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New discoveries could rewrite the history of early Americans — and the 4-ton sloths they lived with
Sloths weren’t always slow-moving, furry tree-dwellers. Their prehistoric ancestors were huge – up to 4 tons – and when startled, they brandished immense claws.
For a long time, scientists believed the first humans to arrive in the Americas soon killed off these giant ground sloths through hunting, along with many other massive animals like mastodons, saber-toothed cats and dire wolves that once roamed North and South America.
But new research from several sites is starting to suggest that people came to the Americas earlier – perhaps far earlier – than once thought. These findings hint at a remarkably different life for these early Americans, one in which they may have spent millennia sharing prehistoric savannas and wetlands with enormous beasts.
“There was this idea that humans arrived and killed everything off very quickly – what’s called ‘Pleistocene overkill,'” said Daniel Odess, an archaeologist at White Sands National Park in New Mexico. But new discoveries suggest that “humans were existing alongside these animals for at least 10,000 years, without making them go extinct.”
Some of the most tantalizing clues come from an archaeological site in central Brazil, called Santa Elina, where bones of giant ground sloths show signs of being manipulated by humans. Sloths like these once lived from Alaska to Argentina, and some species had bony structures on their backs, called osteoderms – a bit like the plates of modern armadillos – that may have been used to make decorations.
Júlia d’Oliveira / AP
In a lab at the University of Sao Paulo, researcher Mírian Pacheco holds in her palm a round, penny-sized sloth fossil. She notes that its surface is surprisingly smooth, the edges appear to have been deliberately polished, and there’s a tiny hole near one edge.
“We believe it was intentionally altered and used by ancient people as jewelry or adornment,” she said. Three similar “pendant” fossils are visibly different from unworked osteoderms on a table – those are rough-surfaced and without any holes.
These artifacts from Santa Elina are roughly 27,000 years old – more than 10,000 years before scientists once thought that humans arrived in the Americas.
Originally researchers wondered if the craftsmen were working on already old fossils. But Pacheco’s research strongly suggests that ancient people were carving “fresh bones” shortly after the animals died.
Her findings, together with other recent discoveries, could help rewrite the tale of when humans first arrived in the Americas – and the effect they had on the environment they found.
“There’s still a big debate,” Pacheco said.
“Really compelling evidence”
Scientists know that the first humans emerged in Africa, then moved into Europe and Asia-Pacific, before finally making their way to the last continental frontier, the Americas. But questions remain about the final chapter of the human origins story.
Pacheco was taught in high school the theory that most archaeologists held throughout the 20th century. “What I learned in school was that Clovis was first,” she said.
Clovis is a site in New Mexico, where archaeologists in the 1920s and 1930s found distinctive projectile points and other artifacts dated to between 11,000 and 13,000 years ago.
This date happens to coincide with the end of the last Ice Age, a time when an ice-free corridor likely emerged in North America – giving rise to an idea about how early humans moved into the continent after crossing the Bering land bridge from Asia.
Mary Conlon / AP
And because the fossil record shows the widespread decline of American megafauna starting around the same time – with North America losing 70% of its large mammals, and South America losing more than 80% – many researchers surmised that humans’ arrival led to mass extinctions.
“It was a nice story for a while, when all the timing lined up,” said paleoanthropologist Briana Pobiner at the Smithsonian Institution’s Human Origins Program. “But it doesn’t really work so well anymore.”
In the past 30 years, new research methods – including ancient DNA analysis and new laboratory techniques – coupled with the examination of additional archaeological sites and inclusion of more diverse scholars across the Americas, have upended the old narrative and raised new questions, especially about timing.
“Anything older than about 15,000 years still draws intense scrutiny,” said Richard Fariña, a paleontologist at the University of the Republic in Montevideo, Uruguay. “But really compelling evidence from more and more older sites keeps coming to light.”
In Sao Paulo and at the Federal University of Sao Carlos, Pacheco studies the chemical changes that occur when a bone becomes a fossil. This allows her team to analyze when the sloth osteoderms were likely modified.
“We found that the osteoderms were carved before the fossilization process” in “fresh bones” – meaning anywhere from a few days to a few years after the sloths died, but not thousands of years later.
Her team also tested and ruled out several natural processes, like erosion and animal gnawing. The research was published last year in the journal Proceedings of the Royal Society B.
