tl;dr: Two new papers (Nature, Cell) propose that aging isn't just cumulative damage but also loss of cell identity, driven by erosion of the "slow" epigenetic layer (chromatin architecture maintained by PRC2) that normally locks cells into their differentiated state. As this erosion progresses, cells undergo "mesenchymal drift" toward fibroblast-like states, driving fibrosis, inflammation, and age-related diseases from atherosclerosis to Alzheimer's. Potential interventions include caloric restriction, partial epigenetic reprogramming via Yamanaka factors (OSKM or OSK), and lithium—which stabilizes neuronal identity—while chronic stressors like poor diet, sleep, and inactivity likely accelerate the erosion.