A hand pressed to a cave wall should not leave much behind after thousands of years. Neither should a breath of pigment, a smear of skin, or a trace of saliva blown toward stone in the dark.
But in caves across Spain and Portugal, researchers have now recovered ancient human DNA directly from cave wall surfaces for the first time, including from walls with no visible art or markings. The finding, published in Nature Communications, opens a new way to study who was present in prehistoric caves and what they were doing there.
“This study fundamentally changes how we think about where ancient DNA can be found,” said senior author Matthias Meyer in a press release. “We were surprised to see that ancient DNA can be recovered not only from pigmented samples, but also from cave walls that show no visible evidence of past human activity. We can now ask new questions.”
Read More: What Is the Origin Story of Language? Our Ancient Ancestors May Have Developed Communication Rapidly
Ancient Human DNA Found on Cave Walls in Spain and Portugal
Pigmented cave wall sample from Balmori Cave
(Image Courtesy of Kevin Nota/Bossoms Mesa et al., Nature Communications (2026))
Until now, most ancient DNA work in caves has relied on bones, teeth, sediments, or objects that people once handled. Cave art has been harder to connect to specific people because paintings and marks are often separated from archaeological deposits on the cave floor.
The new study tested whether ancient DNA could survive on the walls themselves. The work was part of the First Art project, which aims to date the earliest cave art and study the chemical makeup of ancient pigments. Researchers analyzed material from 24 rock art panels across 11 caves on the Iberian Peninsula, including simple marks, hand stencils, pigment fragments from the Cave of Altamira, and both pigmented and unpigmented cave wall surfaces.
Of the dozens of samples collected, only five contained traces of ancient human DNA.
Cave Walls May Preserve Traces of Human Touch
At Escoural Cave in Portugal, researchers found human DNA in a pigmented calcite crust with no detectable animal DNA alongside it.
Cave sediments often hold DNA from both humans and animals. When human DNA is found alongside animal DNA, it may have arrived indirectly via sediment transport or water movement. When human DNA appears without animal DNA, direct human contact becomes more likely, through touching the wall, rubbing pigment onto it, or leaving behind saliva, sweat, or other bodily fluids.
The DNA found on the pigmented sample could be linked to the creation of the art, but it could also have been deposited at another time.
“Although we cannot directly connect the traces of ancient human DNA we have found to the creation of rock art, this is the first evidence for human DNA preservation on cave walls for thousands of years”, said first author Alba Bossoms Mesa. “It is exciting to think that we may have uncovered a new way to study prehistoric human presence.”
Cave Walls Could Become Genetic Archives
That one pigment-containing sample was the only pigmented material to preserve DNA. Several unpigmented cave wall samples from Escoural and Covarón Caves in northern Spain also contained ancient human DNA, with some also containing animal DNA and one without.
The team also tested a prehistoric bird bone airbrush from Altamira Cave, likely used to blow red ochre onto cave walls, but it yielded no DNA.
Two unpigmented wall samples from Covarón belonged to Western hunter-gatherers, a genetic group also seen in other ancient Iberian populations. Three unpigmented samples were mostly female-derived, while one Escoural sample without animal DNA was mostly male-derived.
DNA damage patterns indicate the cave wall traces are at least 2,000 years old, though they could be older. At Escoural, where the cave was sealed after the Chalcolithic period and not reopened until 1963, the DNA recovered there is at least 4,000 to 5,000 years old.
“This is not just about rock art,” said co-author Hipólito Collado Giraldo. “It's about understanding how people used caves and where they left their marks.”
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Nature Communications: Investigating ancient human DNA preservation on cave walls and in rock art
