Humans may have contributed to the demise of cave bears some 20,000 years ago, the Washington Post reports.
Cave bears, Ursus spelaeus, are closely related to modern brown bears, though cave bears outweighed brown bears by hundreds of pounds, the Post adds. Researchers from Germany and Poland have reconstructed the mitochondrial genomes of 59 cave bears from more than a dozen places in Western, Central, and Eastern Europe, which they compared to 64 published cave bear mtDNA sequences. As they reported in Scientific Reports last week, the researchers uncovered five major mtDNA lineages among these cave bears, suggesting a more complex biogeography of European cave bears.
The researchers also estimated that the cave bears' population decline began about 40,000 years ago, which coincides with the spread of modern humans into Europe. While the Post notes that some scientists have attributed the cave bears' extinction to climate change, study author Hervé Bocherens from the University of Tubingen points out that cave bear populations were unaffected by climate fluctuations prior to then. There's also fossil evidence that humans hunted cave bears, the Post notes.
Or it could be a combination of the two. Study author Verena Schünemann from the University of Zurich adds at the Post that there "might be still a synergistic effect of both factors: humans and climate."