The twin incentives for engineering greater human longevity: on the one hand, we have the stick of disease, degeneration, and suffering. On the other hand we have the carrot of a life that in all other aspects generally keeps getting better. Being older brings with it wisdom, knowledge, experience, and perhaps most importantly independence - the ability to be your own person and forge your own path.
It is inevitable. The muscles weaken. Hearing and vision fade. We get wrinkled and stooped. We can’t run, or even walk, as fast as we used to. We have aches and pains in parts of our bodies we never even noticed before. We get old. It sounds miserable, but apparently it is not. A large Gallup poll has found that by almost any measure, people get happier as they get older, and researchers are not sure why.
It's because everything except the degeneration improves with time. Getting the most out of being human is a skill, just like any other, and practice makes perfect. I think that this comment from Glenn Reynolds is quite to the point:
Well, I’m certainly happier than I was in my 20s, or even 30s. But I’m not really feeling any physical effects of aging yet. I suggest, however, that this is a good argument for life extension - if people get happier as they live longer, and if that remains true even as their bodies fall apart, they’re likely to be happier still if they remain healthy.
Youth is wasted on the young, as they say - so why not work at making youth available to everyone? It's the horror of the human condition that just as we get to the point of being practiced and elegant, the rug is pulled out from under us. But engineered healthy longevity is a very possible, plausible goal for this present age of biotechnology. Like all good things it requires work to realize: the longer we hang around not working on it, the longer it'll take to arrive.