When humans migrated from Africa about 60,000 years ago as studies suggest, they moved for one of the same basic reasons people move today. They thought they would find better opportunities.

Of course in those times, better opportunities usually meant more plentiful food and water, said Spencer Wells, the scientist who has led the effort to study that migration.

Wells, an official explorer for National Geographic who spoke at the Medical University of South Carolina Wednesday, has spent the past six years collecting more than 400,000 DNA samples from people around the globe to map humanity's migration from Africa.

As part of the so-called Genographic Project, Wells' team has collected samples from indigenous people in remote field offices and has sold "public participation" kits to people in the industrialized world.

Some people might know about their ancestry through documents or oral history, but eventually they hit what Wells called the "brick wall" of research.

DNA samples can trace ancestral history to the original waves of migration from the African continent, he said.

The lecture was part of a three-day global health event at MUSC.