New research, conducted in part at Texas State University, has dated Pecos River rock art to 6,000 years ago and identified complex metaphysical concepts in the imagery that influenced the belief systems of multiple Mesoamerican cultures.

The research was conducted by a team composed of Karen Steelman, Ph.D., science director at Shumla Archaeological Research and Education Center; Carolyn Boyd, Ph.D., Shumla Endowed Research Professor in the Department of Anthropology at TXST; and Phil Dering, Ph.D., associated faculty in the Department of Anthropology at TXST. Their findings, “Mapping the chronology of an ancient cosmovision: 4000 years of continuity in Pecos River style mural painting and symbolism,” are published in the journal Science Advances.

“We have securely dated one of the most distinctive rock art traditions in the world—the Pecos River style murals of Southwest Texas,” Boyd said. “With 57 radiocarbon dates from 12 sites, we’ve learned that Indigenous communities began to paint these sacred, polychromatic murals almost 6,000 years ago.

“But it didn’t stop there,” she said. “Using the same graphic style, symbol system and rules of paint application, they continued to create these visual manuscripts for more than 4,000 years.”

Forager societies in southwest Texas and northern Mexico painted multi-colored Pecos River style murals—known as pictographs—in limestone rock shelters. The paintings depict humanlike, animal-like, and geometric figures arranged in deliberate compositions, some spanning 100 feet long and 20 feet tall. The desert climate has preserved these prehistoric art works exceptionally well. For years, many modern archaeologists believed that these expansive murals had been added to and expanded by prehistoric peoples over a period spanning centuries. Radiocarbon dating conducted by the research team told a vastly different story.

“Another huge shocker is that the dates within many of the murals clustered so closely as to be statistically indistinguishable, suggesting that they were produced during a single painting event as a visual narrative,” Boyd said. “This contradicts the commonly held belief that the murals were a random collection of images that accumulated over hundreds or thousands of years.”

The researchers obtained 57 direct radiocarbon dates and 25 indirect oxalate dates for pictographs across 12 sites using plasma oxidation and accelerator mass spectrometry. Bayesian modeling estimates that Pecos River style began between 5,760-5,385 years ago and probably ended 1,370-1,035 years ago.

Stratigraphic and iconographic analyses revealed eight of the murals were created as compositions adhering to a set of rules and an established iconographic vocabulary. This suggests consistent messaging throughout a period marked by changes in material culture, land use and climate. From this evidence, the researchers concluded that Pecos River style paintings, embedded in a cultural keystone landscape, faithfully transmitted sophisticated metaphysical concepts that later informed the beliefs and symbolic expression of Mesoamerican agricultural societies.

“The compositional nature of the murals was further supported by our analysis of the painting sequence. Using a digital microscope to retrace the steps followed by the original artists, we discovered that the painters adhered to a rule-bound color application order,” Boyd explained. “As a result, paint layers of multiple figures are intertwined, forming well-planned, highly sophisticated compositions – some spanning more than 100 feet long and 20 feet tall. They are visual manuscripts created according to a set of rules passed down from one generation to the next for more than 4,000 years.

“But perhaps the most exciting thing of all is that today Indigenous communities in the U.S. and Mexico can relate the stories communicated through the imagery to their own cosmologies, demonstrating the antiquity and persistence of a pan-New World belief system that is at least 6,000 years old,” she said. “Think about it, the canyons of Southwest Texas house a vast and ancient library of painted texts documenting 175 generations of sacred stories and Indigenous knowledge. As an artist and an archaeologist, I can tell you that this is a breathtaking discovery.”