It was a widely accepted fact since the 1930s: The first people to arrive in the Americas, now known as the Clovis culture, came here about 13,000 years ago.

The first crack in the theory came around in the 1970s, when archaeologists began turning up sites that predated the arrival of the Clovis culture—although acceptance of a pre-Clovis human arrival has been slow.

However, a newly-excavated site in Florida now offers substantial proof for those who doubt, as researchers there have dated human-made tools to 14,550 calendar years before present—and offers up a rare insight into when certain megafauna disappeared from the continent.

The Clovis culture

More than 13,500 years ago, the northern reaches of North America were covered entirely by sheets of ice—which, spanning thousands of miles in solid blocks, hindered the movements of humans and animals looking to move from Bering land bridge southward.

But around 13,500 years ago, a path known as the ice-free corridor opened up, and perhaps 300 years later, the Clovis culture—a prehistoric Paleo-Indian culture—used it to reach the United States.

The Clovis then spread throughout North and South America, leaving behind a myriad of evidence in their wake, including their extremely characteristic projectile points.

Clovis First?

But slowly, evidence began to show that they were likely people in the Americas before the ice-free corridor ever opened up. The sites of Monte Verde in Chile (dated ~14,500 years before present) and Meadowcroft in Pennsylvania (~15,000 years BP) are extremely famous examples—and researchers in Brazil may have even uncovered fire pits and tools that are 50,000 years old, and researchers in South Carolina may have done the same.

But the evidence has not convinced many archaeologists. In particular, a pre-Clovis site must have three key criteria to offer acceptable proof: First, there must be artifacts that are undeniably associated with humans. Second, they must be found in an undisturbed geological context. And third, they must be reliably dated.

Many of the sites throughout the years didn’t satisfy the researchers, and it didn’t help that so few were available to study.

“The rarity of these early site is due to low population densities, resulting in few archaeological sites and low site visibility thanks to their deep burial [underground] and, in some cases such as at Page-Ladson, the evidence is submerged [underwater],” explained Mike Waters, professor of anthropology at Texas A&M University, in a press teleconference.

But though the evidence has been slow to accumulate, it has been adding up over the past few decades.

“There has been is slow change in the dominant thinking,” added another researcher. “In 1981 you were a quack if you thought there was anything pre-Clovis. I think over the ensuing 25 or 30 years, that has started to slowly change to where it’s become a viable research question again to test whether or not sites are older than Clovis.”

The sinkhole site in Florida can only add to the idea’s feasibility.

Page-Ladson offers new insights

As detailed in the study found today in the journal Science Advances, the site in Florida—dubbed the Page-Ladson site—has been studied before. From 1983 to 1997, the original investigators uncovered eight stone artifacts as well as butchered mastodon remains, which they dated to around 14,400 years BP. But these findings were challenged, and the accuracy of the data remained uncertain afterwards.

Then, starting in 2012, several more archaeologists returned to the site, in hopes of confirming previous finds. It was a challenging excavation—mainly because the site was located at the bottom of a 30-foot (9 meter) sinkhole along the Aucilla River in Florida. Underwater archaeology, incidentally, is a specialty that doesn’t have anywhere near as many working experts in North America as regular archaeology.

(“The number of people who are specialists in prehistoric archaeology and work underwater…is probably less than 10 of us across the entire continent,” said one researcher.)

After some two years of painstaking underwater excavations plus plenty of research and analysis of artifacts, they were able to give a new date to the site: 14,550 years before present, more than a millennia before the Clovis could have arrived.

This date was derived from eight new stone artifacts (including a knife and stone fragment from creating or reworking a stone tool) uncovered onsite made of a type of stone known as chert. In archaeology, many types of rock cannot be directly dated, but instead is dated using the material found near or around it—which is what the researchers here had to do.

71 samples of wood from the relevant layers of sediment were tested using radiocarbon dating, and the dates all fell in right near 14,550 years BP—matching the accurate date criteria for proving a pre-Clovis site. Moreover, the dates of each layer matched one-another, showing that the sediment layers had been undisturbed until this excavation—another criteria checked off.

“Because the Page-Ladson site provides unequivocal evidence of human occupation that predates Clovis by over 1500 years, the site contributes significantly to the debate over the timing and complexity of the peopling of the Americas in several ways,” said Waters.

“First, Page-Ladson is essentially the same age as Monte Verde in Chile, and these sites show that people were living in both hemispheres of the Americas by at least 14,500 years ago. Second, prehistoric people were not alone. Archaeological evidence shows us that people were also present between 14,000 and 50,000 years ago in what are now the states of Texas, Oregon, Washington, and Wisconsin.”

The site also contains two previously-found specimens of interest: A possible (but not yet verified) domesticated dog, as well as a mastodon tusk that shows marks from human tools.

There are two general options for how the pre-Clovis peoples may have arrived. The first: They somehow managed to walk down the Pacific Coast, thereby avoiding the ice sheets, and then spread from there–although it’s unclear whether this was truly a viable option. The second, more popular theory is that they arrived by boat. In fact, there are three suggested places of origin for the pre-Clovis peoples: Beringia, where they sailed down the Pacific Coast; the Iberian Peninsula, where they sailed up and around before arriving in the northeast of North America; and West Africa, where they sailed directly across to Brazil.

Of course, lacking further evidence, one or all of these ideas may be correct

Mastodon-be-gone

The site further shows evidence of when the megafauna known as mastodons went extinct in North America—a date which is currently uncertain.

By tracking a fungus spore associated with herbivore (and therefore mastodon) poop, Sporormiella, throughout the layers of sediment, they were able to associate the decline and disappearance of the fungus (and thus herbivore poop, and thus mastodons) with a layer dated to around 12,600 years ago—meaning these pre-Clovis people likely coexisted with them for around 2,000 years before they went extinct.

For more background on the pre-Clovis people of the Americas,we highly recommend reading Nikhil Swaminathan’s article America, in the Beginning.

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Main image: Overview of the Page-Ladson site. Photo by B. Fenerty.

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