How did people first get to America?
The route by which people first entered the Americas from Asia – and when it happened – has generated decades of research.
Now, a new study concludes that both an inland route through present-day western Canada along with a route along the Pacific coast should be considered as viable pathways for the first humans' foray into the Americas.
The inland route theory – known as the "Ice Free Corridor" – suggests humans moved across present-day Alaska and the Yukon, then took a right turn between two massive ice sheets. They then trekked along the British Columbia/Alberta border into the northern Plains of the present-day United States. This theory was the established thinking for much of the 20th century.
The other "North Pacific Route," also known as the "Kelp Highway," said humans traveled along the west coast of North America and has become the favored hypothesis over the past 20 years.
“We can’t exclude either coastal or inland routes for the first Americans,” study lead author Ben Potter of the University of Alaska-Fairbanks said at a press conference earlier in the week. "I suspect both probably were used."
He added that "what we wanted to do was provide a framework to discuss the peopling process – not based on speculation but rather on a careful and critical review of the current evidence we have."
"Rather than confusion, there really is growing congruence of the archaeological record, the paleoecological and the genetic records," he said.
“As geneticists and archaeologists and Indigenous communities work together in a respectful and mutually beneficial manner,” the study said, “the opportunities to analyze additional human remains to infer population history in the Americas grow.”
The peopling wasn't all at once, either: It happened in "pulses" of migration. Current evidence shows that there are three primary branches of Native American ancestors, Potter said.
One group, southern Native Americans, penetrated through all of North and South America. Another group, northern Native Americans, are present now in northern parts of North America.
A third group, Ancient Beringians, were located in the far north, in Beringia and present-day Alaska and the Yukon Territory. (Beringia was an area of land that covered both Siberia and Alaska, much of which no longer exists.)
And as for when this all happened, the data suggests that "peopling occurred between 16,000-14,000 years ago," Potter said.
The study argued that more research is needed to determine how the migration occurred.
“It’s premature to speculate we know at this point with such certainty,” Potter said. “We’re saying there’s not enough evidence yet – we need more science on both routes.”
The study was published Wednesday in the peer-reviewed journal Science Advances.