A gerontological distance metric for analysis of survival dynamics.

A metric for quantifying a gerontological mapping 'distance' or displacement consistent with the historical concept of velocity of aging and with the more recent concept of acceleration of aging, is introduced using the paradigm of a simple linear dynamics system of elementary physics. This analysis is extended to recent analytical methods utilizing intrinsic or internal time scaling so that biological or gerontological similarity can be distinguished from chronological age similarity, not only among various intraspecies populations but also among interspecies populations which may not even have the same underlying mechanisms of senescence or survival distributions. Illustrative examples are provided and discussed. Also, applications involving the comparison of an individual from one population to an individual from another population, when both can be assessed with respect to their respective group properties, are considered.