Lyion wrote:Random Mutation & Natural Selection is fact, don't you know.
Why yes, yes it is, thank you for finally admitting it, Lyion.
We actually just discussed origins of life in my Paleontology class recently. Intersting stuff. More details:
The oldest rocks we have dates for on Earth are about 4 billion years old. The oldest rocks we've found from the Moon are 4.5 billion years old, and the single oldest rock crystal on the earth ever found (a chunk of mineral crystal inside a sandstone) is 4.4 billion years old. So, given that the Moon was created about 4.5by ago, and the formation rather radically changed the Earth (gee, what a shock, take a planet the size of the earth, slam a planet the size of Mars into it, and you get lingering effects) we don't know a whole lot about Earth 1.0 which existed before that impact, most of what we know is post-Moon formation.
Now, by looking at rocks going back to just after Earth 2.0 got going, we can actually learn a lot about the state of the primitive Earth. First, certain kinds of minerals and compounds will form only when there's no water around, and some require water to form. (this is how we just figured out there was once water on Mars from those rovers, looked at the types of rocks). The earliest rocks we have with evidence for any appreciable amount of water are about 3.8 billion years old. Now, along with the influence of water, the gas makeup of the atmosphere also effects what kind of rocks and minerals, etc. are formed. So, by looking at the types of rocks, we can get a good idea of what the atmosphere was like back then too. Apparently, by looking at the gases released in volcanic eruptions (H2O, CO2, CO, H2, N2, SO2, H2S, CH4, NH3, etc.) and their relative quantities, it's entirely feasable to go from no water to liquid oceans & that atmosphere in 700my mostly from volcanic eruption byproducts. Also, the types of minerals formed back then are consistent with an atmosphere composed largely of volcanic gasses. (Also, by looking at the % of noble gasses in the atmosphere, we can tell it's very different from that which was left over from the original cloud that formed the solar system)
Now, as an additional factor, we know that lightning has always been occuring. As of right now, lightning strikes the earth 300 times a second. So, there's a constant energy influx to the ground and the water as well, so keep that in mind.
So, about 40-50 years ago, someone did an experiment to test the possibility of spontaneous generation of life. What they did, is they basically took a bunch of water, then added to the closed system an atmosphere just like that of the primitive earth, then sealed it all off, with the added feature of a spark generator in one part of the system to simulate lightning. What they found is that in a remarkably short time, starting with nothing but water and atmosphere, you get a large amount of amino acids spontaneously forming. This is most interesting, because amino acids are the basis for every living thing. In a more recent experiment, where they've added the additional factor of adding some fine grained sediment to the water, they found that the specks of dirt acted as bonding points, and the amino acids were using them as anchors to combine into complex protein-like structures.
Now, none of those experiments lasted decades or centuries, or millions of years. The earliest fossils we have of primitive life (single celled organisms, so primitive they have no cell nucleus, just goop with some DNA strands floating in it) are from about 3.5 billion years ago. So, if we, in the lab, with conditions like primitive earth are getting amino acids combining into complex forms in a matter of weeks or at most months, it is not a very large leap to posit that given an entire planet and 300 million years, that things could go from amino acids & proteins to something that we'd call life. Heck, if you want to believe goddidit, certainly makes more sense to me that "God" or whatever you want to term it was the spark needed for that final step, than to believe that the earth is 6000 years old and that Dinosaurs lived with Adam and Eve in the Garden of Eden, which I've heard a ID proponent claim in a speech.
Now, it is certain that comets did indeed import significant amounts of water and organic compounds to the early earth, but even if we are to assume that they actually brought the original life, that merely puts off the question. If life isn't native to here, it must be native to somewhere, and we're right back to the same question on how it got started THERE.
In any case, we know mutation & natural selection happen, we can observe them occuring, especially in short-lived species like bacteria. (ex: How many influenza versions are there? How many diseases are now antibiotic resistant due to selection processes?) We simply don't have the life span to observe 50000 generations of something that lives for, say, 20 years, to be able to chart the incremental changes that, when put together, mark the evolution of one species into another.
-Arlos