Upthorn wrote:I agree with this. I suspect that it probably evolved pretty early as a part of the disgust response that helps many animals avoid infectious diseases?
This is one of the most prominent theories posited, yeah. Most of the theories are thoroughly boring explanations, it's really just a question of which one. We may not find out exactly why due to the difficulty in testing subjective "canniness", but It Is A Thing; it's just that it's played up, in same manner as, say, déja vu.
In any case, no one's claiming that that the existence of the Uncanny Valley means it's something exclusive to humans and only humans.
In general I find that mental phenomena or things commonly thought of as typically human, are often present in varying degrees throughout the higher mammals/mammals in general.