For a long time, scientists thought, as any reasonable person would, that the female ancestor of modern polar bears came from some Alaskan island. But it turns out that, like humans, bears are sometimes attracted to bears that come from foreign places, especially if they have cute accents. In fact, the female ancestor of polar bears came from, of all places, Ireland. (A press release from the Office of the Polar Bear King confirmed that yes, polar bears will be participating in St. Patrick's Day parades worldwide next year.)
The love story goes something like this: some time between 20,000 and 50,000 years ago, changes in Arctic ice sheets brought old-style polar bears into the same habitat with brown bears from Britain and Ireland. The two types of bears checked each other out and liked what they saw. The result (many, many reproductive cycles later): modern-day polar bears! Sadly, the species that's the momma of all polar bears went extinct about 9,000 years ago. So if all the polar bears die, there's no getting them back, barring some sort of creepy Jurassic Park-like scenario.