Why do turtles and tortoises live so long?

Giant tortoises can live well past 100 years, with some exceeding 180. Their slow metabolism means cells divide less often, accumulating fewer DNA mutations. A hard shell reduces predation pressure, so natural selection has favoured long lifespans. Some turtles show negligible senescence: their organs do not deteriorate measurably with age, and mortality rates do not increase as they grow older. A 2022 study in Science found that many turtle species show very slow or no biological ageing. Their immune and DNA repair systems may also remain active longer than in most mammals.