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The first American settlers traveled there on an "ice highway"

The debate over the first human settlement of America has long captivated the archaeological community. Traditional theories posited that early humans arrived in American through an ice-free corridor around 13,000 years ago.

However, recent archaeological and genetic discoveries, such as the 23,000-year-old human footprints found in New Mexico, challenge this timeline, suggesting an earlier arrival.

First Americans traveled on ice

Increasing evidence indicates that the first Americans might have traversed the Pacific coastline from Beringia, a land bridge connecting Asia and North America. This route became accessible during the last glacial maximum as ice sheets trapped vast water amounts, lowering sea levels.

At the American Geophysical Union Annual Meeting (AGU23) in San Francisco, researchers presented paleoclimate reconstructions of the Pacific Northwest. These findings suggest that sea ice might have facilitated southward migration.

The kelp highway hypothesis

The idea of coastal migration isn’t novel. Scientists speculate that early Americans were south of the continental ice sheets at least 16,000 years ago, long before the ice-free corridor opened.

The “kelp highway” theory proposes that these individuals traveled in boats down into North America, exploiting coastal waters’ rich resources.

Archaeological evidence from western Canada indicates coastal settlements dating back to 14,000 years ago. However, a 2020 study highlighted potential challenges to coastal migration, such as strong currents from glacial meltwater.

Ocean conditions for the first Americans

Summer Praetorius from the US Geological Survey and colleagues turned to climate proxies in ocean sediment to understand ocean conditions during these migration periods. By analyzing fossilized plankton, they reconstructed past ocean temperatures, salinity, and sea ice cover.

Praetorius’ presentation is part of a session focusing on the Pleistocene climate history and geology of Beringia and the North Pacific. The AGU23 conference, attracting over 24,000 experts, explores various Earth and space science topics.

Praetorius’ team used climate models and discovered that, around 20,000 years ago, ocean currents were over twice as strong as today, making boat travel challenging. However, their records also indicated significant winter sea ice presence until about 15,000 years ago.

The sea ice highway concept

Praetorius suggests that early Americans, adapted to cold environments, might have used sea ice as a platform for migration, similar to how Arctic people today use dog sleds and snowmobiles.

This “sea ice highway” could have been a viable route between 24,500-22,000 and 16,400-14,800 years ago.

While proving sea ice travel remains challenging due to underwater archaeological sites, this theory offers a new perspective on how humans might have reached North America.

Praetorius emphasizes that various migration methods, including sea ice and later coastal boat travel, are not mutually exclusive. Praetorius concludes, “Nothing is off the table. We will always be surprised by ancient human ingenuity.”

This statement encapsulates the ongoing quest to understand the complex and ingenious ways early humans conquered new frontiers.


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