Final answer:
Racial categories are not supported by biology because genetic variation within these categorizations is often greater than the variation between them. They lack a scientific basis, with traits such as skin color providing an insufficient foundation for racial division. Furthermore, the concept of race as a social construct has been widely accepted over biological explanations.
Step-by-step explanation:
Research by biological anthropologists has repeatedly shown that racial categories do not have a scientific basis when looking at human genetic diversity. Visible characteristics such as skin color or invisible traits like blood type do not justify a division of humans into different races because the genetic variation within so-called races often exceeds the variation between them. For example, only a fraction of genetic markers, specifically about 15 out of 45,000, determine skin pigmentation, yet society often uses this characteristic to assign race. The plight of describing human differences through racial categories is evident also in the way different societies construct these categories differently, with some nations having no formal racial classification systems while others have multiple categories.
The sequencing of the human genome further invalidated the biological foundation of race; a higher degree of genetic variation is found within the same racial group than between different racial groups. This understanding raises concerns about the appropriateness of using race in medical research and treatment, as it has led to misdiagnosis or underdiagnosis of diseases. Distinctly, the social construction of racial categories has known effects of discrimination and inequality, making anthropologists dispel biological definitions of race in favor of sociocultural considerations.
Social science organizations including the American Anthropological Association, the American Sociological Association, and the American Psychological Association, have rejected biological explanations of race, emphasizing its nature as a social construct with real-world consequences on inequality and discrimination. This perception further attests to the fact that there are no distinct biological racial categories and emphasizing the need to acknowledge both their sociocultural impact and the false nature of their supposed biological roots.