Louis Agassiz

Louis Agassiz was a Swiss-born American biologist and geologist, recognized for his deep study of Earth’s natural history. He is best known for classifying fish—both living and extinct, including the megalodon—and for advancing historical geology, especially by founding the field of glaciology. His ideas about polygenism, which claimed separate origins for different human, animal, and plant groups, have been condemned for lending support to scientific racism.

Agassiz was born on May 28, 1807, in the hamlet of Môtier, in the Swiss canton of Fribourg. His father, a Protestant clergyman from a long line of ministers, and his mother, the daughter of a physician and an intellectual who helped educate her children, raised him at home. He attended secondary school in Bienne starting in 1818, finished elementary studies in Lausanne, and then studied at the universities of Zurich, Heidelberg, and Munich. At Munich, he deepened his knowledge of natural history, especially botany. He earned a PhD from the University of Erlangen in 1829 and a medical degree from Munich in 1830. Moving to Paris, he studied under Alexander von Humboldt and Georges Cuvier, who launched his careers in geology and zoology. Humboldt also provided financial support. Ichthyology soon became his main focus.

In 1819–1820, German biologists Johann Baptist von Spix and Carl Friedrich Philipp von Martius had traveled to Brazil and brought back many natural specimens, including a large collection of Amazonian freshwater fish. Spix died in 1826, likely from a tropical disease, before he could study the fish. Martius chose Agassiz for the task. Agassiz threw himself into the work with characteristic enthusiasm, completing and publishing the description of Brazilian fish in 1829. He then studied fish from Lake Neuchâtel. In 1830, he announced plans for a *History of the Freshwater Fish of Central Europe*; the first part appeared in 1839, and the work was finished in 1842.

In November 1832, Agassiz became professor of natural history at the University of Neuchâtel, earning about $400 a year. He turned down better offers in Paris because the position gave him time for private study. The fossil fish in the local rocks—the slates of Glarus and the limestones of Monte Bolca—soon caught his attention. At the time, little scientific work had been done on them. As early as 1829, Agassiz had planned a major publication. That work, *Recherches sur les poissons fossiles*, came out in five volumes from 1833 to 1843, with magnificent illustrations mostly by Joseph Dinkel. To gather material, Agassiz visited Europe’s main museums; in Paris, Cuvier gave him much encouragement and help.

In 1833, Agassiz married Cecile Braun, sister of his friend Alexander Braun, and set up a household in Neuchâtel. Trained in scientific drawing by her brothers, Cecile contributed some of the most beautiful plates in the fossil and freshwater fish works. Agassiz’s paleontological studies required a new fish classification. Since fossils rarely preserved soft tissues, he based his system on teeth, scales, and fins, dividing fish into four groups—ganoids, placoids, cycloids, and ctenoids—according to scale type and other skin features. This improved fish taxonomy, though it has since been replaced.

With Louis de Coulon and his son, Agassiz founded the Societé des Sciences Naturelles, serving as its first secretary. Together with the Coulons, he also set up a provisional natural history museum in an orphanage. To continue his work, he needed financial help, which came from the British Association and the Earl of Ellesmere (then Lord Francis Egerton). The Earl bought the 1,290 original drawings for Agassiz’s fossil fish work and gave them to the Geological Society of London. In 1836, that society awarded Agassiz the Wollaston Medal for his fossil ichthyology research.