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Louis Agassiz

Louis Agassiz H6.jpg
Born (1807-05-28)May 28, 1807
Môtier, Canton of Fribourg, Rhodanic Republic
Died December 14, 1873(1873-12-14) (aged 66)
Citizenship United States
Education University of Erlangen-Nuremberg (PhD)
University of Munich
Known for Ice age, Polygenism
Spouse(s) Cecilie Braun
Elizabeth Cabot Cary
Children 3, including Alexander and Pauline
Awards Wollaston Medal (1836)
Scientific career
Institutions University of Neuchâtel
Harvard University
Cornell University
Doctoral advisor Carl Friedrich Philipp von Martius
Other academic advisors Ignaz Döllinger, Georges Cuvier, Alexander von Humboldt
Notable students William Stimpson, William Healey Dall, Carl Vogt, David Starr Jordan
Author abbrev. (zoology) Agassiz, Ag., L. Ag., Agass.
Appletons' Agassiz Jean Louis Rudolphe signature.svg

Jean Louis Rodolphe Agassiz (/ˈæɡəsi/ ag-Ə-see; French: [aɡasi]) FRS (For) FRSE (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 Erlangen and a medical degree in Munich. 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 geological history, including the founding of glaciology.

His theories on human, animal and plant polygenism have been criticised as implicitly supporting scientific racism.

Early life

Louis Agassiz was born in the village of Môtier (fr) (now part of Haut-Vully which merged into Mont-Vully in 2016) in the Swiss Canton of Fribourg. He was the son of a pastor, Louis Rudolphe and his wife, 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 her boys. He 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 Universities of Zürich, Heidelberg and Munich. 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 Erlangen and, in 1830, that of doctor of medicine at Munich. 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.

Early work

Jean Louis Agassiz 1870
Agassiz in 1870

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 1844–1(45: 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 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.

Louis Agassiz H3
Portrait photograph by John Adams Whipple, circa 1865

In 1842 to 1846, Agassiz issued his Nomenclator Zoologicus, a classification list with references of all names used in zoological genera and groups.

He was elected as a member of the American Philosophical Society in 1843.

Ice age

Agassiz, Louis – Nouvelles études et expériences sur les glaciers actuels, 1847 – BEIC 12025435
Nouvelles études et expériences sur les glaciers actuels, 1847

The vacation of 1836 was spent by Agassiz and his wife in the little village of Bex, where he met Jean de Charpentier and Ignaz Venetz. Their recently announced glacial theories had startled the scientific world, and Agassiz returned to Neuchâtel as an enthusiastic convert. In 1837, Agassiz proposed that the Earth had been subjected to a past ice age. He presented the theory to the Helvetic Society that ancient glaciers flowed outward from the Alps, and even larger glaciers had covered the plains and mountains of Europe, Asia, and North America and smothered the entire Northern Hemisphere in a prolonged ice age. In the same year, he was elected a foreign member of the Royal Swedish Academy of Sciences. Before that proposal, Goethe, de Saussure, Ignaz Venetz, Jean de Charpentier, Karl Friedrich Schimper, and others had studied the glaciers of the Alps, and Goethe, Charpentier, and Schimper had even concluded that the erratic blocks of alpine rocks scattered over the slopes and summits of the Jura Mountains had been moved there by glaciers. Those ideas attracted the attention of Agassiz, and he discussed them with Charpentier and Schimper, whom he accompanied on successive trips to the Alps. Agassiz even had a hut constructed upon one of the Aar Glaciers and for a time made it his home to investigate the structure and movements of the ice.

Agassiz visited England, and with William Buckland, the only English naturalist who shared his ideas, made a tour of the British Isles in search of glacial phenomena, and became satisfied that his theory of an ice age was correct. In 1840, Agassiz published a two-volume work, Études sur les glaciers ("Studies on Glaciers"). In it, he discussed the movements of the glaciers, their moraines, and their influence in grooving and rounding the rocks and in producing the striations and roches moutonnées seen in Alpine-style landscapes. He accepted Charpentier and Schimper's idea that some of the alpine glaciers had extended across the wide plains and valleys of the Aar and Rhône, but he went further by concluding that in the recent past, Switzerland had been covered with one vast sheet of ice originating in the higher Alps and extending over the valley of northwestern Switzerland to the southern slopes of the Jura. The publication of the work gave fresh impetus to the study of glacial phenomena in all parts of the world.

