19. There Are no Dedicated Aging Genes, Drivers, or Pathways

There are no genes whose evolved purpose is to cause aging, although many genes and pathways strongly influence aging trajectories. Thus, the idea of designated aging genes, drivers, or pathways is misleading. What exists are genes and pathways that support fitness while shaping the rate, topology, and heterogeneity of aging by tuning development, growth, resource allocation, and maintenance/repair. Manipulation of these genes may affect lifespan (38, 39). There are a myriad of age-related changes that include genes and pathways. Genetic factors that extend lifespan in model organisms typically act by shifting these balances (often with tradeoffs), not by switching off a dedicated aging module. Likewise, many genes influence specific deleteriome components, so their effects can be organ- and context-dependent. Thus, the relevant question is not whether there are aging genes, drivers, and pathways, but which genetic programs set maintenance capacity, and which failures become limiting.