Never heard of an uncanny valley.
The uncanny valley, often used in connection with robots, describes the way humans feel if they see something that clearly isn't human but looks so close to human it makes people uncomfortable. Like, Disney animals are fine because they're unrealistic, the robots in Blade Runner are fine because you literally can't identify them as robots. But the area in between, where it's almost human but not quite, is the UV. I've always suspected the reaction developed when Neanderthals still roamed the earth, but of course I have no idea.
Here's my favorite example, from the movie
Splice.