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For Jesus_Freak: The Science of Evolution

Taffer

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Jul 16, 2004
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You'd think I would learn, wouldn't you? :rolleyes:

This thread is for jesus_freak to ask any questions he likes regarding evolution and evolutionary theory. I, and others I hope, will answer your questions to the best of our ability. Ask away. :)
 
How did life start? I know you will say evolution has nothing to do with the begining of life, but at some point non life had to evolve into life. Is that fair?
 
jesus_freak said:
How did life start? I know you will say evolution has nothing to do with the begining of life, but at some point non life had to evolve into life. Is that fair?
Click to expand...

Well, sort of. It certainly is a very valid question, but it is not an evolution question. Before life it wasn't evolution, unless you really stretch the definition of evolution.

But we can help you with beginning of life questions also.
 
jesus_freak said:
How did life start? I know you will say evolution has nothing to do with the begining of life, but at some point non life had to evolve into life. Is that fair?
Click to expand...

That's technically abiogenesis, not evolution. Evolutionary theory deals with the way life adapts, changes, and differentiates over time. Abiogenesis deals with the development of life from non-life.

And, to answer the question, we don't know. There are several theories, each with varying levels of support, but there simply isn't enough evidence available yet to answer the question. Unlike complex organisms--such as trilobytes or dinosaurs or people--simple organisms like viruses, protozoa, or even the proposed self-replicating molecues don't really have any hard parts that are preserved int he geological or fossil record. Also considering the amount of time that's passed, and changes on the Earth's surface due to tectonic forces, means that even if such direct evidence existed at one time it's likely destroyed now.

What this means is that we have to infer rather than deduct, and that we'll likely never be 100% positive of how life first appeared on Earth. We have to deveolp theories consistent with what we know of chemistry, biology, physics, and other disciplines, then test those theories to see if they are possible. And the best we'll be able to say is that "method so-and-so" is a possible cnadidate, as it can produce life and the conditions for it existed in the early Earth."

To my knowledge, current theories rely on the idea of molecular evolution, where molecules become "self-catalyzing", making other molecules like themselves from available materials. This starts an evolutionary process, which can them develop into greater complexity. The problem, as i understand it, is the exact process of catalyzing and how it is conducted. Clay structures are one example I recall. Also the old "lightning and primordial stuff" experiments. I'm sure educated individuals could give more specific examples; I'm just a well-read layman, and haven't kept up the last few years, so I could well be out of date.
 
Jesus Freak...

Still here then !

How can anyone take you seriously from now on.

DB
 
jesus_freak said:
How did life start? I know you will say evolution has nothing to do with the begining of life, but at some point non life had to evolve into life. Is that fair?
Click to expand...

You're making the mistake of confusing ambiogenesis with evolution. Evolution is a fact, we've observed it happening all around us in real time. Evolution describes how living things adapt and speciate. Even if a mystical sky chieftain had deposited all living thing son this planet that wouldn't change the fact that evolution is plainly observable.
 
Hi everyone! I have started a book challenge over in R&P to help JF get started in understanding Evolution. I will be reading a book of his choice, and he will be reading one of mine. I would appreciate any help here or over there in answering any questions that may come from our readings. Thanks! Now, back to the definition of abiogenesis . . .
 
jesus_freak said:
How did life start? I know you will say evolution has nothing to do with the begining of life, but at some point non life had to evolve into life. Is that fair?
Click to expand...

It is a fair enough question, evolution and abiogenesis are closely related. I think Huntsman has summed up the state of current scientific knowledge of abiogenesis as good as any other layman could. There's no shame in admitting that we don't know something. An Old-Earth-Creationist could easily claim his/her preferred deity started life on the evolutionary path that we see in the fossil record and be perfectly happy with the theory of evolution (and with principles of geology and physics as well). In my opinion, that's just worshipping a gap in our understanding but you are free to do it. Do you have any questions about the theory of evolution?
 
I'm trying to find a good, well organizing, not-too-technical, pretty complete discussion of abiogenesis. I'm not having too much success. JF, if you want to tackle abiogenesis, you're going to have to do some reading. But hopefully we'll find you something to start with.
 
jesus_freak said:
How did life start? I know you will say evolution has nothing to do with the begining of life, but at some point non life had to evolve into life. Is that fair?
Click to expand...

Others have said what needed to be said on the origin of life but I just want to make something crystal clear:

No matter how life started...evolution still happened.

A detailed understanding of abiogenesis might be beyond our current grasp but that has no impact on the theory of evolution. Do you understand that?
 
jesus_freak said:
How did life start? I know you will say evolution has nothing to do with the begining of life, but at some point non life had to evolve into life. Is that fair?
Click to expand...

