Final answer:
Anthropologists, biologists, and geneticists argue that the concept of race is not scientifically valid. There is no accurate way to divide human populations into racial categories biologically. Biological anthropology demonstrates that our common notions of race are inaccurate, as each human trait varies along a spectrum.
Step-by-step explanation:
Anthropologists, biologists, and geneticists argue that the concept of race itself is not scientifically valid. While there are genetic markers for physical characteristics, like skin color and hair texture that are evident in the DNA of each person, only a few of the many thousands of DNA markers align with the convenient categories we use to categorize into racial groups. For example, only about 15 of our 45,000 genetic markers control for skin pigmentation. If we wanted, we could choose from thousands alternative genetic characteristics to classify people. If our social constructions were to change, and we suddenly decided to group people by height, fingerprint patterns, or blood type (rather than skin color, hair texture, and eye shape), we would have an entirely different set of races across the globe.
Whether looking at visible characteristics such as skin color or invisible genetic markers such as blood type, biological anthropologists have demonstrated time and time again that there is no scientifically justifiable way to divide the human population into racial categories. Any way you draw the lines, there will be more variation within categories than between categories.
Importantly, biological anthropology demonstrates that our common notions of race are inaccurate. Biological anthropologists such as Agustín Fuentes (2012) and Nina Jablonski (2006) have looked carefully at the global distribution of human traits such as skin color, facial features, hair texture, and blood type, among other markers, in order to determine if humans are indeed grouped into discrete categories based on race. Short answer: biologically speaking, there are no real racial categories. Each human trait varies along a spectrum, and the various traits are mixed and matched among people in ways that make racial distinctions impossibly inaccurate. As an example, take the issue of skin color, which is the most common way people assign race. Jablonski demonstrates that skin color varies along a spectrum, from pinkish beige to dark brown, with people throughout the world having skin of every possible shade between those two. Originally, humans evolving on the African continent had dark skin to protect them from the direct ultraviolet light of the sun. As some early humans migrated north into environments with less direct sunlight, their skin lightened to allow the absorption of vitamin D from the much weaker sunlight.