Original Americans lived near Austin Oldest site of habitation has been confirmed.

Artifacts from the 15,500-year-old site in Texas. Artifacts from the 15,500-year-old site in Texas. Photo: Associated Press/Michael R. Waters, Science Photo: Associated Press/Michael R. Waters, Science Image 1 of / 6 Caption Close Original Americans lived near Austin 1 / 6 Back to Gallery

Texas scientists have found the oldest confirmed site of human habitation in the Americas just north of Austin, where the Edwards Plateau meets the coastal plains.

The unprecedented haul of artifacts from as far back as 15,500 years ago brings archaeologists much closer to answering the mysteries of who the first Americans were, where they came from and how they got here.

The new work, published Thursday in the journal Science, may definitively prove humans lived in the Americas prior to the “Clovis” people, who spread widely across the western hemisphere beginning about 13,000 years ago.

These people, identifiable by their characteristic fluted spear points, long were thought to be the first Americans.

The discovery of such an old settlement also suggests the first Americans must have come from Asia, not through an ice-free corridor over land, but along the Alaskan and Canadian coasts in boats as long as 16,000 years ago.

“I think we’re getting closer and closer to understanding how and when the first people came into the Americas,” said Michael Waters, a Texas A&M University archaeologist who led the study.

Waters and his colleagues found the trove of some 15,000 stone artifacts about 50 miles north-northwest of Austin at the Debra L. Friedkin site along Buttermilk Creek.

Fed by permanent springs, this area between the Edwards Plateau and lower coastal plains would have offered ample game from both ecosystems, and its limestone held an abundant supply of flint-like rock, or chert, ideal for making Stone Age tools.

Since the 1930s, archaeologists have believed the ancestors of the Clovis people —so named for a small number of stone “points” found near Clovis, N.M. — walked into North America from Asia across the Bering Sea landmass as the last Ice Age waned about 13,500 years ago.

They feasted on large game unaccustomed to human predators and possibly contributed to the extinction of animals such as the mammoth. They followed this game and quickly spread throughout the continent. Eventually the Clovis technology gave way to varied, ancient Indian peoples.

This is the story long told in textbooks and museums.

In recent years, however, this “Clovis first” theory has come under mounting attack by some archaeologists, linguists and geneticists who suggest people may have been in this hemisphere for far longer, predating the Clovis by thousands of years.

Some sites in Virginia and Pennsylvania have produced artifacts that archaeologists claim show evidence of habitation 15,000 to 17,000 years ago. But this evidence, generally measured in dozens of artifacts rather than thousands, hasn’t convinced some Clovis-first archaeologists.

The new evidence, however, is difficult to dismiss. Waters’ team found the thousands of older artifacts in sediments beneath a layer of Clovis artifacts. The design of the older points is cruder than Clovis technology, but there are enough similarities to suggest Clovis points were derived from the older points.

“Some people will say this is the final nail in the coffin for the Clovis-first theory,” said Gary Haynes, a professor of anthropology at the University of Nevada at Reno, who long has been skeptical of pre-Clovis peoples in the Americas. “I don’t think this is the last nail, but I do think they’ve done some pretty good work here.”

Haynes said he still has questions about the accuracy of the dating of sediments — without carbon-based material it’s difficult to get precise estimates of dates — and he has concerns that artifacts from later eras could have slipped down into older sediments.

But Lee Nordt, a co-author of the Science paper and a geologist at Baylor University, dismissed that concern. He said there’s no evidence of such post-burial redistribution in the sediments.

“They demonstrated to us unequivocally that the peopling of the Americas occurred prior to Clovis times and more than 13,000 years ago,” Nordt said.

If Waters’ conclusions are correct, the first Americans evidently were handy with boats.

Prior to about 13,500 years ago, sheets of ice two miles thick covered nearly all of Canada, making a land route impassable.

The most plausible solution is that the first Americans traveled a coastal route, using boats to come down the Alaskan and Canadian coasts, parts of which probably would have been free of ice.

There is little archaeological evidence of this trek, however.