Darwin- would he have changed his theory?

Actually, you'll find most of us evolutionists have. For my part, I used to be a creationist; as an English major, it's a formative work for our culture.

It's of significant cultural interest, after all. Why wouldn't we have read it? If only to understand the Biblical "model" our opponents are trying to advance?

I think one of the testaments to Darwin's genius is how little he actually would have had to change. Obviously, he would have had to incorporate Mendel's genetic work; that's really about it. Traits in organisms don't work quite the way that Darwin thought they did; but natural selection works exactly as Darwin originally formulated it.

But punctuated equilibrium doesn't change the theory in the least; punk eek is just a way of looking at the rates of change based on population size and the opening of niches. Since Darwin's theory didn't really dwell on that, it's not really a change to the theory.

Darwin posited that environment places selection pressures that shape organisms; punk eek doesn't change that.

Which I mentioned, already. Mendel's work was already done, but unknown to the rest of the world. As it was, though, Mendel's work only changed our thoughts about the nature of traits (as I said), not our knowledge about how they interact with their environment. Darwin was dead-on about that, and still is.

Huh? Sorry, buddy, that's astronomy, down the hall and to your left. This is the Biology department, where we study evolution.

Actually, it hasn't really changed that much. The core of Darwin's theory, that environment selects organisms that have hereditary adaptations, is still very much the same. It's the nature of the adaptations themselves that we've learned more about, and had to revise. Darwin thought all traits were continuous; we've learned since that most traits are discreet.

{Fixed a quote box (a vital service). - AM}

This message has been edited by Adminnemooseus, 10-21-2004 10:57 AM

Actually, this is incorrect; the person who discovered microorganisms was, predictably, the guy who invented the first usable microscopes: Anton van Leeuwenkoek, in the 1600's.

This is also not true. Mold is fungus; bacteria are not. Mold comes from spores.

But what you're talking about and what he's talking about is something entirely different. He;s talking about taking myth at face value, without question. You've given examples of how we've learned some myths were originally based in historical truth. But we didn't come to that conclusion by taking myth at face value; we came to it by the analysis of evidence.

You've mistaken conclusion for evidence.

The evidence is the inference of heredity between disparate groups of organisms. The conclusion is common ancestry and a last common ancestor. You don't start with the common ancestor, oddly enough; you end with it, because we're looking backwards in time.

So, no. Even without specific knowledge of the last common ancestor, we conclude it was there, because that's what the evidence says.

Which is a probability predicated on a number of erroneous assumptions. As it turns out:

quote:

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Functional sequences are not so rare and isolated. Experiments show that roughly 1 in 10^11 of all random-sequence proteins have ATP-binding activity [Keefe and Szostak 2001], and theoretical work by Yockey [1992, 326-330] shows that, at this density, all functional sequences are connected by single amino acid changes.

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So, actually, the odds are pretty good that you'll hit something functional as you crawl, randomly, through the protein space. Furthermore:

quote:

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Denton [1998, 276] wrote, "One of the most surprising discoveries which has arisen from DNA sequencing has been the remarkable finding that the genomes of all organisms are clustered very close together in a tiny region of DNA sequence space forming a tree of related sequences that can all be interconverted via a series of tiny incremental natural steps." Meyer cites an older work of Denton [1986] without alerting readers to Denton's changed view. Denton now criticizes intelligent design advocates for ignoring the overwhelming evidence [Denton 1999].

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The fact that all organisms have proteins so close to each other, so clustered in the protein space, is a pretty good indication that they're all decendants of one common ancestor.

(from http://www.talkorigins.org/indexcc/CB/CB150.html)

Life hasn't ever, really. The vast, vast majority of life on Earth, by individual or by mass, is single-celled. There's no evolutionary trend towards complexity - only a few, isolated, rare examples of life more complex than single-cells.

What's happened in billions of years has not been any kind of trend towards complexity, but rather, an expansion of variety.

Mm, not really. There's considerably more variation represented within single-celled organisms than within anything else. What's happening is a kind of selection bias in your mind - because you're one of the rare complex organisms, the only organisms of significance to you are the complex ones.

