Emily Nix and Nancy Qian just put out a paper – The Fluidity of Race – that has gotten some attention. They claim (based on their analysis of US Census records from 1880-1940) that at least 19% of black males ‘passed’ for white during this period, with about 10% switching back. And this wasn’t a one-time thing: it kept happening for at least several generations, so there was a continuing net black-to-white flow, about 20% of each generation! They don’t talk about women, since their surnames change, but presumably there would be at least some race-switching among black women as well.
So let’s say that 17% of black males permanently passed over into the white category. During the time in question, the black percentage of the US population was around 11%; 1 13.1% in 1880, 11.6% in 1900, with a low in 1930 of 9.7% due to lots of recent immigration from Europe.
I think we can assume that half of the black population was male, at least until someone publishes claims of long-secret, industrial-scale parthenogenesis.
The period in questions covers about two generations. So:
the fraction of the population called white should have absorbed about
2 generations x 17% of the black male population x 0.5 (male fraction) x 11% (black fraction of the population) = 1.87% . The white population during this period was about 89% of the population. So you’d expect that whites in this country, on average would have about 2% black ancestry. Or maybe less, since blacks average about 75% African ancestry: more like 1.5% African ancestry.
But they don’t : the average amount of African ancestry among self-labeled whites is , according to a recent, massive 23andme study, 0.19%. The majority don’t have any African ancestry at all. 0.19% is way less, at least ten times less, than suggested by the Nix-Qian paper. Considerably less than you’d see in one generation, if they were right, and remember that they thought this was an ongoing process over many decades. Moreover, for most of those whites that have any detectable African ancestry at all, the amount is small, a percent or two – which suggests the admixture event happened quite a while ago.
In the South, the amount of African admixture is larger among whites: about 5% of self-labelled whites in South Carolina have at least 2% African ancestry. About 12% have over 1% African ancestry. But that amounts to an average African ancestry well under 1% among whites in South Carolina, a state in which blacks used to be the majority. That strongly suggests that the fraction of blacks that ever successfully passed into the white zone, over the entire history of the US, is more like 1 in 100, rather than 20% per generation.
So: what can we conclude about this paper? It’s a classic case of economic imperialism, informed by what ‘intellectuals’ [ those that have never been introduced to Punnet squares, Old Blue Light, the Dirac equation, or Melungeons] would like to hear.
It is wrong, not close to right.