The discovery, along with other recent findings, strengthens the theory that people arrived in South America via ocean crossings long before humans might have walked into North America from northeastern Asia, during the end of the last glacial period around 16,000 years ago. The study was published in the latest Proceedings of the Royal Society B.
These brave individuals apparently did not shy away from big game either, with giant sloth being at the top of the menu.
"If our interpretation is correct and the sloths were consumed, they might have been an interesting source of meat because of their very large size," lead author Richard Fariña told Discovery News. Giant sloths could grow to 15 feet and are estimated to have weighed between 2-4 tons.
Fariña, a paleontologist at the University of the Republic in Uruguay, and his team analyzed over 1,000 bones excavated at a site called Arroyo del Vizcaíno near Sauce, Uruguay. The bones belonged to at least 27 individuals, mostly from the giant sloth Lestodon. Radiocarbon dating suggest the site and bones date to 30,000 years ago.
The researchers determined that several of the giant sloth bones feature deep, asymmetrical marks consistent with those produced by human stone tools.
A stone, shaped like a scraper tool and found at the site, shows signs of wear from probable use by humans, according to Fariña.
He added that there is no evidence that the bones were part of a river deposit or some other nature-made collection.
Virtually all of the bones belonged to large, meaty adult giant sloths, which again suggests human may have been eating them. A natural collection of sloth bones likely would have included individuals representing multiple age groups.
When the sloths were alive, the landscape would have featured a "stream going through gently rolling grasslands," he said. The site today is somewhat similar.
Just last month, another team of researchers in nearby Brazil brought together artifacts -- including cave paintings and ceramic art -- from Serra da Capivara national park in Brazil's northeastern Piaui state. The oldest artifacts date to 30,000 years ago.
Franco-Brazilian archaeologist Niéde Guidon, who worked on the project and has led explorations of Piaui's interior, said that, in light of the findings from Uruguay and Brazil, she believes that it is time to reconsider how and when the Americas were first populated.
Piecing together the latest evidence, she believes that humans came to South America at least 30,000 years ago, and possibly much earlier, by water.
"130,000 years before the present, Africa suffered from a very dry climate, which was the origin of the deserts (there)," she said. "People tried to find food in the sea, and the streams and winds (flow) from Africa to the northeast of Brazil. It is possible to think that some boats arrived at the coast of Piaui."
To this day, these same water and wind currents benefit cruise ships coming into Brazil.
The indigenous people from Piaui and surrounding regions had ancestors with "dark skin (and) their hair was black, but smooth and not curly," Guidon said.
Visitors to Uruguay will soon be able to see the Arroyo del Vizcaíno artifacts.
Viegas, Jennifer. 2014. “First South Americans Ate Giant Sloths”. Discovery News. Posted: November 19, 2013. Available online: http://news.discovery.com/human/life/first-south-americans-dined-on-giant-sloths-131119.htm