When Did People Arrive in the Americas?

LAWRENCE, KANSAS—Bethany Potter of the University of Kansas and her colleagues reviewed migration models for the arrival of modern humans in the Americas, Phys.org reports. They then compared the possible arrival times—either before the Last Glacial Maximum, more than 25,000 years ago; during the Last Glacial Maximum, between 20,000 and 14,000 years ago; or after the ice finally retreated, some 14,000 years ago—with DNA samples, archaeological evidence, and environmental data. Genetic evidence indicates that population lineages had already split into Northern and Southern Native American lineages some 15,000 years ago. No DNA evidence for such splits in the population more than 25,000 years ago have been identified. Archaeological evidence of human activity before 25,000 years ago may have been left by groups of people who did not survive or did not leave many descendants. According to the researchers, it is also possible their DNA has yet to be recovered or identified in later populations. The study therefore suggests that it is most likely that people arrived in the Americas between 20,000 and 14,000 years ago. “It is critical that paleogenomics research be rooted in questions articulated by archaeologists and tribal historians, and that such research be attuned to the needs and priorities of descendant communities,” Potter concluded. Read the original scholarly article about this research in Current Opinion in Genetics & Development. To read more about theories regarding how the Americas were populated, go to "America, in the Beginning."