Negligible senescence

Negligible senescence describes organisms that show no measurable functional decline, increase in mortality risk, or loss of reproductive capacity with chronological age. The term was coined by biogerontologist Caleb Finch in his 1990 book 'Longevity, Senescence, and the Genome' to characterize species such as certain rockfish, certain tortoises, and hydra. Naked mole-rats, often cited in this context, exhibit extremely slow but not strictly negligible senescence and became associated with this discussion through later work (e.g., Buffenstein 2008 onward). Negligible senescence is studied as a comparative biology benchmark for understanding why most mammals, including humans, do age.