Loss of Earth's old, wise, and large animals

Earth’s old animals are in decline. Despite this, emerging research is revealing the vital contributions of older individuals to
cultural transmission, population dynamics, and ecosystem processes and services. Often the largest and most experienced,
old individuals are most valued by humans and make important contributions to reproduction, information acquisition and
cultural transmission, trophic dynamics, and resistance and resilience to natural and anthropogenic disturbance. These
observations contrast with the senescence-focused paradigm of old age that has dominated the literature for over a century
yet are consistent with findings from behavioral ecology and life-history theory. Here, we review why the global loss of old
individuals can be particularly detrimental to long-lived animals with indeterminate growth, increasing reproductive output
with age, and those dependent on migration, sociality and cultural transmission for survival. Longevity conservation is needed
to protect the important ecological roles and ecosystem services provided by old animals.