Final answer:
Buffon's stance on race is not directly detailed in the information provided, but historical context indicates a shift from pseudoscientific beliefs in fixed racial differences to a contemporary understanding that race is not biologically valid and varies along a spectrum.
Step-by-step explanation:
The question regarding Buffon's stance on the reversibility/fixedness of race pertains to the historical views on race and its supposed fixity or flexibility. Although Buffon's specific views are not detailed in the provided information, we can contextualize his stance within the broader history of the concept of race.
Historically, many ideas surrounding race were grounded in pseudoscience and used to justify racist ideologies and practices. This includes beliefs about the determination of intelligence by race, which were later debunked by research indicating that environmental factors, such as access to education, were far more influential (Dickens 2006). Additionally, polygenism, the belief in separate origins for different races as advocated by figures like Louis Agassiz, wrongly suggested fixed biological differences and hierarchies (Graves 2003).
In contrast to these doctrines, anthropological and genetic research has shown that the concept of race is not biologically valid. Traits used to categorize race, like skin color or facial features, do not denote discrete categories but vary along a spectrum, dispelling the idea of fixed racial distinctions (Fuentes 2012, Jablonski 2006).