Brazilian scientist rewrites the history of human arrival in South America

The peopling of the Americas is one of the most fascinating and controversial topics of anthropology and archaeology.

It refers to the process by which humans first arrived in the Americas, with the most widespread theory being that small groups of hunter-gatherers crossed the Bering land bridge from Asia into North America at the end of the last Ice Age, when sea levels were lower and the land was still exposed. From there, humans spread southward into South America.

This theory, supported by archeological findings, DNA analysis, and complex dating techniques, suggests that humans first reached South America no later than 16,000 years ago. However, a recent discovery in central-western Brazil may put an end to that hypothesis, indicating human activity in the region at least 25,000 years ago.

At the Santa Elina rock shelter in the state of Mato Grosso — where archaeologists have previously uncovered cave paintings and the skeletons of two giant sloths — French husband and wife duo Denis and Agueda Vialou came across sloth bones which they suggested may have been manipulated by humans, apparently polished and perforated to be used as pendants.

Earlier this month, Brazilian paleontologist Thaís Pansani published a paper in the journal Proceedings of the Royal Society B confirming that supposition. 

The bones, which consist of the bony plates, or osteoderms, of giant sloths, are shaped in a way that strongly suggests human manipulation. Ms. Pansani’s work managed to date the bones to between 25,000 and 27,000 years ago — i.e. still during the so-called Last Glacial Maximum, or the peak of the last Ice Age.

“At first, I was skeptical myself,” Ms. Pansani tells The Brazilian Report. “The holes made in the bones were so polished, without any of the imperfections that you would expect from human perforation.”

“But...