Researchers may have discovered a biochemical "vector" for aging. A new study in Metabolism shows that a DNA-binding protein called HMGB1, when released by aging or stressed cells, can induce senescence in nearby healthy cells—essentially spreading aging. The reduced (low-oxygen) form of HMGB1 triggered this effect in both cell cultures and live mice; oxidized HMGB1 did not. Mice injected with the reduced protein began to show signs of aging within a week. The findings suggest that aging may be transmissible at a cellular level—at least in part—through circulating proteins in the blood.

Makes me wonder if this is responsible for the effect of rapid aging at (around) 44 and 60.