Scientists Compared the DNA of Every Bear Species on Earth — The Results Shocked Everyone

When scientists collected DNA samples from all eight bear species alive today — polar bears, grizzly bears, giant pandas, sun bears, spectacled bears, sloth bears, Asiatic black bears, and American black bears — and compared all of it, the family tree that came out looked nothing like what the textbooks showed. The polar bear, which everyone pictures as its own distinct animal perfectly adapted to the Arctic, turned out to be genetically so close to the brown bear that the two species are still producing fertile offspring in the wild today. The giant panda spent nearly 20 million years completely alone on its own branch, more distant from all other bears than any bear is from any other. And a population of brown bears on three small Alaskan islands carries more polar bear DNA than polar bears from other regions. This video covers what the full DNA comparison of every bear species revealed — where bears originally came from, why the polar bear result confused everyone, what is happening right now in the Canadian Arctic with hybrid bears, and what the panda's lonely evolutionary history actually means. Sources: — Krause J. et al. (2008). Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary. BMC Evolutionary Biology, 8, 220. — Hailer F. et al. (2012). Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage. Science, 336(6079), 344–347. — Kumar V. et al. (2017). The evolutionary history of bears is characterized by gene flow across species. Scientific Reports, 7, 46487. — Lan T. et al. (2022). Genome of the Spectacled Bear. Molecular Biology and Evolution. — Liu S. et al. (2014). Population Genomics Reveal Recent Speciation and Rapid Evolutionary Adaptation in Polar Bears. Cell, 157(4), 785–794.