The Uncanny Valley: Why We Are Afraid of Things That Look Like Humans

Why do humans have it uncanny valley effect? Why are we afraid of things that look almost human? Well, before you get to what I assume, your point would be I'll come up with a couple options. The other theory is that the uncanny valley applies to things that are pale, shallow-eyed, pale skins, gaunt. So from an evolutionary standpoint, it doesn't make a ton of sense.