North America's First People May Have Arrived by Sea Ice Highway as Early as 24,000 Years Ago
upstart writes:
North America's first people may have arrived by sea ice highway as early as 24,000 years ago:
One of the hottest debates in archaeology is how and when humans first arrived in North America. Archaeologists have traditionally argued that people walked through an ice-free corridor that briefly opened between ice sheets an estimated 13,000 years ago.
But a growing number of archaeological and genetic finds-including human footprints in New Mexico dated to around 23,000 years old-suggests that people made their way onto the continent much earlier. These early Americans likely traveled along the Pacific coastline from Beringia, the land bridge between Asia and North America that emerged during the last glacial maximum when ice sheets bound up large amounts of water causing sea levels to fall.
Now, in research to be presented Friday, 15 December at the American Geophysical Union Annual Meeting (AGU23) in San Franciso, paleoclimate reconstructions of the Pacific Northwest hint that sea ice may have been one way for people to move farther south.
[...] To get a fuller picture of ocean conditions during these crucial windows of human migration, Summer Praetorius of the US Geological Survey and her colleagues looked at climate proxies in ocean sediment from the coast. Most of the data came from tiny, fossilized plankton. The abundance and chemistry of these organisms help reconstruct ocean temperatures, salinity, and sea ice cover.
[...] Praetorious' team used climate models and found that ocean currents were more than twice the strength they are today during the height of the last glacial maximum around 20,000 years ago due to glacial winds and lower sea levels. While not impossible to paddle against, these conditions would have made traveling by boat very difficult, Praetorius said.
However, the records also showed that much of the area was home to winter sea ice until around 15,000 years ago. As a cold-adapted people, "rather than having to paddle against this horrible glacial current, maybe they were using the sea ice as a platform," Praetorius said.
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