Andy is mortal now. And she has a lot of knowledge about history, that no one else has. So, Copley coaxes her to write it down and after a while Andy agrees. So, she sits down and writes a book. Or more, because 6000 years is a lot of time and lots of stuff happened. She knows that it probably won't be published, but it can't hurt to write it down, right?
Joe, Nicky and Nile agree to help her. I mean, Joe is good with words, Nicky is good with grammattics and Nile... Nile can type really fast :D