So I went back and started reading, or just looking at, really old questions about Naruto, including Shippuden. I read this question, but this answer got my attention. After looking at the answer, I started to wonder how exactly Kakuzu's methods of getting the chakra natures work.
We know that he gets all the chakra natures by stealing people's hearts throughout the years but once the hearts he has on are damaged or just get too old he has to get new ones. But how does that work? I always thought the nature of the chakra was in the body not exactly the heart. Or do both, body and heart, have the chakra nature, so when Kakuzu gets the hearts he gets part of the chakra nature?
Also, since we also know that Kakuzu has been living for a while, until Kakashi killed him, exactly how old is he? I know he has been living since the First Hokage was alive, which I guess was about 100 years ago, so I think he was at least a little more than 100 years old.