Death, disease, drought, famine — at last a question that speaks to me. To simplify matters, let’s just talk about trees. One may speak of trees having life spans, in the sense of having an average life expectancy. The Encyclopaedia Britannica notes that the “lifespans of trees, like those of all organisms, are limited.” But while this is certainly true — no tree is immortal — it’s also deceptive. Trees may have life spans, but they don’t have fixed life spans, as animals do. It is reasonably certain that no human, no matter how coddled, would survive past some definite point — say, 120 years. But this cannot confidently be said of trees.
Source: The Straight Dope