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DNA Kits Provide Insight into Genetic Ancestry

July 20, 2006 at 6:35 PM EDT
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RICK KITTLES, African Ancestry: Anyway, I’m going to talk about uncovering the African in African ancestry.

TOM BEARDEN, NewsHour Correspondent: Rick Kittles is a geneticist, but lately he’s been more of a salesman, traveling across the United States making a pitch to African-Americans. On this night, he spoke to a standing-room-only crowd at the Urban League in Columbus, Ohio.

RICK KITTLES: For decades, all through primary school, middle school, and high school, and college, I wanted to know where I was from. While we know we can claim some part of that dark continent, there’s still this disconnect because we don’t know exactly where in Africa, right?

TOM BEARDEN: What Kittles is selling is the chance for African-Americans to use science to find out where their ancestors came from. His company, African Ancestry, uses DNA to peer deep into the past.

Kittles’ business got a big boost earlier this year when it was included in a PBS series called “African American Lives.” It featured nine prominent people being tested to see where their ancestors came from. Some people, like series host Henry Louis Gates, Jr., were surprised to find that family lore about their origins is just plain wrong.

AFRICAN ANCESTRY EMPLOYEE: The bar chart shows 50 percent European and 50 percent African.

HENRY LOUIS GATES, JR., Host: Does that mean I’m half-white?

AFRICAN ANCESTRY EMPLOYEE: Yes, yes, you could say that.

HENRY LOUIS GATES, JR.: Fifty percent European? I never expected that.

TOM BEARDEN: Kittles tells his audience that you don’t need to be a rich celebrity to get the test. He says advances in technology now make DNA testing affordable for anyone.

AFRICAN ANCESTRY EMPLOYEE: There’s a sample of our results package over on that table…

Science when the paper trail ends

Rick Kittles
African Ancestry
Just like in "CSI," we isolate the DNA that's attached to the cotton swab. And then we do a series of chemical reactions to do the DNA sequencing.

TOM BEARDEN: His company has sold more than 6,000 test kits. Each costs $349. The kits contain two swabs that people use to scrape skin cells from inside their cheeks. The swabs are mailed to a laboratory, which extracts and decodes the DNA.

RICK KITTLES: Just like in "CSI," we isolate the DNA that's attached to the cotton swab. And then we do a series of chemical reactions to do the DNA sequencing.

TOM BEARDEN: DNA is the double-helix of molecules inside cells that carry every animal's genetic information and determines individual hereditary characteristics.

Kittles then compares each sample to a huge database of other DNA samples he has collected over the years, mainly in West Africa. If a match is found, customers get a certificate back in the mail saying they are related to groups of people in specific places in Africa.

RICK KITTLES: There's shared common ancestry within the last 1,000 years, OK? And the samples that we have available are samples from present-day Africans. And so what that means is the match, for instance, from my northern Nigerian ancestor means that I share common ancestry with people in northern Nigeria right now.

TOM BEARDEN: Tamar Johnson has done a fair amount of traditional genealogical research to trace her heritage, but she came to Kittles' presentation because there are almost no written records for people brought here in slavery before the Civil War.

TAMAR JOHNSON, Tracing Ancestry: I've traced us back to about 1880, I believe the census was.

TOM BEARDEN: That's a dead end?

TAMAR JOHNSON: A dead end, because if you go a little bit further back, you're pretty much getting just chattel records, which just gives you more of a gender, no name, and there's no tie. So it's pretty difficult beyond a certain point if you're African-American.

Still a rough science

Deborah Bolnick
Geneticist, University of Texas
There are a huge number of unknowns when you do the test. You are only looking at a few of your ancestors of all of your ancestors' DNA that have been contributed to you.

TOM BEARDEN: The DNA tests aren't just for African-Americans. Some two dozen companies are now selling DNA tests they say can trace anyone's ancestry back to many regions of the world. But some in the scientific community are concerned that people can be misled about just what these tests actually reveal.

Deborah Bolnick is a geneticist at the University of Texas.

DEBORAH BOLNICK, Geneticist, University of Texas: DNA can tell you where other people live in the world today that share identical or similar DNA sequences, but there's no reason to necessarily think that your ancestors must have lived in the same location.

There has been so much migration around the world among humans that your ancestors maybe came from the same general region, but it would be very difficult to pinpoint that specific location based simply on the DNA patterns that exist in the world today.

TOM BEARDEN: She also cautions that these tests only trace one small part of a person's ancestry. There are two main DNA tests. One examines mitochondrial DNA, which is handed down from mother to child.

DEBORAH BOLNICK: The mitochondrial DNA sequence in me is only tracking this one part of my family tree, only of my mother's mother's mother's mother. It doesn't tell me anything about all of my other ancestors.

So if you go back four generations, it's only looking at one out of my 16 ancestors. If you were to take this diagram back much further and look at, say, 10 generations into the past, my mitochondrial DNA will only track one out of over 1,000 of my ancestors. And so it's leaving out a lot of information about the ancestors in my family.

TOM BEARDEN: ... who could have come from anywhere?

DEBORAH BOLNICK: Who could have come from anywhere, yes.

TOM BEARDEN: Bolnick says the same is true for the other commonly used test, which tracks paternal lineage using the y-chromosome. Only men have y-chromosomes.

So the bottom line is there's a lot of unknowns when you do the test?

DEBORAH BOLNICK: Yes, there are a huge number of unknowns when you do the test. You are only looking at a few of your ancestors of all of your ancestors' DNA that have been contributed to you.

Finding one's origins

Spencer Wells
"Journey of Man"
The idea that you can create a cocktail mix of someone, you know, "You are 10 percent such and such, and 80 percent such and such, and so on," that's a little worrying to me, in part because it kind of reifies old-fashioned racial classifications.

TOM BEARDEN: Bolnick says DNA testing for ancestry may become a little more reliable as more and more parts of the world are tested and databases get larger.

Expanding the global database is geneticist Spencer Wells' mission. Wells heads the National Geographic Society's "Genographic Project."

The project kicked off with a PBS documentary called "The Journey of Man." Wells trekked around the world, tracing the early migrations of humans out of Africa 60,000 years ago into Australia, the Middle East, Asia, Europe, and finally into the Americas.

He now heads a team of scientists who are continuing the five-year, $50 million effort to collect 100,000 DNA samples to further refine mankind's history.

SPENCER WELLS, "Journey of Man": Thank you for purchasing the genographic participation kit.

TOM BEARDEN: "National Geographic" is also offering the general public a chance to participate, selling $100 test kits.

SPENCER WELLS: After collecting the sample, move one of the small specimen tubes marked with your participant number.

TOM BEARDEN: But Wells says the results people will get back will be pretty generalized.

SPENCER WELLS: This is not going to tell you about where your grandfather came from in Ireland necessarily. It's about deeper ancestry than that.

Now, you can say some very broad things about where the rest of your genome may have come from, things like, was it Western Eurasia or was it Sub-Saharan Africa? But the idea that you can create a cocktail mix of someone, you know, "You are 10 percent such and such, and 80 percent such and such, and so on," that's a little worrying to me, in part because it kind of reifies old-fashioned racial classifications.

TOM BEARDEN: But many African-Americans say even getting a general idea of where their ancestors came from is better than not knowing anything at all.