All in the family, all around the world

Yvonne Lim
yvonne@newstoday.com.sg

AT A time when racial divisions are flaring up once again around the world, one ambitious project to map the genetic family tree of humanity is underlining the fact that we are all cousins — "just separated by 2,000 generations", as Dr Spencer Wells puts it.

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As the director of the Genographic Project, Dr Wells and his team already know, from genetic evidence, that there is an "Eve" — one woman who lived 150,000 years ago in Africa from whom every living woman today is descended.

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Then there is the African "Adam", a man who lived 60,000 years ago, whose Y chromosome, which is passed only from father to son, marks every male today.

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Now what the five-year non-profit project — a collaboration between National Geographic and IBM — aims to do, is map out what happened between then and now.

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To do so, it is inviting anyone to send in DNA samples to find out what surprising lineages they may share with others. The results show the likely paths one's ancestors took over the 150,000-year migratory journey.

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Since its launch in April, more than 60,000 of the US$99.95 ($170) test kits have been sold to the public — the original aim was to collect about 100,000 DNA samples.

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Said Dr Wells in an interview with Today in August: "We're selling something like 1,000 or 1,500 kits a week ... The public seems to be fascinated by this kind of research and we're pleased with the response."

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DNA samples — in the form of cheek swabs that participants take themselves and mail to the testing lab — are analysed for two types of genetic markers. In men, their lineage is traced via the Y chromosome, while women trace their genetic heritage through Mitochondrial DNA (mtDNA), which is passed from mother to offspring only.

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Such genetic "footprints" undergo mutations over the years, and each set of mutations that happen at the specific time and place in history, and end up marking a group of individuals, is known as a haplogroup.

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Broadly, each haplogroup — which is named for an alphabet — marks one particular migratory route across the globe. Haplogroup H, for instance, is found in about half of all Europeans, whose ancestors thousands of years ago moved there from Asia.

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But as this journalist found out when she tested her DNA, a lesser known branch of H also stayed in Asia. Colleague Margaret Thomas found her material lineage marked her with the haplogroup F, which is found in Eastern China, South-west Asia and Japan.

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"The key, take-home message from the search for Adam is that we all spring from a common source and, therefore, we're all more closely related than we ever suspected," said Dr Wells, a population geneticist.

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Another segment of the project focuses on indigenous populations, such as aboriginal tribes, whose DNA contain genetic markers that are key to understanding ancient migratory patterns.

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Proceeds from the public project are channelled back into a fund to support the preservation of such indigenous groups, some of whose cultures are disappearing.