Lots of speculation about how the New World was populated by the old may have been answered by an exhaustive DNA study. The findings: the Americas were settled in three waves from northeast Asia beginning at least 15,000 years ago:
CS Monitor— Ruiz-Linares and colleagues around the world analyzed DNA samples, primarily from blood, taken from hundreds of modern-day Native Americans and other indigenous people representing 52 distinct populations. These included Inuits of east and west Greenland, Canadian groups including the Algonquin and the Ojibwa, and a larger variety of people spanning the southern regions of the Americas from Mexico to Peru.
Investigating patterns in more than 350,000 gene variants, the scientists determined that most of the groups they studied did indeed descend from an original “First American” population.
However, they also saw that Eskimo-Aleut populations of the Arctic inherited almost half of their DNA from a second ancestral group, and the Na-Dene-speaking Chipewyans, from Canada, got about 10 percent of theirs from yet another group.