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How did life begin on Earth?

 
 
Reply Tue 14 Dec, 2004 01:27 pm
I'm leaving out the metaphysical options on this one.
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Type: Discussion • Score: 3 • Views: 4,242 • Replies: 33
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fresco
 
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Reply Tue 14 Dec, 2004 01:55 pm
I favour your first option but I'd want to change "evolutionary forces" to "tendencies for the spontaneous generation of dissipative structures".

<<Dissipative structures
The structure of a living system has been described in detail by Ilya Prigogine in his theory of dissipative structures. Like Ludwig von Bertalanffy, Prigogine recognized that living systems are open systems that are able to maintain their life processes under conditions of non-equilibrium. A living organism is characterized by continual flow and change in its metabolism, involving thousands of chemical reactions. Chemical and thermal equilibrium exists when all these processes come to a halt. In other words, an organism in equilibrium is a dead organism. Living organisms continually maintain themselves in a state far from equilibrium, which is the state of life. Although very different from equilibrium, this state is nevertheless stable: the same overall structure is maintained in spite of the ongoing flow and change of components.

Prigogine called the open systems described by his theory "dissipative structures" to emphasize this close interplay between structure on the one hand, and flow and change (or dissipation) on the other.

According to Prigogine's theory, dissipative structures not only maintain themselves in a stable state far from equilibrium, but may even evolve. When the flow of energy and matter through them increases, they may go through points of instability and transform themselves into new structures of increased complexity. This phenomenon - the spontaneous emergence of order - is also known as self-organization. It is the basis of development, learning, and evolution. >>
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rosborne979
 
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Reply Tue 14 Dec, 2004 02:28 pm
fresco wrote:
I favour your first option but I'd want to change "evolutionary forces" to "tendencies for the spontaneous generation of dissipative structures".


Yeh, I thought we might get down to the definitions of evolutionary forces on this.

I'm not entirely sure what branch of science deals with pre-biological, or chemical theory. I used the phrase evolutionary forces because I wanted to acknowledge some level of non-random functionality within the process.

I'm not familiar with spontaneous generation of dissipative structures. Can you summarize that at all?
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Einherjar
 
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Reply Tue 14 Dec, 2004 02:29 pm
I'm with fresco.
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rosborne979
 
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Reply Tue 14 Dec, 2004 02:44 pm
Einherjar wrote:
I'm with fresco.


Nobody favors the "it started somewhere else" and got seeded here by asteroid theory? Even after Mars rocks showed up on Earth, and even after Mars rovers detected signs of water on Mars?
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Einherjar
 
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Reply Tue 14 Dec, 2004 02:53 pm
It's entirely possible of course, I just wanted to get rid of "evolutionary forces" working beore self replication.
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rosborne979
 
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Reply Tue 14 Dec, 2004 03:04 pm
Einherjar wrote:
It's entirely possible of course, I just wanted to get rid of "evolutionary forces" working beore self replication.


Fair enough. I was using "evolutionary forces" in a broad sense to include some type of selection in favor of replicative molecules. But I guess there wouldn't need to be any selection in favor or self replication, it's just that once self replication got going, you would tend to have more of those types of molecules forming than others at random.

If Biological Evolution is one set of evolutionary principles which come into play once biology has developed, then what set of principles are in play before biology gets started? Is there any set of conditions which makes replicative molecules more likely, or do they just occur at random, and then begin to perpetuate themselves?
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Einherjar
 
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Reply Tue 14 Dec, 2004 03:34 pm
rosborne979 wrote:
Einherjar wrote:
It's entirely possible of course, I just wanted to get rid of "evolutionary forces" working before self replication.


Fair enough. I was using "evolutionary forces" in a broad sense to include some type of selection in favor of replicative molecules. But I guess there wouldn't need to be any selection in favor or self replication, it's just that once self replication got going, you would tend to have more of those types of molecules forming than others at random.


Alright.

Quote:
If Biological Evolution is one set of evolutionary principles which come into play once biology has developed, then what set of principles are in play before biology gets started? Is there any set of conditions which makes replicative molecules more likely, or do they just occur at random, and then begin to perpetuate themselves?


The laws of physics and chemistry are applicable. Lots of "random" molecules included in creationists oh-it's-so-unlikely-models are impossible.

