Getting aging to stop looks positively trivial in comparison - The average lifespan of different animals already varies /way/ to much for there to be any biological law underlying it. So turning senescence off altogether should be possible. I suspect evolution has not already done so because overly long-lived creatures in the wild were on average bad news for their bloodlines - banging their grand daughters and occupying turf with the cunning of the old. Uhm. Now I have an itch to set up a simulation and run it.. Just so stories are not proof. Math is proof.