This article searches exactly on this questions. Probably it has some nice parts. It can give some answers to questions you maybe had for a long time. Have you seen this article before. What do you learn through this paper?
edit: this has some great point in the essay. If someone has a connection to such reading. Mayby you can edit my post and post them here. Or post the below,if you cant edit. Its on lifespan and how it is affected.