An estimate of black admixture in white Americans

An ICHG/ASHG 2011 abstract (below) reports some results from a study of the 23andMe database. I see various potential issues with the research as described in the abstract; but while the numbers are not definitive, these estimates are likely to be by far the most accurate to date. What's clear is the overwhelmingly huge majority of white Americans have zero black ancestry. All previous sensible analyses of genetic data agree, and any other result would be difficult to reconcile with American history -- however disappointing that might be to "Multiracial Voice"-types and race denialists.

In 2002, Mark Shriver claimed 30% of white Americans have on average about 2% African ancestry, the average for the population as a whole coming out to about 0.7%. Shortly thereafter, in a different interview, Shriver lowered his estimate, purporting "about 10 percent of [the European-American population] have some African ancestry". Subsequently, another principal of DNAprint revised the estimate still further downward: "Five percent of European Americans exhibit some detectable level of African ancestry". That too was an overestimate. 23andMe, examining the genomes of vastly larger numbers of people using thousands of times as many SNPs, estimates "about 2%" of "European Americans" have any detectable autosomal black ancestry. And three quarters of that 2% have only "about 0.5%" African ancestry (i.e., less than Shriver in 2002 claimed the average American carried).

Exceptions to the "One Drop Rule"? DNA evidence of African ancestry in European Americans. J. L. Mountain1, J. M. Macpherson1, C. B. Do1, B. T. Naughton1, R. A. Kittles2, N. Eriksson1 1) 23andMe, Inc, Mountain View, CA; 2) Institute of Human Genetics, University of Illinois at Chicago, Chicago, IL.

Genetic studies have revealed that most African Americans trace the majority (75-80%, on average) of their ancestry to western Africa. Most of the remaining ancestry traces to Europe, and paternal lines trace to Europe more often than maternal lines. This genetic pattern is consistent with the "One Drop Rule,” a social history wherein children born with at least one ancestor of African descent were considered Black in the United States. The question of how many European Americans have DNA evidence of African ancestry has been studied far less. We examined genetic ancestry for over 77,000 customers of 23andMe who had consented to participate in research. Most live in the United States. A subset of about 60,000 shows genetic evidence of fewer than one in 16 great-great-grandparents tracing ancestry to a continental region other than Europe. They are likely to consider themselves to be entirely of European descent. We conducted two analyses to understand what fraction of this group has genetic evidence of some ancestry tracing recently to Africa. We first identified individuals whose autosomal DNA indicates that they are predominantly of European ancestry, but who carry either a mitochondrial (mt) DNA or Y chromosome haplogroup that is highly likely to have originated in sub-Saharan Africa. Of the 60,000 individuals with 95% or greater European ancestry, close to 1% carry an mtDNA haplogroup indicating African ancestry. Of approximately 33,000 males, about one in 300 trace their paternal line to Africa. We then identified the subset of these European Americans who have estimates of between 0.5% and 5.0% of ancestry tracing to Africa. This subset constitutes about 2% of this set of individuals likely to be aware only of their European ancestry. The majority (75%) of that group has a very small estimated fraction of African ancestry (about 0.5%), likely to reflect African ancestry over seven generations (about 200 years) ago. We estimate that, overall, at least 2-3% of individuals with predominantly European ancestry have genetic patterns suggesting relatively deep ancestry tracing to Africa. This fraction is far lower than the genetic estimates of European ancestry of African Americans, consistent with the social history of the United States, but reveals that a small percentage of “mixed race” individuals were integrating into the European American community (passing for White) over 200 years ago, during the era of slavery in the United States.

8 comments:

hailtoyou said...

So,
(1) 98.0% of self-identified "unmixed-Whites" in the USA have ~zero detectable Black ancestry. (Though, from my reading of the abstract, this may mean "under 0.5%", not 'zero').

(2) 1.5% of self-IDed unmixed-Whites have Black ancestry averaging ~0.5%

(3) 0.5% of self-IDed unmixed-Whites have Black ancestry greater than 0.5%, with someone in the sample even reaching 5.0%. (Indicating, e.g., that 1 of 16 great-great-grandparents was 80%-Black).

The conclusion is that the self-IDed White-American genepool is no more admixed with Subsaharan-African genetics than than are Swiss-French who have never left Switzerland. Swiss-French weigh-in at 0.1%. Mean admixture among USA whites may be may be a tenth higher. Considering centuries of cohabitation between the races in North-America, this is truly remarkable.

Further: if (a) the above-linked estimates of Black admixture in Arabs and Jews is correct, and (b) if a significant number of the USA's Jews and Arabs were counted as white in the study (which appears to be based on self-ID, so it is unlikely), that alone may account for a fair share of the Black ancestry, rather than it all coming from posited interracial mixing in Colonial or 19th-century America.

Anonymous said...

The conclusion is that the self-IDed White-American genepool is no more admixed with Subsaharan-African genetics than than are Swiss-French who have never left Switzerland.

As well as being less admixed than some Southern European countries, notably Portugal.

Quite an accomplishment in racial preservation considering North America's significant population of sub-Saharan Africans. You can thank Southerners and Jim Crow (and the Black Codes) for that.

We always hear about how bad Jim Crow was, but it played a vital role in preserving our people.

Contrast that with Latin America that never had any anti-miscegenation laws.

We need to reinstate and expand the Racial Integrity Act and National Origins Act to classify all racially non-European Caucasoids as non-White as well.

Anonymous said...

These are people who identify themselves as unmixed.

I am not arguing against the point that Nordish views on race helped to keep the situation in check. As a contrast, you can go to Latin American countries where people identify themselves as "white" and the actual reality based on genetic testing is that they're "off white" at best.

However in modern America, there is plenty of race mixing going on. The difference is that the offspring of these unions rarely if not never identify themselves as "white". There are social benefits in not being white (as opposed to the contrary, where it is a social cost), so anyone who has a chance to claim some non-white ancestry will do so to gain preferential treatment in obtaining grants, jobs, college admission, and etc.

It's rather ironic that the very social order we live in is unwittingly helping to enforce this definition of whiteness. A small victory.

Anonymous said...

It's rather ironic that the very social order we live in is unwittingly helping to enforce this definition of whiteness. A small victory.

Small victory...?!?

Actually call it a **HUGE VICTORY** for White America .. since at least no matter how 'few in number' we may become .. WE will always know *exactly* who really is 'one of US' .. even unto 'the tenth generation' will we know that a White American is in fact A WHITE AMERICAN.....

Hoorah!

Anonymous said...

23andMe is now giving away results that should be personal, so white supremacist like yourselves to use it to promote your silly ideology? This is sickening.

Anonymous said...

23andMe is now giving away results that should be personal, so white supremacist like yourselves to use it to promote your silly ideology? This is sickening.

Looks like another libfag is mad as hell that scientific progress continues to validate the racist worldview.

Anonymous said...

The genetic evidence supporting the historical fact of racial segregation and its prevalence in the United States hardly validates "the racist worldview". The fact that institutional racism existed does nothing to prove the actual validity of the ideology that was behind it, it simply proves that the ideology was the status quo at that particular time and held great social power.

Anonymous said...

White Americans are mongrels, mixed with Natives, Blacks and Jews.