By analyzing DNA from people in all regions of the world, Spencer Wells has concluded that all humans alive today are descended
from a single man who lived in Africa around 60,000 to 90,000 years ago. Now, Wells is working on the follow-up question: How did this man, sometimes called "Ychromosomal Adam," become the multicultural, globe-spanning body of life known as humanity?
Wells was recently named project director of the National Geographic Society's multiyear Genographic Project, which uses DNA samples to trace human migration out of Africa. In his 2002 book The Journey of Man: A Genetic Odyssey, he shows how genetic data can trace human migrations over the past 50,000 years, as our ancestors wandered out of Africa to fill up the continents of the globe.