A molecule in the blood known as CtBP2 may act as a master signal for aging, influencing how quickly the whole body grows old. Measuring its levels could help track health, longevity, and the pace of biological aging. Credit: Shutterstock Aging affects every part of the body, inside and out. The wrinkles and gray hair that appear on the surface often mirror similar changes happening deep within our organs. This connection suggests that aging does not occur in isolation but instead spreads