Video of the event
Aravinda Chakravarti's slides
Scott Woodward's slides
Sandra Soo-Jin Lee's slides
Transcript of the event
DNA, life’s biochemical book of instructions, also narrates humankind’s migration out of Africa and around the globe. Over tens of thousands of years, variations have appeared in individuals’ DNA. Their descendents inherited these variations and carried them forth generation after generation. Like signposts, these variations are charted by scientists from today’s humans back thousands of years to their ancestors’ geographic origins.
At the most recent Genetics Perspectives on Policy Seminar (GenePOPS) on March 2, an expert panel moderated by Center Director Kathy Hudson discussed how genetics is used to trace human migrations, grow family trees, and characterize diversity. Together they explored how genetics research challenges conventional notions of race in society and medicine and how it stands to redefine us as individuals and as populations. The event drew more than 70 audience members.
Geographical origins and genetic diversity
Aravinda Chakravarti of Johns Hopkins’ Institute of Genetic Medicine kicked off the seminar, emphasizing that despite the wide variation we see in physical characteristics, humans as a species are incredibly similar. In fact, he said, other primates such as gorillas and chimpanzees are far more genetically diverse than we – a result of their much larger ancestral populations. And while much is made about our differences, the landmark Human Genome Project showed that genetically we are 99.9 percent the same.
Chakravarti said the conventions frequently used to classify people have no basis in genetic variation, although “Geography has been the major determinant of genetic differences.”
With a map showing the global distribution of the mutation that causes sickle cell disease, he illustrated geography’s effect on gene patterning. Dark red blots indicated a higher frequency. Moving outward from the center of these blots, areas on the map bled gradually to pink, indicating a lower frequency of the mutation. “There are seldom any sharp, distinctive, and sudden boundaries” by geography, he said, explaining that the sickle cell pattern holds true for many other genes that have been studied.
National Geographic’s Genographic Project – a blend of science, adventure moviemaking, and philanthropy – collects DNA from people around the world in an effort to map ancient global human migrations. Project Director Spencer Wells presented a clip from his PBS documentary Journey of Man, which gave an overview of the project and chronicled its preliminary phase.
The project will collect 100,000 DNA samples from 10 different isolated indigenous populations over the course of the next five years. Wells defined indigenous as “people [whose ancestors] have lived in the same place for a very long period of time.” DNA analysis of these populations will provide the project with “insights into the genetic patterns of their ancestors,” he said. So far the project has sampled more than 25,000 indigenous people.
Although the focus is on isolated populations, the project gives everyone the opportunity to contribute and learn about their personal ancestries. The same DNA test kits used in the field to sample indigenous peoples can be purchased by the public from the project’s Web site. Proceeds from kit sales help support the project and the Legacy Fund, which makes grant funds available to the indigenous communities from which samples are collected.
Thus far, the public’s interest in the project exceeds expectations, with nearly 200,000 kits sold so far. Wells hopes to publish the project’s most recent findings in a peer-reviewed journal later this year.
Scott Woodward, director of the Sorenson Molecular Genealogy Foundation, said his organization’s goal is “to bring families together.” The non-profit foundation maintains a database of genetic information correlated to paper genealogical records. Contributing to the database is free; the only condition is that participants must submit four generations of family records with their DNA. This is a challenge for some, but anyone is free to search records in the online database.
The foundation incorporates three kinds of DNA into its database: Y-chromosome DNA, which is passed down from father to son; mitochondrial DNA, which is inherited from mother to child; and autosomal DNA, which represents the bulk of DNA in the body, and is inherited in equal parts from both parents. With enough DNA data and written records, Woodward said that someday, “we’ll be able to take any two of you in this room and sit you down at the table and not just show you that you are related to each other, but specifically how you are related.” So far, the foundation has collected more than 75,000 samples.
A recent proliferation of genetic ancestry testing companies, many of which sell kits online, has given individuals a swift, easy route to explore their family heritages. Most provide only Y-chromosome or mitochondrial DNA analysis. But as Woodward pointed out, these tests are of limited use without accompanying genealogical records. He said autosomal DNA is more difficult to analyze but “has a lot more information about who we are and how we are connected.” As autosomal DNA analysis technology improves, Woodward foresees discovering the genetic makeup of populations from the last 500 years.
Implications of genetic ancestry testing
Like medically-related genetic tests, those that test for ancestry have consequences, according to Sandra Soo-Jin Lee, senior research scholar at Stanford’s Center for Biomedical Ethics. She cautioned that “the decision-making process when you’re in front of the Internet and you want to buy one of these services is very quick, without, perhaps, a lot of time to think about what the broader implications might be.”
She cited the case of Wayne Joseph, a self-identified black American in his fifties who sent off a DNA sample to be tested. The testing company reported he was 57 percent European, 39 percent Native American, and 4 percent East Asian – but 0 percent African. The results forced Joseph to reconsider his ethnic identity and, according to Lee, “puts in stark relief how this information may challenge personal ideas about who and what we are.”
Lee said defining people by their genetic ancestry also has societal implications, including the way we think about race. She said that although the science of genetic ancestry is reported with nuances, “somehow the ways in which it gets translated to the public is through a prism of conventional ideas about skin color.”
To illustrate her point she displayed a cover Scientific American cover bearing portraits of six women who appeared virtually identical with the exception of skin color. The caption read, “Does race exist? Science has the answer.” The cover implies race can be deciphered scientifically, and that it is a matter of skin color. But, Lee said, “race is not genetic, but a product of sociohistorical processes that changes depending on what social context you are in.”
Lee’s other concerns about genetic ancestry tests centered around risks posed by “recreational genetics” generally. She cited privacy risks and genetic counseling needs as areas that should be evaluated. Misinterpretation of results, she said, “could prove to be quite psychologically damaging.”
When the talks concluded, panelists fielded questions from the audience including: How do companies assure genetic privacy? How do people cope with genetic studies that may conflict with cultural stories about ancestral origins? How are some testing companies able to return results in percentages of geographical origins, e.g., 60% African, 20% Native American, and 20% European? What oversight is there for genetic ancestry testing?
Genetic privacy is a major issue in medicine, research, and ancestry genetic testing. Both Wells and Woodward described how their organizations deal with privacy issues, assuring the audience that samples and information are coded in a way that protects confidentiality.
Asked to comment on explaining the Genographic Project to indigenous peoples, Wells cited the Tubu people of Chad who, he said, were very interested in the project because of their conflicting stories about their tribal origins. He said, “they actually want to get the information back… it’s not meant to replace a traditional belief. It’s meant to accentuate it.”
Lee also responded, saying, “one of the difficulties is knowing what the motivations are for people who engage or who want to have these services done... and making sure that once they get the information, that they’re able to process it in a way that makes sense.” She added, “It’s very important to make sure that the individuals who are signing up understand what the parameters are.”
Companies that return test results in percentages of geographic origin do so by comparing a client’s DNA to ancestry informative markers – essentially gene signatures that are thought to be indicative of a particular geographic region. While Chakravarti did not disagree with the principle of this method, he cautioned there is not enough data to rule out these markers’ existence in other, still-unsampled populations.
Asked about who ensures the accuracy of genetic genealogy tests, Woodward responded, “we need to make sure that people have access to reputable testing companies.” He said his foundation’s labs are certified by the AABB (American Association of Blood Banks), and that they use a double-blind process to analyze data.
It is unclear what the future holds for genetic ancestry testing. Lee said testing already is being explored as grounds to establish tribal membership or refugee status, or to qualify for certain programs, such as college admissions.
Read the transcript of the event