Life Extension? No Thanks

Would it be good if the average human life-span were not 75 to 80, but 150? 500? 1000?  Peter Singer raises the question in this online editorial. To get the ball rolling, let's ponder three mini-worlds.  The first world is more or less like ours, while the second and third involve longer life-spans.  In "30-90" people on average have a child at 30 and die at 90 (couples have two children).  So,