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Author Topic:   Evolution starting with a single bacterium
Ooook!
Member (Idle past 5815 days)
Posts: 340
From: London, UK
Joined: 09-29-2003


Message 46 of 56 (117828)
06-23-2004 6:38 AM
Reply to: Message 44 by XenoGenisis
06-23-2004 6:08 AM


Regarding your call for a liitle fossil of a simple cell with a little label on it saying "LUCA" :
To repeat an age old scientific mantra: Lack of evidence is not evidence of lack!
Why does it need to fossilise to be proof anyway? What about the evidence gleaned from ribosomal RNA and the common genetic code which point to a common ancestor?
edit: I messed up ancient scientific mantra....bum!
This message has been edited by Ooook!, 06-23-2004 06:02 AM

This message is a reply to:
 Message 44 by XenoGenisis, posted 06-23-2004 6:08 AM XenoGenisis has replied

Replies to this message:
 Message 47 by crashfrog, posted 06-23-2004 6:39 AM Ooook! has not replied
 Message 52 by XenoGenisis, posted 06-23-2004 7:39 AM Ooook! has replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 47 of 56 (117829)
06-23-2004 6:39 AM
Reply to: Message 46 by Ooook!
06-23-2004 6:38 AM


Well put. I strongly suspect that anything we find out about the LUCA won't come out of the rocks; it'll come out of our cells.
Fascinating stuff.

This message is a reply to:
 Message 46 by Ooook!, posted 06-23-2004 6:38 AM Ooook! has not replied

  
XenoGenisis
Inactive Member


Message 48 of 56 (117830)
06-23-2004 6:50 AM
Reply to: Message 45 by crashfrog
06-23-2004 6:19 AM


We know they must have existed
First you said that there must be. Now you just think it’s most likely?
I posted-predecessor of the first prokaryotes Circa 4.0 billion years ago Any fossil evidence of? Which you would not answer.
Well, the procaryotes are the ancestors of all life we're aware of.
We? I don’t believe that.
That would make the predecessors of the procaryotes the predecessors to everybody else.
If ToE were true yes. I never assumed it was. I was asking if there was evidence of them. My intention was to get a question answered. Which you could have done very easily by saying No. on your first post to me. That would have sufficed.
Which we have - the prokaryotes. Who were their predecessors? We may never know, though I imagine we'll have some ideas
The question Who were their predecessors?, presupposes that they should have predecessors. You should be asking did they have predecessors. Can’t you see that you frame your questions on the presuppositional foundations of ToE. You have to hold out the possibility that there are no progenitors to prokaryotes. And there is no evidence that there are.
This isn’t a single progenitor. We have 2 different, completely formed, prokaryotes.
Archaea and true bacteria. Thus ToE falls apart as there is no single progenitor.
That’s how I figure it. I will have to get back to you tomorrow.

This message is a reply to:
 Message 45 by crashfrog, posted 06-23-2004 6:19 AM crashfrog has replied

Replies to this message:
 Message 49 by crashfrog, posted 06-23-2004 6:58 AM XenoGenisis has replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 49 of 56 (117832)
06-23-2004 6:58 AM
Reply to: Message 48 by XenoGenisis
06-23-2004 6:50 AM


First you said that there must be. Now you just think it’s most likely?
I used an unfortunate choice of words. The conclusion that there's a prokaryotic ancestor is not a certainty, merely the most likely conclusion. Nothing, of course, is a certainty in science.
If ToE were true yes. I never assumed it was.
You don't have to assume it's true. You can look at the evidence, and see that it is. No assuming required, except for the Cartesian Doubt assumption.
My intention was to get a question answered.
A question that you already knew the answer to? Why would you ask such a thing?
You should be asking did they have predecessors.
Ok, let's see. Are prokaryotes living things? Check. Then they most likely had ancestors.
When did you last see a living thing with no ancestors? I sure never have. What makes you think prokaryotes are different, somehow?
You have to hold out the possibility that there are no progenitors to prokaryotes.
Oh, I do. It is very much a possibility.
It's just not the most likely one.
Thus ToE falls apart as there is no single progenitor.
Except, obviously, the single progenitor of both Archaea and true bacteria, which, most likely, existed.
This message has been edited by crashfrog, 06-23-2004 05:58 AM

