Variations in senescence and longevity include the possibility of negligible senescence.

The variations in senescence observed in different species span an enormous range of rates that may be described by mortality rate doubling times. This review considers examples of very slowly senescing conifers and fish from natural populations in which advanced age may not compromise reproductive functions. There is thus a basis for considering the possibility that some organisms may experience negligible degrees of senescence in certain environments. A tissue bank is urgently needed to provide specimens of long-lived organisms for study of possible antiaging mechanisms that permit achievement of great ages.