Familiar then with recent glaciation, Agassiz and the English geologist William Buckland visited the mountains of Scotland in 1840. There, they found clear evidence in different locations of glacial action. The discovery was announced to the Geological Society of London in successive communications. The mountainous districts of England, Wales, and Ireland were understood to have been centres for the dispersion of glacial debris. Agassiz remarked "that great sheets of ice, resembling those now existing in Greenland, once covered all the countries in which unstratified gravel (boulder drift) is found; that this gravel was in general produced by the trituration of the sheets of ice upon the subjacent surface, etc."

SAM PC 0 - Ice auger of Louis Agassiz and Eduard Desor
The man-sized iron auger that was used by Agassiz to drill up to 7.5 m deep into the Unteraar Glacier to take its temperature (Swiss Alpine Museum, Bern)

In his later years, Agassiz applied his glacial theories to the geology of the Brazilian tropics, including the Amazon. Agassiz began with a working hypothesis which could be tested by the results of fieldwork to find either inconclusive, or conclusively supporting or refuting evidence. A hypothesis that can be conclusively refuted is better than a hypothesis that difficult to test. Agassiz had a close association with his student and field assistant, the geologist Charles Hartt who eventually refuted Agassiz's theories about the Amazon based on his fieldwork there. Instead of evidence for any glacial processes, he found chemically weathered sediments from marine and tropical fluvial, not glacial, processes, a finding that later geologists confirmed. Agassiz hypothesis that the Amazon was affected by the Last Glacial Maximum was correct, although the mechanism causing the effect was non-glacial. The Amazon rainforest was split into two large blocks by extensive savanna during the LGM.

United States

With the aid of a grant of money from the king of Prussia, Agassiz crossed the Atlantic in the autumn of 1846 to investigate the natural history and geology of North America and to deliver a course of lectures on "The Plan of Creation as shown in the Animal Kingdom" by invitation from John Amory Lowell, at the Lowell Institute in Boston, Massachusetts. The financial offers that were presented to him in the United States induced him to settle there, where he remained to the end of his life. He was elected a foreign honorary member of the American Academy of Arts and Sciences in 1846.

In 1846, still married to Cecilie, who remained with their three children in Switzerland, Agassiz met Elizabeth Cabot Cary at a dinner. The two developed a romantic attachment, and when his wife died in 1848, they made plans to marry, and the ceremony that took place on April 25, 1850, in Boston, Massachusetts at King's Chapel. Agassiz brought his children to live with them, and Elizabeth raised and developed close relationships with her step-children. She had no children of her own.

Agassiz had a mostly cordial relationship with the Harvard botanist Asa Gray despite their disagreements. Agassiz believed each human race had been separately created, but Gray, a supporter of Charles Darwin, believed in the shared evolutionary ancestry of all humans. In addition, Agassiz was a member of the Scientific Lazzaroni, a group of mostly physical scientists who wanted American academia to mimic the more autocratic academic structures of European universities, but Gray was a staunch opponent of that group.

Agassiz's engagement for the Lowell Institute lectures precipitated the establishment in 1847 of the Lawrence Scientific School at Harvard University, with Agassiz as its head. Harvard appointed him professor of zoology and geology, and he founded the Museum of Comparative Zoology there in 1859 and served as its first director until his death in 1873. During his tenure at Harvard, Agassiz studied the effect of the last ice age in North America. In August 1857, Agassiz was offered the chair of palaeontology in the Museum of Natural History, Paris, which he refused. He was later decorated with the Cross of the Legion of Honor.

