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Some argue that humans flourished for thousands of years on a fertile intercontinental land bridge until melting glaciers opened the route to the Americas. But major gaps in the evidence remain.
Twenty thousand years ago, the Earth was hostile territory. Hulking glaciers smothered much of North America. Deserts claimed swathes of every continent, and winters were 40 degrees colder than today in some spots. But far to the north lay a sprawling, unlikely haven that stretched from modern-day Canada to Siberia. This was Beringia, a refuge of tundra and grasslands dotted with wildflowers, ponds, and scrubby willow trees. Mammoths and bison roamed its plains for thousands of years. And, if a controversial theory is to be believed, people did too.
About 20,000 years ago, when the Earth was still in the throes of the last major ice age, humans are thought to have inhabited Beringia, which stretched from modern-day Canada to Siberia. The general vicinity includes well-established archeological sites (labeled here) from before and after that ice age. But little evidence supports the presence of humans in Beringia at the right time. Bones at the Bluefish Caves site have been dated to the ice age, but that timing is controversial. Reproduced with permission from ref. 8 and adapted by Lucy Reading-Ikkanda (graphic artist).
Researchers once envisioned Beringia, an area that included the now-submerged land bridge connecting Alaska to Siberia, as flyover country, a mere corridor to the New World. But growing evidence suggests that bands of hunter-gathers from Asia tarried there for thousands of years. An idea originally devised to explain genetic variation among Native Americans is now reaping support from fields as disparate as linguistics and paleoecology. Recent analyses of massive DNA databases and ancient DNA have only shored up the genetic underpinnings of the theory, known as the …
A long layover en route to the Americas?
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