Oh, man. That was pretty common back in the day. I'm originally from Pocatello, ID, a couple hours from Yellowstone. My family and I have been there many times. I have a fantastic picture that my grandfather took, circa 1930, of his aunt holding up some food while my grandfather, then a teen snapped a photo. He got a great shot of a black bear standing on hind legs with his aunt holding a half of a sandwich shoulder high at arm's length. But apparently, she decided she didn't want to give up her sandwich to the bear after the photo was taken, a development the bear found highly annoying. So he chomped on her hip. She tossed the sandwich in terror and pain and the bear dashed away after it. Fortunately, she was wearing a thick fur coat and was only bruised. But it could've been a lot worse. Pro tip: when it comes to holding out food to bears, don't pull the food away and tell the bear: "Psych!"