The route humans took from Africa to the Americas over the course of tens of thousands of years can now be tracked on the map as if the travelers were moving, albeit extremely slowly, on a series of interconnected superhighways. Alphanumeric route signs, such as I-95, can be recast as alphanumeric genetic markers. In the case of the Y chromosome, for instance, cross the Bab el Mandeb on highway (genetic marker) M168, which becomes M89 when heading north through the Arabian Peninsula. Make a right at M9 and set out toward Mesopotamia and beyond. Once reaching an area north of the Hindu Kush, turn left onto M45. In Siberia, go right and follow M242 until it eventually traverses the land bridge to Alaska. Pick up M3 and proceed to South America.
Mitochondrial DNA and the Y chromosome remain powerful analytical instruments. The National Geographic Society, IBM and the Waitt Family Foundation have joined in a privately funded $40-million collaboration through 2010, research that is primarily devoted to using these tools. With the help of 10 regional academic institutions, the so-called Genographic Project is gathering DNA from up to 100,000 indigenous people worldwide. “What we’re focusing on is the details of how people made the journeys,” says Spencer Wells, who heads the project. In a recent report its researchers found that the Khoisan people of southern Africa remained genetically separate from other Africans for 100,000 years. In another study, they demonstrated that some of the gene pool of Lebanese men can be traced to Christian Crusaders and Muslims from the Arabian Peninsula