You're right, it doesn't make sense, because it's all in your head, in your biases. There's been no evolutionary trend towards complexity.

But you got it backwards. You didn't supply examples of applying myth to science; you supplied examples of applying science to mythology.

Big, big difference. In no case has myth been used to substantiate scientific endeavor; rather, scientific evidence has been used to substantiate the origin of mythology.

What, like the Bible? Wrong about the flood? To the contrary, ancient documents aren't any more accurate, generally, than modern documents. Which makes sense - people sometimes get things wrong, now and then; ancient peoples weren't idiots, they were just ancient. Poorly informed, if you will.

Well, that was layman's terms, but ok...

It means that you can go from one functional protein to another, changing only one amino acid each time, and have functional proteins at every step.

No, it's the chance of a randomly-generated sequence of amino acids having a certain functionality - in this case, binding ATP, the energy storage molecule in cells.

And one in 10^11 is great odds. At that rate, we would expect one or two new functional proteins in every single generation of a moderate population of vertebrates - one or two proteins every ten years, or so.

More than fast enough.

It doesn't really show that. A plethora of living things probably did arise, spontaneously and individually - but only one group of them survived. Competition, you see. The fact that only one sprinter wins the race is not evidence that he was the only one who ran.

I'm surprised you couldn't think of that yourself. You seem fairly insightful.

This message has been edited by crashfrog, 10-22-2004 11:40 AM

We don't know the exact process. Who said we did? The problem here is that the chemical precursors of life don't exactly leave fossils.

Goodness, no. Wouldn't you think, if it was easy to figure out, we'd have done that by now? It's not for want of trying, at this point.

Well, "which amino acids to use" is all of them, at least, all of the left-handed ones. But here's the problem - all living things are made of the same amino acids.

Unfortunately, our genetic code doesn't have that many instructions. The genetic code is not, as is commonly believed, a "blueprint of life", in the sense that a blueprint is an abstraction of the physical shape of something. All our genetic code does is make proteins. It doesn't describe structure, or anything like that. There's not enough genes in the genome to do that.

What? No, it's been decoded for, I dunno, 50 years or more. Here it is:

It's a simple as can be - three bases code for any given amino acid, or they're a stop codon that tells the process where to end.

There's not actually all that much information in the genome. Just recently, scientists redacted the estimate of the number of genes in the human genome from the upper 30k down to 20k. That's 20,000 genes. That's not a lot. That's almost as few as a certain mustard plant, I understand.

What information?

Snowflakes self-assemble; crystals self-assemble into very complex structures. Neither one of them requires any "information" to do so. We're just talking about chemical reactions, here - chemicals don't need "information", whatever that is, to react.

Didn't I just tell you that it wasn't your genetics that built you? There's no "genetic blueprint" in your cells that describes the structure of your body.

There's just a complicated molecule that catalyzes protein synthesis. It's just chemistry. Just because chemicals react they way they're supposed to, over and over again, doesn't mean they need "information", whatever that is, to do so.

We don't know what proteins we need, because we don't know how to predict, yet, what the function of a protein will be from it's genetic representation.

It's called the "folding problem." Proteins do what they do because they take a certain shape. We have a very limited ability to predict how a protein will fold because it's a very, very complicated interaction of literally thouands of atoms.

Well, right now we're working to pin down exactly what the "minimal orgamism" would be. There's currently no such thing as a "simple single-celled life form." All the single-celled life on Earth is the result, at this point, of billions of years of evolution.

When we know what the minimal organism has to be, then we can start sythesizing it. At that point it shouldn't take longer than about ten years.

No. Chemicals react. That's pretty much it.

No, that's behavior. And it's something that could arise by trial and error; in other words, by selection.

That would be hard, since, as I've said, we don't know anything about what the first life was.

But yes, computer programs have been written to simulate simple living things. Most famous is Conway's "Game of Life." I suggest you google for it; you can download it and run it on your computer.

What all these simulations tell us is that, thanks to random mutations and natural selection, all kinds of incredibly complex function can evolve and flourish; very simple rules can give rise to incredible complexity, even irreducable complexity.