My experience with black bears, limited though it may be, is that they really don't want anything to do with humans. That being said a couple of years ago one took a small child locally. http://www.cbsnews.com/stories/2002/...in519289.shtml
here's an article about the attack. This is the only attack on a human that I've heard about around here and we have plenty of bears. The few that I've come across in the woods usually take off pretty quick. Had a buddy ran into a momma and 2 cubs about 5 years ago while hunting. Cubs skittered up trees and mom squared off on him. Ended well with the bears leaving the area before I got to him, but he was pretty shaken up by the whole thing. I always have a sidearm in the woods but not because I'm afraid of bears, I just like having it with me.