A diver collecting samples of ochre from the mine, now submerged underwater

An ancient ocher mine discovered in submerged caves on Mexico’s Yucatan Peninsula was used by some of the earliest inhabitants of the Americas around 12,000 years ago

There are nearly 2,000 km of known underwater cave systems in Mexico’s Yucatán Peninsula. Previously dry and accessible, they were submerged as sea levels rose about 7,000 years ago. As many of the passages flooded, it created the ideal conditions for preserving ancient history.

Skeletal remains of at least 10 humans, including a female teenager, had already been found in the passages caves, as well as the remains of Pleistocene megafauna like elephants, giant ground sloths, and sabre-tooth cats.

For over two decades, it led researchers to debate what on earth drew people down here. Now, we may finally have an answer… it was ochre!

An expert team of divers, archaeologists, and geologists have discovered a series of remarkably preserved mining sites, including ochre extraction beds and pits, digging tools, shattered and piled flowstone debris, navigational markers and hearths.  In some areas, the ceiling is still visibly blackened, likely by the soot from small fires made to light their work.

The evidence is between 10,000-12,000 years old, making it one of the world’s oldest known ochre mines.

Red ochre is one of the most famous accessories in the vast story of human evolutionary development and behavioral complexity. It’s the most commonly identified inorganic paint used throughout history, and ochre minerals have been collected around the world for use in rock paintings, mortuary practices, decorating objects and personal adornment.

It may also have been used as an antiseptic, sunscreen, or even a repellent for pests such as ticks or lice.

It was clearly valuable stuff and, however they used it, was extremely important to the lives and culture of America’s earliest inhabitants. Such large-scale extraction of the ochre would have required sophisticated and organised efforts by large teams of people.

The team involved in the research included divers, archaeologists, and earth sciences experts from McMaster University, the University of Missouri Research Reactor, Centro Investigador del Sistema Acuífero do Q Roo (CINDAQ), and Instituto Nacional de Antropología e Historia.

“The underwater caves are like a time capsule,” says Ed Reinhardt, an expert diver and professor in McMaster’s School of Earth, Environment and Society who collected, analyzed and dated samples from the caves. “There is clear evidence of ochre mining which would have taken place thousands of years ago.”

A diver examines a rock pile thought to be an ancient navigational marker inside a 12,000-year-old ochre mine in Quintana Roo, Mexico. © CINDAQ.ORG

“What is remarkable is not only the preservation of the mining activity, but also the age and duration of it… Our study reinforces the notion that ochre has long been an important material throughout human history,” says Brandi MacDonald, professor at the Archaeometry Laboratory at the University of Missouri.

We hope that these amazing discoveries of ancient human activities preserved in these waters from so long ago will draw attention to the threats these waters face from human activity now” says Sam Meacham, cave exploration researcher and founder of CINDAQ. ” Ultimately the real treasure within the caves is what flows through them that allows people and wildlife to thrive.”

Their findings are reported in the journal Science Advances.

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Maiya Pina-Dacier

Head of Community at DigVentures, Maiya digs with a trowel in one hand, and a Twitter feed in the other. She reports on all our discoveries live from the trenches, and keeps our Site Hut full of the latest archaeology news. Got a story? Just drop her a line...

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