I do not think fear of wild animals is irrational. But it is how you react to and use that fear that makes you paranoid or not. I think that backpackers who have no fear of wild animals either do not backpack much or have not had many encounters. Wild animals are unpredictable at times. Human habituated bears who no longer fear humans can be dangerous. Habituated bears live in wilderness areas where there is a lot of human use. In this case, you have to convince them to fear you. The information given by others is all good information. I personally feel that learning about animal behavior is very useful. Learning what makes them tick helps you to make better decisions about your own behavior when you run into a bear. I am not sure what I do personally makes much difference! But, if I run into bear sign when I am solo, I start a fake conversation with myself, two different voices, pound my trekking poles so that I sound like two people or at least some weird legged animal, and talk directly to the bear too! Hay, bear, you are on MY trail, get OFF!