Evidence of Evolution

Discussion in 'Archive: The Senate Floor' started by king_alvarez, Apr 24, 2008.

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  1. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
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    It looks like all of the old evolution threads have been locked, so I thought I'd start a new one based on a discussion of types of evidence that support evolution. If someone finds an old thread to resurrect, I'll gladly move to that one instead.

    Typically, evolution is such a slow, gradual process that it can be very difficult to document it actually happening. But sometimes we happen to stumble upon some significant findings.

    Lizards Rapidly Evolve After Introduction to Island

    In just a few decades the 5-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say.
    ...
    Genetic testing on the Pod Mrcaru lizards confirmed that the modern population of more than 5,000 Italian wall lizards are all descendants of the original ten lizards left behind in the 1970s.
    ...
    Researchers found that the lizards developed cecal valves?muscles between the large and small intestine?that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation's cellulose into volatile fatty acids.

    "They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. "This was a brand-new structure."

    Along with the ability to digest plants came the ability to bite harder, powered by a head that had grown longer and wider.

    The rapid physical evolution also sparked changes in the lizard's social and behavioral structure, he said. For one, the plentiful food sources allowed for easier reproduction and a denser population.

    The lizard also dropped some of its territorial defenses, the authors concluded.

    Such physical transformation in just 30 lizard generations takes evolution to a whole new level, Irschick said.

    It would be akin to humans evolving and growing a new appendix in several hundred years, he said.

    This is actually an amazing find. While it's still uncertain whether this can be classified as a conclusive example of speciation, it is still very good documentation of evolution and adaptation in action. />/>
  2. VadersLaMent Chosen One

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    Apr 3, 2002
    star 9
  3. darthOB1 Jedi Grand Master

    Member Since:
    Mar 22, 2000
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    MY SMALL TOES ARE DISAPPEARING!!!!!! :rolleyes:
  4. DarthDogbert Force Ghost

    Member Since:
    Sep 2, 2004
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    I don't have nearly the time available to really get involved in this thread this time, but I may pop in from time to time if I can't help myself. :-B

    As for the story, as a Biblical creationist, it doesn't surprise me one bit. That's exactly the sort of rapid changes I envision when thinking of the years after the Flood when small populations were reintroduced into different environments. The story even gives a basis for how a change in diet (say, herbivore to carnivore) could force rapid changes and even speciation within a kind.

    [Legitimate question not even trying to get in an argument about evolution, merely wanting to understand]

    The way evolution is presented in that article as well as in others always puts a picture in my mind of single animal changing over time. Obviously, that is not the case, because the change occurs when considering the population over generations, not an individual member at any point in time.

    Correct me if I'm wrong, but not counting mutations, isn't the difference from one generation to the next merely statistical. That is, before their introducation on the island, the characteristics the lizards needed to survive on the island were present, in their DNA if not some of the original population, but these characteristics were not dominant before the island because they did not need to be leveraged for survival. Therefore, only the offspring that was given birth with the right combination of characteristics (already inherent to the population) were able to survive and reproduce. (Concerning mutations, with enough info about the inherent characteristics in the DNA, I would assume that they could largely be boiled down to a statistical presence as well.)

    So, honestly, I don't see what's so surprising about this finding. It's natural selection at its purest. However, I do find it ironic that a creationist is less surprised about a finding that "proves" evolution that an evolutionist.

    EDIT: After watching LOST last night, all this talk about islands is stirring some wild theories in my mind...
  5. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
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    When it comes to the cecal valve, it appears that this was not present anywhere in that species or genus, so it would seem this is a completely new gene. Of course, more will be known once DNA testing is conducted. But this does provide a great opportunity for scientists to study the actual progression of genetic mututation and how it spreads.

    Edit:
    I don't find it ironic at all. A Creationist is accustomed to taking things on faith alone. Whereas others are actually excited when actual evidence presents itself.

    Now to be clear, I'm not really as bothered by people that believe in some form of guided process of evolution as I am about people that deny evolution altogether.
  6. DarthDogbert Force Ghost

    Member Since:
    Sep 2, 2004
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    Just so you can have more of an understanding where I'm coming from, it's not "faith alone" that drives my beliefs. From my perspective, there is ample evidence to reasonably believe in the inspiration of the Scriptures. While that does color my interpretation of everything else, it is based on evidence. If there's no evidence, I don't care to form that much of an opinion about it.

