DNA from soil could soon reveal who lived in Ice Age caves. But here’s where it gets controversial: the dirt beneath our feet might be the oldest, most revealing archive of human and ecosystem history, even when bones are gone. This update rewrites how we trace the past, offering a clearer picture of who inhabited ice-age Europe and how environments shifted alongside them.
Over the last twenty years, science has transformed thanks to advances in extracting and analyzing ancient DNA. Researchers can now read genetic material from bones, but they can also recover DNA directly from cave sediments. This field, palaeogenetics, is turning sediment layers into biological time capsules, revealing long-dormant histories without a single bone in sight.
Caves trap genetic records for tens of thousands of years, preserving interactions between humans and their ecosystems. At the Geogenomic Archaeology Campus Tübingen (GACT) in Germany, a collaborative network mixes archaeology, geoscience, bioinformatics, microbiology, and ancient-DNA expertise to map who lived in Ice Age Europe, how ecosystems changed, and what role humans played. For instance, researchers wonder whether modern humans and Neanderthals overlapped in the same shelters, and they even study genetic traces from cave droppings—such as a 40,000-year-old cave-hyena coprolite—to piece together past ravines of life.
The oldest sediment DNA discovered so far comes from Greenland and dates back about two million years. This work marks a leap from the first fully sequenced extinct animal genome (the quagga) in 1984 to today’s high-throughput capabilities, which use robots, automated labs, and powerful data analysis to process immense volumes of DNA data. A human genome, which once took more than a decade to sequence, can now be decoded hundreds of times over in a single day.
In 2022, Svante Pääbo received the Nobel Prize for physiology or medicine, highlighting the field’s global impact. Ancient DNA research now regularly headlines—from attempts to resurrect mammoth-like creatures to tracing human presence across continents over hundreds of thousands of years. The key shift is that DNA can be recovered not only from bones but also from sediments, widening the spectrum of possible discoveries.
GACT’s network spans beyond Germany, enabling fieldwork in cave sites around the world. This summer, for example, researchers collected hundreds of sediment samples in Serbia for ancient DNA and ecological analyses. Future projects plan to sample in South Africa and the western United States to test how well sediments preserve ancient DNA across different climates and time frames.
Yet recovering DNA from sediments is far from simple. DNA molecules are scarce, degraded, and often mixed with modern contamination from visitors and wildlife. Authentic Ice Age DNA is identified by subtle damage patterns, requiring ultra-clean laboratories, robotic extraction, and sophisticated bioinformatics. Each confirmed finding reveals hidden patterns that traditional archaeology might miss.
A central focus is understanding humans’ presence in caves: who lived there, when, and whether modern humans and Neanderthals shared spaces. Sediment DNA also helps map life outside caves—predators dragging prey into shelters and humans leaving waste behind—illuminating broader ecosystem changes and potential biodiversity crises today.
With hundreds of samples already processed, the field anticipates major breakthroughs: genomes of cave bears, early human traces, and intricate microbial communities that once thrived in darkness. Will sediments unlock all their secrets? Time will tell, but the prospects are electrifying.
— By Gerlinde Bigga, Scientific Coordinator of the Leibniz Science Campus Geogenomic Archaeology Campus Tübingen, University of Tübingen. Original publication: The Conversation (republished under Creative Commons).
