Why do living things have a life span?

Answer 1

Some micro-organisms do not necessarily die (after they reproduce both new cells have an equal claim to being the parent cell)

If you regard death as an essential part of the lifecyle, they lack life cycles

Answer 2

By answering this question I assume that you mean why do living things die, as the actual question why there is a life cycle seems rather pointless or obvious to me. (correct me if I'm wrong). As in why do living things die: It's because chromosomes carry a tiny part of seemingly useless material at their ends. This material shrinks alittle everytime these chromosomes are duplicated, once the material is too small, the cell won't duplicate and unless replaced, the living creature dies.
Native is not my English language, sorry for any typos. :)

Answer 3

Living things have a definite lifespan because living things cannot live forever as if everybody lived forever, the earths" population would increase rapidly and people would have to leave this earth and live in or settle in a different planet.

Answer 4

No one knows. There are many guesses (sometimes called theories) as to how the first living things came to be, but the only thing known for sure is that it happened for earth more than 3 billion years ago when earth was a completely different place that few if any modern living things could survive in.

Since these exact conditions cannot be replicated with certainty, it likely took millions of years for the necessary chemical reactions to happen, and it only needed to happen once (although it likely took place many times in many places on earth) we can never perform experiments that could prove how it happened. However several experiments have confirmed that many chemicals necessary for life (e.g. amino acids, RNA) can form spontaneously and surprisingly rapidly under conditions assumed to exist on earth more than 3 billion years ago.

Answer 5

it's so that there's no over population. if there is too much animals or people they would (sorry but) have to kill them

Answer 6

All living organisms have a life cycle because it is a natural cause.

There is really no answer to why living organisms have a life cycle.