A new study of DNA suggests North America was originally populated by just a few dozen people who crossed a land bridge from Asia during the last Ice Age.
About 14,000 years ago, humans crossed the Bering land bridge from Siberia to North America, most experts agree.
But just how many intrepid explorers were involved in spawning subsequent populations has not been known.
Previous DNA analyses of the New World's founding looked at just one gene and assumed populations sizes have been constant over time.
The new study looked at nine genomic regions to account for variations in single genes, and it assumed that sizes of founding populations change over time.
The method favored actual genetic data over estimates used in previous calculations.
http://www.livescience.com/289-north-america-settled-70-people-study-concludes.html
