Evolution is based on an overwhelming mass of surrounding evidence and its postulates are constantly updated by nearly all of the scientific community that analyze the implications leading up to life as we know it now.
Creationism is based on a book writen in the Bronze Age called The Bible and is only speculation based off that "evidence" alone.
It is likely that while it is nearly impossible if not completely impossible to know the origins of life, life likely started off by a sort of pool of precursors to life. These are amino acid chains and lipids, which are found in the non-organic world. This soup was likely subjected to some kind of heat, perhaps a strike of lightning. This enegrized these chains and they became what we might consider to be alive. These were merely single celled organisms, and no where near as complex as most of the life we know today. You must understand that these organisms were not self aware, did not have any cognition and had no instincts of any kind. From there it was split and the first self replication began. It could have split because of physical influences from the non-organic world, such as rocks shifting, or gravitiy, or any number of things of the like. Then from there, the strong organisms, or the ones that survived the desolate world that was at the time, they lived on and could pass their strengths down to their offspring. This is the process of natural selection, or survival of the fittest.
From there, they became multicellular and the process continued ad infidium. Of course this precursor phase took a LONG time, talking in the ballpark of millions of years. Life may have began many many times and been destoryed. However, the strong ones that survived evolved and werent as frail.
So then as natural selection kept on its course, and life began to become more complex, life was closer to what we see today. Small organisms grew bigger and bigger and more complex. Then you saw things like insects, then you saw bigger and even more complex things like reptiles or birds. And you get the point.
Evolution can be seen and observed time and time again, but it does admit its own short comings. We do not know and do not claim to know the exact origins of life on this planet. No human and know this, and its near impossible to ever know for sure. What we do know, is based of logical conjecture of the apparent nature of the organic world around us.
Also one of the problems with creationism falls with its timeline of lifes existance. Its somthing like 4,000 years, which is no where close to the millions upon millions of years that we can acurately measure that life have existed through methods of radioactive dating, where we measure the radioactive decay and it shows us the approximate age of a particular fossil or what have you. We know this planet and the sun are much older than that too. Plus, ive made this point many many many times; God could not have be the origin of existance, because for one, he himself would have no origin, and also, since in the hypothetical universe of nonexistance, creation would have been impossible, even if god existed in that. He did not have time to do so. Creation is an action that requires causality which demands time. Without it, creation is impossible. There is no time duration meaning everything was always here and was instantanious. So God did not even need to create existance, since its obviously always been here.
This whole issue basically boils down to wheather you're religous or not. I dont think any intelligent person can deny the process of natural selection, but the contraversey is in the origin of said life. It is alright to say that you do not know. This is once again another case where religon has the burden of proof, since evolution does not claim to have the definitive answer to the origin of life. Since creationism is asserting the claim, it is up to them to show actual valid scientific data to support their position. Best ive ever seen is passages from the bible. Not very convincing and not even close to scientifically valid.
tl;dr version; evolution makes sense. scientists moslty agree with it, its postulates are backed by observable evidence. Creationism is based off the bible and thats about it.
This post was edited by Toothfariy on Jan 9 2011 11:54pm