No, bears do not necessarily attack humans because they are threatening offspring or caught them by surprise. This 82-year-old woman was in bed sleeping when a 400 lb. bear broke into her house and beat her up some. So, what prompted that? She must have been encroaching on the bears.
In Minnesota, a woman had been seeing 4 bears in her yard. When she wanted to let her dog out, she looked around for the bears. Not seeing them she let the dog out. The bears were under her deck. Ultimately the woman was attacked by the mother bear. Take note of the idiocy in the article explaining the high level, rational thinking of bears when a DNR “specialist” says, “bears are very cautious of people and bears do not want to get themselves in a situation where they might have to attack a person.” This is akin to a pack of wolves huddled up having a discussion and pointing out which of the herd of elk are sick, lame and old, explaining to each other to only kill those animals because it is their responsibility to do so.