Over here I attempted to explain to the ever-polite Rus (and, linking, I find he's still going strong) that he didn’t understand speciation because he was thinking Platonically. He wasn't 'aving it, it goes without saying, but such is life. The attempt to demonstrate the impossibility of an evolutionary leap from one species to another is, as anyone with a passing interest in the subject will know, an old device used by Intelligent Design theorists, the idea being that if you can show that nature can’t do it on its own, then Divine Intervention is required to bridge the gap. Of course, once you grasp that species are not Platonic Forms (whether defined by DNA or any other characteristic) but the names we give to populations of genetically individual creatures, the speciation ‘problem’ disappears because there isn't, in fact, a gap to bridge. A speciation event is merely anything that divides a population into reproductively isolated sub-populations. Time and differing evolutionary pressures (whether natural selection in differing environments or fluke or genetic drift or anything else) might lead to some degree of divergence between the populations and eventually we might or might not decide to call them different 'species'. Much like maddening after-dinner riddles, or those 3-D ‘magic eye’ pictures, when you can’t ‘see’ population thinking it’s impossible and you get bogged down in red herring details (in Rus's case "when the sperm meets the egg", or indeed, "hits the road", yuck), but once you can, it’s so simple and obvious it’s hard to remember what the problem was in the first place.
Peter B suggests that I do a post about why Intelligent Design doesn’t work for biology but might for physics. I'd like to oblige but the difficulty there is that while I do have a passable grasp of the rudiments of evolutionary theory, I know even less about physics than I do about parenting, so arguing the details about fine tuned universes and multiverses etc is really beyond me.
That said, I would always be very wary of any kind of Intelligent Design approach to anything. Science is one way of seeing the world, religion is another. They are different frameworks, both have their insights and internal validity. Scientists like Dawkins, as I have increasingly come to realise, stray beyond their remit when they insist that science equals hardline atheism and argue, for example, that religious approaches to questions are ‘nonsense’ or invalid. The most they should say is that they are unscientific.
The problem with ID is that it insults both religious and scientific approaches. It insults science by hijacking its language but bastardising its method. It insults religion by degrading its role to that of a loon in denial, repeatedly crying “this far and no further!” as he is pushed backwards once again. As a defence of the existence of God, ID is embarrassing: the business of accepting everything the scientific method tells you, but attempting to squeeze in whenever there is a gap. Then every time the gap is filled the result is only further humiliation and damage for the religious cause. Best give up on that particular cause, just as Dawkins should give up on his. God deserves more than the ever-shrinking gaps, and science deserves more than to be pestered by the loon. ID benefits nobody. My advice, for whatever that’s worth, is to give it a wide berth.