I’ve been wondering about lifespans in Westeros/AWOIAF. In general, the reason why the average lifespan was so short in the Middle Ages was simply because so many people died in infancy or early childhood. It’s further dragged down by the deaths of young men in battle and women in childbirth, and of course any Medieval lifespan average also has to take into account intermittent but devastating epidemics of various diseases. Although we see all of these things in AWOIAF, we also see people

(Lifespans in AWOIAF, cont.) like Bloodraven or Old Nan, both of whom are evidently in their 120s by the time the ASOIAF books are taking place. In the Harry Potter franchise, JK Rowling has specifically said that the wizarding world generally has longer lifespans, so that people like Dumbledore, who was something like 117 when he died, was not at all uncommon. I haven’t seen GRRM making any similar clarifications in this regard.

Yeah, this is something that bugs me. GRRM falls into it a little in weird ways – everyone gets married super-young, Ned Stark is only a few years older than I am when the series starts and is a parent of six children which I would in no ways be ready for, etc. 

The super old age thing I think is meant to be magical in nature – Bloodraven is basically being kept in suspended animation by the weirwood tree, and I think we’ll find out about Old Nan’s source of longevity whenever “She-Wolves of Winterfell” comes out.