Agassiz continued his lectures for the Lowell Institute. In succeeding years, he gave lectures on "Ichthyology" (1847–1848), "Comparative Embryology" (1848–1849), "Functions of Life in Lower Animals" (1850–1851), "Natural History" (1853–1854), "Methods of Study in Natural History" (1861–1862), "Glaciers and the Ice Period" (1864–1865), "Brazil" (1866–1867), and "Deep Sea Dredging" (1869–1970). In 1850, he had married Elizabeth Cabot Cary, who later wrote introductory books about natural history and a lengthy biography of her husband after he had died.

Agassiz served as a nonresident lecturer at Cornell University while he was also on faculty at Harvard. In 1852, he accepted a medical professorship of comparative anatomy at Charlestown, Massachusetts, but he resigned in two years. From then on, Agassiz's scientific studies dropped off, but he became one of the best-known scientists in the world. By 1857, Agassiz was so well-loved that his friend Henry Wadsworth Longfellow wrote "The Fiftieth Birthday of Agassiz" in his honor and read it at a dinner given for Agassiz by the Saturday Club in Cambridge. Agassiz's own writing continued with four (of a planned 10) volumes of Natural History of the United States, published from 1857 to 1862. He also published a catalog of papers in his field, Bibliographia Zoologiae et Geologiae, in four volumes between 1848 and 1854.

Stricken by ill health in the 1860s, Agassiz resolved to return to the field for relaxation and to resume his studies of Brazilian fish. In April 1865, he led a party to Brazil. After his return in August 1866, an account of the expedition, A Journey in Brazil, was published in 1868. In December 1871, he made a second eight-month excursion, known as the Hassler expedition under the command of Commander Philip Carrigan Johnson (the brother of Eastman Johnson) and visited South America on its southern Atlantic and Pacific Seaboards. The ship explored the Magellan Strait, which drew the praise of Charles Darwin.

Following the establishment of the first U.S. Society for the Prevention of Cruelty to Animals in New York City in 1866, Agassiz was called on to help settle disputes about animal behavior. He deemed the way turtles were shipped caused them suffering, while P.T. Barnum argued with Agassiz' support that his snakes would only eat live animals.

His second wife, Elizabeth Cary Agassiz, the daughter of Thomas Graves Cary, of Boston, who was president of Radcliffe college in 1898, desired to share his studies and aided her husband in preparing his A Journey in Brazil. In connection with their son, Alexander Agassiz, she wrote Seaside Studies in Natural History and Marine Animals of Massachusetts. Elizabeth wrote at the Strait that "the Hassler pursued her course, past a seemingly endless panorama of mountains and forests rising into the pale regions of snow and ice, where lay glaciers in which every rift and crevasse, as well as the many cascades flowing down to join the waters beneath, could be counted as she steamed by them.... These were weeks of exquisite delight to Agassiz. The vessel often skirted the shore so closely that its geology could be studied from the deck."


Agassiz Louis 1807-1873
Agassiz in middle age

From his first marriage to Cecilie Braun, Agassiz had two daughters, Ida and Pauline, and a son, Alexander. In 1863, Agassiz's daughter Ida married Henry Lee Higginson, who later founded the Boston Symphony Orchestra and was a benefactor to Harvard and other schools. On November 30, 1860, Agassiz's daughter Pauline was married to Quincy Adams Shaw (1825–1908), a wealthy Boston merchant and later a benefactor to the Boston Museum of Fine Arts. Pauline Agassiz Shaw later became a prominent educator, suffragist, and philanthropist.

Later life

In the last years of his life, Agassiz worked to establish a permanent school in which zoological science could be pursued amid the living subjects of its study. In 1873, the private philanthropist John Anderson gave Agassiz the island of Penikese, in Buzzards Bay, Massachusetts (south of New Bedford), and presented him with $50,000 to endow it permanently as a practical school of natural science that would be especially devoted to the study of marine zoology. The school collapsed soon after Agassiz's death but is considered to be a precursor of the nearby Woods Hole Marine Biological Laboratory.

