Calling race a “social construct” does not mean that the biological ancestry — and specifically West African ancestry — of African Americans is mythical. It also doesn’t mean that my ancestry has no actual implications. (See the map of sickle-cell density above.) And in the future, it may mean even more. Ancestry — where my great-great-great-great grandparents are from — is a fact. What you call people with that particular ancestry is not. It changes depending on where you are in the world, when you are there, and who has power.
Despite the fact that constructivism is the dominant perspective on nationalism (only instrumentalist, which could be thought of as a peculiar subtype of constructivism, rivals it) in academia, it’s one of the toughest concepts for many students to grasp. Especially since so many academic works implicitly rely on primordial it’s assumptions whenever they tackle ethnicity, culture, religion, or other similar concepts. And especially if they do so in quantitative studies.