(ORDO NEWS) — Oregon State University scientists have identified two time periods when climate change allowed early humans to migrate from Asia to North America.
The researchers analyzed cores (cylindrical sediment samples) collected in the Pacific Northeast and also performed simulations of ocean conditions.
It turned out that at the end of the last ice age there were two periods when a combination of winter ice cover and ice-free summer conditions was observed. This contributed to the migration of people further south.
Sediment cores collected in the Gulf of Alaska contained molecular traces of algae that grew around sea ice along the coastline.
In two periods – from 22 thousand to 24.5 thousand years ago and from 14.8 thousand to 16.4 thousand years ago – sea ice was present in winter, while the summer period became increasingly warm.
This likely provided early Americans with the opportunity to travel along the coast.
The findings are consistent with a growing body of evidence that the most likely route for the early Americans was the Pacific coastal route, which was in use before the large ice sheets covering much of present-day Canada and parts of the US began to recede.
The early Americans occupied part of Beringia, a land mass in the present-day Bering Strait that created a bridge between Asia and North America.
According to most archaeological evidence, the first peoples of the Americas appeared no earlier than 13,000 years ago.
However, new evidence indicates that people began arriving on the new continent long before the ice-free interior corridor opened.
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