To learn who the first Americans were and when they arrived requires following a trail that has grown very cold during the past 15,000 or 20,000 years.

After millennia of erosion and environmental change, much of the land they walked, hunted, and camped on is now submerged and inaccessible beneath the Bering Sea and along the Atlantic and Pacific coasts, where rising sea levels have flooded wide, previously exposed coastal plains. Most of the numerous Paleo-Indian sites archaeologists have excavated were occupied more than a hundred centuries after the first migrants arrived. These sites often yield spear points and large animal bones, but Paleo-Indian human skeletal remains are very rare. And yet evidence that Paleo-Indians inhabited the Western Hemisphere is overwhelming and indisputable. Human craftsmanship is the only credible explanation for Clovis points, and carbon dating establishes that the oldest Clovis sites are about 13,500 years old.

Scattered and controversial evidence suggests, however, that Clovis peoples were not the first arrivals. The Monte Verde excavation in Chile has persuaded many archaeologists that the first Americans resided in South America sometime between 14,750 BP and 14,000 BP. This site and a few other likely pre-Clovis sites in North America, most notably Meadowcroft in Pennsylvania, contain no Clovis-era artifacts, suggesting that their inhabitants arrived earlier and differed from the later Clovis peoples. But if the first Americans already lived in Chile and Pennsylvania 14,000 or more years ago, when did they first arrive and from where?

Some experts hypothesize that pre-Clovis peoples sailed or floated across the Pacific from Australia or Antarctica. Most scholars consider those ideas far-fetched. The Pacific is too wide and tempestuous for these ancient peoples and their small boats to have survived a long transoceanic trip.

Ancient Siberians had the means (hunting skills and adaptation to the frigid climate), motive (pursuit of game animals), and opportunity (the Beringian land bridge) to become the first humans to arrive in America, and most archaeologists believe they did just that. But when they came is difficult to determine since the Beringian land bridge existed for thousands of years. The extreme rarity of the earliest archaeological sites in North America also makes it difficult to estimate with confidence when pre-Clovis hunters arrived. A rough guess is 15,000 BP, although it might have been earlier. The scarcity of pre-Clovis sites discovered so far strongly suggests that these ancient Americans were few in number (compared to the much more numerous Clovis-era Paleo-Indians), very widely scattered, and ultimately unsuccessful in establishing permanent residence in the hemisphere. Although they and their descendants may have survived in America for a millennium or more, pre-Clovis peoples appear to have died out. The sparse archaeological evidence discovered to date does not suggest that they evolved into Clovis peoples. Although Clovis peoples evidently were not the first humans to arrive in the Western Hemisphere, they probably represent the first Paleo-Indians to establish a permanent American presence.

To investigate where the mysterious first Americans came from, experts have supplemented archaeological evidence with careful study of modern-day Native Americans. Although many millennia separate today’s Native Americans from those ancient hunters, most scholars agree that telltale clues to the identity of the first Americans can be gleaned from dental, linguistic, and genetic evidence collected from their descendants who still live throughout the hemisphere.

Detailed scientific analyses of the teeth of thousands of ancient and modern Native Americans have identified distinctive dental shapes—such as incisors with a scooped-out inner surface—commonly found among ancient Siberians, ancient Americans, and modern Native Americans, but rare elsewhere. This dental evidence strongly supports the Asian origins and Beringian migration route of the first Americans.

Linguistic analysis of more than a thousand modern Native American languages demonstrates that Native Americans throughout the hemisphere speak some form of Amerind, the consequence (presumably) of its arrival with the earliest wave of ancient migrants around 13,000 BP. This migration chronology and linguistic analysis remain controversial among experts, but they suggest that Clovis peoples spoke some ancient form of Amerind.

Genetic research into the mutation rate of DNA reveals that many modern Native Americans share genetic characteristics commonly found among Asians. Estimates of the evolutionary time required to produce the subtle differences between Asian and Native American DNA suggest a migration from Asia as early as 25,000 BP or before. But like the other high-tech evidence, this genetic evidence is sharply disputed by experts.

Fascinating as the genetic, linguistic, and dental studies are, they are unlikely to win widespread support among experts until they can be corroborated by archaeological evidence that, so far, has not been found. Until then, specialists will continue to debate when the first Americans arrived and how they were related to subsequent generations of ancient Americans.

Thinking about Evidence

Connect to the Big Idea

In what ways were the first Americans related to their ancestors elsewhere in the world?