In the long human search for how to age well, not merely long, researchers in Japan and Italy have found two proteins in the blood that quietly foretell the loss of independence years before it arrives. Working across two aging populations on opposite sides of the world, scientists at Keio University identified beta-2-microglobulin and cystatin C as reliable harbingers of disability in adults past eighty-five — markers already within reach of any standard laboratory. The discovery suggests that the boundary between prevention and decline may be written in biology long before it is felt in the