I should finally learn to read the whole thread before responding; half of this post repeats Tony's response
Actually, I kind of liked seeing the same point driven home again.
We currently don't know how the 'first spark of life' came into existence.
Right. We've got ideas, and some experiments that show it could have happened a certain way, but no way to find out if it really did happen that way. Ditto for the existence of the universe itself. They talk about the Big Bang, but that one is still very much in the "theory" department because evidence for it is sketchy (but mounting).
One of the things that bugs me is when some creationists try to talk about biological evolution and the Big Bang theory in the same breath. They're two different and completely unrelated theories.
Evolution doesn't try to answer the question "where did the universe come from?" It only answers the biological question of how life on this planet became so intricate and complex. Heck, even the Big Bang theory doesn't answer the "where did the universe come from" question, it only theorizes about the first moment of the universe's existence.
Obviously, if they were different we would not be here to observe them
Ah, exactly. Now there's something that's really fun to think about. I remember the first time this "hit" me. I was young, pre-teen, and it was an eye-opening idea for someone my age.
The idea: Sure, the chances are billions to one against any given planet supporting life (the creationists like to use this as an argument for I.D. sometimes). Fine, but here we are, sitting on that one-in-a-billion planet. Does that mean we were incredibly lucky?
NO, it means we were
inevitable, and the fact that we're sitting here contemplating our own existence simply means that our brains evolved enough intelligence to perform that activity. Put another way (perhaps existentialism, but anyway): If we weren't able to sit here contemplating our own existence, then we wouldn't be contemplating our own existence.
I forget who said it first, but here's the corollary: Sure, you could say that the odds of winning the lottery are millions to one. But the guy holding that winning ticket would be a fool to throw it away because "it must be wrong, the odds are millions to one against it being right".
Creationists like to argue that the first spark of life on this planet, the first time molecules assembled into self-replicating strands, had astronomical odds against it. Scientists counter with: "Yeah, but we had oceans of molecules working on the problem for eons". I counter with: "You're both forgetting that we had an entire universe full of planets, many of them with oceans of molecules working on the problem." (and I use the term 'working' metaphorically, of course.)
See, any argument about how "unlikely our biology could have come about by chance" is forgetting to look at it in the proper scale. They think it has to apply just to our planet, or our solar system, or our time period. It doesn't.
We're sitting on a winning lottery ticket, and we've got the evidence to show it. Those who say the game was rigged are missing out on the true wonder and appreciation for the situation.