I've ran across somebody that doesn't believe that Neanderthal existed......and I'm just wondering how they could think that? Why would somebody have a problem with cavemen? 

You know, there are many people in this world that don't believe something that appears to be fact. And, the best thing is, it's okay for them to believe what they believe. They aren't creating a ruckus over this. They are not going to die for not believing in Neanderthals. And the world is not going to end. 

You can be astonished over what you believe is ignorance, but just because they aren't believing about this particular fact (or is it?), doesn't mean they're stupid. They just have a different belief system.