On a clear fall day almost 80 years ago, an amateur fossil hunter was exploring the remote hills of eastern New Mexico. Near the small town of Clovis he found something very exciting. By the 1930s researchers from around the world were investigating human artifacts found at the site.
Spear points and other stone tools unearthed at Clovis changed how scientists thought about the peopling of the Americas. The artifacts soon became known as “Clovis Points.” In the hands of ice age hunters they would have represented an advanced technology. Some 13,000 years later, in the hands of archaeologists, these stone tools helped explain a great mystery: who were the first humans in the New World and how did they reach two American continents?
Because similar tools were present at sites in northeastern Asia, the finds at Clovis revealed a great deal about human prehistory. Scientists believed they had solved the mystery. Early humans traveled between Asia and North America across a land bridge – a strip of land exposed in the Bering Sea during the last ice age. They made their way into Alaska and then moved south.
Well-armed with Clovis spear points, they successfully hunted large, ice age mammals such as mammoths and mastodons. As glaciers melted, these skilled hunters spread out across North and South America. For decades this “Clovis First Theory” was the respected foundation of American prehistory.
That’s not the case anymore.
Recent evidence has caused scientists to change their views. In fact, experts think the now reopened debate about who migrated to America first and how they got here will last for many years.
A chance finding halfway around the world provided the first real evidence against the Clovis hypothesis. Tom Dillehay, an archaeologist at Vanderbilt University in Tennessee, uncovered the remains of a large campsite in Chile, near the tip of South America. Radiocarbon dating indicated the site, called Monte Verde, was around 14,600 years old. This would mean that humans were in South America before the Clovis people ever reached the New World. The artifacts found at Monte Verde were at least a thousand years older than the oldest known Clovis tools.
Throughout the 1980s and into the 90s most experts disregarded the Monte Verde discovery. Many thought the evidence had been contaminated. But slowly, some in the scientific community began to question the Clovis First theory.
At about the same time Dillehay was digging in Chile, other archaeologists were exploring caves in western Pennsylvania. This site was called the Meadowcroft Rockshelter. It was known for some time that Indians of the Woodland culture lived there. Then, as they dug deeper at the site, scientists discovered stone tools that seemed much older. They used radiocarbon dating techniques to determine that these artifacts were at least 16,000 years old -- in other words pre-Clovis. Again, most experts disregarded this new evidence.
But scientists were investigating. New finds were made at dig sites in South Carolina, Texas, and Brazil. Just as more scientists seemed willing to question Clovis first, important clues were unearthed in Oregon.
An archaeologist from the University of Oregon, Dennis Jenkins, was examining stone tools found in caves in a remote area of south-central Oregon. The university set up a field school at the site. By 2007 they knew they were onto something big. Their first study, published in 2008, contradicted the Clovis First theory. The researchers said improved radiocarbon dating and DNA evidence proved humans were living in North America much earlier than previously thought.
Then, earlier this year, an international team struck what they call the final blow to the Clovis first theory. These scientists say further examination of the Paisley Caves site proves once and for all that pre-Clovis humans reached the Americas. According to the study, published in the journal Science, “a non-Clovis culture was present in North America at least as early as Clovis people themselves and likely before.”
One of the study’s authors, Dr. Thomas Stafford of the Center for GeoGenetics in Denmark says, "No other archaeological site in the United States has been as thoroughly and exhaustively dated as the Paisley Caves.” According to Stafford “Our conclusion is that humans were present in North America at least one thousand years before Clovis and that these earlier peoples probably had no technological or genetic similarity to the Clovis Culture. The Clovis First debate has ended. The theory is now dead and buried."
But if not Clovis, what? How did early humans reach the Americas? And when did they settle here?
Scientists have proposed several theories in an attempt to replace Clovis First theory. So far there is plenty of debate, but not much agreement. Some believe in a so-called “short chronology” model. This line of thinking says the earliest movement into the Americas occurred no earlier than 14,000 – 16,000 years ago. Another school of thought says humans migrated to the New World much earlier, perhaps as much as 40,000 years ago. This is called the “long Chronology” model.
The route (or routes) used to get the Americas is also in doubt. Did these migrating hunter-gatherers travel in boats or use the Bering Land Bridge? Did they cross the Pacific or the Atlantic Ocean?
Thirsty for knowledge, scientists are searching on several continents for answers. In a special three-part series, Simpson Street Free Press reporters will examine one the great mysteries of human history. We will follow ancient migration routes and follow the latest research. Answers to ice age mysteries don’t come easy, but following the trail is fascinating.
[Sources: Science; Pittsburgh Post-Gazette; NewsDaily.com; Nature.com; Atlas of World History]