Aging and longevity are to a large extent determined by our genetic make-up. Indeed, it has become possible to extend healthspan and lifespan in many animals by manipulating their genomes. The genetic basis for lifespan is the result of evolutionary processes that have shaped the aging program, causing it to proceed at dramatically different rates between animal species. CALS research seeks to understand the genes and gene relationships that underlie the rate of aging in both model animals and through analysis of the genomes of human populations with differences in lifespan and occurrence of age-related diseases. They are also uncovering the genetic changes that occur in each of us as we age. Discoveries from these studies can lead to pharmacological interventions that slow aging rates and extend healthspan and lifespan.