    And, by the way, the implication that creationists do not love science (and other knowledge-seeking ventures) is false. I personally love to read about new scientific findings, not to mention archeological findings. Many of these findings either corroborate or do not affect the ideas that I have about things, but when I do come against something that bothers me, I don't ignore it, I try to learn about it. Thus, my interest in this thread.
  7. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
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    Well, I'm not interested in debating the merits of your system of evaluating different types of evidence here in this thread. The fact that we both agree that evolution has and continues to take place is enough for me to be happy in this specific matter.
  8. Quixotic-Sith Manager Emeritus

    Member Since:
    Jun 22, 2001
    star 6
    No, statistical differences are useful for showing variation among phenotypes (population genetics deals with morphologies), but the underlying source of the difference is genetic. The necessary characteristics are not present from birth or in historical populations (this is a variation of a common misunderstanding and/or misrepresentation of genetics); new genes evolve due to a number of factors, including crossing over of homologues during meiosis II, sequence inversion, SNPs (single-nucleotide polymorphisms, when one base is replaced by a different base, which can affect the protein for which that codon codes), VNTRs (variable number tandem repeats - a series of nucleotides repeats itself multiple times, which affects the protein chain coded as a result), microsatellites (smaller than VNTRs, similar mechanism), sequence inversion (-C-T-T-G-A-G- is reversed, becoming -G-A-G-T-T-C-, which affects the protein coded), etc. This isn't information already present, it's new functions brought about by fundamental biochemical changes.

    Think of it this way:

    1. Your parent/founding organism has the DNA sequence -CAATTGAGCTAC- || Parent protein chain: -gly-leu-ser-tyr-

    2. During meiosis, crossing over occurs, producing the new sequence -CAATGCGGTATC-, which produces a different protein in the next generation (which may or may not affect the overall organism). || F1 protein chain: gly-cys-gly-tyr-

    3. During replication of this second generation, a sequence inversion occurs, making the gene -CAATGCGATGTC-. This produces a phenotypical change two generations removed from the founding population. || F2 protein chain: gly-cys-asp-asp-

    4. And so on - the "basic information" was not there - it evolved as a result of shifting biochemistry.

    To make it explicit, I've underlined the chain every three base pairs, as these three-base codons are what yield the proteins that make up the phenotype. These proteins will fold and form hydrogen bonds yielding alpha helices and beta pleated sheets, which affect final protein structure and subsequent functionality.
  9. JMJacenSolo Jedi Master

    Member Since:
    May 21, 2006
    star 4
    Somewhat of an ancillary question, but I've been wondering this lately;

    Why is there such a variation in humans' talent for artistry? What type of evolutionary advantage did artistic talent offer in the past?
  10. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4
    DarthDogbert,

    You asked a fair question, in fact, as quoted from the article King_Alvarez linked to;


    "What could be debated, however, is how those changes are interpreted?whether or not they had a genetic basis and not a "plastic response to the environment," said Hendry, who was not associated with the study.

    "no dispute that major changes to the lizards' digestive tract occurred. "That kind of change is really dramatic," he added.

    "All of this might be evolution," Hendry said. "The logical next step would be to confirm the genetic basis for these changes."


  11. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
    star 3
    It is unlikely that this was merely a "plastic response to the environment" since this has not been observed in any of the other members of the species or genus. Of course, more will be known once the genetic testing has taken place.
  12. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4
    King_Alvarez,

    Maybe so and maybe not. I don't know, nor was able to obtain any pertinent info from a quick net surf for more specific clarification. How many species of reptile have such a valve, what other members of the family or order may have one.

    How are we defining "species" and "genus"?

    I can think of a whole slew of questions to be answered prior to the NG headlines being published. But then most individuals realize NG is not a peer-reviewed periodical and has in the past published misleading articles subsequently shown to be "premature."

    Even, still, it would seem the first area to check would be the genetics. Are we seeing the re- emergence of a recessed archaic characteristic?

    Items like the enlargement of the head are certainly nothing novel, although the article might lead one to think so.

    I dunno, I would be curious to see further investigative results.
  13. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
    star 3
    You haven't actually added anything new to the conversation. As I mentioned, it would seem unlikely that it (the cecal valve) is a re-emerging trait, otherwise it would have emerged in the other lizards that had populated that particular island or in other lizards at all, which it has not*. Yes, nothing can be confirmed until further testing takes place.

