New research suggests humans lived in South America at the same time as now-extinct giant sloths, supporting evidence that humans arrived in the Americas earlier than once thought.
Scientists analyzed triangular and teardrop pendants made from the sloths’ bony material. They concluded that the cut and polished shapes and drilled holes were the work of deliberate craftsmanship.
Dating of the ornaments and sediment at the Brazil site where they were found indicate an age of 25,000 to 27,000 years ago, the researchers reported. That’s several thousand years before some previous theories had suggested that the first humans arrived in the Americas, having emigrated from Africa and then Eurasia.
“We now have good evidence — along with other sites from South and North America — that we need to rethink our ideas about human migration to the Americas,” said Mirian Liza Alves Forancelli Pacheco, study co-author and archaeologist at the Federal University of Sao Carlos in Brazil.
Over the past decade, other research has challenged the conventional wisdom that humans only reached the Americas a few thousand years before rising sea levels covered the Bering Land Bridge between Russia and Alaska, perhaps some 15,000 years ago.
The ornaments were discovered about 30 years ago in a rock shelter called Santa Elina in central Brazil. The new study is the first to comprehensively analyze them and rule out the possibility that humans had found and excised them thousands of years after the animals perished.
The team of researchers from Brazil, France and the United States said their analysis shows this handiwork was done within days to a few years after the animals died and before the materials fossilized. The researchers also ruled out natural wear and other things that could explain the shapes and holes. They reported their findings Wednesday in the British journal Proceedings of the Royal Society B.
“We think they were personal objects, possibly for personal adornment,” said Thais Rabito Pansani, a study co-author and paleontologist at the Federal University of Sao Carlos in Brazil.
Once one of the largest creatures in South America, giant ground sloths stood 10 to 13 feet (3 to 4 meters) tall and usually walked on all four legs, using their sharp claws to dig burrows. They weighed over a thousand pounds (450 kg), and their skin included bony structures under their fur – somewhat similar to the bony plates of modern armadillos.
Two years ago, another team of researchers reported that fossilized human footprints found near White Sands, New Mexico, date from 21,000 to 23,000 years ago — though some researchers dispute these dates. Other evidence from Mexico suggests human presence about 26,000 years ago, and findings from Uruguay may indicate human habitation as far back as 30,000 years ago.
Jennifer Raff, an anthropological geneticist at the University of Kansas who was not involved in the study, said the new paper was “an important addition” to the conversation, but like all findings on the topic, it could also draw some backlash.
Still, the evidence from multiple sites is forcing scientists to reconsider old assumptions that humans only came across the Bering land bridge in one major migration wave, said Briana Pobiner, a study co-author and paleoanthropologist at the Smithsonian Institution’s National Museum of Natural History in Washington. .
Some may have died out, “but it’s very likely that several waves of people came to America,” she said.
Follow Christina Larson on Twitter at @larsonchristina
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