The stone walls have begun to speak, but only faintly
Etched into the limestone walls of ancient caves in Spain and Portugal, human DNA has waited thousands of years to be heard. Researchers from the First Art project, working alongside the Max Planck Institute for Evolutionary Anthropology, discovered that genetic material deposited through touch, breath, and bodily presence can survive on cave surfaces across millennia — offering archaeology a new kind of witness. The finding suggests that the walls themselves, long regarded as mere canvases, are also archives of the people who stood before them, and that the story of prehistoric humanity may be written not only in pigment, but in stone.
- Five samples from European caves yielded authentic ancient human DNA — found not where researchers expected, but in unpigmented wall sections collected as negative controls, upending the assumptions that guided the study.
- Two samples contained no animal DNA at all, pointing to direct human contact — a touch, a breath, a moment of presence pressed into stone and preserved across thousands of years.
- DNA analysis identified cave visitors as mostly female or male individuals belonging to Western hunter-gatherer genetic clusters, quietly reframing who moved through these spaces and how.
- A prehistoric bone airbrush from Altamira, once used to blow red ocher onto walls, yielded nothing — decades of modern handling had erased whatever ancient signal it once carried, a reminder of how fragile this evidence remains.
- Of 24 rock art panels examined, ancient DNA appeared in only a handful of locations, signaling that preservation is rare and condition-dependent, tempering the breakthrough with the discipline of uncertainty.
- The field now faces a new horizon: refining sampling methods to improve recovery rates, and moving toward the possibility of identifying the biological sex and genetic ancestry of the artists themselves.
In caves across Spain and Portugal, researchers have found something unexpected in the stone itself — traces of human DNA that have endured for thousands of years. The discovery, published in Nature Communications, grew out of the First Art project, a multinational collaboration that set out to study the chemical makeup of prehistoric cave art. In partnering with the Max Planck Institute for Evolutionary Anthropology, the team stumbled onto a method that could reshape how archaeologists study the deep past.
The researchers collected 54 samples from 24 rock art panels across 11 caves, including the famous Cave of Altamira. Five samples yielded authentic ancient human mitochondrial DNA — one from beneath pigment at Escoural Cave in Portugal, two from unpigmented sections deeper in the same cave, and two from unpigmented areas near rock art in Covarón Cave in northern Spain. Crucially, the unpigmented sections had been gathered as negative controls, baseline measurements meant to show what caves contained in the absence of human activity. Instead, they contained human DNA.
How the DNA arrived matters as much as the fact that it survived. Two samples showed no animal DNA, suggesting genetic material was deposited directly through saliva or bodily contact — someone touching or breathing on the wall. The other three contained both human and animal DNA, pointing to indirect deposition through sediment or water. This distinction offers a glimpse into how people actually inhabited these caves: not merely as visitors to art, but as presences who moved, touched, and left themselves behind.
Analysis of the DNA revealed that three samples came mostly from female individuals, one mostly from males, and one remained indeterminate. Nuclear DNA from Covarón placed those individuals within the Western hunter-gatherer genetic cluster, consistent with other ancient Iberian populations. A prehistoric bird bone airbrush from Altamira — used to blow red ocher onto walls — yielded nothing; decades of modern handling had overwhelmed any ancient signal.
Alba Bossoms Mesa, the doctoral researcher who led the analysis, noted that while the DNA cannot yet be directly linked to specific artworks, this is the first evidence that human genetic material can persist on cave walls across millennia. The rarity of successful recovery — ancient DNA appeared in only a handful of the 24 panels examined — tempers the excitement, but the direction is clear. The cave walls have begun to speak, and researchers are only beginning to learn how to listen.
In caves across Spain and Portugal, researchers have found something unexpected in the stone itself: traces of human DNA that have endured for thousands of years. The discovery, published in Nature Communications, emerged from work by the First Art project, a collaboration among institutions in Spain, Portugal, the United Kingdom, China, and Germany. The team set out to understand the earliest cave art and its chemical makeup, but in partnering with the Max Planck Institute for Evolutionary Anthropology, they stumbled onto a method that could fundamentally reshape how archaeologists study the deep past.
The researchers collected 54 samples from 24 rock art panels across 11 caves, including the famous Cave of Altamira. They examined pigmented surfaces, unpigmented wall sections, sediments, bones, and even a rare ancient bone tool used to spray paint onto stone. What they found was striking: five samples yielded authentic ancient human mitochondrial DNA. One came from a calcite crust beneath pigment at Escoural Cave in Portugal. Two others came from unpigmented wall sections in the same cave's deeper galleries. Two more emerged from unpigmented areas near rock art in Covarón Cave in northern Spain. These were not the samples the team expected to work. The unpigmented sections had been collected as negative controls—baseline measurements meant to show what the caves contained when humans were not involved. Instead, they contained human DNA.
