Long before the Arctic became what it is today, a stretch of Norway’s northern coast supported an unexpectedly rich mix of wildlife. This image has emerged from a cave where thousands of years of natural sediments quietly protected the remains of animals that lived during a relatively mild phase of the last ice age.
The site provided an unusually complete record of life in an environment that rarely preserves such ancient evidence. By collecting bones, sediments and genetic material, scientists were able to reconstruct a coastal ecosystem that included creatures from the sea, tundra and freshwater habitats simultaneously. The findings extend beyond identifying individual species. They provide a glimpse into how entire Arctic communities responded when climate change reshaped the landscapes they depend on, and why some populations disappeared rather than adapting.
A 75,000-year-old ecosystem has emerged hidden under Norway
The PNAS journal, titled “75,000-year-old Scandinavian Arctic cave deposits reveal animal diversity and ancient environment of the past,” reveals that the discovery comes from Arne Qvamgrotta Cave, a cave on the northern coast of Norway that remained largely unexplored for decades after it was discovered during tunnel construction in the 1990s. Although its entrance had been known for years, the sediments within remained largely undisturbed until archaeological excavations conducted in 2021 and 2022 revealed what had been preserved beneath the sediments.
These excavations revealed the remains of 46 species, including mammals, birds and fish. Together they represent the oldest currently known record of an animal community from the European Arctic dating back to a warmer period about 75,000 years ago. The study describing the findings was published in the Proceedings of the National Academy of Sciences.
Species that reveal ancient Arctic habitat
The collection paints a more diverse picture of the region than the frozen wilderness.
Marine animals shared the coastline with birds and terrestrial mammals, suggesting an environment in which several habitats coexist.Species identified include polar bears, walruses, bowhead whales and porpoises. Bird remains included Atlantic puffins, common eiders and rock ptarmigan, while Atlantic cod appeared alongside freshwater fish, marking rivers and lakes across the surrounding tundra.
Reindeer also occupied the landscape, taking advantage of land that became more accessible after the glaciers retreated.One unexpected discovery was the presence of collared rodents. Although this species still exists elsewhere, it disappeared from Europe long ago, and so far there is no evidence that it lived in Scandinavia during this period.
Computer: BNAS
The ecosystem is hidden within the cave sediments
Each species contributes another piece to the ecological picture.
Freshwater fish indicate the presence of inland bodies of water outside the cave, while bowhead whales and walruses indicate that sea ice is still forming offshore. At the same time, porpoises generally avoiding heavy ice indicate that the frigid conditions were seasonal rather than permanent.Rather than being locked under ice year-round, the area appears to have experienced variable conditions that created opportunities for a wide range of animals.
Coastal waters, open tundra, and freshwater systems were all available within relatively short distances, allowing different species to occupy the same broader ecosystem.This combination helps explain why such a wide range of remains accumulated in one place.
DNA hints at a missing chapter
Bones provided more than just physical identification. Genetic analysis allowed scientists to compare these ancient animals to later populations.The results indicate that many of the species represented within the cave were unable to survive once cold conditions returned. Rather than persisting through subsequent climate shifts, they appear to have disappeared as advancing ice reshaped the landscape and reduced available habitat.For a region where well-preserved animal remains older than 10,000 years are exceptionally uncommon, the cave fills an important gap in the fossil record.
It embodies a period that had previously been understood only in parts.
What happened when the climate changed
Evidence suggests that these animals expanded into northern Norway after the retreat of glaciers during the warmer period. When cold conditions eventually returned, that opportunity disappeared.Rather than simply moving elsewhere, many residents appear to have become trapped when advancing ice once again covered the area. Suitable habitats are no longer connected by routes that allow easy movement, leaving some communities unable to establish themselves elsewhere.This pattern is particularly important because it reflects the response of species that have already adapted to cold environments. They even suffered when their surroundings changed beyond the limits they could bear.
