Most of them didn't live long enough to get ptsd. It was a hard life, with gorging on food when it was plentiful, and scrounging for whatever when it was not. Arthritis, disease, extreme winters, etc. took it's toll. So I guess, like the food situation, when you were young and healthy, you enjoyed life to fullest in whatever way you could, and then sat around the fire, and relived those days, when you couldn't, and hoped the tribe respected you enough, and found you useful enough to keep you around.
Wayne