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Study Explains Evolution's Molecular Advance
pnewhook writes "The New York Times is reporting that 'by reconstructing ancient genes from long-extinct animals, scientists have for the first time demonstrated the step-by-step progression of how evolution created a new piece of molecular machinery by reusing and modifying existing parts. The researchers say the findings, published today in the journal Science, offer a counterargument to doubters of evolution who question how a progression of small changes could produce the intricate mechanisms found in living cells.'"
Carl Zimmer,who is of course, THE MAN! of parasite parables and paraphenalia, has posted a more in-depth analysis of this story at his weblog, The Loom , going into the genetic/molecular mechanism. Additionally, Zimmer responds to the creationist take on the story (the usual move-the-goalpost panic of those advocating irreduceable complexity). Of larger concern, why does this incredibly fascinating discussion about scientific sleuthing and the potential and beauty of proteomics, get automatically sidelined into a discussion on "what does creationism say about this?" I don't blame Zimmer for responding; indeed, that's the duty of science writers as gifted as he. But it diminishes the power of the story itself to have to ask, imnsho.
I don't know that we have as of yet been able so show a living cell bootstrap from basic inert materials (I'm using non-living as the definition of inert in this context. There may be a better word, but I didn't think "dead" would be appropriate, as it has an implication of "once was living".)
However, it has been shown that many organic materials can be created in an environment similar to primordial earth. It has also been shown that many of these materials do tend to self-organize in a way that would be compatible with a cell possibly forming given enough organic material and time.
Cell wall: phospholipids, mostly being hydrophobic with one or two ends being hydrophilic tend to organize in sheets or water filled bubbles, and so could naturally form a cell wall. Amino acids do self aggragate to some extent, and a random aggregation could form a useful protein, ditto for RNA (which I believe preceded DNA evolutionarilly for a number of reasons.)
There is only one protein that would have to aggregate naturally before life as we know it could arise... ribosomes (or some suitable analog.) From there RNA could be transcribed into protein. At first most of the protein would pretty much be useless globs, untill a protein arises that can create copies of RNA. This protein could either aggregate naturally or be encoded by random chance into a strand or RNA. From there Darwinian evolution kicks in and as more beneficial RNA sequences come about that improve the transcription process and copying mechanism as well as the defense mechanisms, cellular life would not be too wild of an outcome. The progression of life would seem to be fairly slow at first, but the copying mechanism in RNA would probably be so imperfect that new variations arise very frequently, but most of those variations would likely be detrimental. Eventually better copying mechanisms arise, and eventually use of a more stable genetic material (DNA) make life blossom, expanding at a decent pace. Once some organism figured out a way to systematically capture and store energy from sunlight (or any energy source, really... thermal vents, gradiants across a thermo/chemocline etc) and a way to release that energy, then evolution can start proceeding at an exponential rate.
So, if it can be proven that a ribosome or some other RNA-Protein copying method could eventually arise from a random mix of amino acids it would greatly support the possibility of some method of abiogenesis. It does not have to be likely that this ribosome would arise in a human time scale... it could take millions or billions of years. It just has to happen eventually.
Complex hemes, carbohydrates and many other materials that are necessary for life at a complexity of ours would not be necessary to bootstrap the system from inert materials. Just some strands of RNA and something like a ribosome. Once you have those, something as complex as an RNA transcriptase could eventually arise from random permutations of RNA strands. And once you have RNA that has RNA -> RNA transcriptase encoded somewhere inside of itself and has some ribosome analogue working on it, then you have the bare bones beginning of organic life.
I'll never make that mistake again, reading the experts' opinions. - Feynman
The solution is that the original precursor gained the ability to bind a new hormone by a single point mutation, and this did not disrupt the ability of it to bind its old hormone. The new receptor then diverged and through a well known process of gene duplication, begat multiple and independently evolving molecules. One retained the function of binding the old hormone, whereas another mutated further to lose the ability to bind the old hormone and could now only bind the new hormone. Viola -- two seemingly "designed" systems out of one precursor -- evolution at its finest, and IMHO, damning evidence against the basic principle of Intelligent Design.
On a personal note, it never fails to amaze me how much people deny the intelligence of humans to figure things out... the old "just because we can't explain it now, it must have be an unexplicable force, like God." I'm sure lightning and earthquakes seemed supernatural too. Evolution is no different -- it can be dissected and explained.
Can you believe it's 2006 and we still care about the near-high-school drop-outs who continue to question evolution?
For those of you who don't read science, I would like to add that the paper itself made no mention of ID at all. Of course, biologists are interested in evlotution of complex mechanisms for its own sake, not for the sake of convincing some young earth creationists.
However, Dr Christoph Adami, who wrote in Perspecives (basically, giving an opinion of the significance of a new finding and providing the non-specialist with a context of the paper) made the point of how fatal this finding is for the ID argument. Here we have parts that have exactly the "irreducable complexity" that ID proponents love to talk about, and now someone has managed to reconstruct their evolutionary history.
Tor
Scientific American gives 15 Answers to Creationist Nonsense.
Memorize them for your next party
"The greatest obstacle to discovery is not ignorance - it is the illusion of knowledge." - Daniel Boorstin
Sorry to nitpick, but quantum "fluctuations" are not random. People often confuse the terms "random" and "probabilistic" when they talk about quantum physics. A "random" system is a system where any outcome of measurement is just as likely as any other outcome. However, quantum particles are more likely to be at the expectation value of position than at any other place, though there is a NON-zero probability of it being anywhere else in the system. So quantum "fluctuations"(I'm not sure what you mean by this) are NOT random, because some outcomes of measurement are vastly more likely than others. The only requirement for a quantum particle is that the probability of it being SOMEWHERE is 1.
Quantum particles are associated with probability WAVES that fluctuate with time. When we say wave-particle duality we mean that the particle does NOT have a definite classical trajectory but instead a WAVE of probability associated with it that describes the positions, energies, and momentums at which the particle is most likely to be. This is called a wave function; it is a solution to Schrodinger's differential wave equation and its square is a probability curve.
Depending on your interpretation, quantum mechanics does indicate some things about reality such as there is an ONTOLOGICAL limit on what we can know for certain about objective reality such that it appears meaningless to talk about an absolute objective reality at all. That is, reality changes by being observed. However, unlike general relativity which does indeed EXPLAIN gravity by saying that gravity is identical with a curved space-time geometry, you are quite right in saying that quantum mechanics does not explain anything. Nor does particle theory or E&M explain why there are electric and magnetic forces without beginning to conjure up force-carrying particles and the like. They are currently trying to explain all these things by means of string theory.