Image Source: Jupiter Images
This is interesting from an evolutionary perspective, but not all that shocking and certainly not inexplicable. It does, however, create a dilemma for creationists: why would Neanderthals have the genetic basis for speech if they are not us? Christian theology holds that humans and humans alone were created with souls and with a place in God's plans, but if the Neanderthals were as capable of speech as us, it's difficult to explain what their place in "creation" must be.
There has been much speculation about Neanderthals' ability to speak. They were endowed with a hyoid bone, which anchors the tongue and allows a wide variety of movements of the larynx. Neanderthal skulls also show evidence of a large hypoglossal canal. This is the route taken by the nerves that supply the tongue. As such, it is a requisite for the exquisitely complex movements of speech. Moreover, the inner-ear structure of Homo heidelbergensis, an ancestor of Neanderthals, shows that this species was highly sensitive to the frequencies of sound that are associated with speech.
That Neanderthals also shared with moderns the single known genetic component of speech is another clue that they possessed the necessary apparatus for having a good natter. But suggestive as that is, the question remains open. FOXP2 is almost certainly not “the language gene”.
Source: The Economist
If one believes in souls, then one must consider whether Neanderthals had souls. It would be bizarre to think that they would not have souls if they could speak to some degree like we do, had culture, and may have even had religious beliefs. On the other hand, how can a person believe that they had souls if they believe that we homo sapiens were specially created by God, separate from the rest of the animal world?
The existence of Neanderthal souls is not entirely compatible with traditional Christian theology; the non-existence of Neanderthal souls is also not entirely compatible with traditional Christian theology — especially if we remember all the evidence for their more advanced capabilities. This is hardly surprising because traditional Christian theology was created without knowledge of Neanderthals — it is, after all, a human creation without any divine or supernatural influence.
If we dispense with all the nonsense of souls and theology, though, there aren't any problems or incompatibilities. The ability of Neanderthals to speak is an interesting evolutionary question and it would be nice to know just how extensive their language skills might have been. The only "problem," if there is one, is for human egos:
The idea that the forebears of modern humans could talk would scupper the notion that language was the force that created modern human culture—otherwise, why would they not have built civilisations? But it would make that chat with a Neanderthal much more interesting.
So if Neanderthals could talk — perhaps not quite as well as our species, but reasonably well nevertheless — why didn't they create civilizations and cultures to the same extend as we did? To be fair, our species didn't do it for quite a while after Neanderthals died out so perhaps they didn't have a chance and maybe they would have done very well if they had and more time. We can wonder, though, what the driving force behind the construction of civilization, culture, and religion might have been if the key ingredient might not have been language.