An Ice Age dormitory
In the limestone caves of Italy's Majella National Park, thousands of bones tell the story of an extinct Ice Age giant: the cave bear, Ursus spelaeus. These animals, larger than modern brown bears, used the deep caverns of the Apennine Mountains as hibernation sites for millennia. Radiocarbon dating on remains from various European sites places these bears in the Late Pleistocene, with populations declining drastically around 40,000 years ago, coinciding with the arrival of anatomically modern humans. They went extinct about 24,000 years ago during the Last Glacial Maximum.
The name spelaeus means "of a cave," and for good reason. These animals were tied to their subterranean shelters. Analysis of the cave walls reveals deep, parallel claw marks. Scientists interpret these markings as evidence of bears preparing their hibernation nests, a behavior seen in living bears today. The scratches show how they scraped away rock to create more comfortable sleeping hollows. This physical evidence, frozen in time, links between the behavior of an extinct species and its modern relatives.
The vast number of remains found in these caves suggests they were used repeatedly over many generations. Mitochondrial DNA studies from other European cave sites show that each cave often housed a unique and closely related genetic lineage. This points to an extreme fidelity to their birthplaces, a "homing" behavior where females returned to the same cave system to give birth and hibernate.
Reading the bones
The story of the Majella cave bears is behavior. Genetic analysis of a 42,000 to 44,000-year-old tooth provided the first nuclear DNA sequences for this species. This genetic material confirmed that cave bears and modern brown bears (Ursus arctos) split from a common ancestor, Ursus deningeri, around 1.2 to 1.5 million years ago. Despite their size, isotopic studies of their bones and the specialized shape of their teeth show they were primarily herbivores. Their large molars were adapted for grinding tough plant matter, a diet that likely made them vulnerable to the rapid climate and vegetation shifts of the Late Pleistocene.
Alongside the bears, paleontologists have found remains of other Pleistocene megafauna in the region, including cave lions and rhinoceroses, showing a complex ecosystem. The extinction of Ursus spelaeus was not one event but a gradual decline. A combination of factors, including climate cooling that reduced their food supply and increasing competition with early humans for the same cave shelters, likely sealed their fate. The very caves that were essential for their survival became a point of conflict, contributing to their disappearance.