When you said that fears can be evolutionary, it made me think. Have you heard of the uncanny valley? It's when something, like a doll, looks almost human, but there is just something slightly....off.
For some reason, things that are almost humanlike, like a doll or a lifelike robot, are creepy and disturbing to almost all humans.
Why is that? Well, too many people share this fear for it to be just something from their past. So then it must be evolutionary.
Perhaps your caveman ancestors were sitting around the fire one night, then one of them noticed that the caveman across from him seemed...off.
The smile was a bit too wide, he had just a few too many teeth, his skin was just a bit too tight. Then perhaps the caveman would notice that it was so, incredibly, quiet.
He could not even hear the fire crackling, or the birds chirping. And then he would notice that the thing that was almost human was looking straight at him, grinning a too-wide smile.
Or perhaps there is another reason that us humans have a fear of the uncanny valley. Who knows?