Jean Louis Rodolphe Agassiz (1807–1873) was a Swiss-born American naturalist, geologist, and zoologist whose contributions to science were monumental but whose legacy is deeply tarnished by his racist views. A towering figure in 19th-century science, Agassiz’s work laid foundational stones in glaciology, paleontology, and ichthyology. However, his belief in polygenism—the idea that human races were separately created species—cemented his role as a proponent of scientific racism, influencing discriminatory ideologies of his time and beyond.
Born in Môtier, Switzerland, on May 28, 1807, Agassiz displayed an early fascination with the natural world. He studied medicine and natural history at universities in Zurich, Heidelberg, and Munich, earning his doctorate in 1829. His early work focused on fossil fish, culminating in the seminal Recherches sur les Poissons Fossiles (1833–1843), which cataloged thousands of species and established him as a leading ichthyologist. Agassiz’s most enduring scientific contribution was his theory of glaciation. In 1837, he proposed that Earth had experienced an Ice Age, with vast glaciers shaping its landscapes. His fieldwork in the Alps and later in North America provided evidence for this revolutionary idea, transforming geology. In 1846, Agassiz immigrated to the United States, where he became a professor at Harvard University and founded the Museum of Comparative Zoology in 1859, a hub for biological research. His charisma and ability to popularize science made him a celebrity. Agassiz mentored a generation of scientists and established institutions like the Anderson School of Natural History, fostering hands-on scientific inquiry. His studies of marine life, coral reefs, and glacial phenomena remain influential.
Despite his scientific brilliance, Agassiz’s views on race were abhorrent and rooted in the era’s prejudices. He was a leading advocate of polygenism, a pseudoscientific theory asserting that human races were distinct species with separate origins, contradicting the monogenist view of a single human origin. Agassiz believed God created Black people as an inferior species, a conviction that drove his racist theories. This belief aligned with his observations of physical differences among races but was steeped in bias rather than evidence. His racism became pronounced after his arrival in the United States. Encountering Black people for the first time in Philadelphia in 1846, he wrote to his mother of his “repugnance” and described them as inherently inferior.
He argued that Black and White people could not share equal social or political status, views he expressed in letters and lectures. His 1850 essay in the Christian Examiner defended polygenism, claiming racial differences were fixed and divinely ordained. Agassiz’s racism extended to his scientific work. In 1850, he commissioned daguerreotypes of enslaved African Americans in South Carolina, taken by Joseph T. Zealy, to document supposed racial differences. These images, now housed at Harvard’s Peabody Museum, were used to support his theories of racial hierarchy. He also opposed interracial marriage and endorsed segregation, arguing that racial mixing would degrade society.
Agassiz’s views were not universal among scientists. Charles Darwin, whose On the Origin of Species (1859) challenged polygenism by emphasizing shared ancestry, was a vocal critic. Yet Agassiz’s influence in America, where slavery and racial segregation were entrenched, lent credibility to pro-slavery arguments and later Jim Crow policies. His views must be understood in the context of 19th-century science and society, where racial hierarchies were widely accepted, and many scientists used their authority to justify slavery and colonialism. Agassiz’s Swiss Protestant background and exposure to European racial theories shaped his worldview. In America, he aligned with elites who benefited from slavery, reinforcing his biases. However, Agassiz was not merely a product of his time. His resistance to Darwin’s evolutionary theory, which undermined polygenism, suggests a stubborn commitment to his beliefs. Even as evidence mounted against separate racial origins, he clung to his views until his death in 1873. His influence helped legitimize scientific racism, impacting policies and attitudes long after the Civil War.
Agassiz’s scientific contributions remain undeniable, but his racism has prompted reevaluation of his legacy. Harvard University, where he spent much of his career, has grappled with his shadow. In 2020, the Peabody Museum acknowledged the harm caused by Agassiz’s daguerreotypes and began repatriation discussions with descendants of the photographed individuals. Statues and namesakes, like Agassiz Peak in Arizona, have faced calls for renaming. In 2008, Switzerland’s Agassizhorn mountain became a flashpoint when activists proposed renaming it Rentyhorn, after Renty, an enslaved man photographed for Agassiz, to honor victims of racism. While the name persists, the debate reflects ongoing efforts to confront his legacy.
Louis Agassiz was a scientific pioneer whose discoveries shaped our understanding of Earth’s history and biodiversity. Yet his advocacy for polygenism and racial hierarchies, exemplified by his belief that God created Black people as an inferior species, reveals the dangers of science divorced from ethics. His story is a reminder that intellectual brilliance does not preclude moral failure. Today, Agassiz’s life is studied not only for his contributions but as a cautionary tale of how science can be weaponized to dehumanize. Acknowledging both his achievements and his wrongs is essential to understanding the complex interplay of knowledge, power, and prejudice.