Researchers led by the University of Vienna have extracted human DNA dating back roughly 22,000 years from sediment inside El Mirón Cave in Spain, according to ScienceAlert. The sample contained no human remains of any kind — just a scoop of dirt weighing about as much as a few grains of rice. The findings were published in Science Advances.
Why it matters
The result adds to a growing body of work showing that genetic material shed by ancient people can survive in cave floors and walls long after their bones have vanished. According to ScienceAlert, sedimentary DNA, or sedaDNA, is positioned to reshape archaeology by loosening the field's dependence on the fossil record. Physical remains from this particular time and culture are extremely rare, and ScienceAlert reports that two of the few that exist are in very poor condition. The cave dirt effectively doubled the genetic evidence available for the period.
A billion fragments, one faint signal
Getting usable data from the El Mirón sample was not simple. The team had to sequence the sediment 100 times before enough readable material accumulated, and they sorted through more than a billion DNA fragments to isolate the human traces, ScienceAlert reports. The genetic material was likely left behind by skin, hair or blood from people who took shelter in the cave during the harshest stretch of Europe's last ice age.
What the team recovered points to a western ancestry group with dark skin, dark hair and dark eyes. The DNA appears to have come from more than one person, with males outnumbering females in the mix.
The authors wrote that the result demonstrates what sedaDNA can do when no human remains are available, and that it firmly links the archaeological record to human genetic identities, according to ScienceAlert.
Nuclear DNA and a question about ice age mixing
Earlier sedimentary work recovered only mitochondrial DNA, which passes down the maternal line. The El Mirón study went further, pulling nuclear DNA from the cave sediment — genetic material inherited from both parents that carries far more detail about a person's lineage. That extra detail lets researchers test whether western and eastern populations in ice age Europe interbred or kept to separate regions.
Lead author Pere Gelabert and colleagues compared the El Mirón nuclear DNA with two other specimens: the remains of a woman from France who lived about 31,000 years ago, and a tooth from northern Spain dated to around 25,000 years ago. Both of those individuals showed signs of eastern ancestry, suggesting people at opposite ends of Europe were mixing before the last glacial maximum. The El Mirón DNA, by contrast, showed only western ancestry.
The authors concluded that their genomic data argue against any major population replacement or break at that point in time, according to ScienceAlert. Instead, the population of southwest Europe between 30,000 and 20,000 years ago appears to have stayed relatively continuous.
A technique spreading across the field
El Mirón is one entry in a fast-growing list. In 2021, researchers recovered mitochondrial DNA from the muddy floor of a cave in Georgia. This year, ancient human DNA was found preserved on the wall of a rock-art cave in Argentina. Alba Bossoms Mesa, an evolutionary anthropologist at the Max Planck Institute, described that find as the first evidence that human DNA can persist on cave walls for thousands of years, while cautioning that the traces cannot be directly tied to the creation of the artwork. In 2025, scientists identified both animal and human mitochondrial DNA in dirt dated between 46,000 and 21,000 years ago.
A 2025 review argued that sedaDNA could deepen understanding of how humans spread across landscapes, how hunter-gatherers interacted, and the origins of agriculture, domestication and disease. Its authors predicted that applications of the method at a wide range of sites will increase rapidly in the coming years, according to ScienceAlert.
Technical hurdles remain before the approach becomes routine, but the direction of travel is clear. Watch for the next round of cave-sediment studies to push the method into older layers and new regions — and for nuclear DNA, not just mitochondrial, to become the standard target.