One of her collaborators, paleontologist Thaís Pansani, recently based at the Smithsonian Institution, is analyzing whether similar-aged sloth bones found at Santa Elina were charred by human-made fires, which burn at different temperatures than natural wildfires.
Her preliminary results suggest that the fresh sloth bones were present at human campsites – whether burned deliberately in cooking, or simply nearby, isn’t clear. She is also testing and ruling out other possible causes for the black markings, such as natural chemical discoloration.
“A giant ground sloth”
The first site widely accepted as older than Clovis was in Monte Verde, Chile.
Buried beneath a peat bog, researchers discovered 14,500-year-old stone tools, pieces of preserved animal hides, and various edible and medicinal plants.
“Monte Verde was a shock. You’re here at the end of the world, with all this organic stuff preserved,” said Vanderbilt University archaeologist Tom Dillehay, a longtime researcher at Monte Verde.
Other archaeological sites suggest even earlier dates for human presence in the Americas.
Among the oldest sites is Arroyo del Vizcaíno in Uruguay, where researchers are studying apparent human-made “cut marks” on animal bones dated to around 30,000 years ago.
At New Mexico’s White Sands, researchers have uncovered human footprints dated to between 21,000 and 23,000 years ago, as well as similar-aged tracks of giant mammals. But some archaeologists say it’s hard to imagine that humans would repeatedly traverse a site and leave no stone tools.
Peter Hamlin / AP
“They’ve made a strong case, but there are still some things about that site that puzzle me,” said David Meltzer, an archaeologist at Southern Methodist University. “Why would people leave footprints over a long period of time, but never any artifacts?”
Odess at White Sands said that he expects and welcomes such challenges. “We didn’t set out to find the oldest anything – we’ve really just followed the evidence where it leads,” he said.
While the exact timing of humans’ arrival in the Americas remains contested – and may never be known – it seems clear that if the first people arrived earlier than once thought, they didn’t immediately decimate the giant beasts they encountered.
And the White Sands footprints preserve a few moments of their early interactions.
As Odess interprets them, one set of tracks shows “a giant ground sloth going along on four feet” when it encounters the footprints of a small human who’s recently dashed by. The huge animal “stops and rears up on hind legs, shuffles around, then heads off in a different direction.”
The Transportation Security Administration (TSA) has cautioned that a looming government shutdown could lead to longer wait times for travelers at airport security checkpoints. The warning comes as the TSA announced it is expecting a record 40 million airline passengers to take to the skies over a two-week period that began Thursday.
Most TSA workers, about 95%, are considered essential, and would therefore remain on the job in the event of a shutdown — but without pay — TSA administrator David Pekoske said in a post on X.
Air traffic controllers are also deemed essential employees and would be asked to work while foregoing a paycheck. Employees would be paid after a shutdown were to end.
Here is how a government shutdown will affect air travel for consumers.
Will the government shutdown affect flights?
Not for now. Passengers will still be able to travel on flights they have booked, with operations expected to continue as normal at least in the early days of a shutdown. That’s because TSA agents, air traffic controllers, and other essential airport staff will remain on the job.
Will TSA screening lines be longer?
While passengers are always advised to arrive at the airport earlier than usual during peak travel periods, that advice could be even more applicable in the event of a shutdown.
“While our personnel are prepared to handle high volumes of travelers and ensure safe travel, please be aware that an extended shutdown could mean longer wait times at airports,” the TSA’s Pekoske warned.
“My advice? Arrive at your airport early, with plenty of time to park your car, check your bags and make your way through security,” he added.
The last government shutdown in 2018-2019, lasted 35 days. While TSA officers were also deemed essential then, the number officers who called out sick rose as the shutdown dragged on and financial woes ensued.
“It was after TSA officers started missing paychecks that you saw the sick call numbers increase,” said senior CBS News senior transportation and national correspondent Kris Van Cleave. “There may not be an immediate impact at all airports, particularly if it is a short shutdown. If it drags on, then you have a workforce that is among the lowest-paid government employees,” he said.
If, in the event of a prolonged government shutdown, TSA employees stop showing up to work in significant numbers, wait times at security screening checkpoints would likely increase.
What about air traffic controllers?
The Federal Aviation Administration (FAA) is already grappling with a shortage of air traffic controllers, who are responsible for securing the national airspace by guiding takeoffs and landings and ensuring that aircraft don’t fly too close to one another. About a month into the last shutdown, LaGuardia Airport temporarily delayed flights because of staffing shortages, including among air traffic controllers.
