Why do some animals live longer than others?
In: Biology
It’s based on a few different things: size, environment, temperatures, and the ways cells divide. Aging is the process of cell division slowing, so our decaying cells don’t renew as efficiently.
Some things, like flies, are made mostly of cells that don’t replicate. And then there’s the freshwater polyp hydra, whosr cells constantly regenerate, so it can live 1400 years!
Many small creatures are vulnerable to predators, so their evolution focused on reproducing quickly rather than living long (mice, rats, rabbits), or on other defensive tactics like hiding.
Cold temperatures slow heart rate and body processes, so we see longer lifespans in marine and deep sea life.
Large animals’ defense mechanism is just being large. Many large animals are highly social and evolved by positive selection of traits, preferring longevity because of the reproductive advantage and being large enough or fierce enough to select instead of breed indiscriminately.
Sources: [this 5 minute TED talk](https://ed.ted.com/lessons/why-do-animals-have-such-different-lifespans-joao-pedro-de-magalhaes#review), and various articles about elephants and large marine animals.
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