Polar bears and grizzly bears diverged about 500,000 years ago. Now, a changing planet appears to be bringing them back together. Live Science reports that the two species have been running into each other—and mating—with greater frequency in recent years, resulting in a hybrid bear known as a "pizzly" or a "grolar." Two factors are behind the phenomenon: Grizzlies are moving north because of hotter temperatures, and polar bears are moving south in search of food as Arctic ice melts. Here's how Alyse Stanley of Earther puts it: "What do you get when you cross a polar bear and a grizzly bear? A fluffy reminder of how climate change is transforming our planet at an alarming rate." Because the two bears diverged recently, relatively speaking, they're still able to mate and produce offspring, says Vanderbilt's Larisa DeSantis in a YouTube video.
"Usually hybrids aren't better suited to their environments than their parents, but there is a possibility that these hybrids might be able to forage for a broader range of food sources," she tells Live Science. Polar bears, unlike grizzlies, have a specific diet, and their longer skulls make them adept at grabbing seals from the sea. Given all the blubber they eat, polar bears also have relatively small teeth. "We don't know yet, but perhaps the intermediate skull of the pizzly could confer a biomechanical advantage," says DeSantis. Pizzlies have been spotted as far back as 2006, but their numbers are growing. A 2017 study found that at least eight of the hybrids emerged from pairings of one female polar bear and two separate male grizzlies. Researchers have confirmed that pizzlies can produce offspring of their own. (A mystery ailment strips bears of their fear of humans.)