Howard,
I don't know if you're being serious or you just like to be argumentative because I find your question totally pointless. The fact exists - just like many millions of animals do in the world - that, it's not so much a case of "why" as one of "must" because the animals simply cannot look after themselves - can they?
Anyway, now that I've addressed that ultra important point, try answering the one I made to you a couple of posts back, eh?
And try smiling as well..... oh, go on, don't worry, your face won't crack - maybe?