Agassiz had a profound influence on the American branches of his two fields and taught many future scientists who would go on to prominence, including Alpheus Hyatt, David Starr Jordan, Joel Asaph Allen, Joseph Le Conte, Ernest Ingersoll, William James, Charles Sanders Peirce, Nathaniel Shaler, Samuel Hubbard Scudder, Alpheus Packard, and his son Alexander Emanuel Agassiz. He had a profound impact on the paleontologist Charles Doolittle Walcott and the natural scientist Edward S. Morse. Agassiz had a reputation for being a demanding teacher. He would allegedly "lock a student up in a room full of turtle-shells, or lobster-shells, or oyster-shells, without a book or a word to help him, and not let him out till he had discovered all the truths which the objects contained." Two of Agassiz's most prominent students detailed their personal experiences under his tutelage: Scudder, in a short magazine article for Every Saturday, and Shaler, in his Autobiography. Those and other recollections were collected and published by Lane Cooper in 1917, which Ezra Pound would draw on for his anecdote of Agassiz and the sunfish.

In the early 1840s, Agassiz named two fossil fish species after Mary Anning (Acrodus anningiae and Belenostomus anningiae) and another after her friend, Elizabeth Philpot. Anning was a paleontologist known around the world for important finds, but because of her gender, she was often not formally recognized for her work. Agassiz was grateful for the help that the women gave him in examining fossil fish specimens during his visit to Lyme Regis in 1834.

Agassiz died in Cambridge, Massachusetts, in 1873 and was buried on the Bellwort Path at Mount Auburn Cemetery, joined later by his wife. His monument is a boulder from a glacial moraine of the Aar near the site of the old Hôtel des Neuchâtelois, not far from the spot where his hut once stood. His grave is sheltered by pine trees from his old home in Switzerland.


The Cambridge elementary school north of Harvard University was named in his honor, and the surrounding neighborhood became known as "Agassiz" as a result. The school's name was changed to the Maria L. Baldwin School on May 21, 2002, because of concerns about Agassiz's involvement in scientific racism and to honor Maria Louise Baldwin, the African-American principal of the school, who served from 1889 to 1922. The neighborhood, however, continued to be known as Agassiz. Circa 2009, neighborhood residents decided to rename the neighborhood's community council as the "Agassiz-Baldwin Community". Then, in July 2021, culminating a two-year effort on the part of neighborhood residents, the Cambridge City Council voted unanimously to change the name to the Baldwin Neighborhood. An elementary school, the Agassiz Elementary School in Minneapolis, Minnesota, existed from 1922 to 1981.

Geological tributes
Agassiz's grave, Mount Auburn Cemetery, Cambridge, Massachusetts, is a boulder from the moraine of the Aar Glaciers, near where he once lived.

An ancient glacial lake that formed in central North America, Lake Agassiz, is named after him, as are Mount Agassiz in California's Palisades, Mount Agassiz, in the Uinta Mountains of Utah, Agassiz Peak in Arizona, Agassiz Rock in Massachusetts and in his native Switzerland, the Agassizhorn in the Bernese Alps. Agassiz Glacier (Montana) and Agassiz Creek in Glacier National Park and Agassiz Glacier (Alaska) in Saint Elias Mountains, Mount Agassiz in Bethlehem, New Hampshire in the White Mountains also bear his name. A crater on Mars Crater Agassiz and a promontorium on the moon are also named in his honor. A headland situated in Palmer Land, Antarctica, is named in his honor, Cape Agassiz. A main-belt asteroid, 2267 Agassiz, is also named in association with him.

