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Author Topic:   Did life start only once?
Explorer
Junior Member (Idle past 5869 days)
Posts: 24
From: Sweden
Joined: 02-24-2008


Message 1 of 13 (457642)
02-24-2008 4:47 PM


Nice to be here, totally new! Many interesting discussions.
Suggestion then, to a thread!
I would like to hear your opinion on this subject and some more. If this has been up before and widely discussed, please tell and redirect me to the threads, I have searched and read quite much in here.
I know from discussions in here that most of the Darwinists only apply natural selection on life AFTER its own creation (there wasn’t life before life therefore no natural selection could occur, logical). However... is it a widely accepted idea that life only started once? I mean.. is there any evidence that it started more than once? As far as I know there are no such evidence. There are no creatures crawling around that are fundamentally different from ours. This is really strange. I mean... evolution through natural selection creates (or evolves) new species all the time. And yes, even if it doesn’t apply to creation OF life the whole thing seems strange. Why is a winning concept (evolution) so rare? Why don’t we see other kinds of life emerging? Why don’t we see some traces from "flawed life" that didn’t make it due to some critical flaw in another line of evolution (another combination of amino acids with completely different ways to ours)?
I find it hard to believe that life only came to be once and the only time it did... it somehow got so lucky that we sit here and wonder why that is. I am baffled. That’s why I ask. And I must point out that I am not a big fan of either ID or creationism. Sometimes I have a hard time accepting evolution in every aspect... I believe some things (not going to debate that in this thread) lies in the future to explain fully. I do believe in the scientific method for exploring the world wherever it leads us. 500 years ago most of today’s stuff would be magic and the same for us in 500 years.
Edited by Explorer, : No reason given.

Replies to this message:
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Adminnemooseus
Administrator
Posts: 3974
Joined: 09-26-2002


Message 2 of 13 (457655)
02-24-2008 5:54 PM


Thread moved here from the Proposed New Topics forum.

  
Chiroptera
Inactive Member


Message 3 of 13 (457659)
02-24-2008 6:13 PM
Reply to: Message 1 by Explorer
02-24-2008 4:47 PM


Welcome, Explorer.
Good question. I don't think anyone really knows the answer.
Darwin himself, when he proposed his theory of common descent, wasn't sure how many times life originated and how many distinct ancestries there were. Modern genetics and molecular biology indicates that all known life has evolved from a single ancestral population. That doesn't mean that a totally new and different species won't be found in some obscure environment that will be found to be descended from a completely different lineage, but among all that we know of now, we all have a common ancestor.
But we don't know how many times life originated on earth. Life appears in the geologic record immediately after the end of the Late Bombardment, the early part of the earths history when it was still being smacked by god-awfully big meteors. During the Late Bombardment, life would be pretty much impossible -- these meteors were big enough to sterilize the planet! But life appeared almost "immediately" when it was possible, suggesting that by whatever processes life originates, it originates pretty quickly (quickly, of course, meaning perhaps as long a few million years). So it is possible that life originated several times between large impacts, only to be wiped out, until the last large impact occurred.
It could have been that there were several different kinds of life on the early earth, but for whatever reason only one survived to the present day. Perhaps our kind out competed the rest and drove them all to extinction early on; perhaps it was the result of a statistical fluke -- just like some dynasties end up dying out because all the branches leave no heirs for no discernable reason, so maybe the other different kinds of life simple left fewer and fewer species.
Another possibility is that we may be the result of several different "starts". There is a theory that during the very early part of life lateral gene transfer was important -- that is, instead of inheritance occurring strictly between generations, maybe living organisms swapped genetic material with each other. In that case, there may be no real way to distinguish different "starts" of life early on, since they all eventually came to share their genetic material and so homogenize. This is why I refer to this hypothetical ancestor as the ancestral population rather than the ancestral species.
Finally, once life began, there probably was no chance for another "biogenesis" event. Any organic material that could conceivably become the start of new life would be eaten up by the now ubiquitous life that is already present.
Hope this helps.

If I had a million dollars, I'd buy you a monkey.
Haven't you always wanted a monkey?
-- The Barenaked Ladies

This message is a reply to:
 Message 1 by Explorer, posted 02-24-2008 4:47 PM Explorer has not replied

  
AZPaul3
Member
Posts: 8513
From: Phoenix
Joined: 11-06-2006
Member Rating: 5.3


Message 4 of 13 (457667)
02-24-2008 6:50 PM
Reply to: Message 1 by Explorer
02-24-2008 4:47 PM


