Reddit mentions of The Language Instinct: How The Mind Creates Language (P.S.)

This is a really wide open question. There are theories, but no one has any truly strong evidence. Steven Pinker is an evolutionary psychologist and linguist, and wrote an excellent book on the subject. It goes into several of the more common theories, and then lays out his own theory. Much of the book may be fairly dry if you don't have a real interest in language itself (how language works, as opposed to how it evolved), but I found it very worthwhile and fascinating.

I've a few recommendations here, both about writing and about langauge as a whole

• Cuneiform by Irving Finkel as a (very) short but nice introduction to Cuneiform. I enjoyed it a lot, especially since I couldn't seem to find other popularized introductions to the subject.
  
• Empires of the Word by Nicholas Ostler. This is a behemoth, a world history in the context of languages. I love the book, although it can be a bit information heavy at times. The focus is on langauges, but comes with lots of nice examples of writing as well. (I found this book through The Language Instinct by Stephen Pinker, which is tries to describe language from a neurological PoV, an amazing book)
  
• Breaking the Maya Code by Michael Coe, one of the players in the breaking of the Maya script. I didn't know a thing about mayan language or script before reading this, and albeit being too detailed on who-did-what, the mayan script is beautiful and this books documents this wonderfully.
  
• The Riddle of the Labyrinth by Margalit Fox. The theme is similar as the one above, but this is focused on the decipherment of Linear B, where both script and language was unknown. Very recommended, especially in the methodology on how to catalogue large number of correlations between script pairs in the time before SQL...
  
  I'm following this thread closely... :)

Second John McWhorter--I became a linguist in part due to reading Doing Our Own Thing. I think a standard pop-linguistics text is Steven Pinker's The Language Instinct.

EDIT: Phrasing

I just did some quick searching on google and found it. It’s called The Language Instinct by Steven Pinker.