Aging is a recent development in human history with nearly half of all median life expectancy gains occurring in the last two to three centuries. Aging is the strongest risk factor for medical conditions that predominately account for morbidity, mortality, and health care costs: cancer, heart disease, stroke, arthritis, and neurodegenerative disease. The geroscience hypothesis postulates that mechanisms of aging simultaneously drive multiple chronic illnesses and functional decline/disability, and intervening in the rate of aging can prevent multiple diseases. Geroscience now relies on 12 identified "hallmarks" or "pillars" of aging that involve alterations in genomic stability/repair, telomere length, epigenetics, proteostasis, macroautophagy, nutrient-sensing, mitochondrial function, cellular senescence, stem cell regeneration, intercellular communication, inflammation, and the microbiome. These pillars are mechanisms/pathways associated with aging, and evidence for causal associations is rapidly becoming more robust. Geroscience-based interventions may reduce illness burden-preserving function and independence-to a greater degree than addressing illnesses one by one. However, the pathway from promise to success is riddled with obstacles and potential pitfalls. Even success can have negative impacts on human populations and our planet that will require major shifts in society. Both the promises and perils of geroscience are likely to shape medical research and ethical debate for years to come.