Did All Modern Human Evolve From Africa?

Scientists in southern China have discovered human teeth dating back at least 80,000 years -- 20,000 years earlier than modern humans were previously believed to have left Africa to migrate around the world.

The 47 teeth were found in a cave in Daoxian, in China's Hunan province, and are the strongest proof yet that modern humans first migrated from Africa to Asia 80,000 to 120,000 years ago, according to a study published in the journal, Nature.

"This is stunning, it's major league," Michael Petraglia, an archaeologist from the University of Oxford in the UK, who was not involved in the study, told Nature. "It's one of the most important finds coming out of Asia in the last decade."

The widely accepted theory of modern human migration, known as "Out of Africa," is based on

available scientific evidence that indicates modern humans originated in Africa and made their first successful migration to the rest of the world in a single wave between 50,000 and 70,000 years ago.

These teeth challenge that theory, both in terms of the timing of the first migration from Africa and whether a different group of modern humans evolved separately in Asia. 

Maria Martinón-Torres, a researcher at University College London and one of the co-leads of the study, said the new finds open up a raft of questions to be answered.

"What does this mean? What is the origin of this population (of people in China)? And what is their fate?" she asked. "Some people really now have to reconsider models. Maybe there's not only one (migration) out of Africa, (maybe) there are several out of Africa."

"And also we have to understand what happened in Asia," she added. "These populations, did they really evolve also for a while outside Africa?"

The research also raises questions about how and why modern humans reached Asia earlier than Europe, where the earliest modern human remains found so far are around 45,000 years old.

Liu said the research group plans to extract DNA from the teeth samples to shed more light on the origins of the Daoxian people.