By about 13,000 years ago, the Ice Age had finally begun to wane. As the glaciers that once blanketed the westward flank of what’s now Canada receded, a thin, iceless corridor appeared between two towering walls of ice—clearing, at long last, an accessible path from modern-day Alaska to the rest of the Americas.
But when—or even, if—humans utilized this newly exposed strip of land in their southbound migration, the footprints they left probably weren’t the continent’s first: Another group of early people almost certainly beat these terrestrial migrants to the punch.
Reporting today in the journal Science, an international team of archaeologists has uncovered a cache of artifacts from Idaho that suggest humans had already settled the Pacific Northwest 16,000 years ago, long before rising temperatures had time to expose the continent’s ice-free footpath. The findings lend support to the idea that the continent’s inaugural human inhabitants were migrants from across the Pacific who first entered the New World not by land—but by sea.
“This is really exciting work...that presents some of the oldest evidence of a human presence in North America,” says Alia Lesnek, a geologist at the University of New Hampshire who studies early coastal migrations, but was not involved in the study. The dates associated with the site’s artifacts, she adds, “basically preclude the idea that people first traveled here [through] the ice-free corridor.”
The new study isn’t the first to challenge the ice-free corridor hypothesis. In recent years, evidence found at sites from modern-day British Columbia to Chile has bolstered an alternative theory of coastal migration, which posits that humans beach-hopped their way down the Americas by boat, hugging—but not directly traversing—the still-icy landscape.
But for decades, most archaeologists swore by a different story—that the members of the Clovis culture were the first to colonize North America around 13,000 years ago, when they took advantage of Canada’s timely melt.
Following the discovery of several sites in New Mexico in the 1930s, the Clovis became best known for their signature tool-making style, emblemized by the thousands of distinctively fluted spearheads they left scattered across the continent. If the “Clovis first” theory held true, these spearheads should be the oldest found on American soil. But in 1997, Oregon State University archaeologist Loren Davis was one of several wondering if the bigger picture was more complex.
Davis, then a graduate student, was leading an excavation at a site in western Idaho called Cooper’s Ferry, known to the Nez Perce Tribe, or the Nimíipuu, as the ancient village of Nipéhe. While the team’s digs had turned up a series of spearheads dating back to around the time the Clovis people first appeared, they didn’t resemble Clovis points. Rather, these spearheads were “stemmed,” bearing the vague silhouette of a Christmas tree. And no matter how deeply researchers dug, no Clovis points appeared—suggesting, perhaps, that their makers had never inhabited Cooper’s Ferry at all.
The find, which didn’t match most archaeologists’ long-held narrative of the Americas, sparked a bit of controversy at the time, Davis recalls.
Undeterred, Davis returned to Cooper’s Ferry in 2009. More than a decade had passed since his initial excavation, and in the intervening years, evidence against “Clovis first” had begun to accumulate from a smattering of sites predating the 13,000-year benchmark. But many of the field’s most staunch traditionalists remained unconvinced.
So Davis and his team broadened their search, this time hoping to nail down a more concrete chronology of events. In the decade that followed, the researchers uncovered a series of pits, including what appeared to be a food processing station containing the fragmented remains of an extinct horse, as well as a hearth brimming with ancient charcoal-speckled sediments. The site was also littered with more stone tools, including stemmed spearheads similar to those recovered from Davis’ first Cooper’s Ferry dig.
“The fact that they found actual features [that suggest] humans were controlling fire...is really exciting,” says Nancy Velchoff, an archaeologist at the University of Texas at Austin who was not involved in the study. Pits like these, which hint at a level of culinary sophistication, breathe life into such ancient sites, where this type of evidence is often nonexistent, she adds.
The team then used a combination of radiocarbon dating, luminescence dating, and a computer model to determine the ages of the site’s artifacts. Though several were relatively recent, with origins around just 8,000 or 9,000 years ago, many of the tools were older, closer to 13,000 years in age. These people weren’t Clovis. But perhaps the two groups had coexisted—half a world away from each other.
As the researchers dug deeper, the dates kept ratcheting further backward in time, culminating in a set of charcoal and animal bones determined to be 15,000 to 16,000 years old. These numbers, Davis recalls, left him “numb” with excitement: Human habitation at Cooper’s Ferry wasn’t just contemporaneous with Clovis culture; it had preceded it.
“This drives home the idea that while the Clovis were a really important cultural tradition in North America, they probably weren’t the first humans living [there],” Lesnek says. “And that’s a really big contribution.”
The study’s results also muddle more than the who of early American history. Currently, the most liberal estimates for when the ice-free corridor opened stretch only about 15,000 years into the past—well after people appear to have settled Cooper’s Ferry, Davis says. It’s still possible people made use of the land bridge at a later date, but the site’s artifacts place it firmly in Team Coastal Migration.
That leaves open a lot of questions about how, when, and from where these original boat trips took place. According to Davis’ current working theory, early people from Asia probably wove their way down the Pacific coast before encountering the mouth of the Columbia River. This formidable landmark, which sits at the boundary of Washington state and Oregon, roughly 500 miles from western Idaho, could have coaxed the migrants into a left turn. “This was essentially the first major off-ramp south of the ice,” Davis says. “We don’t think it’s an accident that Cooper’s Ferry is so early.”
The peoples’ Asian point of origin is also supported by the shape of the same stemmed spearheads that started it all at Cooper’s Ferry. Similar artifacts from roughly the same time period have been unearthed in Japan—a connection the team is now following up on.
To truly make the case for coastal travel, however, researchers will need to shore up evidence from the journey’s midpoint. So far, none of the boats or beachside pitstops that presumably sustained these early wayfarers have revealed themselves to archaeologists—and it’s likely that many never will, Lesnek says. Sea levels have risen since the end of the Ice Age, drowning many archaeological sites.
But for now, the timing tentatively makes sense. Last year, findings from Lesnek’s team suggested that the Pacific coast had de-iced by about 17,000 years ago. With vegetation and animal life burgeoning on the shores, intrepid seafarers might have made use of this well-resourced route before making that fateful turn inland.
In the meantime, the finds at Cooper’s Ferry reaffirm the cultural legacy of the Nez Perce Tribe, who occupied the site for many generations before it became federal land. One of the tribe’s early stories describes an ancient avalanche that left two survivors—a girl and a boy—who then founded Nipéhe. In an homage to the pair, the root of the village’s name is derived from the word nipe, an affectionate term for a young male relative.
The role of snow in this tale might suggest a connection to the same ice age that North America’s first people weathered many millennia ago, says Nakia Williamson-Cloud, the Nez Perce Tribe’s cultural resources program director. “From our stories, it’s apparent that we’ve been here for a very long time,” he says. “Some of the work that’s happened here at Nipéhe…is a testament to the enduring relationship the Nez Perce people have fostered with this land.”