You'll find a great discussion over at the Immortality Institute forums on the difference between the engineering approach to repairing aging and the metabolic tinkering presently favored by the mainstream: "metabolism is so ridiculously complicated that it could take centuries use such a strategy to achieve negligible senescence in humans, and even then, the damage that you already have wouldn't go away. Research into repairing the damage, rather than slowing it's accumulation, is far more logical. If you can repair the damage once, you can do it again and again. ... The scientists doing this [metabolic work] will swear up and down that aging doesn't have a chance in hell of being fixed in any of our lifetimes, because they know just how complicated metabolism is, and fixing metabolism is the only thing that fits in their conception as being a fix for aging. ... Repairing the damage is massively more beneficial than slowing down aging. Slowing down aging leaves the assumption that natural death related to aging is still inevitable. However, through repair mechanisms, as long as there's a will to repair, you could technically continue to repair for as long as possible. And as technology becomes more advanced, the gaps between the periods required for repair will become longer and longer. It's a win-win in both cases."