AN INTERVIEW WITH SPENCER WELLS
Geneticist Spencer Wells spends his life traveling the globe taking blood samples from men and women in order to unravel the secrets of the human story: Where did humans come from? How did they spread over the globe? How did different races evolve? In THE JOURNEY OF MAN: A GENETIC ODYSSEY (Princeton University Press), Wells answers those questions for the first time using the latest discoveries of human genetics. We talked to Spencer as he sat for a moment between trips to Lebanon and Tunisia:
You say that there really was an Adam--a common male ancestor for all humans. How did you find that out?
We study a historical document carried in the blood of everyone alive today - DNA. Tiny spelling mistakes - changes in the DNA sequence - that occurred in the past can give us clues about genealogical relationships. If two people share a change, then they are likely to share an ancestor. If we look at the spelling mistakes carried by people all over the world, we find that ultimately all of us share a common ancestor. In the case of the male line, defined by a piece of DNA known as the Y-chromosome, this analysis allows us to trace back to a common male ancestor for everyone alive today. In other words, Adam.