New Theory on American Migration

via ScienceDaily, a new theory has been proposed regarding the migration of Native Americans to the New World based on DNA research conducted by the University of Illinois. The new theory speculates that the Bering "Land Bridge" connecting Siberia and Alaska 30,000 years ago didn't allow the peoples that entered the area to move on into the Americas initially. Rather, they tarried in the area for a period of up to 15,000 years, with some groups actually returning back to Asia, before moving on to populate the empty American continents.

"the ancestors of Native Americans who first left Siberia for greener pastures perhaps as much as 30,000 years ago, came to a standstill on Beringia – a landmass that existed during the last glacial maximum that extended from Northeastern Siberia to Western Alaska, including the Bering land bridge – and they were isolated there long enough – as much as 15,000 years – to maturate and differentiate themselves genetically from their Asian sisters."

623 DNA sequences were examined, including 20 new ones from the Americas and 7 from Asia, and 3 new sub-clades (a group of DNA sequences descended from a common ancestor) were discovered that covers nearly all of the American populations but not found in Asia. This discovery appears to solidify both the archaeological evidence in the Americas (nothing has been found from before 15,000 years ago that can be definitively dated) and the climate evidence showing that the Rocky Mountains were impassible due to glaciation before that time.