Study suggests first people reached North America via ‘sea ice highway’ around 24,000 years ago

How and when did humans get to North America? It is arguably one of the most hotly debated topics in archaeology. There have been many theories and studies over the years, and a recent study suggests that sea ice may have played a role in one way for people to move farther south.

Traditionally, scientists have believed that around 13,000 years ago, Stone Age hunters made their way across a land bridge between eastern Siberia and western Alaska and eventually walked their way to an ice-free corridor that briefly opened between ice sheets during this time.

However, recent findings, including human footprints in New Mexico which date back to 23,000 years have once again reignited the debate since the discoveries suggest that people made their way onto the continent much earlier.

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What does the recent study propose?

Research presented on December 15 at the American Geophysical Union Annual Meeting (AGU23) suggests that sea ice may have been one way for people to move thousands of years ago.

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While the idea that early Americans may have travelled along the Pacific Coast isn’t new, the conditions were not exactly favourable. In 2020, researchers noted that freshwater from melting glaciers at the time may have created a strong current which would make it difficult for people to travel along the coast.

In line with this, Summer Praetorius the United States Geological Survey (USGS) and her team tried to study climate proxies in ocean sediment from the coast. Archaeologists have previously found evidence of coastal settlements as early as 14,000 years ago.

Although most of the data for Praetorius’ study came from tiny, fossilised plankton, researchers also used climate models to check ocean currents at the time. The abundance and chemistry of these organisms helped scientists reconstruct ocean temperatures, salinity, and sea ice cover.

What did they find?

Praetorious’ team found that ocean currents were twice the strength they are today at the height of the last glacial maximum around 20,000 years ago due to glacial winds and lower sea levels, conditions which would have made travelling by boat nearly impossible.

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Therefore, Praetorius suggests that sincepeople back then who were adapted to the cold, would “rather than having to paddle against this horrible glacial current, maybe they were using the sea ice as a platform.” Similar to how people living in the Arctic travel along sea ice on dog sleds and snowmobiles.

Early Americans could have used the ‘sea ice highway’ to get around and hunt marine mammals, slowly making their way into North America in the process, said Praetorius.

While proving this will be difficult given that most of the archaeological sites are underwater, the recently proposed theory does provide a new framework.

The USGS scientist also noted that the sea ice highway isn’t mutually exclusive with other human migrations which took place later since their models show the Alaskan current had calmed down by 14,000 years ago, making it easier for people to travel by boat along the coast.

(With inputs from agencies)