Editor's note: For those who are wondering about the retro title of this black history series, please take a moment to learn about historian Joel A. Rogers, author of the 1934 book 100 Amazing Facts About the Negro With Complete Proof, to whom these "amazing facts" are an homage.
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(The Root) — 100 Amazing Facts About the Negro No. 18: How much African ancestry does the average African American have?
A few years ago, it occurred to me that it might be fun to try to trace the family trees of a group of African Americans all the way back to slavery, and then when the paper trail disappeared, analyze their DNA through biologist Rick Kittles' company, AfricanAncestry.com. The payoff would be to reveal the ethnic group from which their maternal or paternal slave ancestors descended back in Africa. We would trace their family trees using the massive number of records now digitized by websites such as Ancestry.com, and supplement the paper trail using new tools of genetic science to find more distant details about each person's ancestry. My goal was to create a contemporary version of the television series Roots — think of it as Roots in a test tube, Roots for the 21st century.
The result has been four PBS series on genealogy and genetics, starting with African American Lives 1 and 2, featuring guests such as Oprah Winfrey, Quincy Jones, Maya Angelou and Tina Turner, and Faces of America, in which we included guests from across the ethnic spectrum, such as Meryl Streep, Yo-Yo Ma, Dr. Oz and Stephen Colbert. These four-part series proved to be popular enough for PBS to ask us to do a weekly program, Finding Your Roots, which aired on Sunday nights for 10 weeks this past spring. And soon we will be filming season two.
Making these series has been quite a learning experience for me, especially in terms of the genetic makeup of the African-American people. So, for The Root, I asked five DNA companies who analyze our guests' ancestry if we could publish for the first time their findings about the ancestral origins of the African-American community. (By "African American," I mean descendants of African slaves brought to this country before the Civil War, not recent African immigrants.) How African — how "black" — is the average African American? The results astonished me, just as they have surprised the guests on our TV show, and I think they'll surprise you as well. But before revealing those results, I want to provide a short introduction to the secrets that DNA holds about a person's ancestry.
What a DNA Test Can Reveal About Your "Racial" or Genetic Roots
Many of the DNA tests that we give our guests today didn't even exist a decade ago. One of the genuine pleasures of making Finding Your Roots has been working with some of the world's most brilliant geneticists and introducing their exciting new technologies to a broad lay audience. These new tests measure what scientists call "autosomal DNA," which can be used to figure out how much of your ancestry traces to each of the world's ancestral populations, people who lived in a particular geographical region, say, 500 years ago, via an "admixture test." Or a test can be used to identify long stretches of identical DNA that two individuals share, therefore establishing the fact that they are related genetically even more recently from a common ancestor, and thus are cousins.
In other words, if we could produce an ideal family tree for two individuals being tested, one person would appear by name on both of their family trees. Analyzing your autosomal DNA allows you to find your "lost" ancestors by connecting you to these genetic relatives. These DNA companies have features such as "Cousin Connect" (Ancestry.com), "Family Finder" (Family Tree DNA) and "DNA Relatives" (23andme.com) that automatically inform you of your cousins who are located in their databases. And most exciting of all, adoptees can use it to find biological parents, or we can even find children born out of wedlock to one of our ancestors, discovering blood relatives we never even knew we had.
When I started producing Finding Your Roots, I thought that the emotional high point for an African American would be learning the ethnic origin of their mother's or father's family line, all the way back to Africa. After, all, that's what Roots was ultimately about, right, finding one's "Kunta Kinte moment"? And learning one's African ethnic origins has proven to be quite meaningful to our guests. But to my surprise, among the most moving revelations to many have been learning the actual names of long-lost ancestors who were slaves and second, learning their admixture results.
These admixture tests reveal surprising information about the complex genetic makeup of the African-American community, and speak volumes about the hidden history of American racial and social relations encoded in our genes. Before I share those results, a bit of the science behind the tests.
Are You Mixed? Admixture Tells Us
What exactly is admixture? I asked a few prominent geneticists to define it for this article. Dr. George Church, a professor at the Harvard Medical School and a pioneer in the mapping of the human genome, defines it this way: "Genetic admixture is the breeding between two or more previously isolated populations."
Dr. Joanna Mountain, the senior director of research for 23andme.com, defines admixture this way: "Every one of us has the story of our ancestry hidden in our DNA. Any section of DNA — say, one piece of chromosome 3 — can be linked with people who lived in a particular geographic location thousands of years ago. By adding up the fractions of DNA from each location, we can determine the percentage of a person's ancestors who lived in each location."
She also stresses the fact that it is very important to use regional or geographic categories in genetic ancestry-tracing, rather than the standard four or five so-called "racial" divisions that have been employed in the West since the 18th century, which is one reason why her company now uses 17 categories of "Ancestry Composition," and will soon expand that number to 24. All of the other companies mentioned in this article now use between nine and 20 such categories. However, for convenience sake, I'll be presenting the admixture results in three large regional summaries: sub-Saharan African, European and Native American.
Dr. Nathan Pearson, the principal genome scientist at Ingenuity, tells us that "interbreeding has occurred throughout history, and notably leaves telltale traces in our genomes that hint strongly at who came together, and when." In conclusion, he says, "the ingredients in your genome track which regional populations mingle in your family tree, and in what proportions," revealing "the mix of recent continental origins among your ancestors." Think of admixture, he says, "as gene mingling."
So what do the collective genomes of the African-American community reveal about the mix of ancestral populations — of mingled genes — that we have inherited? Here are the surprising results from five DNA companies.
Exactly How "Black" Are Black Americans?
* According to Ancestry.com, the average African American is 65 percent sub-Saharan African, 29 percent European and 2 percent Native American.
* According to 23andme.com, the average African American is 75 percent sub-Saharan African, 22 percent European and only 0.6 percent Native American.
