Evolution - please explain

Discussion in 'Biology & Genetics' started by root, Oct 7, 2005.

  1. root Registered Senior Member

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    I notice some well qualified people on this forum, I am no scientist but I have a nagging, maybe stupid, question to ask regarding Evolution. I know more or less the workings of Evolution and can understand how abnormalities in the offspring of a creature can make it fitter for survival and how change can therefore be propagated through natural selection. This is all understandable as long we are talking about small changes that could bring immediate benefit to the creature (Like color change for example). I cannot see this functioning when we are talking about the development of something complex (like wings for example) that does not give the creature any advantage in the survival game while it is busy developing (over millions of years). I can only see that partly developed wings could be to the detriment of the animal. So the question: What is it that drives the development of a complex feature (like wings) over a period of millions of years?
     
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  3. spidergoat Valued Senior Member

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    You are wrong when you say, "something complex... that does not give the creature any advantage in the survival game". This never happens. Besides survival, there is sexual selection that drives the development of something like a peacock's wings. Rudimentary wings served a purpose before flying. I have read that they were used by aquatic bugs for skimming the surface of water.
     
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  5. kenworth dude...**** it,lets go bowling Registered Senior Member

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    and also for fast creatures to maintain balance while running.
     
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  7. jayleew Who Cares Valued Senior Member

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    Good question, I've been trying to get answers myself:

    http://www.sciforums.com/showthread.php?t=49053&page=1&pp=20

    http://www.talkorigins.org/faqs/faq-speciation.html

    Talkorigins is a helpful site on evolution, but the author of this article makes excuses for the lack of evidence of large "complex" gaps in species. Evolution, as you know, does occur, but there is no evidence of divergence into a new species. Evolution results in mutations of a species, not new species. Of course, that depends on your definition of a new species. Is a donkey a species? Would a fertile donkey be considered a new species?

    Even if it were, I have a problem that the species was bred and not genetically altered without an external influence like breeding. I would define a fertile donkey as a freak of nature, a new breed of the horse family, not a new species.
     
  8. spidergoat Valued Senior Member

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    Of course there is evidence of divergence into new species. At one point in the fossil record, there were no horses, later, there were, and they were astoudingly similar to a primitive horse like creature, which could no longer be found after a certain date. The fossil record is full of periods of speciation, almost explosions of divergence.
     
  9. jayleew Who Cares Valued Senior Member

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    Yes, explosions. Evolution does not work that way. Evolution and natural selection should show consistent record of coexisting intermediate species. Otherwise, I can just as easily say, the old species was destroyed by aliens and a new species was put in its place.

    According to talkorigins, there is little recorded evidence of speciation, but they leave the article open for evidence that is undiscovered, but assumed to be there.

    And what is your definition of a new species? At what point does a breed become a species?
     
    Last edited: Oct 7, 2005
  10. J.B Banned Banned

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    Achiving the best quality of survival based on a being's enviroment.
     
  11. spuriousmonkey Banned Banned

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    See for instance this link
    http://www.ucmp.berkeley.edu/vertebrates/flight/evolve.html
     
  12. jayleew Who Cares Valued Senior Member

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    Horrible! Science and philosophy combined is called fact! That's disgusting.

    The article's second sentence:
    Since flight evolved millions of years ago in all of the groups that are capable of flight today, we can't observe the changes in behavior and much of the morphology that the evolution of flight involves.

    Right out of the gate, an assumption is made that flight evolved over millions of years.

    Then, the article forms hypotheses, predictions, and rationalizations, but provides no evidence because there is no recorded observations of the creatures' behaviors. We can only speculate how wings were formed. We can even agree based on perceived evidence, but that doesn't make it reality. The theory of evolution has gone from scientific theory to a new religion. Get rid of all assumptions, and maybe we can start learning about the science again.

    Things like this just don't make any sense. The first animals that took to the air likely didn't know how to fly and would break their necks when they crashed to the ground. What about the odds of survival of a new flying creature? There's always a bigger fish.

    What came first: The predator or the prey?
     
  13. spidergoat Valued Senior Member

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    What do you mean, it doesn't work that way? There's even a name for them, the cambrian explosion, for instance. There are periods of time when the environment is stable, and creatures don't change very much. There are other times when they change quite rapidly, and the intermediate species are relatively short lived.

    In the case of the horse, there are more primitive horses, and then modern horses, it's pretty clear. You could always say that the intermediate species was unique and not related to went before, but you would have to ignore the acknowledgement of visible trends.

