Moore Foundation grantee Beth Shapiro and colleagues at UC Santa Cruz have determined when an ice-free corridor opened up along the Rocky Mountains during the late Pleistocene using evidence from bison fossils.
The corridor has been considered a potential route for human and animal migrations between the far north (Alaska and Yukon) and the rest of North America, but when and how it was used has long been uncertain.
The researchers combined radiocarbon dating and DNA analysis to track the movements of into the corridor, showing that it was fully open by about 13,000 years ago. Their findings indicate that the corridor could not account for the initial dispersal of humans south of the ice sheets, but could have been used for later movements of people and animals, both northward and southward.
In the 1970s, geological studies suggested that the corridor might have been the pathway for the first movement of humans southward from Alaska to colonize the rest of the Americas. More recent evidence, however, indicated that the Cordilleran and Laurentide ice sheets coalesced at the height of the last ice age, around 21,000 years ago, closing the corridor much earlier than any evidence of humans south of the ice sheets.
The initial southward movement of people into the Americas more than 15,000 years ago now seems likely to have been via a Pacific coastal route, but the Rocky Mountains corridor has remained of interest as a potential route for later migrations.
Previous work by Shapiro showed the bison populations north and south of the ice sheets were genetically distinct by the time the corridor opened. By analyzing bison fossils from within the corridor region, the researchers were able track the movement of northern bison southward into the corridor and southern bison northward.
Read the full article here and watch a video about ancient DNA here.
Message sent
Thank you for sharing.