This is a really difficult question to answer because language vastly predates written records. While the biological fossil record dates back millions of years, the linguistic "fossil" record only dates back a few thousand.

We do know (or have at least inferred) a great deal about proto languages such as Proto-Indo-European, which is the common ancestor of most European languages and many Asian languages.

Your question might be better answered in /r/linguistics or /r/askanthropology.

This is the biggest question in historical linguistics and has not been definitively answered. Check at /r/linguistics and you'll hear a lot of interesting theories.