Mixed roots: Science looks at family trees
After his parents died, Malcolm Dodd began to suspect he wasn't his father's son. A relative came forward with a story, and the pieces seemed to fit. His father had spent three years fighting in Southeast Asia during World War II, when Mr. Dodd was born. Some sleuthing led him to suspect that his biological father might have been an American soldier stationed in Britain. But Dodd - born and raised in Britain and now retired in Portugal - wanted stronger evidence.
That's when he turned to DNAPrint Genomics Inc., in Sarasota, Fla. He sent the company a cotton swab he had brushed along the inside of his cheek to collect some of his DNA. What he got back wasn't ironclad proof. If anything, it was even more surprising: Some of his ancestors were likely to have been native Americans.
"I expected I would be 100 percent European," Dodd says. The result added to his conviction that his father was an American, and since then he's visited California to follow more leads. "I've got a shrewd idea as to who my father was," he says, although they can't be reunited, since the man died long ago. The DNA test "was a great help," says Dodd, who says he loved the father who raised him as his own and bears no ill will to anyone involved.
Among the many spinoffs from the 2003 completion of the Human Genome Project - a government-funded effort to sequence and map all the human genes - is a new ancestry industry. Companies are using DNA markers passed from generation to generation to let people peer into the past to learn their genetic roots. The DNA data, rarely conclusive on their own, need proper interpretation to be understood fully. And while the for-profit nature of such research raises ethical issues for some, the availability of such tools is proving alluring for many.
In the United States, for example, some people are eager to prove they have native American ancestry in order to join a tribe, many of which are growing wealthy from casino revenues. Others are fascinated to learn of hitherto unknown ties to the past. But in a country where "one drop" of ancestral African blood once meant the risk of enslavement, news of DNA origins can come as a shock.
The bottom line: We're not as racially pure as we think we are.
An African-American, for example, on average will find that he or she has about 20 percent European ancestry, says Tony Frudakis, founder and chief scientific officer of DNAPrint.
Last fall, Samuel Richards, who teaches a race-relations course at Penn State University, arranged for 100 of his students to take the DNA test. About 20 percent were "very surprised" to find out they had a mixed heritage, he says, and about 20 percent more were somewhat surprised. The DNA test helped the students "see outside the race box," Professor Richards says. "We generally think that there are these set and well-demarcated boxes, when race is, in fact, really very fluid and changing."Next year, Professor Richards plans to offer the DNA test to 1,000 of his students.
Sometimes, the tests raise more questions than answers. Richards's wife, Laurie, who also took the test, found that her ancestry was 13 percent native American, 87 percent European. That was odd because she traced her ancestors back to Poland and Ireland and had no knowledge of any native Americans in the family tree. It led her to interview older relatives to try to solve the mystery.
The case also illustrates the limits of DNA testing, says Mark Shriver, a professor of anthropology at Penn State and a consultant for DNAPrint. Native Americans are believed to have immigrated from central Asia thousands of years ago. These same central Asians also migrated into eastern Europe, meaning that her "native American" DNA could have come from there, he says. Greeks and Ashkenazi Jews also may show significant percentages of "native American" ancestry for the same reason. Eventually, a more sophisticated test will be able to sort out these differences, Dr. Shriver adds.
The dozen or more companies doing ancestral research using DNA - with names like DNA Heritage and GeneTree - employ three principal methods. They analyze: 1) mutations of the male Y chromosome to track the geographic origin of male progenitors, 2) the mitochondrial DNA for information about female ancestors, or 3) the 23 chromosome pairs in humans.
"We measure just about all of those," says Dr. Frudakis. He says his company is the only one that looks broadly at 172 genetic markers in both sexes.
So far, DNAPrint has analyzed more than 10,000 samples at a cost of $219 per test. Clients learn what percentage of their ancestral DNA is from four broad population groups: Indo-European, sub-Saharan African, East Asian, or native American. About one-third of clients test as 100 percent from one of these groups; another third show statistically insignificant blending, and a final third show substantial mixtures. A second test can also break down the broad category of Indo-European ancestry into Northern European, Mediterranean, Middle Eastern, and South Asian subgroups. Other new tests may follow.
