In the spring of 2017, a pair of divers first moved their fins through a narrow passageway in a water-filled cave below the Mexican Yucatan peninsula. They had already swum nearly half a mile through the cave system, spinning around rock needles jutting out from the roof and floor, when they finally reached the threshold that stretched just 28 inches wide.
“That was the portal to this other side,” recalls one of the divers, Sam Meacham, director of the Quintana Roo Aquifer System Research Center (CINDAQ).
In the chamber that extended beyond the small passage was an ancient scene preserved in astonishing detail: an 11,000-year-old mining site for ocher-red pigments, complete with tools and bonfires. The mine, described in a new study published today in Scientific advancesIt is one of the few archaeological sites that reveals where and how ancient humans mined the vibrant pigments that have been used around the world, including mortuary rituals, cave painting, and even sunscreen.
“I’ve spent a long time imagining the different ways people have collected mineral pigments in the past,” says study author Brandi MacDonald, an archaeologist at the University of Missouri and an expert in ocher pigments. “But to be able to see it like this in such an interesting state of conservation, left me speechless.”
The discovery also gives a rare insight into the lives of some of the earliest residents of the Americas, who lived in Yucatan thousands of years before the rise of the ancient Mayan state. One of these early inhabitants was a girl archaeologist named Naia, who likely died in another cave near the newly discovered mine about 13,000 years ago. At least nine other ancient individuals have been identified in the tangled cave system below Quintana Roo, their remains preserved for thousands of years after the caves were flooded from the rising seas approximately 8,000 years ago.
But scientists are still debating what people were doing at the bottom of this dark underworld. Were they burying their dead? Looking for fresh water sources?
What the hell were they going to go there for? says Roberto Junco, director of the Underwater Archeology office of the National Institute of Anthropology and History (INAH), the regulatory body for archeology in Mexico. “We now have very, very strong evidence that at least one of the reasons … was for the extraction of ocher.”
Venture into the dark
The mine discovery began with a chance find when students in a cave surveying class led by Fred Devos, a cave diver with CINDAQ, discovered a previously unnoticed tunnel as they plunged into the Sagittarius cave system. Devos and Meacham returned soon after to explore. After a long swim and passing through the narrow passageway, the divers were amazed at what they saw.
The site is a time capsule of human activity: the pits mark the floor of the chamber, and scattered by broken speleothems (stalagmites or stalactites) that had been used as improvised hammers. They burned burnt rocks and charcoal that once lit the cavern, and neat piles of rocks, known as cairns, marked the miner’s path.
“Fred and I immediately started pointing out all these things,” says Meacham. “It is not natural, and there is nothing that could have done this other than humans.”
Devos contacted Eduard Reinhardt, a geoarchaeologist at McMaster University to discuss the site. Although Reinhardt was initially skeptical, he headed to Mexico the following year to dive into the section of the cave with artifacts, which was later called La Mina (“the mine”). “The site is phenomenal,” says Reinhard.
Furthermore, mining was not only limited to a cave.
During previous dives, Meacham says, “We have noticed these strange and misplaced things,” including rocks stacked in piles and speleothems arranged on the cave floors. However, with many people diving in the Yucatan caves, there were always doubts about whether these oddities stemmed from ancient or modern activities, Reinhardt says.
Now, with such a pristine example of an ancient ocher mine in hand, the team was able to confirm that at least two other suspected submerged cave sites some 20 miles south of La Mina in Quintana Roo were also mining operations. The trio of mines was in use between 10,000 and 12,000 years ago, according to radiocarbon dates.
“It is not just a unique thing,” says Reinhardt. “There was an active program to prospect, find and mine ocher. There will certainly be more locations. “
Colorful Connections
Working as a team with other scientists and divers, the research team began documenting the ancient mining activity within the identified sites. In 100 dives that totaled more than 600 hours underwater, the team collected samples and captured videos, along with tens of thousands of photos to build a three-dimensional model of the La Mina site. The analysis paints a colorful picture of well-planned underground expeditions by generations of landscape-savvy people for some 2,000 years.
The charcoal found around the mines comes from high-resin woods, and was likely selected for its ability to burn bright and long, according to analysis by study author Barry Rock of the University of New Hampshire. The site also appears to preserve the ancient miners’ thought process about excavation materials, Reinhardt notes: The miners continued along the deposit beds until the ocher was depleted. Then they moved sideways to dig another hole. “They understood … some basic geological principles that were not really codified or formalized until the mid-17th century,” he says.
The pigments themselves were also of very high quality, adds MacDonald, with few impurities and a very fine grain size. This means that it easily imparts its vibrant tones to everything you play. “It stains like crazy,” she says.
However, what exactly were people doing with this abundance of pigment? Ocher is an iron-rich material that humans around the world have used for hundreds of thousands of years. Pigments were used to mix a vibrant mix in abalone shells in South Africa about 100,000 years ago. They illuminate the outline of the hands raised against the cave walls in Chauvet, France, some 30,000 years ago. They cover a woman buried in a cave in northern Spain about 19,000 years ago.
Ocher’s uses are also practical. It can act as a mosquito repellent or sunscreen. It may have formed the basis for adhesives in tool making. Some indigenous Africans and Australians still use these vibrant pigments today for ritual and practical purposes.
However, for people who mine ocher in the Yucatan caves, the ultimate goal remains unclear. “Right now, we just don’t know,” says MacDonald.
Why were they there?
Some scientists see clues in the mines themselves that may hint at a ritual or spiritual side of the find. The mining sites are located deep in underground systems, out of reach of light, says Holley Moyes of the University of California, Merced, who specializes in the ritual use of Mayan caves and was not part of the project. In almost all the cases found so far in the early history of humanity, she says, the uses of this so-called “dark zone” are limited to ritual purposes.
“The caves produce all kinds of good and evil; they are probably the most sacred natural feature, “says Moyes. Viewed as entrances to the underworld and sources of sacred water, the caves are particularly spiritual places for the Maya, who built their towns and cities in Yucatan thousands of years after the mine was abandoned. Ocher was also sacred to the Mayans and other Mesoamerican cultures, such as the Aztecs, and figured prominently in art and ritual. “It’s something about that color red,” she says.
Part of the challenge in understanding ancient actions comes from a modern separation of the spiritual and the practical, says James Brady, an expert in cave archeology at California State University, Los Angeles, who was not part of the study team. For many people today, “religion is one hour on Sunday morning,” he says. But that was not the case thousands of years ago. “It could be very significant that this came from a sacred place,” he says of the ocher, “[And] that there was a trip to the cave especially to get it. “
Regardless of the intention behind the extraction, the researchers are delighted with the finding. The astonishing conservation of the site provides an unprecedented window into the activities of the first residents of the Americas, and promises to help direct future research on cave use.
“We are very excited here in Mexico to work on this project,” says Junco of INAH. “This is really one of those moments when there is a big change in the game.”
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