How do souls age in Soul Society?
People cannot die of old age resulting in the Captain Commander keeping his position for a thousand years.
There are some souls who look like kids and some who are adults. In the manga, the makers flashbacked into the past of the Captian Commander showing that he had black hair instead of looking like what he was then. Also, when Ichigo left the Precipice World he aged what looked like a couple years.
So how do souls age in Bleach?