Thank you for your question.
Dear soul,

In Gyan all you have to remember is that from the “seed, everything develops into a tree.”
In Language that means, the original way of “communication” was telepathy, not “pure Hindi.” Many Bks, and other souls can do this at this time, although they do not advertise it.

Then, language appears sometime in the copper age, for language means the knowledge of duality. Language has been evolving from a highly expressive language with feelings to a more mechanical, business like language. There are some languages in the world when pronouns are not being used (she) and perhaps other pronouns. If you want to know when sign language appeared, I recommend that you do a google search on that.. 🙂 Here is a link: http://deafness.about.com/cs/featurearticles/a/signhistory.htm
Sign language has to appear when there was a need for it. When karmic accounts were calling for it.

As the seed expanded into a tree, we can see how language does not completely express our thoughts or feelings, so there is a variety of it. Each language with its own specialty. I have heard that German is adequate for conveying thoughts in philosophy, I understand that “Quechua” (Native Peruvian language) has a richer spectrum of words to express feelings. For me Spanish is the language for poetry ( Haven’t heard any English lines that could convey the beauty of feelings as Spanish poets were able to do it, but that is just my perception.) English is definitely a more business like, practical language. etc. However, all the array of languages will go back to the seed, that is telepathy.

Best wishes!