For what reason do the cells that make up multicellular organisms need to reproduce?

Answer 1

If they don't, then you'll deterioate because all your cells are dying without being able to reproduce. Cells die all the time. In order for your body to maintain itself, the cells need to divide. Just imagine if you trip and fall down. Your dermis will not be able to divide and repair. That's one of the reason why it divides.

Answer 2

It doesn't need to reproduce. Reproducing is just something organisms do. The question is roughly analogous to asking "Why does water need to be liquid?" (The answer to which is, again, it doesn't need to be: being liquid is simply a property of water.)

Answer 3

Individuals don't, but species in total do.

There seem to be two schools of thought, either of which may or may not be totally correct.

The obvious and often apparently discredited one is so that their species does not become extinct - but that concept is available only to those organisms able to consider it, i.e. limiting it to us humans. In all others it's purely instinct or non-sentient mechanism. The last point is used to refute the notion of species-continuation for as long as that species is evolutionarily viable - but even if a plant or animal does not know why it is breeding, then if breeding is not for that continuation, what is it for?

The other, more subtle, reason for reproduction is to maintain the species' gene pool but that starts to drag the matter into philosophy more than science since you could argue that gene-marshalling is merely part of the reproductive mechanism; or that it implies the gene is more important than the organism as a whole rather then being a tiny, albeit vital, part of it. That then raises the very awkward question, what is reproducing which, for the benefit of which - organism or gene?

Answer 4

I think it's because when the cells become more old they begin to die then they will need a new and strong cell to replace it!!!

Answer 5

to make more of them!

Answer 6

Growth & repair.