Oldest art or symbolic expressions in North America? Pleistocene modified bones and a human remain at Sima de las Golondrinas cave, Zacatecas, Mexico

The discovery of Pleistocene human presence at Chiquihuite Cave (state of Zacatecas, Mexico) dating to, or even before, the Last Glacial Maximum (LGM, over 18,000 years ago), prompted the search for another cave site in the same region, where the implications of Chiquihuite could be tested and corroborated in a second context. In January 2020, we started work at Sima de las Golondrinas (“Chasm of Swallows”), a cavern in the Zuloaga mountains. Excavation unit X-20 focused on an older profile left behind by unknown early-20th-century explorers. Previous radiocarbon dating of three charcoal-rich deposits had indicated the stratigraphy contained deposits ranging in age from the Terminal LGM to the Middle Holocene. The short-timed excavation revealed the stratigraphic sequence had been slowly deposited in an aquatic environment, when the cave was partly inundated for thousands of years, until the Holocene. Preliminary palynological studies confirmed the presence of water and nearby lakes, matching the paleoenvironmental reconstructions from Chiquihuite, 100 km away. Excavation X-20 yielded no lithic tools or stone raw materials, but an abundance of zoo-archaeological materials, yet without the presence of traditional megafauna. Some specimens present human modifications in the form of butchery-related cut marks, but also engravings possibly related to early symbolic behaviors. Here, we present a selection of eight bones of elevated archaeological importance. One of them is an ischium bone belonging to a young Homo sp. individual, dating to the Early Holocene. The other seven are modified bones coming from layers dating between the Terminal LGM and Younger Dryas. They belonged to white-tailed deer (Odocoileus virginianus), mountain bighorn sheep (Ovis canadensis), and American pronghorn (Antilocapra americana). The assemblage includes four human-modified animal phalanges, with symbolic expression substrates. Two of them were found in levels older than 16,000 years, and may well represent some of the oldest forms of art in the Americas.