African Ancestry Inc. Traces DNA Roots
by Steve Sailer
UPI, April 28, 2003
Dr. Rick Kittles, whose shaven head and wire-frame glasses make him look a little like Laurence Fishburne playing Morpheus in "The Matrix," felt a desire many Americans share: he wanted to find out more about where his ancestors had come from.
As an African-American, however, he realized that conventional genealogical methods for exploring one's family tree couldn't find him answers more specific than a continent. As a molecular geneticist, though, Kittles was in a position to use the latest DNA technology to ask questions that hadn't been feasible before.
Kittles' day job is co-directing the National Human Genome Center at Howard University in Washington. "My main research focus is looking at the genetic and environmental contributions to the causes of complex diseases that hit African-Americans disproportionately, such as prostate cancer, Type 2 diabetes, obesity, hypertension and asthma," he told United Press International. Kittles noted that African-American men are three times more likely to die of prostate cancer than white men and five times more likely than Asian men.
"All these diseases have both a genetic and an environmental component." Mark D. Shriver, a population geneticist at Penn State, commented, "As a scientist, Rick is solid, careful, and thoughtful. We collaborate on prostate cancer admixture mapping and skin pigmentation studies, and I am continually impressed by his insight and motivation."
To find out more about his mother's ancestors, Kittles examined his own mitochondrial DNA, which is a special kind of genetic material that is inherited exclusively down the maternal line of his family tree. In other words, his came down virtually unchanged from his mother's mother's mothers, back for hundreds of generations. Every so often, tiny mutations in the DNA occur. People who have the same mutation have the same "foremother" somewhere back in their ancestry.
For comparison, Kittles began assembling genetic data from published studies and collecting DNA samples in Africa. He told UPI that he found, "My female line goes back to Northern Nigeria, the land of the Hausa tribe. I then went to Nigeria and talked to people and learned a lot about the Hausa's culture and tradition. That gave me sense about who I am. In a way, it grounded me."
"Two people there looked like cousins I have -- they even behaved like them!" Kittles laughed.
Like a number of other geneticists, Kittles eventually decided to launch a for-profit side business helping people learn more about their ancestry. His is the first to specialize in serving the African diaspora. For $349, African Ancestry Inc. will test either your female or male lines.
The male line is the one down which your last name is passed. The test to find where your father's father's fathers came from relies on the male Y-chromosome and thus it only works in men. Women who want to track their male line heritage can have a male relative on their father's side take the Y-chromosome test.
African Ancestry sends you a kit containing two swabs. You rub them along the inside of your cheeks, then use an overnight delivery service to get the samples to the company's laboratory. There, they will be compared to African Ancestry's competitive advantage: it's exclusive African Lineage Database. This contains the DNA maps of about 9,000 African individuals from 82 population groups drawn from across all the regions exploited by the trans-Atlantic slave trade, from Senegal in the northwest of Africa to Mozambique in the southeast.
Shriver, who consults with DNAPrint, another genetic testing firm that offers a somewhat competing service, commended Kittles' African database. "If you are considering the mitochondrial DNA and Y-chromosome, the African Ancestry test is excellent. There is substantial variation within Africans for both of these markers and Rick has the most complete database of any group."
Kittles pointed out that these two tests will not find the origin of all your ancestors, just those in the purely male and purely female lines. "We can't determine genetically where you got all your DNA, but we can determine with accuracy where you got your Y-chromosome and your mitochondrial DNA."
The firm's Web site AfricanAncestry.com explains, "For about seven out of 10 people we test, we find identical matches in our database. For the remaining people, we find closely related lineages with greater than 90 percent confidence."
It may seem somewhat arbitrary for a geneticist to concentrate on just the male and female lines, yet conventional genealogists, for example, have always paid extra attention to the male line, because it bears the last name.
In contrast, DNAPrint has technology and databases for examining the main body of your DNA, which unlike the Y-chromosome and the mitochondrial DNA gets reshuffled with each conception of a new generation. DNAPrint (DNAPrint.com) can estimate what proportions of all your ancestors, not just your purely male and female lineages, came from each continent. DNAPrint's "autosomal DNA" testing service can tell you how much of your ancestry is from sub-Saharan Africa and how much from Europe, for example.
On the other hand, by focusing on just the male and female lines, Kittles' African Ancestry test can give the most detailed results about where these particular ancestors came from within Africa. Many customers like the direct emotional connection they feel to individual ancestors found through this process.
The original ancestors of all humans probably lived in Africa, but from the end of the Ice Ages 12,000 years ago up until the Age of Discovery beginning in the 15th century, Europeans and sub-Saharan Africans were relatively isolated from each other. During these millennia, some separate genetic markers emerged on each continent. So, geneticists don't have much trouble distinguishing African and European ancestors.
Kittles' Y-chromosome test can raise an issue that might be sensitive to some customers wanting to get more in touch with their African paternal ancestors. The test may uncover white forefathers instead. This can be disconcerting because one of them may have owned a black female ancestor.
How common is it? According to Shriver, of the several thousand people he studied who identify as African-Americans, about 90 percent are at least half black genealogically (and thus genetically). On average, about 82-83 percent of the genes found in African-Americans are indeed from Africa. Still, the odds that a Y-chromosome test will find a forefather from Europe are significant. Kittles noted that about 30 percent of African-Americans' Y-chromosomes originated in Europe.
Kittles, for example, has a Y-chromosome common in Germany, not Africa. "My father had told me for a long time that I had a white ancestor on our paternal line. So, the test confirmed it goes back to Germany."
In contrast, only about 5 percent of African-Americans' mitochondrial DNA comes from Europe, making the maternal line test a surer bet for those primarily interested in their black ancestors. (If African Ancestry finds the customer's DNA doesn't go back to Africa, it can search its databases of European gene markers.)
These numbers suggest that down through the centuries, white men were about six times more likely to father African-American babies with black women, than black men were with white women.
In other countries, population geneticists have found similar sex imbalances stemming from a socially dominant racial group's men using their power to obtain a subordinate group's women. For example, Icelanders' Y-chromosomes tend to trace back to the Vikings, but much of their mitochondrial DNA comes from the Scottish and Irish women kidnapped by the Vikings more than 1,000 years ago.
In recent decades, however, this black-white disparity has begun to reverse. The 2000 Census found that black men were 2.65 times more likely to be married to white women than white men were to black women.