eli5: How do we know different organisms lifespans?

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Have we kept them all in captivity at one point? Are all lifespans a guess from scientists? A general estimate?

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3 Answers

Anonymous 0 Comments

Keeping an animal in captivity won’t tell you how long they could live naturally. Orcas live decades longer in the wild than in captivity for example.

Anonymous 0 Comments

Pretty much, almost every animal has been tracked, not necessarily in captivity, but in the wild by some biologist. Although many are estimates, in nature it’s very rare for animals to die of old age, they pretty much all die of disease, starvation, predation, injury, or severe weather

Anonymous 0 Comments

Observation. The ones in captivity, it’s obviously easy. In the wild, you need to spend a protracted period of time following a group of animals from birth to grave. For some animals, it’s fairly easy because they don’t naturally live very long. For something like a tortoise, you might have several generations of naturalists observing over the course of multiple lifetimes.

That said, we can also make some very accurate predictions from models based on birth rate and changes in population sizes.