Y Trail of the First Americans: DNA data point to late New World entry

People first set foot in the Americas no earlier than about 18,000 years ago, according to an analysis of a newly identified gene variant on the Y chromosome.

This evidence supports the longstanding archaeological theory that New World settlers crossed a land bridge from Asia to North America about 14,000 years ago, say geneticist Mark Seielstad of the Genome Institute of Singapore and his colleagues.