Sloth-bone pendants indicate humans arrived in South America 25,000 years ago

The bones were modified by ancient humans, as shown by a clean, polished surface and carefully drilled holes. Moreover, they were polished into triangle and teardrop shapes for personal ornamentation, such as a necklace pendant. 

The dating of the shelter sediment revealed that the artifacts were created somewhere between 25,000-27,000 years ago. 

Ancient humans co-existed with beast sloths

In the archaeological record, these discovered items are the only ones known to have been carved from big sloth bones. 

The findings show that prehistoric humans likely coexisted with now-extinct giant sloths in South America.

This ice-age beast would have weighed over 600 kilograms (1,323 pounds), making it much larger than most brown bears found today.

North and South America were the last continents to be colonized by modern humans, although when that began has been a topic of ongoing debate. It has been largely speculated that prehistoric humans arrived in the Americas about 16,000 years ago.

Reportedly, the first occupants of the Americas were a group known as the "Clovis culture," who arrived from Eurasia approximately 15,000 years ago.

Therefore, 25,000-year-old evidence of humans in the Americas is notably old. The site also has rock art of animal and humanlike figures; however, experts are unsure of the actual age of the artwork. 

The study results have been published in the journal Proceedings of the Royal Society B.

Study abstract:

The peopling of the Americas and human interaction with the Pleistocene megafauna in South America remain hotly debated. The Santa Elina rock shelter in Central Brazil shows evidence of successive human settlements from around the last glacial maximum (LGM) to the Early Holocene. Two Pleistocene archaeological layers include rich lithic industry associated with remains of the extinct giant ground sloth Glossotherium phoenesis. The remains include thousands of osteoderms (i.e. dermal bones), three of which were human-modified. In this study, we perform a traceological analysis of these artefacts by optical microscopy, non-destructive scanning electron microscopy, UV/visible photoluminescence and synchrotron-based microtomography. We also describe the spatial association between the giant sloth bone remains and stone tools and provide a Bayesian age model that confirms the timing of this association in two time horizons of the Pleistocene in Santa Elina. The conclusion from our traceological study is that the three giant sloth osteoderms were intentionally modified into artefacts before fossilization of the bones. This provides additional evidence for the contemporaneity of humans and megafauna, and for the human manufacturing of personal artefacts on bone remains of ground sloths, around the LGM in Central Brazil.