This message is a reply to:
 Message 48 by XenoGenisis, posted 06-23-2004 6:50 AM XenoGenisis has replied

Replies to this message:
 Message 50 by XenoGenisis, posted 06-23-2004 7:20 AM crashfrog has replied

  
XenoGenisis
Inactive Member


Message 50 of 56 (117837)
06-23-2004 7:20 AM
Reply to: Message 49 by crashfrog
06-23-2004 6:58 AM


Ok one more post.
A question that you already knew the answer to? Why would you ask such a thing?
Believe it or not, I didn’t know. I had some suspicion that my sources might be wrong. Thus the web search, thus this forum. Thus, thus, thus.
When did you last see a living thing with no ancestors? I sure never have. What makes you think prokaryotes are different, somehow?
Obviously one generation of anything alive can pass on another generation of the same.
Prokaryotes. I don’t see a progenitor species. eukaryotes. I don’t see one here either. I don’t by Prokaryotes as progenitor species of eukaryotes. Ediacaran Fauna. The list goes on.
You have to hold out the possibility that there are no progenitors to prokaryotes
Oh, I do. It is very much a possibility.
If true this is catastrophic for ToE. There are 2 species of prokaryotes. TWO. Distinct. Therefore no single original progenitor of all life. This is where we stand today. ToE is dead.
Thus ToE falls apart as there is no single progenitor.
Except, obviously, the single progenitor of both Archaea and true bacteria, which, most likely, existed.
No proof. But great faith.

This message is a reply to:
 Message 49 by crashfrog, posted 06-23-2004 6:58 AM crashfrog has replied

Replies to this message:
 Message 51 by crashfrog, posted 06-23-2004 7:36 AM XenoGenisis has not replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 51 of 56 (117842)
06-23-2004 7:36 AM
Reply to: Message 50 by XenoGenisis
06-23-2004 7:20 AM


Obviously one generation of anything alive can pass on another generation of the same.
That's a statement pretty obviously contradicted by observation. Oh, sure, one generation passes on another generation similar to the first, but certainly not the same. Cross-over, sexual recombination, and outright mutation all work to differentiate each generation.
So, no. Generations don't pass on "the same." They pass on similar, with differences.
There are 2 species of prokaryotes. TWO. Distinct. Therefore no single original progenitor of all life.
Therefore nothing. Your conclusion isn't supported by your premises.
ToE is dead.
Hrm, you'd hardly know it, given that it's one of the best-supported theories in science.
The only thing that's "dead" about evolution is the fossils that it explains so well. As a theory it's very much alive and at work, making sense of biology.

This message is a reply to:
 Message 50 by XenoGenisis, posted 06-23-2004 7:20 AM XenoGenisis has not replied

  
XenoGenisis
Inactive Member


Message 52 of 56 (117844)
06-23-2004 7:39 AM
Reply to: Message 46 by Ooook!
06-23-2004 6:38 AM


"Lack of evidence is not evidence of lack!"
Great.
So assume its there until you prove its not in this case?
Whats your RNA evidence that these 2 different species of Prokaryotes shared a common ancestor? Another missing link among MANY.
Lets face it, you don't have a single progenitor species. If you find it then horray. But the history of ToE is missing link after missing link.

This message is a reply to:
 Message 46 by Ooook!, posted 06-23-2004 6:38 AM Ooook! has replied

Replies to this message:
 Message 53 by crashfrog, posted 06-23-2004 7:40 AM XenoGenisis has not replied
 Message 56 by Ooook!, posted 06-24-2004 6:54 AM XenoGenisis has not replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 53 of 56 (117846)
06-23-2004 7:40 AM
Reply to: Message 52 by XenoGenisis
06-23-2004 7:39 AM


But the history of ToE is missing link after missing link.
Except, of course, for the links we've actually found.

