Ancient Human DNA Recovered From 22,000-Year-Old Cave Sediment, No Bones Required

A scoop of cave dirt no bigger than a few grains of rice has given researchers the genetic signature of several people who lived in northern Spain about 22,000 years ago. The layer it came from, in El Mirón Cave, holds no bones, no teeth, and no fossils of any kind.

Getting anything out of it was hard work. The sample had to be sequenced 100 times to produce enough usable data, and the team sorted through more than a billion DNA fragments to find human traces among them. They also had to account for modern contamination. The study, led by researchers at the University of Vienna, appears in Science Advances.

The genetic material was probably shed long ago, possibly from the skin, hair, or blood of people sheltering in the cave during the coldest stretch of Europe's last ice age. Skeletons from this period are extremely rare. Only a few human remains are known from this time and culture, and two of them are of very poor quality. The El Mirón sediment adds to that thin record.

What the DNA says is specific. The people who used the cave probably belonged to a western ancestry group, with dark skin, hair, and eyes. The DNA came from a mix of individuals, with more males than females represented.

This is also not the first genetic material recovered from the site. In 2025, researchers found animal and human mitochondrial DNA in dirt samples dated between 46,000 and 21,000 years ago, and the animals and humans appeared to have occupied the cave at different times. The new work goes further by extracting nuclear DNA. Mitochondrial DNA passes only through maternal lines, while nuclear DNA comes from both parents and carries more information about an individual's lineage.

That extra detail let lead author Pere Gelabert and colleagues ask whether Western and Eastern European populations mixed during the last ice age or stayed in their own corners of the continent. They compared the El Mirón DNA with two older reference points: the remains of a woman in France who lived roughly 31,000 years ago, and a tooth from northern Spain dated to around 25,000 years ago. Both showed some Eastern ancestry, which suggests populations at both ends of Europe were interbreeding before the last glacial maximum. The El Mirón DNA, by contrast, shows only western ancestry. The authors wrote that their data argue against a major population replacement or discontinuity at this point. The population of southwest Europe between 30,000 and 20,000 years ago appears to have been relatively continuous. Samples from this time and place remain scarce, but sedimentary DNA, or sedaDNA, has practically doubled the evidence available.

The approach has been building for some time. In 2021, researchers pulled mitochondrial DNA from the mud floor of a cave in Georgia, belonging to a woman who lived 25,000 years ago. This year, human DNA was found preserved on the wall of a cave in Argentina decorated with rock art. Alba Bossoms Mesa, an evolutionary anthropologist at the Max Planck Institute, cautioned that the team cannot directly connect the DNA to the creation of the art, but called it the first evidence of human DNA surviving on cave walls for thousands of years.

A 2025 review argued that, once its technical challenges are worked out, sedaDNA could deepen understanding of human dispersal, hunter-gatherer interactions, early agriculture, domestication, and disease. Its authors predicted that applications to a wide variety of sites will increase rapidly in the next few years. Gelabert and colleagues say that integrating more skeletal genomes with sedaDNA datasets will be essential to resolving how Upper Paleolithic populations in Europe took shape.