(ORDO NEWS) — An ice barrier up to 300 stories high taller than any building on Earth may have prevented the first humans from reaching the New World via a land bridge that once connected Asia to the Americas, a new study says.
The results suggest that the first people in the Americas arrived by boat along the Pacific coast, the researchers said.
There are two main hypotheses about how humans first migrated to North America. According to an older idea, people made this journey when Beringia the territory that once connected Asia and North America, now divided by the Bering Strait was relatively ice free.
According to a later view, travelers made their way on watercraft along the Pacific coast of Asia, Beringia and North America.
The main factor influencing the way the first Americans arrived was the giant ice sheets that once covered North America. Previous research has shown that an ice free corridor between the edges of these ice sheets could have allowed travel from Beringia to the Great Plains.
Based on stone tools dating back 13,400 years, archaeologists have long assumed that people from the prehistoric culture known as Clovis were the first to migrate from Asia to the Americas. Previous work regarding the age of the ice corridor has suggested that it may have served as a migration route for the Clovis people.
Recently, however, scientists have uncovered a wealth of evidence for the presence of pre-Clovis humans in North America.
For example, in 2021, 60 ancient footprints in New Mexico suggested that people appeared there about 23,000 years ago, and in 2020, archaeologists discovered stone artifacts in central Mexico that are at least 26,500 years old.
According to the latest estimates, the ice-free corridor was discovered no earlier than 14-15 thousand years ago, which means that the first Americans could not use the land, but the coastal route. However, there remained a great deal of uncertainty about the age of the ice-free corridor.
To help solve this mystery, the researchers tried to determine exactly when the ice-free corridor opened. They examined 64 geological samples taken from six locations located 745 miles (1,200 kilometers) along a zone where an ice-free corridor was thought to exist.
Scientists have studied boulders that glaciers once carried away from their original habitats, much like rivers wash away pebbles in their channels over time.
They analyzed how long these rocks had been on the Earth’s surface – and therefore how long they had been on ice-free ground – by the levels of radioactive elements that were formed when the rocks were bombarded with high-energy beams from space.
The new findings suggest that the ice-free corridor did not fully open until 13,800 years ago, and that the ice sheets “may have been 1,500 to 3,000 feet (455-910 m) high in the area where they covered the ice-free corridor,” lead study author Jori Clark, a geologist and archaeologist at the University of Oregon, told Live Science.
For comparison, the height of the tallest building in the world, the Burj Khalifa in Dubai, is 2,722 feet (829.8 m).
“This is a very well-done study that addresses a longstanding question,” Matthew Bennett, a trace fossil researcher at Bournemouth University in England, who was not involved in the work, told Live Science.
The results are interesting and help to deepen our understanding of this potential migration route.” The authors are to be commended for their excellent scientific work.”
Overall, “we now have solid evidence that the ice-free corridor was not open and available for America’s first settlement,” Clarke said. However, “we still have a lot to learn about whether they really came via a coastal route, and if so, how they traveled. We need to find archaeological sites in the area.”
After the first wave of migration and the opening of the ice-free corridor, other waves of migration may have taken this more direct route, Clark noted. “But again, we need to find the archeological sites in the ice-free corridor to assess when they left.”
John Hoffecker, a paleoanthropologist at the University of Colorado at Boulder who was not involved in this study, noted that the earliest traces of humans in the Americas may indicate that humans were present when both coastal and inland routes to North America were blocked by ice.
If so, “the simplest explanation is that they followed an inland path through a wide ice-free corridor that existed until 30,000 years ago.
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