Scientists have uncovered a stunning collection of stone artifacts at least 15,500 years old from a central Texas archaeological site, proving that people were living in North America thousands of years earlier than previously thought.

The discoveries, reported this week in the journal Science, provide dramatic evidence that people had colonized the middle of the continent long before glaciers melted back to create an ice-free migration corridor from Alaska through Canada.

The inescapable conclusion essentially rewrites the first chapter of Alaska’s prehistory and what’s known about the initial colonization of the New World.

Since ice sheets blocked the way, the people could not have crossed the Bering Land Bridge and then trudged south as many have long argued and school children have always been taught. Instead, these Stone Age pioneers must have traveled along the Alaskan shoreline before continuing down the West Coast and spreading out to populate two continents, according to the study’s lead author, Michael Waters, director of Texas A&M's Center for the Study of First Americans.

“While there is no empirical archaeological evidence that shows that people migrated along the coast, logic tells us they must have,” Waters told Alaska Dispatch in an email earlier this week. “There is no other way to get people into central Texas — the corridor was closed.”

As a result, the very first Americans almost certainly spent time as Alaskan beachcombers — foraging through tide pools and snatching salmon from coastal creeks along the southern rim of Beringia.

Waters and a team that included researchers from Baylor University, the University of Illinois-Chicago, the University of Minnesota, and Texas State University, began three years of excavations in 2006 at the Debra L. Friedkin site about 40 miles northwest of Austin on a terrace next to spring-fed Buttermilk Creek. 

What they found was remarkable — 15,528 stone fragments and tools in an eight-inch-thick layer that hadn’t been disturbed for millennia. 

More than 60 “luminescence dates” — a technique that analyzes sediment and dates when it was last exposed to sunlight — showed that people dropped the artifacts on the surface of the ground more than 150 centuries ago, making the material the oldest archaeological evidence for human occupation in North America.

“It opens up and creates all sorts of new possibilities and new thinking about the first people to enter the continent,” Waters told a Science-sponsored teleconference, held Wednesday morning.

Most significantly, the age of the artifacts predates the bison and mammoth hunters of the Clovis culture  – long thought to be the original settlers of North America — by more than 2,500 years, Waters pointed out.

"What is special about the Debra L. Friedkin site is that it has the largest number of artifacts dating to the pre-Clovis time period, that these artifacts show an array of different technologies, and that these artifacts date to a very early time,” Waters said.

Most of the artifacts were white flakes and tiny chips left on the ground after making new tools or sharpening old ones. But there were also 56 whole tools — including a spear points, knives and choppers, plus small items used for scraping, boring and cutting, Waters said.

“In general, the Buttermilk Creek Complex tools and cores are small in size and lightweight, a tool kit designed for high residential mobility,” the authors wrote. “Although no organic artifacts were preserved, the Buttermilk Creek Complex stone tools have wear that is indicative of use on both soft and hard materials … suggesting that organic materials were also part of this assemblage.”

“This is a mobile tool kit, something which is easily transported,” Waters said Wednesday. “It is lightweight. Also there is evidence to suggest these people were making bone tools as well.”