In his article, "Mixed Blood", Jeffery M. Fish examines the cultural foundation of racial differentiation and claims race to be a myth.

natural selection- but which Americans do not think of as racial". Since racial classification primarily focuses on skin color, people with "compact" or "lanky" body types are merely variants of white, black, or other "racial" groups. A different choice of characteristics would categorize people into different “races” and the choice of which characteristics are significant is an arbitrary cultural construct. Additionally, Fish strengthens his assertion by addressing the fluidity of racial classification. In the United States, race defines ethnicity; in Brazil, it describes distinct physical characteristics. Hence, Fish notes that his daughter can, "change her race from Black in the United States to Morena (brunette)…in Brazil, by simply taking a plane there". Racial classification schemes are always subject to change as they depend on the culture of the observer rather than the genetic makeup of the people being observed. Furthermore, Fish questions the validity of racial classification by studying the biological differences between species. Fish explains that unlike donkeys and horses, human beings are part of a collective species which allows them to, “mate with others from anywhere [around the world] and produce fertile offspring”. If racial classification had a concrete scientific origin, this could not be true. In order for the word race to have any meaning a significant difference in genetic makeup would be required, thus delineating human beings into distinct racial groups. However, this evidently is not the case. Fish believes that race does not exist - it is a myth that has been socially concocted to justify the exclusion of one group of people from the other, thus deterring our growth as a society and needlessly violating individual autonomy.