I know from discussions in here that most of the Darwinists only apply natural selection on life AFTER its own creation (there wasn’t life before life therefore no natural selection could occur, logical). However... is it a widely accepted idea that life only started once? I mean.. is there any evidence that it started more than once?
No. No evidence that we have found to make us believe that life started more than once on this planet. We do not even know the mechanism by which it started on this planet.
Let’s be clear here. “First life” can be defined as a functional cell, albeit simple and rudimentary compared to cells today, or we may define “first life” as that first chain of molecules with an amazing ability to self-replicate. I choose the later.
There are some major hypotheses about abiogenic vectors but nothing conclusive.
Yet, looking at the proposed mechanisms I cannot help but feel that life may indeed have started several thousand times on this planet and all but one failed to prosper.
Further, we can speculate, with reason (not just pulled out of our butts), that successful life on this planet may have started by some combination of replicating chains any one of which would not have survived on its own.
Why is a winning concept (evolution) so rare?
Once life got a foothold without being blasted apart by cosmic rays or being dried up in a drought or drown in a primordial flood, evolution was inevitable.
Why don’t we see other kinds of life emerging?
Consider this. Abiogenic events may still be happening on this planet today. There is nothing in chemistry or other laws of physics that preclude it. The problem may be, however, that this planet is already teeming with life and some small self-replicating chain of molecules is a mighty tempting hors d’oeuvre. It probably wouldn’t be around replicating long enough (hundreds of millions of years) trying to build a cell of its own, like those first ones did, without getting eaten.
Why don’t we see some traces from "flawed life" that didn’t make it due to some critical flaw in another line of evolution (another combination of amino acids with completely different ways to ours)?
Small chains of molecules, or even primitive pre-proto-cells, don’t fossilize too well.
And I must point out that I am not a big fan of either ID or creationism. Sometimes I have a hard time accepting evolution in every aspect...
Ahh . skepticism and an inquiring mind. Good Combination.
Welcome to EvC, Explorer!

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 Message 1 by Explorer, posted 02-24-2008 4:47 PM Explorer has not replied

  
Granny Magda
Member
Posts: 2462
From: UK
Joined: 11-12-2007
Member Rating: 4.0


Message 5 of 13 (457669)
02-24-2008 7:06 PM
Reply to: Message 1 by Explorer
02-24-2008 4:47 PM


Hi Explorer,
This is an interesting question, but genetic science suggests that all life shares one common origin. I think that AZPaul3's point about the post-life world being hostile to new life is a good one. Living organisms have an enormous effect on Earth's atmosphere, and have done ever since blue-green algae ruled the world, which they did for billions of years. Over this time they increased the oxygen content of the atmosphere. It might be that the process that originally started life is not possible under modern conditions.
On the other hand, maybe we'll eventually find a hydrothermal vent or cave system with life forms unrelated to our own. Who knows?

Mutate and Survive

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Explorer
Junior Member (Idle past 5869 days)
Posts: 24
From: Sweden
Joined: 02-24-2008


Message 6 of 13 (457675)
02-24-2008 8:02 PM


Thank you for your answers!
Well... seems to me the most logical reason why we don’t see another line of evolution is that it would be extremely hard for an up comer to win or compete over something that already have taken its place on the planet. I thought of this too at some time and it really is one possible explanation to why we don’t see some other kinds of life surviving to the point where we could observe it. And yes, it could be the fact that "the battle" between the lines of evolution were fought long time ago just after the right time and the right conditions for life... leading to our line out coming as a winner. However . wouldn’t it be possible for emerging life to become parasitic on our line of evolution? Are there any possible candidates for such an “attack”?
Shortly , I thought of this.. long time ago I read that there are some things that don’t qualify fully as life-forms but bear a close resemblance. I cant remember their names or what they were. Is it possible that such things are the remainings of an attempt to start life? Our beaten and "sleeping relatives". Does anyone know what it might have been?
Granny Magda:
quote:
Over this time they increased the oxygen content of the atmosphere. It might be that the process that originally started life is not possible under modern conditions.
That would lead to severe difficulties for other lines of life IF life depends on very unique conditions to emerge.
quote:
On the other hand, maybe we'll eventually find a hydrothermal vent or cave system with life forms unrelated to our own. Who knows?
Yes... like in horror-movies “The cave”.

Replies to this message:
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 Message 8 by Granny Magda, posted 02-25-2008 1:02 PM Explorer has not replied
 Message 9 by Blue Jay, posted 02-25-2008 4:58 PM Explorer has not replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 7 of 13 (457689)
02-24-2008 9:25 PM
Reply to: Message 6 by Explorer
02-24-2008 8:02 PM


Well... seems to me the most logical reason why we don’t see another line of evolution is that it would be extremely hard for an up comer to win or compete over something that already have taken its place on the planet.
You'd think. After all, the first thing life would do on arising from the "organic soup" would be to reproduce ... by eating all the soup.
First come, first served.
However . wouldn’t it be possible for emerging life to become parasitic on our line of evolution? Are there any possible candidates for such an “attack”?
Viruses? Depends on whether they're alive or not ... and on how they originated.
Shortly , I thought of this.. long time ago I read that there are some things that don’t qualify fully as life-forms but bear a close resemblance.
Well, there are viruses, beta prions, RNA species ... none of them can metabolize, and beta prions can't evolve either.
Whether or not they're life depends entirely on your definition of life.

