How scientific progress is changing our understanding of the biology of aging

As recently as the mid-20th century, aging was described by Nobel Prize laureate Peter Medawar as "an unsolved problem in biology." Today, scientists can analyze the activity of thousands of genes in individual cells, identify genetic variants associated with longevity, study molecular pathways affecting lifespan, and estimate biological age using epigenetic clocks. Experimental therapies using senolytics—compounds that eliminate some senescent cells—have also emerged. Paradoxically, however, the more we know about the biology of aging, the more clearly we see how complex this process is.