by Avrel Seale

National Geographic geneticist Spencer Wells explains the genetic journey that reveals how all humans are descended from a single man, and how we came to look so different. Texas-Harvard-Stanford-Oxford educated Dr. Wells has been following the DNA trail, to genetically reconstruct the migratory patterns of early humans. The markers in the Y chromosome (found only in men) indicate a shared lineage, which makes all humans – one big extended family.

Africa was humanity’s birthplace. Among the living today, the hunting-gathering community of Khoisan of South Africa are probably the oldest and closest, genetically, to humanity’s Y link. The migratory pattern of our early ancestors indicates that the first stream of migrants reached Australia 50,000 years ago. It was only 10,000 years later that another group entered Europe. Dr. Wells reveals a little known fact that 70,000 years ago mankind was almost brought to the brink of extinction when Mt Toba, in Sumatra, erupted. Only 2000 humans survived. 'It was the most powerful volcanic eruption for two million years and dropped thick ash and killed vegetation across the globe. Our research now shows Homo sapiens numbers dropped alarmingly at this time and we only just hung on as a species.'

Genetic markers have appeared in strange places. The eleventh century Crusaders left their distinctive Y chromosome among Lebanese men; Genghis Khan’s genetic legacy has been detected among the Hazaras of Pakistan.

Dr Wells also addresses the very real concern of a global monoculture erasing evidence of our diverse histories. He was interviewed by Avreal Seale in Washington, DC.

Read the entire story in the October - December 2008  print edition of

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