Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
3 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Was Lamarck right?
Quetzal
Member (Idle past 5872 days)
Posts: 3228
Joined: 01-09-2002


Message 16 of 35 (93162)
03-18-2004 2:43 PM
Reply to: Message 11 by Denesha
03-18-2004 9:57 AM


I actually prefer the single cell => colonial organism => metazoan hypothesis. If you look at colonial algae like Volvox spp, you can see what might be an illustrative "pathway" for early metazoan evolution.
Volvox are eukaryotes that form spherical colonies embedded in a gelatinous ball in ponds of about 1000 cells. Each member is a fully formed, complete, and distinct organism. They all have flagella, all have their own chloroplasts, and all have their own opsin eyespots. What's interesting about them, is that although all the flagella are beating about, the colony itself seems to have a "front" and "rear". At the front, the organisms have larger eyespots, and the rear group do most of the propelling for the colony. IOW, it moves as a group in a coordinated fashion. In addition, only the rearmost seem to reproduce. Some species even have the cells linked by cytoplasmic threads. To me, this looks like an example of very early cell differentiation - a key element in metazoa.
From something like Volvox it's only a short step to something like a choanoflagellate, for example. And from there, it's an even shorter step to multicellular, highly diversified organisms like the Portuguese Man-o-War (Physalia physalis), which is a colonial jelly-fish like organism composed of four distinct organisms, each one specialized for a particular function within the colony.
I don't disagree with you that there's a great deal of evidence for symbiosis down at this level - chloroplasts, mitochondria, and possibly other sub-cellular structures appear to have been originally free-living organisms in their own right that got coopted. On the other hand, I don't think that two disparate organisms joined together to form the first metazoan. I'm of course open to correction.

This message is a reply to:
 Message 11 by Denesha, posted 03-18-2004 9:57 AM Denesha has replied

Replies to this message:
 Message 18 by Denesha, posted 03-18-2004 3:29 PM Quetzal has not replied

  
Brad McFall
Member (Idle past 5033 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 17 of 35 (93169)
03-18-2004 3:12 PM
Reply to: Message 13 by Quetzal
03-18-2004 11:50 AM


What if no such thing exists but instead there are conspiring MOTIONS that get DNA, RNA and Protein together. I dont think in these extreme terms but you all are missing the boat. Instead I prefer the material direction where ER and Nucleui might direct electons AGAINST inert masses or contrarily but speaking my mind has apparently gone so far that NOT even my plain speak works much any more.
The idea in this post was life from life but by spotaneous forcing not vital.

This message is a reply to:
 Message 13 by Quetzal, posted 03-18-2004 11:50 AM Quetzal has not replied

  
Denesha
Inactive Member


Message 18 of 35 (93173)
03-18-2004 3:29 PM
Reply to: Message 16 by Quetzal
03-18-2004 2:43 PM


Hi Quetzal,
As suggested, I download a few (8) PDF files concerning Symbiosis and Bacteria. I some, there are hypothesis of heterogeneous constitutions of Archae + eubacteria!
Must read them in detail.
Denesha

This message is a reply to:
 Message 16 by Quetzal, posted 03-18-2004 2:43 PM Quetzal has not replied

  
Loudmouth
Inactive Member


Message 19 of 35 (93176)
03-18-2004 3:42 PM


Was Lamarck right? Not really. He usually used large organisms as his examples. One famous example is the giraffe. He hypothesized that the giraffes would keep stretching higher and higher into trees, therefore causing their necks to elongate within that generation. This was thought to be heretable. Another modern day example could be bodybuilders. According to Larmarckism, if a person works out and develops large muscles, this should be heritable. If that same person did not work out and develop large muscles then the next generation would not have large muscles. This is obviously wrong.
Also, heritable genetic information is held in the germline, at least for eukaryotes. The germ line genome has no effect on the characteristics of the somatic line. Therefore, the next generation could have inherited genes that the parent population never displayed. This is in direct contradiction to Larmarckism.
I would say that Lamarck was wrong in how he applied hereditable traits. Larmarck emphasized characteristics first and then heretibality. The actual effect and cause is acquiring the trait and then developing the characteristic. Larmarck got it backwards.

Replies to this message:
 Message 21 by Denesha, posted 03-18-2004 4:12 PM Loudmouth has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 20 of 35 (93178)
03-18-2004 3:47 PM
Reply to: Message 15 by Quetzal
03-18-2004 1:37 PM


LUCA
Thanks. I find the second one more persuasive if for no other reason than that the building blocks must have been the same everywhere and that it is reasonable to see that a single cell consuming another single cell could very easily hijack any part of the "victim" for it's own purposes -- this could result in a homogenization across the board before the cells became complex enough to stand on their own.
But is this species or varieties ... if they all "interbreed" as it were, they would be one 'species' with lots of 'varieties' and the roots default back to a trunk.
If the generation of replicators is by the same process, it is possible to have several variations on a theme in the first ones to develop, ones that then mix and match parts at the local "swamp meet" -- and perhaps DNA and RNA [are \ result from] those variations ...

