How did Louis Agassiz's ideas about race relate to scientific racism?

Louis Agassiz’s views on race were deeply intertwined with the scientific racism of the 19th century. His ideas were fundamentally rooted in his belief in polygenism—the theory that different human races were created independently as separate species, rather than descending from a single origin.12

Agassiz’s transition to this perspective occurred after he moved to the United States in 1846 and encountered Black people for the first time. Influenced by the craniometry work of Samuel Morton, which falsely claimed that brain size correlated with intelligence and racial hierarchy, Agassiz became a prominent advocate for these theories. He promoted the notion of a hierarchy of intelligence among racial groups through public lectures and his teaching.12

These pronouncements, coming from a scientist of his stature, were scientifically unfounded and served to embolden pro-slavery advocates in the United States, particularly in the South. It is essential to recognize that these ideas have been thoroughly discredited by modern science, which affirms the fundamental equality and shared biological origin of all human beings.1