Abstract
One of the most pervasive ideas regarding the causes of aging is that longevity is constrained in large measure by damage to macromolecules. An increasing body of cellular and molecular data, generated over the past decade or so, has generally supported this "damage accumulation" hypothesis of aging. There remain unanswered questions regarding which types of damage are most important for driving aging. In addition, there have been recent challenges to the damage accumulation hypothesis and a new emphasis on the importance of cellular responses and the sequelae to damage, rather damage per se. New tools and approaches are on the horizon and will need to be developed and implemented before we can fully understand whether and to what extent macromolecular damage drives aging phenotypes.