Final answer:
Louis Agassiz, a Harvard professor, promoted the idea of genetic differences between blacks and whites through the theory of polygenism in the 1850s. His work, alongside others', contributed to the pseudo-scientific justification for racism, which has since been refuted by evidence highlighting the role of environmental and social factors.
Step-by-step explanation:
The idea that there were genetic differences between blacks and whites was first prominently proposed by Louis Agassiz, a Harvard professor of zoology and geology. Agassiz popularized the theory of polygenism in the 1850s, which argued that different human races came from separate origins. This theory provided a pseudo-scientific justification for racism by suggesting Black inferiority was supported by science. The publication of 'Types of Mankind' by George Gliddon and Josiah Nott in 1854 bolstered these claims.
However, such racial categorizations and assumptions of genetic differences have been refuted by subsequent scientific research. Studies have shown that disparities, such as those in IQ scores, result more from environmental factors like access to education rather than innate genetic differences. For instance, research has indicated the closing of IQ gaps as Black individuals gained greater educational opportunities.
The pseudo-scientific notions previously believed and propagated by figures like Agassiz have since been debunked by a more nuanced understanding of genetics, environment, and social factors affecting intelligence and other traits.