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The Rediff Special/M D Riti

If R Spencer Wells is to be believed, then Adam probably never met Eve if only because Adam came thousands of years after Eve!

Dr Wells and scientists from eight countries have concluded that the original paternal human ancestor might well have been many thousand years younger than the original maternal human ancestor. The supposition no doubts raises several interesting questions about the start and propagation of the human race!

Wells, 33, is an American scientist who runs a laboratory at the Wellcome Trust Centre for Human Genetics at Oxford University, United Kingdom. The WTCHG, which was established in 1994 to undertake research into the genetic basis of common diseases, is located in the Henry Wellcome Building of Genomic Medicine, University of Oxford.

Wells is currently touring India, talking about the origins of the human race and promoting a television programme based on his book, Journey of Man. The TV programme, produced by National Geographic, will go on air at 9 pm on December 15, Indian Standard Time.

Wells says that all human beings originated from Africa and explains why his research shows that the very first man and woman existed thousands of years apart. "There's a different evolutionary history for each region of the genome, but they all are consistent in placing the ancestor of all modern humans alive today in Africa," he says.

Wells and his team have also concluded that the first man to ever walk the earth walked in Africa about 60,000 years ago. Thus, every man alive today has descended from this single African individual. His book, Journey of Man, propounds this Out of Africa theory. [Incidentally, through DNA studies it is thus far believed that the first woman -- the so-called Mitochondrial Eve -- walked the earth as far back as 150,000 years ago!]

The Out of Africa theory propounds that modern humans originated in Africa before slowly spreading across the world. Some modern-day men living in what is now Sudan, Ethiopia, and southern Africa are believed to be the closest living descendants of the first humans to set out on that great journey tens of thousands of years ago. Interestingly, the San Bushmen of the Kalahari have some of the oldest genetic markers in the world even now.

Wells' research traces the journey of our ancestors across the planet, from eastern Africa into the Middle East, from where our common ancestors spread out into South and Southeast Asia, New Guinea, Australia, Central Asia, and Europe.

For India, our earliest ancestors came from Africa and settled along the western coast, with some moving into Sri Lanka and finally to Australia. Wells suggests underwater excavation of the coast of India to hunt for evidence of our common African ancestors in the form of artefacts, especially near the Mumbai coast, right up to Sri Lanka.

His theory proposes that at the end of the Ice Age, Africa began drying up and a small group of human beings began looking for greener terrain to live in. One group moved towards India and from there onto Australia. The other moved through the Middle East into other parts of Asia and later on to Europe. As a part of his research, Wells has also studied the DNA of the Piramalai Kallar tribe of Tamil Nadu.

Modern genetics has debunked the theory that the different human races sprang up simultaneously but independent of each other. Even as recently as 10 years ago, scientists believed that man's common ancestors lived millions, rather than thousands, of years ago and that modern men evolved separately, but simultaneously, thus accounting for the different races. Many still believe that there are clear genetic boundaries between racial groups. However, Wells' work shows that this is simply not true.

But if we all share the same ancestor, why are there now so many different races, colours and sizes of men and women? Actually, the Human Genome Project has proven that about 99.9 percent of the DNA of every human being on the planet is identical; human variation in height, skin colour, and so forth is actually determined by a tiny fraction of the genome.

Wells, who has studied 200 different genetic markers on the Y chromosome in samples from different areas of the world, argues that most people have multiple markers reflecting extensive migration and intermarriage. Simultaneously, we all also carry in our genes the traces of our common African ancestry.

As Professor Chris Stringer of London's Natural History Museum puts it succinctly, "We are all African under the skin."

"You can ultimately trace every female lineage back to a single female who lived in Africa about 150,000 years ago," says Wells.

He and his colleagues have drawn up a genetic family tree of mankind by studying variations in the Y chromosome of more than a thousand men from different communities around the world. The Y chromosome is one of the two sex chromosomes (X and Y) that men carry, while women have two X chromosomes.

To find the common paternal ancestor, Wells and his team drew up a genetic family tree of mankind. They mapped small variations in the Y chromosomes of 1,062 men in 22 geographical areas, including Pakistan, India, Cambodia, Laos, Australia, New Guinea, America, Mali, Sudan, Ethiopia, and Japan.

Wells sums up the journey of man rather succinctly. "The history of humanity is really a history of movement and mixing," he says, with a smile. "We would have to study the history of who had sex with whom, if we want to do this in greater depth, and that can be quite complicated!"

Where will this journey lead to in the future? "In the past, we took control of our genetic destinies and became superior to other animals," says Wells. "In the future, I see us taking control of our biology and thereby changing either it or our biology. Anyway, biology will be easier to change than the genetic code!"

Image: Rahil Shaikh

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