Recent morphological studies of two groups of skulls support the idea that the New World was settled in two migratory waves, not one, as has been previously suggested by genetic studies. Paleoanthropologists from Brazil, Chile and Germany came to this conclusion by comparing the cranial morphology (or shape of the skulls) of an older group of remains, dating back 11,000 years ago with a more recent gropup of Amerindian skulls. Based on the test results, the scientists believe that 2 groups, one earlier and one much later, began settling  the New World via Beringia; the now-submerged land bridge connecting present-day Russia with Alaska.
     The group of paleoanthropologists commented: "We found that the differences between Early and Late Native American groups match the predictions of a two-migration scenario far better than they do those of any other hypothesis," they continued, stressing the need for further research, stating, "This disparity between our results and those of most genetic studies points to a large gap in our understanding of the peopling of the New World."

Sources: AFP, Yahoo! News (14 June 2010)