An interesting opinion on the direction of aging research from a noted scientist in the field:
Virtually, all research on basic mechanisms of aging has used species that are short lived and thus demonstrably unsuccessful at combating basic aging processes. A novel comparative approach would use a diversity of populations and species, focusing on those with particularly long, healthy lives, seeking the causative mechanisms that distinguish them from shorter lived relatives.
Species of interest from this perspective include the naked mole rat, a mouse-size rodent that lives up to 30 years in the laboratory, and the little brown bat, which lives up to 34 years in the wild. Comparisons among dogs of different sizes, which differ by more than 50% in health span might also prove rewarding, as might novel species chosen because of their similarity to humans in certain key traits. Primates, because of their sophisticated cognitive ability, are a group of special value, and small, short-lived primates like the common marmoset might prove especially beneficial.
Cell repositories and tissue banks from key species, as well as genomic and analytic tools optimized for comparative studies, would make valuable contributions to a new comparative approach to basic aging research.
I see comparative studies - and the naked mole rat versus other rodents is a particularly good example - as a good way to reveal the relative importance of the various forms of cellular and molecular damage that cause aging. Is mitochondrial damage really so important in humans that it should be dealt with first of all, or are other types of damage just as limiting to life span, such that if mitochondria could be repaired, we wouldn't gain much overall benefit? We don't know for sure - though there's nothing to be lost by moving ahead at full speed on all fronts of longevity science outlined in the Strategies for Engineered Negligible Senescence at this stage.