The first humans to enter North America may have paused their travel for up to 10,000 years, as they crossed the Bering Strait. This idea is known as the Beringia standstill hypothesis.

Today, the Bering Strait is a body of water 50 miles wide, separating Russia and Alaska. Tens of thousands of years ago, however, a temporary land bridge connected the two continents. Common belief is humans first crossed into North America over that bridge 15,000 years ago.

Genetic analysis points to a separation of Native Americans from Asian ancestors around 25,000 years in the past. Mutations in mitochondrial DNA, present in nearly all Native Americans, are not found in Asian populations. However, the old archaeological evidence of Native Americans comes from just 15,000 years in the past. This finding, made in 2007, suggests the migration east may have halted for up to 10,000 years. New evidence suggests what happened.

The region of Beringia, which included the land bridge, became a home for numerous shrubs, and other plants adapted to the cold environment. Wild grasses and big game dominated the wilderness of east Asia. Researchers speculate numerous remains of human settlements should be left behind from that time. The remains of insects and pollen from that era can still be found in the region. In what is now eastern Russia and western Alaska, large animals likely roamed in great numbers.

Living in the moderate conditions of Beringia would have provided the travelers with animals to hunt, and brush to burn in fires. This area would have provided one of the only sources of firewood in the area, according to the study.

"Adjoining areas to the west and east supported drier plant communities with a higher percentage of grasses during glacial periods. According to Hultén, when warmer and wetter conditions returned to these areas, the land bridge, which he named Beringia, became a center of dispersal for tundra plants," researchers wrote in the article announcing their results.

One of the challenges to this there is the lack of archaeological sites found in the area. Although the land bridge is washed away, many remains should still be found on either side of the strait.

"[A]t least half of Beringia is still above water, so where are the sites? If people were there for 10,000 years, you'd surely see evidence for them by now," David Meltzer, of Southern Methodist University, suggested to Live Science.

The first theory there may have been a pause in the migration was developed by Latin American geneticists in 1997. The new evidence, supporting abundant plant and animal life on Beringia supports that hypothesis.

Research into the Beringia standstill hypothesis was published in the journal Science on 27 February.

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