I don't remember where the idea came from, but I heard a hypothesis that basically posited this precise thing. If you look at linguistic history many (if not most) of our words derive ultimately from some analogy to another thing or idea. Our modern languages have embedded in them the combined learning of thousands of generations, and since it is much easier to use the words representing analogies than to come up with and communicate those analogies in the first place, this means anyone who learns a modern language is comparatively brilliant to someone who lived a long long time ago.