No, it is not fair because:

a) It has nothing to do with evolution. The first replicating molecules could have been planted by God and the theory of evolution would be just fine with that. All that is important is that at some point life capable of random mutation and subject to natural selection came into being. The mechanism of that is immaterial to discussion of evolution.

b) Any discussion of this is essentially worthless. If we were to succeed in creating life in a test tube it will still most likely be impossible to show that is how life started here. The question is probably scientifically unanswerable because all evidence for it has long since been used for food by later organisms.

Once you get past abiogenesis (which is outside the realm of evolution), evolution is a profoundly powerful tool.
 
Ok here is another question then...
When, where, why, and how did life learn to reproduce itself?
 
jesus_freak said:
Ok here is another question then...
When, where, why, and how did life learn to reproduce itself?
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Again, that's another unfair question. And for the same reason the previous one was. That's still about abiogenesis, not about evolution.

It also indicates a deep category error. "LIfe," as an abstraction, no more "learns" anything than "fire" "learns" how to burn. But just as part of the definition of "fire" involves burning, so do the standard (informal) definitions of life include reproduction.

In short, if it doesn't reproduce itself, it's not life.

The question facing abiogenesis theorists, then, is not explaining how life came to start reproducing itself. We know lots and lots of systems that reproduce themselves already, but that aren't alive -- crystals and clay structures are two obvious and well-studied examples. The question instead is how what we recognize as "life" emerged from other, pre-biotic systems, and what kind of reproduction was involved in those (pre-biotic) systems.
 
jesus_freak said:
Ok here is another question then...
When, where, why, and how did life learn to reproduce itself?
Click to expand...

You've restated your first non-evolution question with some clever anthropomorphizing. There was no "learning" and you're asking again about origin of life.
 
I don't find that an unfair question. There are certain chemicals that can reproduce themselves under the right circumstances. You start with a long chain of doublets. A is next to A, making AA. AA is over BB. BB is over CC.

These molecules split vertically making two copies of ABC. Free bits of A, B, and C hook onto the halves, and you get two copies of the double molecule.

(Chemists, please don't hurt me! :hit: I'm trying to be simple.)

Crystals you probably already know about. Crystals have a nice geometric shape. When there's a hole in the crystalline structure, it gets filled by a crystal with the same nice shape. In this was crystals "grow" a nice regular structure out of a liquid full of free "stuff." Common "stuff" could be ice, salt, sugar.

The next step was probably macromolecules, basically crystals that contained more than one thing. Namely, they contained some of those self-replicating molecules I mentioned above. So you had then a two level structure, something that could create copies of itself and create copies in its inside.

I don't know if this fits your definition of "life" yet or not--probably not. But it is an explanation of how you get something that "learned" to reproduce.
 
ChristineR said:
(Chemists, please don't hurt me! :hit: I'm trying to be simple.)
[...]
I don't know if this fits your definition of "life" yet or not--probably not. But it is an explanation of how you get something that "learned" to reproduce.
Click to expand...

You're overlooking what makes the question unfair. Where's the "learning" in the system?

As Wavicle pointed out, he's simply trying to re-state his original question about abiogenesis in a sufficiently anthropomorphic way as to assume intelligence in the evolutionary process.

If life "learns" to reproduce, there must be a learner -- and possibly a teacher. Since chemicals can't "learn," the learner and teacher must be God. Q.e.d. Argumentum ad anthropomorphum stercum bovinae
 
ChristineR said:
I don't find that an unfair question. There are certain chemicals that can reproduce themselves under the right circumstances. You start with a long chain of doublets. A is next to A, making AA. AA is over BB. BB is over CC.

These molecules split vertically making two copies of ABC. Free bits of A, B, and C hook onto the halves, and you get two copies of the double molecule.

(Chemists, please don't hurt me! :hit: I'm trying to be simple.)

Crystals you probably already know about. Crystals have a nice geometric shape. When there's a hole in the crystalline structure, it gets filled by a crystal with the same nice shape. In this was crystals "grow" a nice regular structure out of a liquid full of free "stuff." Common "stuff" could be ice, salt, sugar.

The next step was probably macromolecules, basically crystals that contained more than one thing. Namely, they contained some of those self-replicating molecules I mentioned above. So you had then a two level structure, something that could create copies of itself and create copies in its inside.

I don't know if this fits your definition of "life" yet or not--probably not. But it is an explanation of how you get something that "learned" to reproduce.
Click to expand...

The problem is that you've conjectured a possible explanation of "How" but have no evidence that this represents what really happened right here on good ol' earth. You've offered no explanation for when, where and why.

I'm not bashing you, I'm saying the question was unfair. If we continue down this road it's pretty obvious that at some point he is going to ask "show me the evidence" and then it will be clear to us that we shouldn't have continued down this debate path.
 
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