For the first time, scientists have shown that ancient human DNA can survive for thousands of years on cave walls, opening new ways to study prehistoric human activity. This interdisciplinary study was conducted within the framework of the First Art project, which is led by researchers from Spain and Portugal in collaboration with institutions across Spain, Portugal, the UK, China and Germany. The First Art project aims to date the earliest cave art and to characterise its chemical composition. In collaboration with researchers from the Max Planck Institute for Evolutionary Anthropology, the team has now extended their analyses to include DNA analysis.

Researchers studied the microbes associated with historical middens conserved in Greenland’s permafrost, left behind by Paleo-Inuit, ancient Norse, and early modern Inuit. These middens harbored biodiverse bacterial communities – including many unknown taxa – that were especially rich in human- and animal-associated groups. The authors concluded that microbial traces of human activities such as defecation, livestock farming, and seal hunting can linger for centuries in Arctic middens. They also found a wide range of antimicrobial resistance genes in the bacterial genomes. However, the limited outward spread of potential pathogens away from the frozen core of the middens means that they currently pose little risk to public health.