Kenneth Glad
The route taken by the first people to reach the Americas has long divided archaeologists. Coastal migration by boat or an inland trek through a gap in the ice sheets? New evidence from Alaska is not settling the argument. But it is forcing scholars to look again at a pathway many had begun to doubt.
For decades, textbooks favored a land-based journey. Migrants, it was argued, crossed the Bering Land Bridge from Siberia during the last Ice Age and later moved south through an ice-free corridor that opened between the massive Laurentide and Cordilleran ice sheets.
That narrative unraveled as older sites came to light. Monte Verde in Chile and the fossilized footprints at White Sands in New Mexico suggested humans were in the Americas earlier than the Clovis culture, known for fluted spear points used in big-game hunting. Coastal migration theories gained traction.
Skepticism about the corridor deepened in 2016, when a Nature study led by Mikkel Pedersen concluded the passage may not have supported plants and animals until about 12,600 years ago. Using ancient environmental DNA, the team reconstructed when the landscape could sustain travelers.
Those findings reshaped the debate and influenced how researchers frame the deep ancestry of Indigenous populations in the Americas. If the corridor opened too late, the first migrants must have arrived another way.
Yet new climate models and fresh Arctic excavations are complicating that picture.
Finds in the Tanana Valley
According to Live Science, archaeologists working at the Holzman site in Alaska’s Tanana Valley uncovered mammoth ivory and stone tools dated to roughly 14,000 years ago. The research appears in Quaternary International. In its coverage, Live Science characterized the findings as strengthening the inland hypothesis.
The valley at the time was a cold, grassy steppe populated by mammoths and bison. During brief summer digs, researchers scrape through thawed mud before hitting permafrost, permanently frozen ground that locks organic remains in place.
In comments to Live Science, co-author Brian Wygal of Adelphi University said: “We argue that the growing evidence from interior Alaska confirms an inland route through an ice-free corridor as the most likely scenario for the initial arrival of people in midcontinental North America.”
Co-author Kathryn Krasinski added: “What’s exceptional [about this site] is its remarkable preservation. The lower components tend to be frozen much of the year, so we have also recovered ancient plant DNA and even a strand of 13,600-year-old bison hair. This type of organic material preservation is quite rare.”
The authors of the Quaternary International paper argue that similarities between the Alaskan artifacts and later Clovis materials indicate cultural continuity, meaning shared manufacturing traditions that may connect northern groups with populations that later expanded across much of North America.
Under renewed review
Other researchers urge restraint. As Jack Ives of the University of Alberta told Live Science, comparable technologies were widespread in northeast Asia, raising the possibility that the tools reflect shared heritage rather than direct lineage.
Genetic studies have also suggested multiple founding populations entered the Americas at different times, complicating any single-route explanation.
The Alaska evidence does not close the case. But it shifts serious attention back to the interior of the continent, an area that had slipped to the margins of the discussion.
For now, the ice-free corridor is no longer treated as a discarded theory. It is back under active investigation.
Sources: Live Science; Quaternary International; Nature (2016 study led by Mikkel Pedersen)
