Seeing as there are animals considered vastly less intelligent than humans who have a working language, wouldn't a structured language have been one of the first skills we mastered?
Or was it more a combination of scents, grunts, and body language? I understand that this is prehistory and all but it seems a bit insulting to our ancestors to portray them with such a limited vocabulary.
This would be a good question for /r/askanthropology.