Humans somehow made their way into the Americas from distant lands, but knowing precisely when and from where they made the journey are matters of heated scientific debate.
New genetic evidence, however, backs up a chilly northwestern arrival to North America from Siberia about 12,000 years ago, via a temporary land bridge spanning the Bering Strait. The findings further challenge an alternative idea that humans sprinkled in to both North and South America on open sea voyages 30,000 years in the past.
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