In the event of a shutdown, the more than 14,000 air traffic controllers in the U.S. would be expected to show up to work without pay.
What would a government shutdown mean for passport processing?
According to the State Department’s contingency plan, consular operations will continue as normal “so long as there are sufficient fees to support operation,” given that they are integral to national security. That includes passport and visa services.
Still, some passport services could be limited, if they are located in buildings run by another agency that is inoperational.
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Washington — Homeland Security Secretary Alejandro Mayorkas warned Friday that his agency could suffer “serious” consequences if Congress fails to pass legislation funding federal agencies and averting a government shutdown in the next few hours.
In an interview with “Face the Nation with Margaret Brennan,” Mayorkas said many components of the Department of Homeland Security would be affected by a lapse in funding, including the Transportation Security Administration (TSA), FEMA and Border Patrol.
The homeland security chief added that a failure by lawmakers to pass a stopgap spending bill before Saturday would also mean staff at the Countering Weapons of Mass Destruction Office would be redirected to other parts of his department.
“The implications and the consequences are serious, especially when it comes to Homeland Security,” Mayorkas said.
He urged Congress to approve legislation that would keep government agencies operating before midnight, when a short-term extension enacted in September will expire.
House Speaker Mike Johnson unveiled earlier this week a legislative package negotiated with Democrats that would have extended government funding through March 14, provided more than $100 billion in disaster aid for states impacted by extreme weather events, and given members of Congress a pay raise, among other provisions.
But the proposal was swiftly met with pushback from some conservative Republicans, who balked at the size and scope of the 1,550 page deal. Crucially, it was also criticized by billionaire Elon Musk, an ally of President-elect Donald Trump, and then by the incoming president himself.
Trump and Musk torpedoed the package, with Musk taking to X, the social media platform he owns, to lambaste provisions of it. The president-elect further upended negotiations over a funding deal when he called on Republicans to address the debt limit — which is set to be reinstated Jan. 1 — in their plan.
Johnson unveiled a second measure Thursday, which would have funded the government for three months, suspended the nation’s borrowing limit until January 2027 and provided $110 billion in disaster relief. The more tailored legislation, which Trump backed, also included health care provisions, a one-year renewal of the farm bill and funding for rebuilding the Francis Scott Key Bridge in Baltimore, which collapsed in March.
But that package failed to pass the House with the necessary support after it was opposed by most Democrats and more than three dozen Republicans.
That defeat sent Johnson and GOP leaders back to the drawing board, with the prospect of a shutdown rising with each passing hour. Republicans are now discussing voting on three provisions of the package individually, sources familiar with the matter told CBS News: a clean extension of government funding; billions of dollars in disaster aid; and assistance to farmers.
Mayorkas told “Face the Nation” that a shutdown just before the holidays — when tens of millions of Americans are traveling — would mean TSA employees at airports throughout the country would be forced to work without pay. However, they would likely receive backpay after a shutdown ends, as has happened before after previous funding lapses.
“We’re going to have tens of thousands of TSA employees working an incredibly high volume of passenger traffic throughout our airports across the country, and they will be doing so keeping the American public safe without pay,” he said.
The Homeland Security secretary also said those impacted would include U.S. Border Patrol agents stationed along the U.S.-Mexico border.
“There are people in government service who are dedicating their talent and their energy to the well-being of the American people, who rely on their paychecks to make ends meet, and it is the holiday season, after all, but our men and women on the border will be guarding the border of the United States at no pay if funding doesn’t come through,” Mayorkas said.
The $110 billion in disaster assistance that will likely be included in a spending deal includes money for FEMA, which has been responding to the hurricanes that devastated the southeast this fall.
Mayorkas said that inaction by Congress would impact those states hit by the storms, including North Carolina and Florida.
“What FEMA will need to do, another significant impact of the failure to fund the federal government, is they will now need to delay — they’ll put on pause certain contracts, certain projects that are actually repairing communities devastated by extreme weather events, by tornados, by hurricanes, by fires, and that will delay the rebuilding of communities and really delay the ability to deliver for people who have suffered so much,” he said.
Mayorkas said a shutdown occurring over the holidays would force the Department of Homeland Security to “make difficult decisions now to delay projects.”
Lawmakers representing those storm-ravaged states have pushed for disaster relief to be included in any legislative package funding the government.