User blog comment:PcRetro/So are Sternritter Human or not?/@comment-1387259-20131006215546/@comment-2211792-20131008041650

Mayuri conducted experiments on thousands of Quincy souls and studied their powers - he even lamented that none of them displayed the ability to use Ransotengai. Guess it means they do retain their powers after they die, so Wandenreich Quincies could very well be souls from 200 or even 1000 years ago.