Science Looks At Family Trees
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MIXED ROOTS: SCIENCE LOOKS AT FAMILY TREES
By Gregory M. Lamb
Christian Science Monitor
April 28, 2005
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
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
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
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."
History lessons sought from ancestral database
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
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
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.
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