The First Art project aims to date the earliest cave art and characterize its chemical composition. In collaboration with researchers from the Max Planck Institute for Evolutionary Anthropology, the team has now extended its analyses to include DNA analysis. The work is published in the journal Nature Communications.

The findings explore the possibility of recovering ancient DNA directly from cave art, going beyond bones, sediments or, more recently, bone artifacts. The research focused on 24 rock art panels from 11 caves, including simple marks, hand stencils and pigment naturally falling from some figurative paintings from the famous Cave of Altamira. Using cutting-edge DNA extraction and sequencing methods, the team analyzed pigmented and unpigmented cave wall fragments, sediments, bones and a rare ancient airbrush tool used for applying paint.

Although the researchers found traces of ancient human DNA in one pigmented calcite crust sampled in Escoural Cave (Portugal), to their surprise they also found ancient human DNA in several nonpigmented parts of the cave wall in Escoural as well as in Covarón Cave (northern Spain), which had initially been sampled as negative controls.

The study shows that human DNA can be preserved on cave walls long after the populations that visited the cave have disappeared.

A hidden legacy in the stone

Of the 54 samples collected, only five yielded authentic ancient human mitochondrial DNA: a calcite crust with pigment underneath from Panel 11 at Escoural Cave, two unpigmented cave wall samples from a deeper gallery also from the same site, and two unpigmented samples adjacent to rock art in Covarón. Importantly, two of these samples showed no detectable faunal mitochondrial DNA, a rare finding that strongly suggests that the DNA was deposited directly by humans through saliva or other bodily fluids. By contrast, three other unpigmented wall samples contained both human and faunal DNA, suggesting indirect deposition, likely via sediment transfer or water movement rather than direct contact.