"Iíll kind of have a foot on the back of my own butt. Thatís just how I do things.Ē -- Bryan Price, 10/22/2013
GRRM draws a lot of inspiration from our own history. People acted as adults at a much younger age 1000 years ago on Earth, especially with women bearing children.
While the events in season 4 look to be set in stone, season 5 will have to work overtime to cram so many characters and events in while making sense. At this point, I predict that half of the storylines in season 5/6 are going to be invented by the writers, and that we see a total of 8 seasons with a prequel as well.