Ever since the discovery of Lucy, the 3.2 million-year-old skeleton of the earliest human ancestor, paleoanthropologists have more or less agreed that Africa is the cradle of mankind and that we are all African in origin.

The only question that remains is about when the first humans fanned out into Europe and Asia. Some say it was over a million years ago, but Dr Spencer Wells, a 33-year-old geneticist based in London who was on a visit to Mumbai recently, says it was just 50,000 years ago. Or just 2,000 generations.

GENEMAN: Wells

So rather than dig for evidence of man's ancestors, Wells chose to voyage across six continents tracking pockets of tribes he believes have the closest links with the first intercontinental travellers. Beginning with the San (Bushmen) tribes of South Africa, believed to be the direct descendants of the first Homo sapiens 100,000 years ago, to the Piramalai Kallar of Tamil Nadu (he was denied permission to visit the Onge and Jarawa tribes of Andaman Islands, another important link), Kazakhs of Central Asia, Navajos of North America and, finally, the Aborigines of Australia.

"If Africa was the cradle of mankind, Central Asia was the nursery," says Wells who believes that Europeans, native Americans and Russians descended from a group living in Central Asia only about 40,000 years ago.

So how does one explain the startling variation-a Bushman doesn't have a lot in common with a Kazakh from the Russian Steppes. Wells feels sexual selection-the way humans choose their mates-and climate fashioned the different races.

Using genetics to unlock human history-Y chromosome tests on blood samples-the peripatetic Wells strings together his fascinating theory in a two-hour documentary, The Journey of Man, to be telecast by National Geographic channel on December 15.

-Sandeep Unnithan

A week short of the 18th anniversary of the world's worst industrial disaster, green activists held a dress rehearsal of sorts in Bhopal. About 30 activists from across the globe climbed the walls of the "sealed" Union Carbide factory wearing gas masks to draw attention to the chemical waste lying there since 1984. It has now contaminated the area to such an extent that the underground water has been declared unfit for drinking.

The activists claim clandestine support from Chief Minister Digvijay Singh, who is reported to have held a round of discussion with Dow Chemicals, which have taken over Union Carbide. There has been a sudden spurt in demonstrations in Bhopal over removal of waste ever since the takeover, with well known NGOs like Greenpeace joining in. The coming weeks are bound to be messy.

-Neeraj Mishra