An international research team has recovered ancient human mitochondrial and nuclear DNA directly from cave wall materials in Portugal and Spain, some of it embedded in a pigmented calcite crust on a painted panel roughly 16,000 years old. The finding, published in Nature Communications, suggests that the people who created or touched prehistoric rock art left behind genetic traces that survived millennia inside mineral layers. If the technique holds up under replication, it could let scientists identify who made specific cave paintings without relying on skeletal remains or rare portable artifacts.
Why cave-wall DNA changes the study of prehistoric art
Until now, connecting ancient DNA to specific human activities inside caves has depended on two imperfect sources: bones found nearby and sediment scraped from cave floors. Sedimentary ancient DNA, or sedaDNA, captures genetic material from many species that occupied a site over thousands of years, making it difficult to link any single DNA fragment to a particular moment or action. A recent overview of sedaDNA methods has shown that floor deposits typically contain a broad mix of animal, plant, and microbial sequences, diluting the human signal.
The new cave-wall approach sidesteps that problem. Because painted surfaces were touched by far fewer organisms than open cave floors, wall-derived samples can, in principle, yield a higher proportion of human DNA relative to microbial or faunal sequences. The team sampled a pigmented calcite crust from a painted panel at Escoural Cave in Portugal and collected unpigmented wall samples from both Escoural and Covarron Cave in Spain. In at least some of those wall samples, the researchers detected human genetic material without the heavy background noise of other species that sediment typically produces. That distinction matters because cleaner human fractions allow more precise genetic profiling, potentially tying a specific art panel to a distinct prehistoric individual or population group.
From pendant to painted wall: the evidence trail
The cave-wall study builds on a 2023 breakthrough that proved ancient “touch DNA” can persist on stone objects for far longer than many geneticists expected. In that earlier work, published in Nature, researchers recovered genetic material from a Palaeolithic pendant handled approximately 19,000 to 25,000 years ago. The pendant yielded mitochondrial genomes and enough nuclear signal to infer the handler’s sex and genetic affinities, demonstrating that skin oils, sweat, and other bodily fluids can leave a durable genetic imprint on porous mineral surfaces.
The 2026 study extends that logic from a portable artifact to an immovable one. A painted cave wall cannot be carried away or reburied, so the DNA locked inside its calcite crust has remained in its original depositional context. That contextual stability is a significant advantage over loose objects, which can be moved, traded, or contaminated during excavation. The reported analysis in Nature Communications describes the successful extraction of both mitochondrial and nuclear DNA from these wall materials, confirming that the preservation mechanism observed on the pendant also operates on vertical rock surfaces exposed to cave conditions over thousands of years.
Access to the article itself runs through an institutional gateway, and the login portal reflects how tightly controlled the underlying sequence data and methods still are. That controlled access is standard for many high-profile genetics papers, but in this case it heightens the tension between excitement over the technique and the need for open scrutiny.
Expert commentary on the pendant work, however, has flagged serious technical hurdles. Low-template DNA, the kind recovered from brief skin contact rather than dense bone, is extremely vulnerable to contamination from modern handlers, excavators, and even airborne particles. Any researcher, tourist, or conservator who has touched or breathed near the sampled surface could introduce misleading sequences. The pendant study addressed this through careful library preparation and bioinformatic filtering, but scaling those precautions to large, publicly accessible cave walls presents a harder challenge.
Contamination risks and missing data for Escoural and Covarron
Several questions remain open. The full raw sequencing datasets and detailed extraction protocols from the Escoural calcite crust have not yet been publicly released beyond the summary in the Nature Communications paper. Without access to those files, independent labs cannot fully evaluate how effectively the team separated ancient sequences from modern contamination. The study also does not include direct statements explaining how the researchers ruled out DNA contributions from modern visitors or conservation workers at either Escoural or Covarron.
A related gap involves institutional roles. It is not yet clear from the published record which specific laboratories performed the DNA library preparation versus the computational analysis that filtered and aligned the sequences. That division of labor matters because contamination can enter at either stage, and independent verification requires knowing exactly where each step occurred. If a clean-room facility handled extraction but a different group processed the libraries, for example, each link in that chain would need separate auditing.
The broader scientific question is whether wall-derived DNA will consistently outperform sediment samples in human-to-microbial ratio across different cave environments. Escoural and Covarron have distinct geological histories, ventilation patterns, and visitor footprints. Results from two caves, while promising, cannot yet establish a general rule. Caves with heavy tourist traffic, active water seepage, or aggressive microbial biofilms may not preserve touch DNA as well as these initial sites did, and in some contexts floor sediments might still provide a stronger or more stable signal.
Another unresolved issue is temporal precision. Even if wall samples yield a higher proportion of human DNA, that does not automatically prove that the genetic material comes from the original artists. Later visitors who brushed against the same wall, or conservation staff who cleaned or stabilized the surface, could have left their own traces. Distinguishing truly ancient molecules from modern ones will rely on characteristic damage patterns in the DNA, such as fragment length and chemical modifications, but those signatures can become ambiguous when sample sizes are extremely small.
What replication needs to show
For archaeologists and geneticists watching this space, the next development to track is whether other teams can replicate the extraction from painted surfaces at additional sites and whether the resulting DNA profiles are detailed enough to distinguish between individual artists or family groups. Replication will need to demonstrate not only that human sequences can be recovered from other cave walls, but also that independent labs, using their own clean-room facilities and pipelines, can reach similar conclusions about the age and ancestry of the DNA.
Clearer reporting standards will be central to that effort. Future publications will likely face pressure to include more exhaustive contamination controls, from video-documented sampling procedures to negative controls at every stage of extraction and library preparation. Open deposition of raw sequencing reads in public repositories, alongside full metadata about sampling locations and handling history, would allow outside specialists to re-run damage pattern analyses and test alternative filtering thresholds.
If those hurdles can be overcome, the scientific payoff could be substantial. Wall-derived DNA might one day reveal whether the same individuals painted multiple chambers of a cave, whether men, women, or children were more involved in particular motifs, or how closely related the artists were to contemporaneous populations known from burials. Combined with stylistic analysis and radiocarbon dating of associated deposits, genetic profiles tied to specific panels could transform debates about cultural transmission, migration, and social organization in the Upper Palaeolithic.
For now, the Escoural and Covarron results mark a provocative proof of concept rather than a settled method. The work shows that human DNA can survive in the mineral skins of painted walls and that modern sequencing tools are sensitive enough to detect it. Whether that signal can be reliably separated from modern contamination, generalized to other caves, and translated into robust narratives about prehistoric artists remains to be seen. As more data emerge and independent teams attempt their own extractions, the field will learn whether cave-wall DNA becomes a routine tool of rock art research or remains an intriguing but technically fragile experiment.
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*This article was researched with the help of AI, with human editors creating the final content.
