Washington, Feb 13 : A new research has determined that humans had inhabited Beringia, which now lies submerged under the icy waters of the Bering Strait, for almost 20,000 years, before stepping into the New World.
Scientists from the University of Florida (UF) Genetics Institute carried out the research.
"Our model makes for a more interesting, complex scenario than the idea that humans diverged from Asians and expanded into the New World in a single event," said Connie Mulligan, an associate professor of anthropology at the College of Liberal Arts and Sciences and assistant director of the UF Genetics Institute.
According to Mulligan, these people didn't know they were going to a new world. They were moving out of Asia and finally reached a landmass that was exposed because of lower sea levels during the last glacial maximum, but two major glaciers blocked their progress into the New World. So they basically stayed put for about 20,000 years.
"When the North American ice sheets started to melt and a passage into the New World opened, we think they left Beringia to go to a better place," he said.
For the research, UF scientists analyzed DNA sequences from Native American, New World and Asian populations with the understanding that modern DNA is forged by an accumulation of events in the distant past, and merged their findings with data from existing archaeological, geological and paleoecological studies.
The result is a unified, interdisciplinary theory of the "peopling" of the New World, which shows a gradual migration and expansion of people from Asia through Siberia and into Beringia starting about 40,000 years ago, a long waiting period in Beringia where the population size remained relatively stable, and finally a rapid expansion into North America through Alaska or Canada about 15,000 years ago.
According to Henry C. Harpending, chairman of anthropology at the University of Utah and a member of the National Academy of Sciences, "The idea that people were stuck in Beringia for a long time is obvious in retrospect, but it has never been promulgated."
"But people were in that neighborhood before the last glacial maximum and didn't get into North America until after it. It's very plausible that a bunch of them were stuck there for thousands of years," he added.
"Our theory predicts much of the archeological evidence is underwater," said Andrew Kitchen, a student in the anthropology department at UF. "That may explain why scientists hadn't really considered a long-term occupation of Beringia," he added.
The research also suggests that the New World was colonized by approximately 1,000 to 5,000 people - a substantially higher number than the 100 or fewer individuals of previous estimates.