Why Do Animals Have Individual Personalities?

The idea that non-human animals have individual personalities has long been very taboo. Describing a hawk as neurotic or a worm as conscientious is usually seen as anthropomorphic, a projection of humanness unto non-humans. Some animals are going to be more scared of other animals and not really move around a lot. And that's just kind of what we see across species - you always get the odd one that just doesn't really do anything.