It can't be a requirement, because at some point there was a first great thinker. That one appeared in a nominal vacuum because otherwise they wouldn't be the first.
That is categorically untrue. Evolutionary, humans are a social species. My comment is it doesn't happen in a vacuum, which is obvious to the extent that it is impossible to live in a vacuum.
A man that somehow survived being raised by wolves would be tremendously irrevocably mentally stunted. We have evolved to learn language from the people around us as children.
It can't be a requirement, because at some point there was a first great thinker. That one appeared in a nominal vacuum because otherwise they wouldn't be the first.