* According to Family Tree DNA.com, the average African American is 72.95 percent sub-Saharan African, 22.83 percent European and 1.7 percent Native American.
* According to National Geographic's Genographic Project, the average African American is 80 percent sub-Saharan African, 19 percent European and 1 percent Native American.
* According to AfricanDNA, in which I am a partner with Family Tree DNA, the average African American is 79 percent sub-Saharan African, 19 percent European and 2 percent Native American.
And for our African-American male guests, there has been still another astonishing fact revealed about their paternal ancestry — their father's father's father's line — through their y-DNA: A whopping 35 percent of all African-American men descend from a white male ancestor who fathered a mulatto child sometime in the slavery era, most probably from rape or coerced sexuality. In other words, if we tested the DNA of all of the black men in the NBA, for instance, just over one-third descend from a white second or third great-grandfather. In my own case, he was my great-great-grandfather, and he was most probably of Irish descent, judging from our shared y-DNA haplogroup.
I find two things quite fascinating about these results. First of all, simply glancing at these statistics reveals that virtually none of the African Americans tested by these DNA companies is inferred to be 100 percent sub-Saharan African, although each company has analyzed Africans and African immigrants who did test 100 percent sub-Saharan in origin. Ranges, of course, vary from individual to individual. Spencer Wells, director of National Geographic's Genographic Project, explained to me that the African Americans they've tested range from 53 percent to 95 percent sub-Saharan African, 3 percent to 46 percent European and zero percent to 3 percent Native American. So there is a lot of genetic variation within our ethnic group, as is obvious to anyone even casually glancing at black people just walking down the street.
What this means is that even the most phenotypically "African" (or what used to be called "Negroid") African Americans have dramatically significant levels of European ancestry, a fact that would have astonished many of our forebears, both black and white. It is also a fact that astonishes the guests on Finding Your Roots. And this finding is important because it deconstructs the very American notion of biologically "fixed races" that our society inherited from the racist pseudoscience of the 18th century and drew upon to justify slavery and the property rights of masters who fathered children with their slaves.
And second, these findings show that the common claim that many African Americans make about their high percentage of Native American ancestry is a myth. Joanna Mountain broke down to me our low amounts of Native American ancestry in this way: "Eighty percent of African Americans have less than 1 percent Native American ancestry. Over 2.5 percent have between 2 percent and 3 percent. And of all African Americans who have at least 1 percent Native American ancestry, the average is 2 percent Native American." So much for all of those putative Cherokee roots on just about every black person's family tree, fabricated to explain why your great-grandmother had "high cheekbones and straight black hair"! Why there is such little evidence of genetic mingling between African Americans and Native Americans deserves a column of its own.
The results for Latinos, however, are quite different: "In our experience," Mountain says, "people who have both African ancestry [at least 10 percent, according to genetics] and a lot of Asian/Native American ancestry [at least 10 percent, according to genetics] are more likely to consider themselves Latino than African American."
So why did we invent, and why do we hold on to, this myth of our putative Cherokee great-grandmothers? (And, by the way, both genealogists and geneticists have told me that white Americans share the same myth, which both their family trees and their admixtures disprove.) I think that Chris Rock put his finger on the answer in African American Lives 2. He said that it was much easier to fantasize about noble ancestors we never had than to deal with the fact of rape during slavery, the heinous act that produced such high percentages of European ancestry in the black community, the component of admixture that is responsible for those high cheekbones and that straight black hair. Despite African-American genealogical mythology, it turns out that we simply do not have many Native Americans on the branches of our family trees.
Rather, it turns out that black people in this country are surprisingly "white," meaning that our genomes are composed of quite a lot of European ancestry. Judging from these test results, the bottom line is that black and white Americans are inextricably interconnected at the level of their genomes, and African Americans are a profoundly "mixed" people, far more than anyone thought possible before these DNA tests were invented. And no matter what your features are — your shade of brown, your hair texture, the shape of your lips and nose — if you are an African American reading this column, you are likely "mixed" as well, even if you don't think you look that way.
And what about the percentages of "black" or sub-Saharan ancestry in the white American community? That will be the subject of another column. But suffice it to say here that, according to Mountain, "The bottom line is that 3 percent to 4 percent of people likely to consider themselves as all 'white' have some African ancestry — between 0.5 percent and 5 percent."
Thinking about the enormous implications of these percentages of admixture for African Americans calls to mind that famous line from Dr. King's "Letter From Birmingham Jail" about what he called "the interrelatedness of all communities" in this country. When he wrote that "We are caught in an inescapable network of mutuality, tied in a single garment of destiny," I wonder if he could possibly have realized how fundamentally this was true of black and white Americans on a biological level. Black and white citizens are bound together in this country at the most fundamental level possible — the level of the genome. And it turns out that Dr. King's stirring conclusion — that "whatever affects one directly, affects all indirectly" — has been literally true genetically of these two groups of the American people for a very long time.
As fascinating as one's admixture results are, it is important to remember that identity can be constructed in various, and deeply nuanced, ways. As George Church told me, "Two people with a certain cancer-causing allele have potentially much more in common than two people with the same admixture." In other words, while "race" is socially constructed, alleles or genetic mutations are not. Biology matters. The challenge for us is to understand how it does and does not matter, especially in a society that has historically called upon "science" to justify an oppressive social order.
If you want to find out your own regional genetic composition, the following companies offer admixture tests:
And here's some additional reading about our collective origins.
As always, you can find more "Amazing Facts About the Negro" on The Root, and check back each week as we count to 100.
Henry Louis Gates Jr. is the Alphonse Fletcher University Professor and the director of the W.E.B. Du Bois Institute for African and African-American Research at Harvard University. He is also the editor-in-chief of The Root.