Via Ouroboros, a look at researchers who declare the mitochondrial free radical theory of aging (MFRTA) over and done with: "MFRTA recently turned 50, and consequently has received a lot of attention lately; q.v. this review and this retrospective by Denham Harman, the originator of the theory. The thesis of most pieces seems to be that the theory hasn't been demonstrated to explain the bulk of age-related decline, but that there's still life in the idea. In contrast, the authors of this review argue that the relevant experiments have been performed and that the theory has been falsified - in other words, we've done our scientific duty and it's now time to move on. I doubt very much that this article will put a permanent end to the controversy. Data reported fairly recently have breathed new life into oxidative theories in general and the MFRTA in particular. While these authors contend that the CLK-1 mouse mutant contradicts the underlying mechanisms of the MFRTA, other recently reported work on this pathway supports the claim that inhibiting mitochondrial respiration delays aging, a key prediction of MFRTA. Furthermore, if mitochondrially generated oxidative radicals are truly not playing a causative role in aging, it becomes much harder to explain how mitochondrially targeted antioxidants can extend lifespan in mammals."