Very Early Humans in Great Plains: Article says human occupation more than 40,000 years ago possible.

From the Winter 2005-06 issue of American Archaeology (a publication of The Archaeological Conservancy).

The article referred to was published in the Quaternary International, a peer-reviewed journal. In it the author, Steven Holen, hypothesizes that people lived on the Great Plains some 20,000 - 40,000 years ago, based on analysis of mammoth bones both here and at an Old Crow site in the Canadian Yukon - this latter site gives signs of dating to 30 - 43 thousand years ago.

The report has been criticized by archaeologists who believe the observed bone breakage patterns could have been a result of natural forces acting over this length of time, based on elephant tusk breakage found in Africa.