Some molecules are naturally more likely to form than others. Polymers are more likely tho form than other "random" molecules of the same size because polymers form from monomers under certain conditions. Monomeres of given types also form under certain conditions, and are therefore ofthen available in numbers in one place.
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fresco
 
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Reply Tue 14 Dec, 2004 05:46 pm
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Acquiunk
 
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Reply Tue 14 Dec, 2004 05:54 pm
fresco wrote:
I favour your first option but I'd want to change "evolutionary forces" to "tendencies for the spontaneous generation of dissipative structures".


I also agree with fresco. The current favored hypothesis is clay as a matrix.
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rosborne979
 
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Reply Tue 14 Dec, 2004 07:49 pm
fresco wrote:
rosborne.

Prigogine studied complexity and chaos theory in Chemistry.

From Google

<<... It is now known that these systems are always likely to give rise to greater complexity...>>


Interesting. I wasn't aware of this. Thanks Smile
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rosborne979
 
  1  
Reply Tue 14 Dec, 2004 07:52 pm
Acquiunk wrote:
fresco wrote:
I favour your first option but I'd want to change "evolutionary forces" to "tendencies for the spontaneous generation of dissipative structures".


I also agree with fresco. The current favored hypothesis is clay as a matrix.


Not "black smokers" at deep ocean vents?

I remember hearing about the clay matrix, but I also remember someone speculating on the geothermal energy as a primary energy input rather than sunlight. And I also remember something about thermophile bacteria being found in deep rock samples, some of them VERY ancient.
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fresco
 
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Reply Wed 15 Dec, 2004 01:12 pm
rosborne,

Your options of extraterrestrial arrival imply an infinite regress to the explanation of the origin of life "somewhere".

Geothermal energy may be a sufficient energy source for "dissipative structures" but did not such energy originate in the sun anyway ? (I'm not familiar with the origin of the planets)
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Einherjar
 
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Reply Wed 15 Dec, 2004 03:54 pm
fresco wrote:
rosborne,

Your options of extraterrestrial arrival imply an infinite regress to the explanation of the origin of life "somewhere".

Geothermal energy may be a sufficient energy source for "dissipative structures" but did not such energy originate in the sun anyway ? (I'm not familiar with the origin of the planets)


No, geothermal energy did not originate in the sun, it remains from when the planet was formed. The interior of the planet is cooling as we speak.
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fresco
 
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Reply Wed 15 Dec, 2004 05:17 pm
...and the planet was formed from...?
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Einherjar
 
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Reply Wed 15 Dec, 2004 05:25 pm
Spacedust, remnants of a supernova. Heated I presume by gravitational compression.
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rosborne979
 
  1  
Reply Wed 15 Dec, 2004 10:56 pm
fresco wrote:
rosborne,

Your options of extraterrestrial arrival imply an infinite regress to the explanation of the origin of life "somewhere".


Yes, but I thought I should include it since I was asking how life started on Earth.
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rosborne979
 
  1  
Reply Wed 15 Dec, 2004 10:59 pm
Einherjar wrote:
Spacedust, remnants of a supernova. Heated I presume by gravitational compression.


Correct. Geothermal energy is primarily a result of gravitational compression. There are also tidal forces from orbital systems (particularly the Moon), and the heat from the Earth's core is at least partially due to nuclear reactions (I think it's a for of heat induced decay, but I would have to look that up).
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Adrian
 
  1  
Reply Wed 15 Dec, 2004 11:44 pm
rosborne979 wrote:
Einherjar wrote:
Spacedust, remnants of a supernova. Heated I presume by gravitational compression.


Correct. Geothermal energy is primarily a result of gravitational compression. There are also tidal forces from orbital systems (particularly the Moon), and the heat from the Earth's core is at least partially due to nuclear reactions (I think it's a for of heat induced decay, but I would have to look that up).


The heat is MOSTLY due to the radioactive decay of uranium, thorium and, it was recently found, potassium. The remnant heat left over from accretion is still there but it's only about 20% of the total.

I tend to favour geothermal energy over solar energy as the driving force behind genesis. Unless it was a lightning bolt or.....god. Razz
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blueveinedthrobber
 
  1  
Reply Thu 16 Dec, 2004 12:57 am
rocks ....ther were rocks...and God spoke and the rocks formed giant rock groups....
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