Brent Kennedy of Kingsport, Tenn., suspected from visual clues and family history that he was more than the Scotch-Irish that most people in the Appalachian region assume as their background. Yet the blue-eyed Mr. Kennedy tested as 100 percent European. He wasn't satisfied.
"My mother looked like she walked out of Saudi Arabia," he says. "And my brother looks very Arabic, like someone out of 'Lawrence of Arabia.' " So he took the second test, which broke down his European background as 45 percent Northern European, 25 percent Middle Eastern, 25 percent Mediterranean (Greek/Turkish), and 5 percent South Asian. Though his brother has a darker complexion, he tested for nearly identical ancestral DNA markers, Kennedy says, just as would be expected of two brothers.
Such DNA tests "upset the apple cart" for some people, who have assumptions about their genetic histories, Kennedy says. "But I think the apple cart needed to be upset." Rather than emphasize differences, he says, "the great social function of these tests is that they absolutely drive home kinship - that [humans] are all related."
Some observers are more skeptical. In a paper in Nature Reviews Genetics last summer, Shriver and colleague Rick Kittles at Ohio State University warn that any DNA-based personalized genetic histories are "far from being an exact science." They urge firms offering genetic histories to provide background materials to help clients understand what conclusions can and cannot be drawn from the statistics. The firms also should urge clients to combine DNA evidence with knowledge gleaned from conventional sources, such as family histories and public records as part of a "mosaic approach," the authors said.
Population geneticists agree that modern humans originated in East Africa and began to spread from there only about 60,000 years ago. Over many generations isolated populations "gradually drifted apart in a very early form of speciation," Frudakis says, creating genetic differences. "It's how nature works. It's a very healthy thing. It instills [a healthy] diversity in a population."
Earlier this month, the National Geographic Society and IBM Corp. announced a plan to take 100,000 blood samples from indigenous populations around the world to build an ancestral DNA database. The Genographic Project is expected to take five years and cost $40 million. Part of the cost is expected to be offset by charging interested people $100 to learn about their paternal or maternal lineage using Y chromosome and mitochondrial DNA testing. The collected data may help answer questions such as: Did Alexander the Great's army leave behind a genetic trail as it conquered much of the ancient world? Which humans first colonized India? Did Homo sapiens interbreed with Neanderthals or possibly with Homo erectus?
"We see this as the 'moon shot' of anthropology, using genetics to fill in the gaps in our knowledge about the connections and differences that make up the human species," said Spencer Wells, the project leader, in announcing the effort.
At least one group, the Indigenous Peoples Council on Biocolonialism (IPCB), has announced its opposition to the research, based on concerns that the data would be misused. The project also conflicts with traditional teachings about ancestral origins, since it promotes the scientific view that all humans originated in east Africa 60,000 to 70,000 years ago.
Dr. Wells, speaking by phone from Delhi, India, where he is promoting the project, says he was surprised by the IPCB's opposition and that a dialogue was under way with the group to address its concerns. The IPCB, he says, was pleased to learn that the project had passed scrutiny by the University of Pennsylvania's Institutional Review Board, which guards the rights of human subjects in clinical trials and addresses other ethical issues involved in scientific research. "We have many ethical and legal safeguards in place to assure that we are in more than full compliance with the law," he adds.
Some biologists and human geneticists not connected with the project say that it will face other ethical and scientific hurdles. "I'm very concerned - not because I think it's a bad idea to study human genetic diversity. I actually think it's a great thing," says Sarah Tishkoff, a biology professor at the University of Maryland who has done extensive research in Africa. "But it has to be thought out extremely carefully." Who will profit from the sale of the ancestry test kits, and will indigenous people be compensated?
"I'm personally very skeptical about what these ancestry kits can tell people," she says. "If this is not done properly in an ethical, careful manner, it can backfire, and it's going to get people very angry and upset and make it very difficult for anybody [else] in the field to do [this kind of] research."
Wells says the quality of the science will be high. "We have 11 leading population geneticists, essentially the best people in the world, engaged as our principal investigators," along with linguists, archaeologists, and other scientists, he says.
