Larger usually means smarter, yet there is a steady improvement at modern-human sights in flints and tools, but Neanderthal sights show zero advancement in hundreds of years. There is also a lack of evidence (which is never conclusive) that they did not make drawings, although they did appear to bury their dead with some sentimentality (flowers). The interbreeding concept was the traditional thought, but modern DNA analysis appears to nullify it (see, THE NEANDERTHAL ENIGMA, by James Shreeve). It does seem odd that there would be no interbreeding, but we don't know the physical and cultural traits of Neanderthals. After all Wolves and Poodles aren't likely to make it happen, although it is possible. Another idea is that offspring were sterile like mules. I recommend the above book to anyone who has a curiosity about this. He is honest in not asserting what he really doesn't know, while exploring the possibilities.
So the scientists say.
From observation, the blue-eyed dogs ARE wolves.