With all the results arriving from comparative study of biochemistry in species of varied longevity, the membrane pacemaker theory is gaining support. For example:
The membrane pacemaker hypothesis predicts that long-living species will have more peroxidation-resistant membrane lipids than shorter living species. We tested this hypothesis by comparing the fatty acid composition of heart phospholipids from long-living Procellariiformes (petrels and albatrosses) to those of shorter living Galliformes (fowl).
The 3.8-fold greater predicted longevity of the seabirds was associated with [a] significantly reduced peroxidation index in heart membrane lipids, compared with fowl. Peroxidation-resistant membrane composition may be an important physiological trait for longevous species.
It is possible that this has a lot more to do with ways in which differential membrane composition correlates with metabolic rate - which in turn correlates with life span - than with oxidative resistance. It is also possible that these results are a sign that dramatically reducing the oxidative load produced by mitochondria, and thereby reducing the molecular damage that follows to mimic the effects of more resistant membranes, could extend life in mammals much further than the 20-30% demonstrated through targeted antioxidants.
It's certainly worth looking into. Something interesting is lurking in the triangle of mitochondria, metabolic rate, and membrane composition.