The Big Idea Published: August 17, 2009
From Africa to Astoria by Way of Everywhere
The Astoria section of Queens, New York, is one of the most ethnically diverse communities on Earth. At the 30th Avenue Street Festival in July 2008, people of all heritages and complexions mingled among booths offering up Thai charms and Peruvian sweaters, Mexican corn and Italian zeppole. The sun was hot, the mood merrily multicultural. Through the crowd walked a tall, blond man with pale skin rapidly turning red. He stopped occasionally to talk to people, and if he found them obliging, asked if they could spare a few cells from the inside of their cheeks.
Graphic: Oliver Uberti and M. Brody Dittemore, NG Staff
For the past four years Spencer Wells and his colleagues with National Geographic and IBM’s Genographic Project have been traveling the globe, collecting DNA in cheek swabs and blood samples from hundreds of indigenous groups. By comparing their DNA, the project has been retracing the ancient history of human migrations since our species originated in Africa some 200,000 years ago.
The Genographic Project focuses on the Y chromosome in males, which is handed down intact from father to son, and on mitochondrial DNA (mtDNA), which a mother passes to her offspring. Over generations, small, harmless mutations accumulate on these two snippets of DNA; to Wells and other scientists these genetic markers constitute a history book. As ancient human populations migrated out of Africa, splitting off from each other and entering new lands, they accumulated different patterns of markers that reflect that history. Each individual today retains such a pattern.
In recent centuries those prehistoric paths have reconnected in New York and other immigrant havens. “From the beginning of the project,” Wells says, “I’ve wondered if it would be possible to sample all the major lineages on Earth on a single street.” On 30th Avenue he almost did—the 193 volunteers turned out to be carrying genetic markers for virtually all the major migrations that peopled the continents. The only missing lineage was the oldest one, which Genographic scientists found in Khoisan hunter-gatherers in southern Africa; their ancestors initially diverged from other modern humans more than 100,000 years ago.
The DNA of small, relatively unmixed groups like the Khoisan still preserves clear signals of their unique population histories. In places like Queens, where people from around the world have been swapping DNA for generations, those histories are being lost; a Y chromosome, say, doesn’t reflect the whole ancestry of its owner, let alone of a population. If the Genographic Project usually targets populations that have so far escaped the melting pots, it’s precisely because those pots are such a rich confusion of genes.
“Everybody talks about Astoria like it's Greek,” says George Delis, a retired community manager and a Greek immigrant himself. “Well, it’s not Greek. It’s everything.” —Jamie Shreeve
Answer the Following Questions based on the article:
1) Spencer Wells and the other researchers on the Genographic Project examine what material to trace the pattern of migration of Homo sapiens throughout the world?
2) Describe two ways in which humans have physically adapted to the conditions in which they live?
3) Two groups were the earliest to leave Africa – in what two continents did their descendents settle?
4) How many groups migrated into Europe? Where did they come from? How might they differ in appearance based on their backgrounds and where they settled?
5) What were the last two continents settled by early humans? What continent did they travel through on their journey? Why might it have taken them so long to get there?
6) What reasons might account for this migration out of Africa and the movement of humans to virtually every corner of the globe?