Emily Chan
For decades, experts believed that early humans first arrived in North America around 13,000 years ago by crossing Beringia, a piece of land that served as a gateway between continents. It connected Alaska with the northeastern tip of Asia. Then, the people would walk through an ice-free corridor that briefly opened up between ice sheets.
However, new archaeological finds, such as the remains of human footprints in New Mexico, suggest that people actually first reached North America using a “sea-ice highway” as far back as 24,000 years ago.
The footprints date back to around 23,000 years old. These early Americans most likely came from northeast Asia and made their way to North America in boats along the Pacific coastline.
This would have been the only available route to take them farther south during that time period since the ice-free corridor did not completely open until thousands of years later.
However, traveling through the sea-ice highway seemed like a difficult journey during the late Pleistocene era, which lasted from 2.58 million years ago to about 12,000 years ago.
In 2020, researchers found that freshwater from melting glaciers at the time may have created a strong current that caused traveling along the coast to be a challenge.
To learn more about ocean conditions during this significant phase of human migration, Summer Praetorius from the U.S. Geological Survey and her team produced a computer-simulated model of the climate during the late Pleistocene era. Their goal was to narrow down the best points in time humans were able to venture along the coast.
They gathered data from ocean sediments collected on the coast, most of which consisted of tiny, fossilized plankton. These organisms helped the scientists reconstruct ancient ocean temperatures, salinity, and sea ice cover.
They discovered that the ocean currents during the height of the last glacial maximum (LGM) 20,000 years ago were two times stronger than they are today because of glacial winds and low sea levels. This would make paddling against the current very strenuous work.
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