Taxa named in his honor

Biological tributes

Several animal species are named in honor of him, including

  • Agassiz's dwarf cichlid Apistogramma agassizii Steindachner, 1875;
  • Agassiz's perchlet, also known as Agassiz's glass fish; and the olive perchlet Ambassis agassizii Steindachner, 1866;
  • The Spring Cavefish Forbesichthys agassizii (Putnam, 1872);
  • the catfish Corydoras agassizii Steindachner, 1876;
  • the Rio Skate Rioraja agassizii (J. P. Müller & Henle, 1841);
  • The South American fish Leporinus agassizii
  • the Snailfish Liparis agassizii Putnam, 1874;
  • a sea snail, Borsonella agassizii (Dall, 1908);
  • a species of crab Eucratodes agassizii A. Milne Edwards, 1880;
  • Isocapnia agassizi Ricker, 1943 (a stonefly);
  • Publius agassizi (Kaup, 1871) (a passalid beetle);
  • Xylocrius agassizi (LeConte, 1861) (a longhorn beetle);
  • Exoprosopa agassizii Loew, 1869 (a bee fly);
  • Chelonia agassizii Bocourt, 1868 (Galápagos green turtle);
  • Philodryas agassizii (Jan, 1863) (a South American snake);

and the most well-known,

  • Gopherus agassizii (Cooper, 1863) (the desert tortoise).
  • In 2020, a new genus of pycnodont fish (Actinopterygii, Pycnodontiformes) named Agassazilia erfoundina (Cooper and Martill, 2020) from the Moroccan Kem Kem Group was named in honor of Agassiz, who first identified the group in the 1830s.

Tribute awards

In 2005, the European Geosciences Union Division on Cryospheric Sciences established the Louis Agassiz Medal, awarded to individuals in recognition of their outstanding scientific contribution to the study of the cryosphere on Earth or elsewhere in the solar system.

Agassiz took part in a monthly gathering called the Saturday Club at the Parker House, a meeting of Boston writers and intellectuals. He was therefore mentioned in a stanza of the Oliver Wendell Holmes Sr. poem "At the Saturday Club:"

There, at the table's further end I see
In his old place our Poet's vis-à-vis,
The great PROFESSOR, strong, broad-shouldered, square,
In life's rich noontide, joyous, debonair

How will her realm be darkened, losing thee,
Her darling, whom we call our AGASSIZ!

Daguerreotypes of Renty and Delia Taylor

In 1850, Agassiz commissioned daguerreotypes, which were described as "haunting and voyeuristic" of the enslaved Renty Taylor and Taylor's daughter, Delia, to further his arguments about black inferiority. They are the earliest known photographs of enslaved persons. Agassiz left the images to Harvard, and they remained in the Peabody Museum's attic until 1976, when they were rediscovered by Ellie Reichlin, a former staff member. The 15 daguerrotypes were in a case with the embossing "J. T. Zealy, Photographer, Columbia," with several handwritten labels, which helped in later identification. Reichlin spent months doing research to try to identify the people in the photos, but Harvard University did not make efforts to contact the families and licensed the photos for use.

In 2011, Tamara Lanier wrote a letter to the president of Harvard that identified herself as a direct descendant of the Taylors and asked the university to turn over the photos to her.

In 2019, Taylor's descendants sued Harvard for the return of the images and unspecified damages. The lawsuit was supported by 43 living descendants of Agassiz, who wrote in a letter of support, "For Harvard to give the daguerreotypes to Ms. Lanier and her family would begin to make amends for its use of the photos as exhibits for the white supremacist theory Agassiz espoused." Everyone must evaluate fully "his role in promoting a pseudoscientific justification for white supremacy."

Polygenism and racism

Agassiz in the Concrete
After the 1906 San Francisco earth­quake toppled Agassiz's statue from the façade of Stanford's zoology building, Stanford President David Starr Jordan wrote, "Somebody—​Dr. Angell, perhaps—​remarked that 'Agassiz was great in the abstract but not in the concrete.'"

After Agassiz came to the United States, he wrote prolifically in the field of scientific polygenism. His purpose was to develop better working hypotheses so a complete theory could explain his and his colleagues collective observations of the natural world. He was a superior scientist in his era, and the outstanding natural scientist of his generation in the North America. Distinguished Professor of English Christoph Irmscher called him the "Creator of American Science".

