Board Thread:Questions and Answers/@comment-3001900-20131024200959/@comment-1493741-20131025235540

I's subscribe to Sei's idea on the subject, as even with characters coming from the same time, relatively, none of them seem to age at all in the same way. The most obvious case being Unohana, Zaraki, and, Yamamoto. One went from middle aged to more wrinkles than man, one grew six feet tall and the other didn't change a lick aside from rotating her hair placement.

It can be seen in the Turn Back the Pendulum stuff too, though to a far lesser degree. Out of everyone present only Byakuya seemed to age much at all, and perhaps Yoruichi.