Baylor University College of Arts and Sciences researchers, along with scientists from Texas A&M University and around the country, have found the oldest archaeological evidence of human occupation in the Americas at a Central Texas archaeological site located about 40 miles northwest of Austin.
The study appears in the April issue of the journal Science.
For the last 100 years, archeologists have believed that the Clovis people were the first to enter the Americas about 13,000 years ago. Artifacts found by this study now place that time back 2,500 years, or to about 15,500 years ago.
At the Debra L. Friedkin archeological site, located about 10 miles outside of Salado in Central Texas, the Baylor researchers, along with their colleagues, found nearly 16,000 artifacts that predated the Clovis people. Most of the artifacts were chipping debris from the making and reshaping of tools; however, about 50 artifacts were tools themselves such as knives and projectile points. The dating process placed these artifacts back to about 15,500 years ago. This find is not only the earliest evidence of human occupation in North, South and Central America, it also has the largest number of artifacts dating to the pre-Clovis time period.
Nordt and Dr. Steve Driese, professor and chair of geology at Baylor, collected samples from the site and analyzed particle-size distribution, organic carbon and calcium carbonate content. The systematic depth functions of these properties demonstrated to the Baylor researchers that the mixing process from the dirt shifting or cracking was not a factor in the formation of the archaeological site. Their analysis proved that the site was undisturbed and that the artifacts were in place since they were discarded 15,500 years ago.
"There is absolutely no evidence that there was erosion or soil movement when the site was formed that could have significantly redistributed the archaeological materials," Driese said. "This was really a critical finding. There have been several credible sites in North and South America which date older than the Clovis people, but the evidence is not real strong. This study proves people inhabited the Americas earlier than previously believed."
The Baylor researchers also said more than 60 "optically-stimulated luminescence dates" show that the early people arrived at the site by about 15,500 years ago. The luminescence dating technique is a method used to date the sediment surrounding the artifacts by dating the last time the sediment was exposed to sunlight.
The Baylor researchers said the artifacts show an array of different technologies and there is no doubt that the tools and weapons were human-made, dating to about 15,500 years ago. Analysis of the site is ongoing, and future studies will help explain where these people came from, show how they adapted to the new environments and help scholars understand the origins of later groups like the Clovis people.
Funding for the project was provided by the North Star Archaeological Research Program and the Chair in First American Studies at Texas A&M.
Researchers from Baylor, Texas A&M's Center for the Study of First Americans, the University of Illinois-Chicago, the University of Minnesota and Texas State University all participated in the study.