After scientific colleagues explained their findings, he became an early proponent of the Last Glacial Maximum (LGM) because there was sufficient evidence. He sought further evidence which could support or refute LGM as he researched worldwide. He wrote to his wife of the discovery of an extinct Mammoth under glacial ice floes in Siberia. Since Agassiz did not have the benefit of the insights of plate tectonics, and the lack of "missing link" fossil evidence in his era, it seemed to him and many others that the evidence indicated that there had been multiple creation events separated by worldwide and/or regional catyclysms, rather than a single creation event.

He did not consider Darwin's Theory of Evolution to have sufficient evidence when it was first presented in 1859. In fact, he had also identified the wide variety of speciation during his own earlier field work. He well knew the earth was much older than some Bible readers assumed. He rejected the Lamarckian idea of inheritance of acquired characteristics that Darwin had accepted and later expanded upon in his writings on heredity.

Agassiz asserted that the evidence being presented by his contemporaries was not sufficient to conclude that migration and adaptation could account for the geographical distribution patterns of flora and fauna. Similar concerns from other fields of scientific inquiry led to the explanatory theory of continental drift being more fully developed in the early 20th century but at an implausibly high rate for the separation of the Americas from Europe and Africa of 250 cm/year. The evidence proving the mechanism of plate tectonics did not occur until 1968, with a rate about 2.5 cm/year.

Agassiz asserted the evidence indicated that the people of earth were not obviously descended from a single biological pair Adam and Eve, a co-Adamist conjecture proven correct in the 21st century by identification of Y-chromosomal Adam and Mitochondrial Eve.

Lurie (1954) mentions that Agassiz developed (what in retrospect is considered) a co-Adamist hypothesis to explain the distribution of life forms, which holds that animals, plants, and humans were all created in "special provinces" with distinct populations of species created in and for each province, and that these populations were endowed with different attributes. A more exacting explanation is that Agassiz succinctly described what was obvious around the world: Various regions have differentiated species of plants and animals, and mankind appeared to be speciated also. "Special provinces" means "uniquely speciated zones" or in Agassiz own words: "natural zoological provinces". He considered this hypothesis testable, and matched to the available evidence. He also indicated that there were obvious geographical barriers that were the likely cause of speciation. His observation and thoughts were presented at a time when it was important to carefully explain why a single creation event was unlikely. The available fossil record showed major gaps rather than a continuum of species through the ages because researchers had not discovered locations that contained the "missing link" fossils. So Agassiz and others focused on Variation, which contributed to the Modern Synthesis in the mid-20th century, while the principles of gene flow would not be developed until over a century in the future.

According to Agassiz, as presented by the anthropologist Josiah Clark Nott in 1854, the conditions in which particular creatures live "are the conditions necessary to their maintenance, and what among organized beings is essential to their temporal existence must be at least one of the conditions under which they were created". Where a modern reader of the above excerpt might conclude he was speaking about individuals being created, he specifically describes swarms, nations and plants – what is now referred to as taxa – as the "beings".

Agassiz was opposed to evolution, believing that the theory of evolution reduced the wisdom of God to an impersonal materialism. Agassiz was influenced by philosophical idealism. Agassiz believed that one species of humans exists, but many different creations of races occurred. According to Agassiz, genera and species were ideas in the mind of God; their existence in God's mind prior to their physical creation meant that God could create humans as one species, yet in several distinct and geographically separate acts of creation. Agassiz was in modern terms a creationist who believed nature had order because God created it directly. Agassiz viewed his career in science as a search for ideas in the mind of the creator expressed in creation. Stephen Jay Gould asserted that Agassiz's observations sprang from racist bias, in particular from his revulsion on first encountering African-Americans in the United States. Referencing letters written by Agassiz, Gould compares Agassiz' public display of dispassionate objectivity to his private correspondence, in which he describes "the production half breeds" as "a sin against nature..." Describing the interbreeding of white and black people, he warns, "We have already had to struggle, in our progress, against the influence of universal equality... but how shall we eradicate the stigma of a lower race when its blood has once been allowed to flow freely into our children." In contrast, others have asserted that, despite favoring polygenism, Agassiz rejected racism and believed in a spiritualized human unity. However, in the same article, Agassiz asks the reader to consider the hierarchy of races, mentioning "The indomitable, courageous, proud Indian, — in how very different a light he stands by the side of the submissive, obsequious, imitative negro, or by the side of the tricky, cunning, and cowardly Mongolian! Are not these facts indications that the different races do not rank upon one level in nature[?]"