This message is a reply to:
 Message 15 by Quetzal, posted 03-18-2004 1:37 PM Quetzal has replied

Replies to this message:
 Message 29 by Quetzal, posted 03-19-2004 8:02 AM RAZD has replied

  
Denesha
Inactive Member


Message 21 of 35 (93186)
03-18-2004 4:12 PM
Reply to: Message 19 by Loudmouth
03-18-2004 3:42 PM


We must speak with courtesy when evaluating our past scientists.
Replaced in he’s context, Lamark was a genius.
However at our days, he’s theories are not supported.
Lamark was not wrong, he is wrong now.
Sounds better, indeed.
Denesha

This message is a reply to:
 Message 19 by Loudmouth, posted 03-18-2004 3:42 PM Loudmouth has replied

Replies to this message:
 Message 22 by Loudmouth, posted 03-18-2004 4:37 PM Denesha has not replied
 Message 23 by Chiroptera, posted 03-18-2004 6:02 PM Denesha has not replied

  
Loudmouth
Inactive Member


Message 22 of 35 (93191)
03-18-2004 4:37 PM
Reply to: Message 21 by Denesha
03-18-2004 4:12 PM


Denesha,
Good point. I think even Larmarck, if he were alive today, would agree that he is wrong without feeling picked on. He arived at his conclusions by looking at the evidence, and would as easily drop his theory with the evidence we have now. I do feel thankful to the scientific greats in history, and strive towards honoring those greats by trying to falsify their theories. The testing of a theory is one of the greatest honors in science. People avidly trying to falsify your theory means that it has merit, instead of being a crackpot idea.

This message is a reply to:
 Message 21 by Denesha, posted 03-18-2004 4:12 PM Denesha has not replied

  
Chiroptera
Inactive Member


Message 23 of 35 (93207)
03-18-2004 6:02 PM
Reply to: Message 21 by Denesha
03-18-2004 4:12 PM


Stephen Jay Gould wrote a wonderful little essay on Lamarck. I was just in the library but couldn't find it, so I can't provide a reference. It is in one of the later books - in the later books I didn't find Gould's writing so interesting, but this particular essay was a gem.
Evidently, Lamarck has been unfairly maligned. Toward the end of his life, he began to realise that his evolutionary theory was inadequate to explain the real data, and he began to modify it somewhat. He ended up a bit closer to modern Darwinian theory (although not quite there). Gould held him up as an example what what scientists are supposed to do: despite the heavy emotional investment he had in his theory, he was willing to reconsider it, modify it, and even abandon large sections of it as the data warrants.

This message is a reply to:
 Message 21 by Denesha, posted 03-18-2004 4:12 PM Denesha has not replied

Replies to this message:
 Message 24 by RAZD, posted 03-18-2004 7:31 PM Chiroptera has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 24 of 35 (93227)
03-18-2004 7:31 PM
Reply to: Message 23 by Chiroptera
03-18-2004 6:02 PM


and Darwin also had a section in his book on inherited characteristics via use and disuse. he didn't get it all right the first time either.

we are limited in our ability to understand
by our ability to understand

This message is a reply to:
 Message 23 by Chiroptera, posted 03-18-2004 6:02 PM Chiroptera has replied

Replies to this message:
 Message 25 by Chiroptera, posted 03-18-2004 7:40 PM RAZD has replied

  
Chiroptera
Inactive Member


Message 25 of 35 (93228)
03-18-2004 7:40 PM
Reply to: Message 24 by RAZD
03-18-2004 7:31 PM


There is a myth that "Lamarckism" was all about the inheritance of acquired characteristics. As you point out, AbbyLeever, Darwin also wrote about the inheritance of acquired characteristics. They didn't have modern genetics back then, so Darwin (and every other evolutionist) had to explain where new variations came from. The theory of pangenesis was the best that they had, at the time.
I don't quite understand Lamarkism, so what I am about to say may be wrong; I am always open to correction. What distinguished Lamarkism as a theory of evolution was that Lamark believed that there was an inherent force that caused species to progress; there was a philosophical belief at the time that civilization was one of improvement and progress (with the positive connotations of the word), and that progress was a natural part of the world. Lamark assumed that it applied to biological evolution, as well.
Darwin, of course, denied that there was any progress, except by accident. All that existed was variation with natural selection picking out those better able to procreate.
I also seem to recall that Lamark believed that each species was part of a unique evolutionary line, or at least there were a lot of lineages, whereas Darwin put forth the hypothesis that all species evolved from a very small number of ancestors.
Edited to add:
I am an idiot. Right after hitting "submit" it occurred to me to google! Here is some information on Lamark. If I am reading the article correctly (and I may be reading my views into it), then Lamark believed that species evolved because all the members were acquiring the same characteristics, while Darwin thought that those who did not acquire the right characteristics were eliminated by natural selection.
[This message has been edited by Chiroptera, 03-18-2004]

