“Change is the only constant” is an ageless truth. In the search for age-related biomarkers, it is also a prosaic confounding factor. Age-related biomarkers will be critical for the development of antiaging therapeutics. “Nobody is planning to do a life span study in humans,” Eric Verdin told the audience at the 10^th Conference on Aging Research and Drug Development in Copenhagen on Monday. “Hence the need for … surrogate markers.” And “we are not there … we are actually quite far from there.”