What makes this finding significant is not just that the DNA survived, but how it got there. Two of the five samples showed no detectable animal DNA, a rare condition that suggests the human genetic material was deposited directly through saliva or other bodily fluids, likely from someone touching or breathing on the cave wall. The other three samples contained both human and animal DNA, indicating the genetic traces arrived indirectly, carried by sediment or water movement rather than direct contact. This distinction matters because it hints at how people actually used these caves—not just as galleries to admire, but as spaces they moved through, touched, and inhabited.
When the team analyzed the DNA more closely, they found that three samples came mostly from female visitors, one mostly from males, and one remained indeterminate. Nuclear DNA from two unpigmented samples at Covarón placed those individuals within the Western hunter-gatherer genetic cluster, consistent with other ancient Iberian populations. The researchers also tested a prehistoric bird bone airbrush from Altamira, hoping to find saliva-derived DNA from whoever used it to blow red ocher onto the walls. They found nothing—the tool had been handled so many times over decades of study that modern human contamination had overwhelmed any ancient signal.
Alba Bossoms Mesa, the doctoral researcher at Max Planck who led the analysis, emphasized that while the team cannot directly connect the DNA traces to the creation of specific artworks, this is the first evidence that human genetic material can persist on cave walls across millennia. Hipólito Collado Giraldo, an archaeologist and rock art specialist from the Extremadura government, noted that the findings open a new window onto prehistoric behavior. "It's about understanding how people used caves and where they left their marks," he said. The implications extend beyond art itself—researchers can now potentially determine the biological sex and genetic ancestry of cave visitors without excavating or disturbing the archaeological record.
Yet the rarity of successful DNA recovery tempers the excitement. Of 24 rock art panels examined, ancient DNA was detected in only one pigmented surface and two unpigmented locations. This suggests that preservation is highly variable and depends on specific conditions—mineral crusts, sealed environments, and other factors that most cave walls lack. Matthias Meyer, the paleogeneticist who co-led the work, acknowledged the surprise: ancient DNA survived not only on pigmented surfaces but also on bare stone that showed no visible sign of human activity. The question now is whether researchers can refine their methods to improve success rates and understand which conditions favor preservation.
The work represents a fundamental shift in where archaeologists might look for evidence of the past. Rather than relying solely on bones, artifacts, and sediments, they can now examine the cave walls themselves as archives of human presence. The next phase will involve testing more sites, different art styles, and various application techniques—particularly hand stencils and figurative paintings in caves with favorable molecular conditions. If the methods continue to improve, it may eventually become possible to identify at least some of the artists who created these works, to assign them a biological sex and genetic identity, and to understand which populations moved through these caves and when. For now, the stone walls have begun to speak, but only faintly, and only in the language of DNA.
Citações Notáveis
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.— Matthias Meyer, paleogeneticist at Max Planck Institute
It's about understanding how people used caves and where they left their marks.— Hipólito Collado Giraldo, archaeologist and rock art specialist
A Conversa do Hearth Outra perspectiva sobre a história
So they found human DNA on cave walls. How is that different from finding it in bones, which archaeologists have been doing for years?
The crucial difference is location and what it tells you. Bones are portable—they get buried, moved, mixed with other remains. A cave wall is fixed. If you find human DNA on a specific panel or section of stone, you know that person was there, in that exact spot, at some point. It's like a fingerprint left in time.
But they only found it in five samples out of fifty-four. That's less than ten percent. Why is that success rate worth celebrating?
Because it's the first time anyone has found it at all. The researchers didn't know if ancient DNA could survive on stone for thousands of years. Now they know it can. The low rate actually tells you something important—it means preservation depends on very specific conditions, which means when you do find it, you're looking at something real, not contamination or noise.
They mention that two samples had no animal DNA, which suggested direct human contact. What's the significance of that distinction?
It's the difference between evidence and inference. If you find human DNA mixed with animal DNA, you can't be sure a human put it there—it might have arrived through water or sediment movement. But if you find only human DNA, with no animal traces, that's much stronger evidence that a person actually touched that spot, breathed on it, left saliva. That's direct contact.
One of the samples came from an unpigmented wall section. Why would a researcher expect to find human DNA there?
They wouldn't—that's why it was a negative control. The team was testing whether DNA could survive on pigmented surfaces where people applied paint. The unpigmented sections were supposed to show what the baseline was, what you'd find if humans hadn't been involved. Finding human DNA there was surprising because it suggested people were leaving traces just by moving through the cave, not necessarily by creating art.
What happens next? Can they actually identify who made specific paintings?
Not yet. They can't connect the DNA they found to the creation of any particular artwork. But now they know it's theoretically possible. The next step is refining the methods, testing more caves and different art styles, and understanding which conditions preserve DNA best. Eventually, yes—they might be able to say a woman from a Western hunter-gatherer population touched this wall, or a man from that group moved through this gallery. That's the promise.