Bering land bridge - The Full Wiki

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Bering land bridge - The Full Wiki: The Bering land bridge is significant for several reasons, not least because it is believed to have enabled human migration to the Americas from Asia about 25,000 years ago.[8] A study by Hey[9] has indicated that of the people migrating across this land bridge during that time period, only 70 left their genetic print in modern descendants, a minute effective founder population—easily misread as though implying that only 70 people crossed to North America. Seagoing coastal settlers may also have crossed much earlier, but scientific opinion remains divided on this point, and the coastal sites that would offer further information now lie submerged in up to a hundred metres of water offshore. Land animals were able to migrate through Beringia as well, bringing mammals that evolved in Asia to North America, mammals such as proboscideans and lions, which evolved into now-extinct endemic North American species, and allowing equids and camelids that evolved in North America (and later became extinct there) to migrate to Asia.

A study published in 2007 in PLoS Genetics, led by University of Michigan and University College London researchers, suggests that the Bering land bridge migration occurred 12,000 years ago, that every human who migrated across the land bridge came from Eastern Siberia, and that every Native American is directly descended from that same group of Eastern Siberian migrants.[10] The authors note a "unique genetic variant widespread in natives across both continents — suggesting that the first humans in the Americas came in a single migration or multiple waves from a single source, not in waves of migrations from different sources".