Agassiz never supported slavery and claimed his views on polygenism had nothing to do with politics. His views on polygenism have been claimed to have emboldened proponents of slavery.

Accusations of racism against Agassiz have prompted the renaming of landmarks, schoolhouses, and other institutions (which abound in Massachusetts) that bear his name. Opinions about those moves are often mixed, given his extensive scientific legacy in other areas, and uncertainty about his actual racial beliefs. In 2007, the Swiss government acknowledged his "racist thinking", but declined to rename the Agassizhorn summit. In 2017, the Swiss Alpine Club declined to revoke Agassiz's status as a member of honor, which he received in 1865 for his scientific work, because the club considered that status to have lapsed on Agassiz's death. In 2020, the Stanford Department of Psychology asked for a statue of Louis Agassiz to be removed from the front façade of its building. In 2021, Chicago Public Schools announced they would remove Agassiz's name from an elementary school and rename it for the abolitionist and political activist, Harriet Tubman.

Following Darwin's elucidation of evolutionary theory in 1859, which in its early years had inconsistencies, Agassiz sponsored expeditions and motivated others to continue to advance natural history in the direction the evidence promoted. He had a great deal of respect for scientists who did actual field work to discover new evidence, even for scientists such as Darwin and his Darwinist colleagues at Harvard. Finding evidence to corroborate or refute a hypothesis could be arduous and life-threatening. The Thayer Expedition of 1865-66 included his personal artist-illustrator Jacques Burkhardt, Brazilian naturalist Joao Coutinho, associate researcher Charles Frederick Hartt and students Walter Hunnewell, William James, and Stephen van Rensselaer Thayer with additional Harvard students. Hartt succumbed to yellow fever on a later expedition, James developed lifelong infirmities and others, including Agassiz himself had shortened lifespans.


Portrait of Louis Agassiz (1840)
Portrait of Louis Agassiz (1840)
  • Recherches sur les poissons fossiles (1833–1843)
  • History of the Freshwater Fishes of Central Europe (1839–1842)
  • Études sur les glaciers (1840)
  • Études critiques sur les mollusques fossiles (1840–1845)
  • Nomenclator Zoologicus (1842–1846)
  • Monographie des poissons fossiles du Vieux Gres Rouge, ou Systeme Devonien (Old Red Sandstone) des Iles Britanniques et de Russie (1844–1845)
  • Bibliographia Zoologiae et Geologiae (1848)
  • (with A. A. Gould) Principles of Zoology for the use of Schools and Colleges (Boston, 1848)
  • Lake Superior: Its Physical Character, Vegetation and Animals, compared with those of other and similar regions (Boston: Gould, Kendall and Lincoln, 1850)
  • Contributions to the Natural History of the United States of America (Boston: Little, Brown, and Co., 1857–1862)
  • Geological Sketches (Boston: Ticknor & Fields, 1866)
  • A Journey in Brazil (1868)
  • De l'espèce et de la classification en zoologie [Essay on classification] (Trans. Felix Vogeli. Paris: Bailière, 1869)
  • Geological Sketches (Second Series) (Boston: J.R. Osgood, 1876)
  • Essay on Classification, by Louis Agassiz (1962, Cambridge)

Taxa described by him

  • See Category:Taxa named by Louis Agassiz

See also

Kids robot.svg In Spanish: Louis Agassiz para niños

  • List of geologists

Archive sources

A collection of Louis Agassiz's professional and personal life is conserved in the State Archives of Neuchâtel.

  • AGASSIZ LOUIS, Fonds: Louis Agassiz (1817–1873). Archives de l'État de Neuchâtel.
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