This message is a reply to:
 Message 24 by RAZD, posted 03-18-2004 7:31 PM RAZD has replied

Replies to this message:
 Message 27 by RAZD, posted 03-19-2004 2:18 AM Chiroptera has not replied

  
JustinC
Member (Idle past 4844 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 26 of 35 (93270)
03-19-2004 1:36 AM


I think the essay you are thinking of is "A Tree Grows in Paris: Larmarck's Division of Worms and Revision of Nature", it's found in his book The Lying Stones of Marrakech: Penultimate Reflections in Natural History.

Replies to this message:
 Message 30 by Chiroptera, posted 03-19-2004 1:17 PM JustinC has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 27 of 35 (93274)
03-19-2004 2:18 AM
Reply to: Message 25 by Chiroptera
03-18-2004 7:40 PM


Lamark
yes, I am always amused when C'ists refer to "Darwinists" as if all of several sciences were defined by one man over 100 years ago, when there were several others that contributed or would have come to the same conclusions in his absence.

we are limited in our ability to understand
by our ability to understand

This message is a reply to:
 Message 25 by Chiroptera, posted 03-18-2004 7:40 PM Chiroptera has not replied

Replies to this message:
 Message 28 by Denesha, posted 03-19-2004 4:54 AM RAZD has replied

  
Denesha
Inactive Member


Message 28 of 35 (93284)
03-19-2004 4:54 AM
Reply to: Message 27 by RAZD
03-19-2004 2:18 AM


Re: Lamark
Dear all,
This is an educational problem. Teachers must teach us "dogmatic/classic" facts and the desire to learn more about them by our own. Honestly, this is a hard task. Mostly, only facts are retained because we are too lazy to search for more.
This is not a fatality! I've learned more about Ernst Haeckel by myself. From this current forum discussion, I learned that JP Lamark accepted to change is mind without constraints.
I was not aware of that. It doesn't change my judgment on his colossal work but this underscore how I was tricked by education system. Navely, I thought there was nothing more to know about he's work.
Denesha

This message is a reply to:
 Message 27 by RAZD, posted 03-19-2004 2:18 AM RAZD has replied

Replies to this message:
 Message 31 by RAZD, posted 03-19-2004 8:56 PM Denesha has not replied

  
Quetzal
Member (Idle past 5872 days)
Posts: 3228
Joined: 01-09-2002


Message 29 of 35 (93321)
03-19-2004 8:02 AM
Reply to: Message 20 by RAZD
03-18-2004 3:47 PM


Re: LUCA
I think we're getting off topic (Q expects a hammer blow from the forum Supreme Beings at any moment). However, a quick note before we get ADMINmonished:
But is this species or varieties ... if they all "interbreed" as it were, they would be one 'species' with lots of 'varieties' and the roots default back to a trunk.
The Woese article uses a tree analogy in the form of early life = tangled roots --> cellular life = trunk --> more complex cellular life = the three great branches (like the top pic in my post). I think this is what you mean. Margulis, among a few others, doesn't agree, and basically states that the situation stayed complicated until much more recent times, even after the rise of metazoans (closer to the bottom pic). She even goes so far as to state that metazoans themselves are subject to this type of genome exchange and fusion. That's the bit I find hard to swallow, btw. The first article I cited is way better than the abstract, so if you can get ahold of the full article, it's worth a read.

This message is a reply to:
 Message 20 by RAZD, posted 03-18-2004 3:47 PM RAZD has replied

Replies to this message:
 Message 32 by RAZD, posted 03-19-2004 9:00 PM Quetzal has not replied

  
Chiroptera
Inactive Member


Message 30 of 35 (93370)
03-19-2004 1:17 PM
Reply to: Message 26 by JustinC
03-19-2004 1:36 AM


DOH!
That was one of the books I was looking through, looking for the essay. I completely missed it!
Thanks, Justin.

This message is a reply to:
 Message 26 by JustinC, posted 03-19-2004 1:36 AM JustinC has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024