Recent studies on the genetics of aging in the yeast Saccharomyces cerevisiae, the roundworm Caenorhabditis elegans, and the fruit fly Drosophila melanogaster have converged revealing the central role of metabolic capacity and resistance to stress in determining life span. Signal transduction has emerged from these studies as an important molecular mechanism underlying longevity. In their broad features, the results obtained in these genetic models are applicable to the dietary restriction paradigm in mammals, suggesting a general significance. It will be of interest to determine whether many of the molecular details will also pertain. The examination of centenarian populations for the frequency of certain alleles of pertinent genes may provide insights into the relevance of the conclusions of studies in invertebrates to human aging. These population genetic studies can be augmented by mechanistic studies in transgenic mice.