The story of humanity is filled with bold journeys into the unknown, from the first migration into the Americas across the Bering Strait to the Apollo 11 Moon landings. But of all these journeys, none have been more significant than the first expedition our species made out of Africa.
Despite its importance, it seems our understanding of this grand voyage is a little hazy. A new study by the Max Planck Institute for the Science of Human History has used data to chronicle the first expansions of populations out of Africa into East Asia in the Late Pleistocene (125,000-12,000 years ago). Reporting in the journal PLOS ONE, the international team of scientists tracked the first movements into East Asia using archaeological data and palaeoclimate data to create “Least Cost Path” models of migration, essentially the route that encounters the least resistance.
Previous attempts to tell this story have often focused on the so-called “southern route” around the Indian Ocean, however, this new method suggests our ancestors might have actually taken several unusual routes to reach East Asia by crossing through or northwards over the Gobi Desert.
"Archaeological discussions of the migration routes of Pleistocene Homo sapiens have often focused on a 'coastal' route from Africa to Australia, skirting around India and Southeast Asia," study co-author Professor Michael Petraglia, of the Max Planck Institute for the Science of Human History, said in a statement.
"In the context of northern Asia, a route into Siberia has been preferred, avoiding deserts such as the Gobi."
Now, the researchers argue that this idea is not as absurd as it once sounded. The Gobi is presently a “rain shadow desert”, parched of rain because the Tibetan Plateau blocks off precipitation clouds from the Indian Ocean. However, recent research has shown that Central Asian environments might have been dramatically different during the Pleistocene, with changing levels of rain and glacial events in the mountains.
Recent archaeological finds, such as the discovery of Denisovan skull fragments on the Tibetan Plateau, suggest that this environment wasn't totally inhospitable to early humans and our other ancestors. As these new models further highlight, it appears that it wasn't totally necessary for early humans to travel across the Indian coastline then up around to East Asia. Instead, they could have reached East Asia simply by slipping through the Gobi Desert at a time when it was a temporary "green corridor".
“Given what we are increasingly discovering about the flexibility of our species, it would be of no surprise if we were to find early Homo sapiens in the middle of modern deserts or mountainous glacial sheets,” added co-author Dr Patrick Roberts, also of the Max Planck Institute for the Science of Human History.
“We should emphasize that these routes are not ‘real’, definite pathways of Pleistocene human movement. However, they do suggest that we should look for human presence, migration, and interaction with other hominins in new parts of Asia that have been neglected as static voids of archaeology.”