Here is a worthwhile article from The Scientist earlier this month. "Understanding the mechanisms that underlie aging remains a bedeviling problem, but not because of a lack of answers. If anything, there seem to be too many answers - or at least enticing clues - each leading in different directions. Thus, researchers are bound to get excited when a single molecule appears to play roles in several perceived longevity pathways, raising hopes that one could weave a coherent theory. Several strands of evidence have linked PolyADP-ribose polymerase-1 (PARP-1) to potential aging-associated processes such as DNA-repair, telomere maintenance, and apoptosis. But many still question PARP's role in longevity." For a good introduction to one small part of the aging puzzle, read on.