“Unearthing the Past: New Findings Reveal Ancient Americans Lived Alongside Giant Sloths and Mastodons!”

SAO PAULO (Associated Press) — Sloths were not always the sluggish, furry inhabitants of trees that we know today. Their ancient predecessors were massive — reaching up to 4 tons (3.6 metric tons) — and when alarmed, they displayed enormous claws.

For many years, researchers maintained the belief that the first humans to set foot in the Americas swiftly hunted these giant ground sloths to extinction, alongside numerous other large creatures like mastodons, saber-toothed cats, and dire wolves that once inhabited North and South America.

However, fresh research from various locations is beginning to indicate that humans may have arrived in the Americas much earlier — perhaps significantly earlier — than was previously thought. These discoveries imply a profoundly different existence for these early inhabitants, where they might have coexisted for millennia with colossal beasts in prehistoric landscapes.

“The prevailing notion was that humans arrived and rapidly exterminated everything — a theory known as ‘Pleistocene overkill,’” stated Daniel Odess, an archaeologist from White Sands National Park in New Mexico. Yet, recent findings propose that “humans were coexisting with these animals for at least 10,000 years, without causing their extinction.”

Some of the most intriguing evidence originates from an archaeological site in central Brazil, named Santa Elina, where remnants of giant ground sloths exhibit signs of human intervention. These sloths once inhabited areas from Alaska to Argentina, and certain species possessed bony structures on their backs, referred to as osteoderms — akin to the protective plates of modern armadillos — which may have been utilized for creating ornaments.

In a laboratory at the University of Sao Paulo, researcher Mírian Pacheco holds a round, penny-sized sloth fossil in her hand. She observes that its surface is unexpectedly smooth, the edges seem to have been intentionally polished, and a small hole is present near one edge.

“We speculate it was purposefully modified and utilized by ancient peoples as jewelry or decoration,” she remarked. Three similar “pendant” fossils stand out in contrast to unaltered osteoderms laid out on a table — the latter being rough and devoid of holes.

These artifacts from Santa Elina are approximately 27,000 years old — over 10,000 years earlier than the previous estimates of human arrival in the Americas.

Initially, researchers questioned whether the artisans were working on already ancient fossils. However, Pacheco’s studies strongly indicate that ancient people were crafting “fresh bones” shortly after the sloths perished.

Her findings, along with other recent breakthroughs, could help reshape the narrative of when humans first landed in the Americas — and the impact they had on the ecosystems they encountered.

“There remains a significant debate,” Pacheco noted.

Scientists understand that the earliest humans originated in Africa, subsequently migrating into Europe and Asia-Pacific, before finally reaching the last continental frontier, the Americas. Yet uncertainties linger regarding the concluding chapter of humanity’s origin story.

Pacheco learned in high school the theory that most archaeologists adhered to throughout the 20th century. “What I was taught in school was that Clovis was the earliest,” she expressed.

Clovis refers to a location in New Mexico, where archaeologists unearthed distinctive projectile points and other artifacts during the 1920s and 1930s, dated between 11,000 and 13,000 years ago.

This timeframe converges with the conclusion of the last Ice Age, a period when an ice-free corridor likely emerged in North America — leading to a hypothesis about how early humans migrated into the continent after traversing the Bering land bridge from Asia.

Additionally, as the fossil record reveals a significant decrease in American megafauna around the same time — with North America losing 70% of its large mammals, and over 80% in South America — many researchers inferred that the arrival of humans precipitated mass extinctions.

“It was a captivating narrative for a while, when all the timings aligned,” remarked paleoanthropologist Briana Pobiner from the Smithsonian Institution’s Human Origins Program. “But it’s not as compelling anymore.”

In the past three decades, innovative research methodologies — including ancient DNA analysis and advanced laboratory techniques — combined with the exploration of additional archaeological sites and the inclusion of a more diverse group of scholars from across the Americas, have disrupted the previous narrative and raised fresh inquiries, particularly regarding timelines.

“Anything older than approximately 15,000 years continues to be met with intense scrutiny,” explained Richard Fariña, a paleontologist at the University of the Republic in Montevideo, Uruguay. “However, increasingly compelling evidence from a growing number of older sites continues to emerge.”

In Sao Paulo and at the Federal University of Sao Carlos, Pacheco investigates the chemical transformations that occur when a bone transitions into a fossil. This enables her team to determine when the sloth osteoderms were likely altered.

“We found that the osteoderms were carved prior to the fossilization process” in “fresh bones” — indicating a timeframe of anywhere from a few days to a few years following the deaths of the sloths, but not thousands of years later.

Her team also conducted tests and eliminated various natural processes, such as erosion and animal chewing. The study was published last year in the journal Proceedings of the Royal Society B.

One of her collaborators, paleontologist Thaís Pansani, who was recently associated with the Smithsonian Institution, is investigating whether similarly aged sloth bones discovered at Santa Elina were burned by human-triggered fires, which differ in temperature from those caused by natural wildfires.

Her initial findings indicate that the newly discovered sloth bones were located at human habitation sites — whether scorched intentionally during cooking, or merely found in proximity, remains uncertain. She is also examining and dismissing other potential explanations for the dark stains, such as natural chemical changes.

The earliest location broadly recognized as predating Clovis is in Monte Verde, Chile.

Concealed beneath a peat bog, researchers found stone tools dating back 14,500 years, fragments of preserved animal skins, and assorted edible and medicinal flora.

“Monte Verde was astonishing. You’re at the edge of the world, surrounded by all this organic material preserved,” commented Vanderbilt University archaeologist Tom Dillehay, a long-time investigator at Monte Verde.

Other archaeological locations indicate even more ancient timelines for human activity in the Americas.

Among the most ancient sites is Arroyo del Vizcaíno in Uruguay, where scholars are examining visible human-caused “cut marks” on animal bones estimated to be about 30,000 years old.

At White Sands in New Mexico, scientists have discovered human tracks dated between 21,000 and 23,000 years ago, alongside similarly aged impressions of enormous mammals. However, some archaeologists argue it’s difficult to believe that humans would frequent a spot and leave behind no stone tools.

“They’ve made a compelling argument, yet some aspects of that site bewilder me,” stated David Meltzer, an archaeologist with Southern Methodist University. “Why would individuals leave footprints consistently over a lengthy time without leaving any artifacts?”

Odess at White Sands mentioned that he anticipates and welcomes such inquiries. “We didn’t aim to discover the earliest anything — we’ve simply pursued the evidence wherever it leads,” he remarked.

While the precise timeframe of human arrival in the Americas remains debated — and may never be definitively established — it appears evident that if the initial people arrived sooner than previously believed, they did not swiftly eradicate the colossal creatures they encountered.

And the White Sands footprints capture a few instances of their early encounters.

As interpreted by Odess, one set of trails depicts “a massive ground sloth moving along on four limbs” when it comes across the footprints of a small human who has just hurried past. The large creature “pauses and stands on its hind legs, shifts around, then proceeds in a different direction.”

The Associated Press Health and Science Department receives assistance from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely accountable for all content.