Aging Isn't One Clock—It's Many Systems Declining at Different Speeds

New research combining blood biomarkers, microbiome data, and machine learning can predict biological age far better than existing epigenetic clocks, revealing that aging happens simultaneously across multiple biological systems—metabolism, immune function, and gut bacteria—each moving at different rates. This shift from single-biomarker measurements to comprehensive aging profiles is changing how researchers think about aging interventions and who will actually experience health decline.