Like pigeons, humans live just about everywhere on the planet, and have proved themselves highly effective colonizers of all types of terrain. Yet it was in Africa that our species was spawned, and only following an ambitious and adventurous journey did we paste ourselves across the globe. The route our ancestors took out of Africa has been hotly debated by scientists, which is why geneticists at Harvard Medical School have come up with a new model that may help to finally map out our history.
As more DNA from ancient humans and other extinct hominin species becomes available for analysis, our ability to trace the early expansion of our species continually increases. This has led to the publication of numerous genetic studies, though while they all agree that Homo sapiens migrated out of Africa around 100,000 years ago, they disagree on many of the details.
For example, some evidence suggests that humans left Africa in a single migration, while conflicting data implies that our forefathers migrated from Africa in several waves.
One such wave is said to have headed to Southeast Asia and Australasia, implying that aboriginal people in these regions descend from a distinct group of African emigrants.
Publishing their work in the journal Molecular Biology and Evolution, the study authors pool together genetic information from all existing "Out of Africa" studies. This provided them with detailed DNA sampling of several modern human populations as well as every extinct hominid known to man.
Using this information, they conclude after humans left Africa, a major eastern-western population split took place. They estimate that this split occurred around 45,000 years ago, and include Southeast Asians and Australasians in the eastern group.
As such, they find no evidence for a distinct migration from Africa to these regions, although the study authors concede that their data sets are incomplete, and must be continually refined as more genetic information becomes available.
"We view our model as a detailed synthesis of existing data and a good basis for further work," said study co-author Mark Lipson in a statement, suggesting that while the model presented in this study provides a good starting point for retracing mankind’s journey from the cradle of life, much more work is still needed in order to fully recreate our ancestors’ incredible adventure.