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Granny Magda
Member
Posts: 2462
From: UK
Joined: 11-12-2007
Member Rating: 4.0


Message 8 of 13 (457770)
02-25-2008 1:02 PM
Reply to: Message 6 by Explorer
02-24-2008 8:02 PM


explorer writes:
Yes... like in horror-movies “The cave”.
You never know!
Seriously though, I was thinking of something more like this; the snottite! Charming little critters aren't they!

Mutate and Survive

This message is a reply to:
 Message 6 by Explorer, posted 02-24-2008 8:02 PM Explorer has not replied

Replies to this message:
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Blue Jay
Member (Idle past 2698 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 9 of 13 (457810)
02-25-2008 4:58 PM
Reply to: Message 6 by Explorer
02-24-2008 8:02 PM


Explorer writes:
Well... seems to me the most logical reason why we don’t see another line of evolution is that it would be extremely hard for an up comer to win or compete over something that already have taken its place on the planet.
Be careful with this, though. The way natural selection is viewed isn't actually "survival of the fittest," but "survival of the fit enough". There isn't any natural law that says the upstart can't win, or that the upstart can't survive. Birds evolved during a time when the skies were filled with already well-adapted pterosaurs. Bats evolved during a time when the skies were filled with already well-adapted birds. However, as you say, the upstart is generally at a disadvantage when trying to compete with something that has been in place and well-adapted for a long time.
Also keep in mind that the earliest fossils consist of microscopic structures that resemble bacterial cells and lumps of rock called stromatolites, which generally form from piles of photosynthetic bacteria that died when new bacteria grew on top of them and blocked the sunlight. We can't actually confirm exactly what made the stromatolites, because their molecular structures didn't fossilize. Because they kind of resemble bacteria in appearance and, based on the minerals of the stromatolites, metabolism, we generally classify them as bacteria. But, there could have been other types of alternatively-evolved organisms that created stromatolites at the same time.
However, it seems infinitely more probable that all the living things around today are related, and science will generally stick to that answer until we find reason to doubt it (and we haven't yet).
Edited by Bluejay, : Added three random words

Signed,
Nobody Important (just Bluejay)

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Replies to this message:
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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 10 of 13 (457864)
02-26-2008 12:01 AM
Reply to: Message 9 by Blue Jay
02-25-2008 4:58 PM


. Birds evolved during a time when the skies were filled with already well-adapted pterosaurs. Bats evolved during a time when the skies were filled with already well-adapted birds.
Yes, but they weren't in direct competition. Flight in itself does not constitute a niche.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 11 of 13 (457904)
02-26-2008 9:09 AM
Reply to: Message 8 by Granny Magda
02-25-2008 1:02 PM


Seriously though, I was thinking of something more like this; the snottite! Charming little critters aren't they!
You should try swimming through them They are in great abundance in a mine I used regularly to dive. And I believe that we have been calling them snottites for far longer than is suggested in Wikipedia...

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john6zx
Member (Idle past 4821 days)
Posts: 66
Joined: 01-27-2007


Message 12 of 13 (464555)
04-27-2008 4:30 AM
Reply to: Message 1 by Explorer
02-24-2008 4:47 PM


Explorer wrote:
I find it hard to believe that life only came to be once and the only time it did... it somehow got so lucky that we sit here and wonder why that is. I am baffled. That’s why I ask. And I must point out that I am not a big fan of either ID or creationism. Sometimes I have a hard time accepting evolution in every aspect... I believe some things (not going to debate that in this thread) lies in the future to explain fully. I do believe in the scientific method for exploring the world wherever it leads us. 500 years ago most of today’s stuff would be magic and the same for us in 500 years.
The question is, What is it that animates matter?

This message is a reply to:
 Message 1 by Explorer, posted 02-24-2008 4:47 PM Explorer has not replied

Replies to this message:
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Chiroptera
Inactive Member


Message 13 of 13 (464567)
04-27-2008 8:39 AM
Reply to: Message 12 by john6zx
04-27-2008 4:30 AM


The question is, What is it that animates matter?
Chemistry. Life is basically a rather complex mixture of molecules that are interacting according to the mundane laws of chemistry.

Speaking personally, I find few things more awesome than contemplating this vast and majestic process of evolution, the ebb and flow of successive biotas through geological time. Creationists and others who cannot for ideological or religious reasons accept the fact of evolution miss out a great deal, and are left with a claustrophobic little universe in which nothing happens and nothing changes.
-- M. Alan Kazlev

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