ABSTRACT
Gerontologists have checked many combinations of different biological markers to discover which, if any, may be useful indicators of “biological age” body and brain age as distinct from “chronological age”. A good guess is that, independently of the “common clock” problem, biological markers that predict our distance from death must also index the progress of our general neurophysiological aging. The most promising has been the progressive shortening in the length of telomeres—caps that preserve the integrity of chromosomes in every cell of our bodies and signal their approach to the point when they unravel and can no longer accurately replace themselves, though recent meta-analyses caution against the assumption that there is a causal, rather than a simply correlational link. Muscle weakness increases with calendar age and differences in elderly people’s leg-muscle strengths predict from 2 to 9 per cent of the differences in their intelligence test scores.
