Pre-Holocene Mining Operations In Mexico

Pre-Neolithic modern human hunter-gatherers in the Americas weren't unsophisticated.

Investigations in the now-submerged cave systems on the Yucatán Peninsula continue to yield evidence for human presence during the Pleistocene-Holocene transition. Skeletal remains are scattered throughout the caves of Quintana Roo, most representing individuals who died in situ. The reasons why they explored these underground environments have remained unclear. Here, we announce the discovery of the first subterranean ochre mine of Paleoindian age found in the Americas, offering compelling evidence for mining in three cave systems on the eastern Yucatán over a ~2000-year period between ~12 and 10 ka. The cave passages exhibit preserved evidence for ochre extraction pits, speleothem digging tools, shattered and piled flowstone debris, cairn navigational markers, and hearths yielding charcoal from highly resinous wood species. The sophistication and extent of the activities demonstrate a readiness to venture into the dark zones of the caves to prospect and collect what was evidently a highly valued mineral resource.

Brandi L. MacDonald, et al., "Paleoindian ochre mines in the submerged caves of the Yucatán Peninsula, Quintana Roo, Mexico" 6(27) Science Advances eaba1219 (July 3, 2020) DOI: 10.1126/sciadv.aba1219

The introduction provides helpful context for the discovery:

By the end of the Pleistocene, humans had migrated to and inhabited the area of Quintana Roo, located on the eastern Yucatán Peninsula, Mexico. This karstic landscape is characterized by a large limestone platform punctuated by a now-submerged system of caves. The cave systems were dry and accessible from the Last Glacial Maximum (LGM) until the middle Holocene transition {>13,000 to 8000 calibrated years before present (cal B.P.) [9 to 8 thousand years (ka)]}, after which time most of the caves flooded during sea-level rise, resulting in a unique and well-preserved paleorecord. In the cave systems of Quintana Roo, the remains of at least 10 individuals dating to the Pleistocene-Holocene transition have been reported; most of these represent persons who had entered when the caves were dry and accessible. However, the reasons why people persisted in their underground exploration of these places have been largely unknown. Previous suggestions have included temporary shelter, access to fresh water, ritual, or intentional burial of human remains, although none are firmly substantiated by available archaeological evidence. 

Here, we present uniquely preserved evidence indicating that people were exploring underground cave systems to prospect and mine red ochre, an iron oxide earth mineral pigment used widely by North America’s earliest inhabitants. Red ochre is the most commonly identified inorganic paint used throughout history worldwide. Considered to be a key component of human evolutionary development and behavioral complexity, ochre minerals were collected for use in rock paintings, mortuary practices, painted objects, and personal adornment for millennia. Red ochre use is a common characteristic of North American Paleoindians and is found associated with human remains, mobiliary art, toolkit caches, ochre grinding stones, ochre-processing areas, hide tanning, or other domestic or utilitarian contexts, including a component of grease, mastic, and hafting adhesive. One instance of ochre quarrying activity has been proposed at the Powars II site (Wyoming), yet evidence for intensive mining activity (i.e., pits and trenches) remains uncertain. Whether ochre procurement or use by Paleoindian groups and their Old World predecessors constitutes evidence for ritual behavior or utilitarian purposes remains an ongoing anthropological discussion, yet consensus suggests that the two are not mutually exclusive. Despite the ubiquitous and sustained use of ochre among Paleoindian peoples, there is virtually no archaeological evidence available concerning ochre prospection and mining methods in the Americas.