As a previous posts explained, I recently visited an exhibit about race that was organized by the American Anthropological Association (AAA) and discovered its 1998 Statement on Race, which has scientific and historical/cultural components.
The exhibit also had informational panels. Here are some that talked about the subjects addressed by the AAA statement.
“Race is a recent human invention. It is only a few hundred years old. . . . Although not scientific, the idea of race proposed that there were significant differences among people that allowed them to be grouped into a limited number of categories or races. Yet, are we so different? All humans share a common ancestry and, because each of us represents a unique combination of ancestral traits, all humans exhibit biological differences.”
“From the beginning, the idea of race was tied to power and hierarchy among people, with one group being viewed as superior and others as inferior.”
“Genetic variation refers to the natural differences in DNA sequences found in a population. These differences exist because tiny, random changes are always occurring in DNA and accumulate over time. Almost all of these differences are ‘silent’ and don’t affect us in any way. But some are at the root of each person’s unique appearance—they might make us taller or shorter or cause some of us to have brown eyes and some of us blue.”
“The more isolated a population, the more it is affected by three evolutionary processes responsible for much of human variation.” First, Mutations. These are “randomly occurring changes in the genetic code,” are “the source of all genetic variations. Geographically separated populations may experience different mutations.” Second, “Random Genetic Sampling.” “Because each generation inherits a random sample of the genes of the previous generation, some alleles (different forms of the same gene) may become more or less common in a population just by chance.” Third, Natural Selection. “Traits that increase the chance of survival in a certain environment are more likely to be passed on to the next generation. Different traits provide an advantage in different environments.”
“People have lived in Africa far longer than anywhere else—scientists estimate between 150,000 to 200,000 years. This time has allowed the population in Africa to accumulate more of the small mutations, or genetic changes, that make up our genetic variation.”
“Because only a small part of the African population moved beyond Africa to begin colonizing the world, only part of Africa’s genetic variation moved with them. For this reason, most genetic variation found in people living outside Africa is a subset of that found among Africans, and more variety remains with Africa even today. [Yet] nearly all the genetic variation in Europe and Asia is found in Africa, too.”
“At the bottom of your skin’s outer layer are cells called melanocytes that produce a brown pigment called melanin, [which] screens the deeper layers of your skin from the Sun’s UV radiation.”
“If your skin is darker, some of your ancestors likely came from more tropical climates. If your skin is lighter, some of your ancestors probably came from places that did not receive much sunlight.”
[An anthropologist has contended] “that different skin colors evolved to balance [everyone’s] need for both folate [folic acid, which is vital to the healthy development of fetuses] and vitamin D [which allows us to absorb calcium and deposit it in our bones] depending on the regions where people lived. Darker skin blocks more folate-destroying UVR [radiation]. Lighter skin lets people absorb more UVR and make more vitamin D. The skin color in any population is a balance between the need to protect folate and the need to produce enough vitamin D.”
[Therefore,] “geography–not race—explains skin-color variation.”