This message is a reply to:
 Message 52 by XenoGenisis, posted 06-23-2004 7:39 AM XenoGenisis has not replied

  
XenoGenisis
Inactive Member


Message 54 of 56 (117851)
06-23-2004 7:55 AM


The only thing that's "dead" about evolution is the fossils that it explains so well. As a theory it's very much alive and at work, making sense of biology.
What about those fossils? Bring them out when favourable. Nevermind the lack of "missing link" fossils or the "progenitors of all life"
The fossil record shows stasis. It shows a lack of transitional forms.
"Therefore nothing. Your conclusion isn't supported by your premises."
My premise isn't based on the idea that there has to be a single progenitor to all life.
Again your ideology is prohibiting you from considering that there doesn't have to be a progenitor to these 2 distinct prokaryotes.
God?Remember- lack of evidence isnt evidence of lack. Goose and gander.
But in your case there is no evidence a progenitor to pros.
"Hrm, you'd hardly know it, given that it's one of the best-supported theories in science"
Thats a matter of debate.
I really have to sleep.

Replies to this message:
 Message 55 by crashfrog, posted 06-23-2004 8:06 AM XenoGenisis has not replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 55 of 56 (117855)
06-23-2004 8:06 AM
Reply to: Message 54 by XenoGenisis
06-23-2004 7:55 AM


Nevermind the lack of "missing link" fossils
Except for the links that aren't missing, of course.
or the "progenitors of all life"
Which, as we established, wouldn't have fossilized anyway, so their absence in the fossil record is hardly significant.
The fossil record shows stasis. It shows a lack of transitional forms.
Well, fossils are static, yes. They're dead.
But there's plenty of transitional forms, even if you discount the fact that basically every fossil is a transtitional form between its decendants and its ancestors. If you're interested in the vertebrate transitionals, I suggest you start here:
Transitional Vertebrate Fossils FAQ
It's fairly surreal that you insist that there are no transitional forms when I'm looking at a page full of 'em.
Again your ideology is prohibiting you from considering that there doesn't have to be a progenitor to these 2 distinct prokaryotes.
My ideology? Hardly. It's just that the most likely conclusion is that they had an ancestor, like everything else. It's just a matter of likelyhood. From where I'm sitting, it looks like you who has the problem with ideology.
Thats a matter of debate.
No, it's a matter of evidence.

This message is a reply to:
 Message 54 by XenoGenisis, posted 06-23-2004 7:55 AM XenoGenisis has not replied

  
Ooook!
Member (Idle past 5815 days)
Posts: 340
From: London, UK
Joined: 09-29-2003


Message 56 of 56 (118202)
06-24-2004 6:54 AM
Reply to: Message 52 by XenoGenisis
06-23-2004 7:39 AM


Xenogenesis,
Maybe it wasn't the most appropriate statement, considering there is evidence for a common ancestor. I'll get to that in a minute but first let's have a look at what you are saying:
Paraphrasing, you say: "There is no [fossil] evidence for a common ancestor, and therefore there was no common ancestor. On top of this, because no common ancestor has been found the entire theory of evolution falls down!" All of these conclusions are based on a percieved lack of evidence.
Which leads me onto the molecular evidence. I apologise in advance if you are familar with this, and it is a bit simplified, but I don't know your level of knowledge so I've tried to keep it basic:
It all revolves around the way that DNA codes for proteins (known as translation), its' a bit long-winded for a short(ish) post, but basically three letters code for each amino acid in a protein sequence. This is the same code for all life. There are a few minor variations, but essentially if you take the human sequence for insulin and put it into an E. coli you will get the same protein produced. I repeat, this is common for all life!
The central player in translation (ie where it all happens) is called the ribosome. This is a complex of protein and RNA, and is of course common to all life. By comparing the sequence of the RNA component of the ribosome (ribosomal RNA [rRNA]) for all of the organisms you know, you can't escape the conclusion that they all derived from a common ancestor. It also throws a few extra pieces of information: like the fact that Archea are closer related to Eukaryotes than Eubacteria are, and that the mitochondria (that are in all Eukaryotes) are closely related to a subsection of the bacterial domain.
Hope this is clear enough, and I'm sure you have lots to say about it.

This message is a reply to:
 Message 52 by XenoGenisis, posted 06-23-2004 7:39 AM XenoGenisis has not replied

  
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