Scientists Disprove 'Ice Bridge' Theory of Human Migration

Scientists have long debated about how the first inhabitants arrived to North America, and now one popular "ice bridge" theory has definitively been disproved, according to new research.

The most widely accepted theory is that sometime before 14,000 years ago, humans migrated from Siberia to Alaska by means of a "land bridge" that spanned the Bering Strait. However, in the 1990s, some researchers proposed that North America was first settled by Upper Paleolithic people from Europe, who moved from east to west through Greenland via a glacial "ice bridge." Now, researchers at the University of Missouri and their colleagues have proven that the latter theory is simply not true.

Until now, evidence of the ice bridge theory came from the Chesapeake Bay, where in the early 1970s fishermen aboard the Cinmar stumbled upon an ancient stone blade, along with pieces of a mastodon skeleton. And since radiocarbon dating cannot be done on inanimate objects, scientists just assumed that the blade and mastodon were from the same time period, dating back more than 22,000 years ago.

"For more than two decades, proponents of the ice bridge theory have pointed to similarities between North American stone blades such as the one allegedly dredged from the Chesapeake and blades left by Solutrean foragers in western Europe," Michael J. O'Brien, one of the researchers, explained in a statement. "We know, however, that Solutrean culture began around 22,000 to 17,000 years ago, which is later than North American dates pointed to by ice bridge theorists as proof that Solutrean people populated North America. That includes the date from the Cinmar mastodon."

The researchers blame the lack of first-hand accounts from the crew of the Cinmar, who actually recovered the blade and mastodon remains, for the belief in the ice bridge theory.

"We reviewed countless snag reports from the Bay and the time frame when the snag should've occurred and didn't find anything to corroborate the story. One of the most famous snags of all time - when the crew pulled up a mastodon - and it's just not reported," O'Brien said.

Due to this error more than 40 decades ago, the ice bridge theory lived on, without any real evidence of its validity.

In addition, while investigating the history of the recovered stone tool, the research team also found discrepancies with the origins and the ownership of the ship itself. They found that differences in photographs of the Cinmar, the size of the ship, and where it was assembled all point to contradictions in key pieces of the ice bridge theory.

"Until inaccuracies are cleared up, there really is no reason to accept the find as evidence of anything connected with the early peopling of North America," O'Brien concluded.

The findings were reported in the Journal of Archaeological Science: Reports.

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