Even though this may seem obvious to all of us... It seems important to me at least, that we are fairly sure this is a valid assumption (of course the alternative would be that life has always existed on earth, which I would agree seems impossible).
You seem to have overlooked the chance that a god had a hand/tenticle/noodly appendage in it.
Many assume that abiogenesis means that there was no supernatural force acting on the chemicals that clumped together. So, gods causing the initial lifeform could be an option.
Aliens too...but you put that in with abiogenesis for some unfathomable reason.
edited to get my quote box right
This message has been edited by LinearAq, 12-29-2005 02:56 PM