Jean Louis Rodolphe Agassiz ( AG-ə-see; French: [aɡasi]; May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history.
Spending his early life in Switzerland, he received a PhD at the University of Erlangen and a medical degree at the Ludwig-Maximilians-Universität München. After studying with Georges Cuvier and Alexander von Humboldt in Paris, Agassiz was appointed professor of natural history at the University of Neuchâtel. He emigrated to the United States in 1847 after visiting Harvard University. He went on to become professor of zoology and geology at Harvard, to head its Lawrence Scientific School, and to found its Museum of Comparative Zoology.
Agassiz is known for observational data gathering and analysis. He made institutional and scientific contributions to zoology, geology, and related areas, including multivolume research books running to thousands of pages. He is particularly known for his contributions to ichthyological classification, including of extinct species such as megalodon, and to the study of historical geology, including the founding of glaciology.
His theories on human, animal and plant polygenism have been criticised as implicitly supporting scientific racism.
Louis Agassiz was born on May 28, 1807, in Môtier, a hamlet within the municipality of Haut-Vully (now part of Mont-Vully), in the Swiss canton of Fribourg. He was the son of Louis Benjamin Rodolphe Agassiz and Rose Mayor. His father was a Protestant clergyman, as had been his progenitors for six generations, and his mother was the daughter of a physician and an intellectual in her own right, who had assisted her husband in the education of their children. Louis Agassiz was educated at home until he spent four years at secondary school in Bienne, which he entered in 1818 and completed his elementary studies in Lausanne. Agassiz studied at the University of Zurich, Heidelberg University, and the Ludwig-Maximilians-Universität München. At the last one, he extended his knowledge of natural history, especially of botany. In 1829, he received the degree of doctor of philosophy at the University of Erlangen and, in 1830, that of doctor of medicine at the Ludwig-Maximilians-Universität München.
Moving to Paris, he came under the tutelage of Alexander von Humboldt and later received his financial benevolence. Humboldt and Georges Cuvier launched him on his careers of respectively geology and zoology. Ichthyology soon became a focus of Agassiz's life's work.
In 1819 to 1820, the German biologists Johann Baptist von Spix and Carl Friedrich Philipp von Martius undertook an expedition to Brazil. They returned home to Europe with many natural objects, including an important collection of the freshwater fish of Brazil, especially of the Amazon River. Spix, who died in 1826, likely from a tropical disease, did not live long enough to work out the history of those fish, and Martius selected Agassiz for this project.
Agassiz threw himself into the work with an enthusiasm that would go on to characterize the rest of his life's work. The task of describing the Brazilian fish was completed and published in 1829. It was followed by research into the history of fish found in Lake Neuchâtel. Enlarging his plans, he in 1830 issued a prospectus of a History of the Freshwater Fish of Central Europe. In 1839, however, the first part of the publication appeared, and it was completed in 1842.
In November 1832, Agassiz was appointed professor of natural history at the University of Neuchâtel, at a salary of about US$400 and declined brilliant offers in Paris because of the leisure for private study that that position afforded him. The fossil fish in the rock of the surrounding region, the slates of Glarus and the limestones of Monte Bolca, soon attracted his attention. At the time, very little had been accomplished in their scientific study. Agassiz as early as 1829, planned the publication of a work. More than any other, it would lay the foundation of his worldwide fame. Five volumes of his Recherches sur les poissons fossiles (Research on Fossil Fish) were published from 1833 to 1843. They were magnificently illustrated, chiefly by Joseph Dinkel. In gathering materials for that work, Agassiz visited the principal museums in Europe. Meeting Cuvier in Paris, he received much encouragement and assistance from him.
In 1833, he married Cecile Braun, the sister of his friend Alexander Braun and established his household at Neuchâtel. Trained to scientific drawing by her brothers, his wife was of the greatest assistance to Agassiz, with some of the most beautiful plates in fossil and freshwater fishes being drawn by her.
Agassiz found that his palaeontological analyses required a new ichthyological classification. The fossils that he examined rarely showed any traces of the soft tissues of fish but instead, consisted chiefly of the teeth, scales, and fins, with the bones being perfectly preserved in comparatively few instances. He therefore adopted a classification that divided fish into four groups (ganoids, placoids, cycloids, and ctenoids), based on the nature of the scales and other dermal appendages. That did much to improve fish taxonomy, but Agassiz's classification has since been superseded.
With Louis de Coulon, both father and son, he founded the Societé des Sciences Naturelles, of which he was the first secretary and in conjunction with the Coulons also arranged a provisional museum of natural history in the orphan's home. Agassiz needed financial support to continue his work. The British Association and the Earl of Ellesmere, then Lord Francis Egerton, stepped in to help. The 1290 original drawings made for the work were purchased by the Earl and presented by him to the Geological Society of London. In 1836, the Wollaston Medal was awarded to Agassiz by the council of that society for his work on fossil ichthyology. In 1838, he was elected a foreign member of the Royal Society. Meanwhile, invertebrate animals engaged his attention. In 1837, he issued the "Prodrome" of a monograph on the recent and fossil Echinodermata, the first part of which appeared in 1838; in 1839–1840, he published two quarto volumes on the fossil echinoderms of Switzerland; and in 1840–1845, he issued his Études critiques sur les mollusques fossiles (Critical Studies on Fossil Mollusks).
Before Agassiz's first visit to England in 1834, Hugh Miller and other geologists had brought to light the remarkable fossil fish of the Old Red Sandstone of the northeast of Scotland. The strange forms of Pterichthys, Coccosteus, and other genera were then made known to geologists for the first time. They were of intense interest to Agassiz and formed the subject of a monograph by him published in 1844–1845: Monographie des poissons fossiles du Vieux Grès Rouge, ou Système Dévonien (Old Red Sandstone) des Îles Britanniques et de Russie (Monograph on Fossil Fish of the Old Red Sandstone, or Devonian System of the British Isles and of Russia).
In 1838, Frederick William III of Prussia founded the Neuchâtel Academy which owes its birth to the impetus of Louis Agassiz. The young scholar endowed with exceptional charisma was recruited by the authorities of the Principality of Neuchâtel as early as 1832. In the early stages of his career in Neuchatel, Agassiz also made a name for himself as a man who could run a scientific department well. Under his care, the University of Neuchâtel soon became a leading institution for scientific inquiry.
From 1836 onwards, Agassiz became increasingly interested in glaciers. At a time when Swiss glaciers were still advancing, the hypothesis of an extensive past glaciation emerged in scientific circles. On 24 July 1837, in his speech at the annual meeting of the Swiss Academy of Natural Sciences in Neuchâtel, which he chaired, he presented this new theory, although a lecture on fossil fish was expected. To support the Ice Age theory, he traveled the Alps in search of traces of previous glacial movements. The research conducted on the Unteraargletscher between 1840 and 1845 was groundbreaking. At that time, his companions added the Agassizhorn to the list of mountains of Switzerland named after people.