This is another thing that I've never really understood, though I know they produce a very visceral reaction in those with snake phobias. My husband isn't really afraid of anything in the world...except snakes, they have the power to make him panic and run away screaming. He knows the types of snakes around here and is well aware that most of the snakes that produce this reaction will not hurt him, but he is still unable to suppress it. In his words, he has no idea why they do that to him, he's never once had a run-in with a snake in his life, but he can barely stand to even watch them on TV. He was raised by his Russian Orthodox grandparents, who were Old Believers, and was always taught to associate the beginning of evil in the world with snakes, and he has mentioned that perhaps that's what it is...but he's not at all convinced that's what caused it. Also, that wouldn't explain the people who are from completely different cultures that didn't have the "snake in the garden" story, yet still have a fear of snakes. As for the patterns, they are intended to be either camouflaging or threatening, and in either case I guess I can see why they would disturb someone...the first because it keeps you from seeing them until they're RIGHT THERE, and the second because they're broadcasting their intentions to anything that gets too close.