    *"No cecal valves have ever been observed before in this species or genus, and are in fact very rare in the entire family Lacertidae (only known in the specialized herbivore Galliota). "

    Herrel A, Vanhooydonck B, VanDammeR (2004) Omnivory in lacertid lizards: Adaptive evolution or constraint? J Evol Biol 17:974-984.

    Edit:
    Here's the actual peer-reviewed study:
    link
  14. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4
    "You haven't actually added anything new to the conversation."

    I added emphasis. :D
  15. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4

    "Very rare", but not non-existent. There is possible extant precedent.
    And, again, the term and notion of species is rather a work of evolution in itself.

    [Adding more emphasis. This might correlate to both DarthDogbert's, and my own, comments.]



    Edit: Corrected sp., DarthDogbert's screen name.
  16. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
    star 3
    That's why I said "seem unlikely" instead of "impossible." So I'm not sure what your point is except to reiterate what I've already said with the hope that you can get the last word on the matter.
  17. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4
    King_Alvarez,

    I've made a number of points, and one "point" is the "point" of emphasis, as stated directly twice.
    So, what's your point other than you feel like I'm raining on your parade by "pointing" out the obvious prematurity of the headline-hype which is good for subscription sales numbers?

    And speaking of "novelty", thus far, while interesting to taxonomic classification, there is nothing startling or particularly compelling about the observation thus far shown, at least not in regard for the over-arching "evidence for evolution."
  18. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
    star 3
    You're responding to arguments that neither I nor the article have made.

    If you accept evolution, then no, it is not at all compelling or startling because it is exactly what one would expect. Is it speciation? As I've said, that will need to be determined later.
  19. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4
    King_Alvarez,

    "You're responding to arguments that neither I nor the article have made."

    I'm not responding to any "argument", I haven't seen an argument. I've placed an emphasis, first in responding to DarthDogbert, who made a pretty good observation.

    What "argument" have I put forth? None.


  20. king_alvarez Jedi Knight

    Member Since:
    May 31, 2007
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    I'm not going to have this debate with you. What I and the author feel this study is evidence of (as well as the limitations of the study) is quite clear from what has already been said. There is nothing more that I need to say on the matter.
  21. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
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    You certainly are not, because while you seem to frame things as "debate" and "argument"...I'm not engaged in either.

  22. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4
    "If you accept evolution, then no, it is not at all compelling or startling because it is exactly what one would expect."

    Why would it be startling or compelling because it is what one would expect, unless those expectations are rarely, if ever, met?

    But, my comments have nothing to do with whether or not I "accept evolution", they are merely applying a modicum of critical analysis. For instance, evolution is predicated upon the building upon of something, not the whole-cloth "puff" of magic where material arises unprompted from thin-air upon a magical cloud...ergo, it is my first critical supposition that per premise of Ockham's Razor, especially in light of the characteristic being extant in other critters, that it is likeliest this is the "magnification" on an "order of magnitudes" of an otherwise dormant/ latent characteristic within the creatures structure.


    "Nothing from nothing leaves nothing, you gotta' have something if you want to be with me."
  23. Quixotic-Sith Manager Emeritus

    Member Since:
    Jun 22, 2001
    star 6
    We'll just ignore the genetic reasoning I posted earlier, as well as the fact that phenotypic variation can exhibit multiple realizability (multiple genetic combinations can produce similar structures, without there being any sort of "latent characteristic").
  24. _Darth_Brooks_ Jedi Master

    Member Since:
    Sep 27, 2000
    star 4
    What does my comment have to do with your "genetic reasoning"? Nada.

    If that's your approach fine, my approach is just as likely at this point, if not more elegantly simple and observable in nature.

    Conjecture is conjecture.
  25. ShaneP Ex-Mod Officio

    Member Since:
    Mar 26, 2001
    star 6
    Can someone explain evolution in a basic sense.

    What is the difference between Darwinism and evolutionary biology?

    Has any of Darwinism been refuted by other ,latter, findings?

    Is adaptation one of the signposts of evolution, but not the whole thing?

    I think some of the rejection of evolution, and science in general, is either:

    A)Not relating what this means to that average person

    or

    B)The teachers stink and put you to sleep

    Educate me.

    BTW, wasn't there some news recently about a band of apes that showed some signs of changing tools after being observed using some methods for decades prior and perhaps some observable adaptation?

    I swear I read or heard this somewhere. Maybe National Geo channel or magazine?
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