Recently I thought a lot about the way a human society would change when almost everyone's natural lifespan was doubled or quadrupled within a few generations. It would completely change the way humans plan their life, wouldn't it? You could live several lives in a row, from our perspective, as you likely wouldn't do the same thing for hundreds of years. You could have children who could be a hundred years apart in age. You likely wouldn't remain married to the same person for hundreds of years, (let's face it, most people can't even manage one of our lifetimes together...)
The whole concept of inheritance as we know it would be gone; as Weber mentions once, a monarch like Elizabeth III could rule for hundreds of years, and by the time he or she died, the oldest child is likely almost as old. To me, it seems much more likely that after, like, eighty years, you would give up the crown and pass it on. Or you jump a few generations when passing on the crown.
As someone once said, much of our life is shaped by the fact that it ends at a certain point. I also wonder how it would affect our inner drive to change and to evolve, which I think is at least partly owed to the knowledge that as individuals, we have very limited time to affect the world.