The new tools are even older than these ancient Clovis points.

For a long time, anthropologists believed that the first people to inhabit the Americas were the so-called Clovis people, defined by their exquisitely chiseled spear points that begin appearing around 13,500 years ago or so. These peoples were so successful that they spread out across the Americas, from Alaska to Venezuela, dominating the ancient archaeological record of the New World.

But that story is rapidly beginning to change, as more and more evidence gets unearthed hinting at a mysterious pre-Clovis population who may have called America home for thousands of years before the Clovis set foot there. Now newly discovered spear points at a 15,000-year-old site in Texas that all but set it in stone: humans were here before Clovis, reports the Washington Post.

Archaeologists have been scouring the Buttermilk Creek complex in central Texas since 2006, after an initial discovery there of scores of stone point fragments, which scientists suspected were the tips of pre-Clovis spearheads. Without any whole spearheads, however, it was difficult to determine whether these stone fragments were from tools, or if they were something else entirely.

Finally, though, eureka! Researchers have now confirmed that two perfectly preserved artifacts — one triangular point, and one lobe-shaped projectile with a tapered, or "stemmed" bottom — are, in fact, pre-Clovis in origin and human-crafted. They are different in design from Clovis points, and they significantly pre-date them. It's the clearcut evidence of pre-Clovis habitation of the Americas that researchers have been looking for.

'It's exhilarating'

"I just thought, 'Holy cow,'" recalled geologist Mike Waters, who oversaw the excavation. "Whenever you see something for the first time that you didn't expect, it's always very exciting and exhilarating."

"This is a really fascinating paper," said Jennifer Raff, an anthropological geneticist at the University of Kansas who was not involved in the new study. "It's filling in some of the gaps in the archaeological record regarding the Clovis complex and the histories of the very first peoples in the Americas.

It's quite possible that these stone tools were held by some of the first cultures to reach North America. There is very little genetic evidence of these people remaining in modern populations of Native Americans, but they left their tools behind. It's a chapter in human history that is only now beginning to be brought to light.

Right now, it's impossible to know who exactly these pre-Clovis peoples were. It's possible that the Clovis were descendants of some of these people; it's also possible that the Clovis may have supplanted them. Right now, it's a mystery that's sure to open up a whole new book into the origins of American colonization.

The study was published in the journal Science Advances.