字幕表 動画を再生する 英語字幕をプリント About a million years ago, some intrepid black bears and ferrets crossed the Bering land bridge into North America. Over thousands of generations, the ferrets and bears on different continents became different species, but they still look and act a lot alike. But the American bear and the Asian ferret are thriving, while the Asian bear and American ferret are at risk of extinction. Both sets of cousins owe their uneven luck to another intrepid species – a hairless ape that began its rapid spread some 60,000 years ago, eventually crossing the same land bridge into North America. As its numbers grew, many other species' numbers and habitats shrank. And everywhere it went, the human's big brain helped it develop the tools for success, but it also gave it all sorts of ideas about the new animals it came across. In Asia, people wrongly came to think that bear bile helped cure common ailments and started killing and imprisoning bears for their gallbladders, which they do to this day. Combined with habitat destruction, this has decimated the Asiatic black bear population, which has been cut in half in the last three decades alone. Meanwhile in America, many fewer people hunted bears after they decided that they were pretty cute. More recently, North Americans have also moved much more rapidly from farms to urban areas; the new-growth forests that are popping up in their absence happen to be the perfect habitat for bears. In fact, it's so good that there are now about twice as many black bears roaming the woods of North America as there were when European colonists first arrived 500 years ago. The North American ferrets haven't been so lucky. Their primary food source, the prairie dog, was happy eating grass and breeding like crazy until ranchers – worried that there wouldn't be any nosh left for their cows – started killing off the liddle fuzzy wuzzies. With nothing to eat, the ferrets went extinct in the wild. Asian ferrets, on the other hand, have a favorite food source that humans haven't killed off, and they're still thriving in most parts of Europe and Asia. So, it's not like the Asian ferret and the American bear are better species than their close cousins - whatever that even means. They just got lucky that humans in their part of the world didn't decide to ferret out their favorite food or bear down on their bile. Thanks for watching this video and thanks to all of our Patreon supporters who make MinuteEarth possible. If you'd like to support us as well, you can go to patreon.com/MinuteEarth. We really appreciate it.