Project Summary Aging, particularly the rapid increase in disease prevalence with age, has emerged as one of the top health challenges in the world today. Life expectancy in the United States has increased by nearly a decade over the last 50 years, but so too has the incidence of musculoskeletal problems, heart disease, cancer, and especially dementia late in life. Discoveries of conserved genetic pathways in animals that increase both longevity and healthspan have raised the hope that we can build upon on growing understanding of the biology of aging to find interventions that allow us to live longer, healthier lives. Most of these genetic studies have been conducted within a few laboratory-adapted model organisms. Using natural variation to investigate the genetics of aging provides the opportunity to discover new pathways that enhance aging, particularly in ways that do not create negative pleiotropic effects across the organism as a whole. Here, we propose to use our recent discovery of an exceptionally long-lived natural isolate of the model nematode Caenorhabditis elegans as a discovery platform to better understand the biology aging and to discover novel genetic targets for aging interventions. We have implemented unique approaches to genetic mapping that capitalize upon the rapid generation time and very large population sizes of C. elegans to select for highly recombinant individuals with extreme phenotypes. Further, we will use a novel genomic engineering approach to generate targeted recombination events within regions of interest. Analyzing these natural isolates, as well as targeted knockouts of known aging related pathways, using a transcriptional “aging clock” will allow us both to isolate the genes of interest and to assess their physiological impacts at single-cell resolution. And most importantly from a translational point of view, we will investigate how genetic background influences the response to longevity extending compound interventions. Specifically, we aim to (1) Identify the genetic basis of longevity extension in an extraordinarily long-lived natural isolate of C. elegans, (2) Analyze the functional landscape of natural variation in longevity and develop tissue-specific aging clocks using allelic substitution lines and genetic knockouts of well-characterized stress-response pathways, (3) Determine the genetic basis of natural variation in the response to life-extending compound interventions. Success of these aims will provide novel insights into the fundamental biology of aging and provide new genetic targets for researchers seeking to enhance healthy aging in humans.