To succumb to the God Temptation in either of those guises, biological or cosmological, is an act of intellectual capitulation. If you are trying to explain something improbable, it can never suffice to invoke an entity that is, in itself, at least as improbable. If you’ll stoop to magicking into existence an unexplained peacock-designer, you might as well magic an unexplained peacock and cut out the middleman.