Richard Dawkins, in (iirc) The Selfish Gene proposed that if we really wanted to increase the average lifespan of humans beyond what it is now (we're on the hig

Richard Dawkins, in (iirc) The Selfish Gene proposed that if we really wanted to increase the average lifespan of humans beyond what it is now (we're on the high side of longevity compared to even other primates) then the way to do it would be if people were only allowed have children progressively later in life with each generation. It may be that we're doing this on our own naturally. I myself am the product of several generations who had children late in life, and it does seem like people in my family age more slowly.