Aging, the progressive decline in biological function with time, is nearly universal, yet its pace varies dramatically across species and environments. Understanding how and why this diversity evolves remains one of the central challenges in biology. My research program integrates field ecology, functional genomics, and systems biology to uncover the molecular and ecological determinants of aging rate in natural populations. In this talk, I will present a research arc that begins with the development of the African annual killifish (Nothobranchius) as a model for natural aging and extends to current work comparing gene expression and proteomic aging markers in laboratory and semi-natural (mesocosm) environments. I will also discuss new genomic studies of wild killifish and their gut microbiota, aimed at mapping environmental and genetic signatures of aging in the wild. In parallel, I use Drosophila melanogaster to experimentally evolve mortality responses, focusing on transcriptomic, microbiome, and life history outcomes. Together, these studies aim to identify conserved molecular pathways that govern the pace of aging, uncover how ecological pressures shape these systems, and contribute broadly to our understanding of lifespan evolution and aging-related disease dynamics. This research sets the foundation for an integrative, cross-species exploration of aging relevant to fundamental biology and healthspan extension.