Tuesday, November 20, 2007

All about my mother 23 September 2007

One night in 1987 a biochemist from New Zealand, Allan Wilson, and his American colleague Rebecca Cann were examining a so-far ignored part of human DNA at the University of California, Berkeley, and they made the astonishing discovery that all human beings have the same parents. This DNA in our bodies remains intact through the generations and is passed on from mother to daughter, but also leaves behind traces of the changes or mutations. When these scientists examined this DNA component in the family tree of each of the continents of the earth, they could trace it back to one woman who lived in Africa about 200,000 years ago.

The Nobel Prize winner, James Watson proclaimed, ‘she was the great-great-great….grand-mother of us all’. Obviously, she was not the only woman alive at that time: she was just the luckiest because her children survived to populate the world, while the lines of the descendants of other women became extinct. One of her three lines, which carry the cells of her daughters, is called Manju because scientists believe that this line evolved in India

When I read this in Nayan Chanda’s lively new book, Bound Together: How Traders, Preachers, Adventurers, & Warriors Shaped Globalization, I exclaimed excitedly, ‘I have found my mother!’ This thrilling history of globalization describes how human beings have been moving and connecting ever since we evolved from the apes. Chanda goes on to explain that in 2000, the Italian geneticist, Luigi Luca Cavalli-Sforza and Peter Underhill found that our father had also come from Africa. They proved this in a study of the Y chromosome which determines the male sex. Our ancestors left Africa only fifty thousand years ago and we can track their genomic journey as they crossed many Ram Setu-like land bridges that are now submerged in the sea. The most famous of these connected Russia with Alaska and explains why American Indians have Asian features. Our migrant ancestors tended to settle down in a region, and hence geneticists can trace the Y chromosome to that region.

If an enterprising Indian reader of this column has his DNA examined he will find that it contains M52 Y-chromosome which dominates on our subcontinent. Nayan Chanda did that. He ordered a kit from National Geographic, dutifully swabbed DNA from his cheeks, and mailed off the vials labeled with a serial number. A few weeks later he logged in his serial number on their website, and discovered that indeed he was from India. But he also found that he had left behind ancestors in Ethiopia, Middle East and Central Asia and other places. ‘It was like finding my family passport with stamps of the countries my ancestors passed through’, he writes.

This is because migrations came in successive waves and hence Wilson’s team has found that all human beings have multiple origins. We are all time-walkers out of Africa and can now trace our ancestors around the world. We are mongrels, and this evidence has finally destroyed the ugly theory of distinct races. Some of us are white, others are black because we have had to adapt to different climates; the Chinese have narrow eyes because their ancestors had to protect them from the blinding sunlight of the snowy Arctic lands. It is quite wonderful I think how science has confirmed the splendid aphorism of the Panchatantra: ‘Vasudhaiva kutumbakam’ or ‘the whole world is a family’. I try to remember this when I get angry with the U.S. for invading Iraq, or upset with Prakash Karat for obstructing the nuclear treaty, or enraged by foreign Islamists for bombing our trains.

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