A fishy fossil find suggests Scottish bears may have descended from polar bears

A new analysis of ancient bones and fossils found in a highland cave has found they are “fishier than the average bear” and could even suggest that polar bears once roamed Scotland.

Advances in the chemical study of bones and teeth have allowed experts from the University of Aberdeen and National Museums Scotland to reassess fossils collected from the Inchnadamph “Bone Caves” in Sutherland. Analysis of samples revealed evidence of fish in the diet of animals previously identified as brown bears.

Working with master’s student Holland Taekema from the University of Edinburgh, and as part of a broader study of the history of bears in Scotland, the researchers compiled new stable isotope data – a technique for reconstructing human and animal diets in ancient populations. They found that in three samples of bears that were about 30,000 to 50,000 years old, long before humans settled on the land, the diet consisted almost entirely of marine fish or other seafood.

This finding, say the researchers who published their results Annales Zoologici Fenniciis significantly different from the meat- and plant-based diet typical of modern brown bears or that was found in the British Isles before their extinction in the last 1,000 years, and may even indicate the presence of polar bears during the period in Scotland lived in the last ice age.

Professor Kate Britton, from the University of Aberdeen, said: “We have identified several samples that differ both from the diet of other bears that lived in Scotland thousands of years ago and from what we would expect from brown bears today Thumbs up.” .

“Instead of eating the flesh of land animals, plants, or even a little salmon, like today’s brown bears, these bears appear to have lived almost exclusively on seafood.”

“This contradicts what we know today, but also throughout history, about the diet of brown bears. Even modern grizzly bears, known to feed seasonally on salmon in some places, do not consume nearly as much seafood in their animal life.” Diet.

“The diet is so unusual that we now need to either re-evaluate what we know about brown bear feeding ecology or question whether these fossils are brown bears at all. Since they are richer in fish than the average bear, we now have work to do to understand why and to answer the question of whether they are brown bears with a unique diet or a different species or subspecies of brown bear, maybe even polar bears.”

While polar bears are now found only in the circumpolar north, researchers say that as the climate cooled to the last glacial maximum, the seasonal sea ice limit in the North Atlantic would have shifted southward, potentially allowing polar bears – which are also great swimmers – to move further south areas to expand than they occur today.

A similar theory was put forward back in the 1990s after a bear skull with some polar bear-like features was discovered, although no further evidence of polar bears has been found in prehistoric Scotland and more modern archaeological techniques since then have called polar bear radiocarbon dating this particular skull into question.

The team will now conduct further work to answer questions about the known presence of brown bear DNA in modern polar bears and polar bear DNA in the broader population of Ice Age European brown bears, which has been documented in other studies, and to understand how this occurs genetically Data could relate to the new isotope evidence from the bone cavities.

Dr. Andrew Kitchener, chief curator of vertebrates at National Museums Scotland, where the fossil bears are kept, added: “With this habitat expansion, the polar bears may have encountered the brown bears that were living in Scotland at the time. As we know.” That polar bears and brown bears can now successfully interbreed where their ranges overlap raises interesting questions about the ancestry of the bears that later roamed our islands.”

The team, together with colleagues in Sweden, is now conducting DNA analysis of the samples to determine the species of bears from the Assynt bone caves and whether they are brown bears, polar bears or even hybrids.

This work is accompanied by a new physical study of the bones themselves using advanced methods. This research will be conducted in 2025 by a newly appointed research fellow, Dr. Alicia Sanz Royo, carried out at the University of Aberdeen as part of the PALaEoScot project.