Agassiz , Jean Louis Rodolphe

(1807–1873) Swiss-American biologist

Generally considered the foremost naturalist of 19th-century America, Agassiz was born in Motier-en-Vuly, Switzerland. He was educated at the universities of Zurich, Heidelberg, and Munich, where he studied under the embryologist Ignaz Döllinger. At the instigation of Georges Cuvier, he cataloged and described the fishes brought back from Brazil by C.F.P. von Martius and J.B. von Spix ( Fishes of Brazil, 1929), following this with hisHistory of the Freshwater Fishes of Central Europe (1839–42) and an extensive pioneering work on fossil fishes, which eventually ran to five volumes: Recherches sur les poissons fossiles (1833–43; Researches on Fossil Fishes). These works, completed while Agassiz was professor of natural history at Neuchâtel (1832–46), established his reputation as the greatest ichthyologist of his day. Agassiz's best-known discovery, however, was that of the Ice Ages. Extensive field studies in the Swiss Alps, and later in America and Britain, led him to postulate glacier movements and the former advance and retreat of ice sheets; his findings were published in Etudes sur les glaciers(1840; Studies on Glaciers).

A successful series of lectures given at Boston, Massachusetts, in 1846 led to his permanent settlement in America. In 1847 he was appointed professor of zoology and geology at Harvard, where he also established the Museum of Comparative Zoology (1859). Agassiz's subsequent teachings introduced a departure from established practice in emphasizing the importance of first-hand investigation of natural phenomena, thus helping to transform academic study in America. His embryological studies led to a recognition of the similarity between the developing stages of living animals and complete but more primitive species in the fossil record. Agassiz did not, however, share Darwin's view of a gradual evolution of species, but, like Cuvier, considered that there had been repeated separate creations and extinctions of species – thus explaining changes and the appearance of new forms. Unfortunately, one of Agassiz's most influential pronouncements was that there were several species, as distinct from races, of man: an argument used by slavers to justify their subjugation of the negroes as an inferior species. His ambitiousContributions to the Natural History of the United States (4 vols. 1857–62) remained uncompleted at his death.