical parts which have a common evolutionary origin. Gegenbaur had been a student of Albert von Kölliker, Rudolf Virchow, Heinrich Müller and Franz Leydig (1821–1908). Life Karl Gegenbaur was born in Würzburg, Bavaria in 1826, and he entered the University of Würzburg as a student in 1845. After taking his degree in 1851, he spent some time in travelling in Italy and Sicily, before returning to Wurzburg as Privatdozent in 1854. In 1855, he was appointed extraordinary professor of anatomy at the University of Jena, and in 1858, he became the ordinary professor, where after 1865, his former student and fellow-worker Ernst Haeckel was professor of zoology. In 1873, Gegenbaur was appointed to Heidelberg, where he was professor of anatomy and director of the Anatomical Institute until his retirement in 1901. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1896. He died on 14 June 1903, at Heidelberg. Impact The work by which Gegenbaur is best known is his Grundriss der vergleichenden Anatomie (Leipzig, 1874; 2nd edition, 1878), translated into English by Francis Jeffrey Bell (as Elements of Comparative Anatomy, 1878), with additions by E. Ray Lankester. While recognizing the importance of comparative embryology in the study of descent, Gegenbaur laid stress on the higher value of comparative anatomy as the basis of the study of homologies, i.e. of the relations between corresponding parts in different animals, as, for example, the arm of man, with the foreleg of a horse, and with the wing of a fowl. A distinctive piece of work was effected by him in 1871