I believe that the so-called Neanderthals weren't too different than us. In fact, most scientists say you wouldn't be able to tell the difference if you saw one next to you. According to some Christian sites I've read, it's entirely plausible that Neanderthals were people who lived in caves and had a bone deficiency.
Like one of the so-called skeletons found was later found out to be a boy with rickets, but scientist's imaginations ran away from them...they gave it a scientific name, had this whole image drawn up just from a few bones.
This part of "science" is very incomplete if you ask me...just some random bones and theories from people desperate to prove macro evolution. There are alternate explanations.