NPR:

If anyone has the credentials to write a book called The Art Of Language Invention, it’s David J. Peterson.

He has two degrees in linguistics. He’s comfortable speaking in eight languages (English, Spanish, French, German, Russian, Esperanto, Arabic and American Sign Language) — plus a long list of others he’s studied but just hasn’t tried speaking yet. He’s also familiar with fictional languages — both famous ones like Klingon and deep cuts like Pakuni (the caveman language from Land Of The Lost).