    A more recent example is the speciation from wolves to dogs. Species that diverge in this way often go through a transition in which they can still produce offspring. Eventually when the populations are isolated for long enough, they will no longer be able to breed together.

    The definition of a separate species is difficult, since the change is so gradual.
     
  14. spidergoat Valued Senior Member

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    Well, no, they said that it happened millions of years ago, not that it took a million years.

    That's called making deductions.

    Don't be stupid, even squirrels can glide. It didn't happen overnight. Each step along the way conferred some advantage.
    The prey.
     
  15. judgesid Registered Member

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    Great question - and it is a Creationist favourite - because Darwinism doesn't really explain feathers / wings very well (if at all)

    I agree that evolution "works" by making species members with given mutations "more fit" for a changing environment. In addition it "works" when a change makes a creature more fit for a particular niche it has begun to live in.

    However, it also "works" when the mutation has no effect. If a mutation doesn't negatively effect fitness the species member and the mutation can still continue. "Bush proposed that an ancestral non-feather ... (recently discovered in alligator claws by Sawyer et al. 2000, making it plesimorphic in archosaurs) underwent duplication and subsequent (change) ... resulting in (the) two distinct sizes. Subsequent duplication and modification explain the similarity of all (the) smaller feathers) ... (Brush 1993, 1996, Prum & Brush 2002)" (http://wiki.cotch.net/index.php/Evolution_of_feathers) .

    So one argument says that the chicken (or at least it's feathers) came first.

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    It is clear that marsupials like the Flying Squirrel were experiments in flying. It is possible that the feather adaptions offered advantages in higher - tree niches etc, and lead to the development of wings, in those creatures that had feathers.

    Of course this require lots of time and lots of failed experiments, but evolution has lots of time. I'm not arguing this idea is right - it's just my take on a theory that argues, first came feathers, then wings. I like this better than the one that says first came birds!
     
  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I am far from an expert in this area, but surprized that no one has mentioned some well documented cases of current, rapid man made evolution:

    (1)About 300 years ago (and more) in London area all moths of some varity were essential white or light in color. London was growing rapidly and began to burn coal. By modern standards, the air was extermely poluted. In less than 200 years, those moths adapted to the change, became dark grey. I do not know what color they are today, perhaps "light" is making a come back.

    (2) I forget the details, but there was even an intentional "evolution experiment" done. Perhaps a preditor was introduced or perhaps it was already there, below the water fall in a small river and some of the prey fish were transported above the water fall and released. In any case, in a surprizingly short period (20 to 40 years? again I do not remember exactly) the "above water fall" fish became larger and delayed their sexual maturity relative to their sisters below the falls. Those "low level sisters" went in for early sex - had selection that promoted reproduction before they were eaten but the above water fall ones could have more eggs when they were larger and older etc.

    (3) Same sort of thing happens in humans. There are more male babies born by a few percent than females in cultures where there is no ability to determine the sex prior to birth. Males tend to be more agressive, adventursome, etc. and have a higher mortality rates so that in the reproductive ages there is essentially a one female to one male ratio. In cultures where female infanticide is practiced and has been for a long time, I bet there has been an increase in the number of females born to try to keep this equality during the fertal period. Based on how rapidly the prey fish adapted the sexual maturity etc. I bet a careful examination of rual Chinese birth ratio would show that the excess of males at birth is less than in western Europe, where female infanticide is rare. Thus, one can even make testable predictions on human evolution theory as well as the many natural and some artifical experiments that have supported evolution theory.

    As far as tiny wings being useless initially, in addition to the two uses already mentioned in this thread, cooling surely was one also. That is why Elephants have big ears. A big thick-skined warm-blooded creature has a cooling problem in the tropics or shadeless non-polar regions. Not sure of the name (They keep changing them, and my memory for such arbitary things was never very good.) but big fat dinosaure StagaSaurous had lots of "dorsal wings" = vertical triangles on his back. (Not well placed for evolution into flying wings, but if that Yucatan impact had not occured, perhaps we could now watch the "stagoHipo" sailing up river when a good wind was blowing.) These primative wings (or sails?) not only greatly reduced his "volume to surface" ratio but also to me at least they look like they could fold to the sunny side and quasi fit together to give significant shade - sort of a natural sun umbrella. Some may object that volume to surface ratios are not very important for a cold-blooded animal - probably true - but how do you know he was cold-blooded? If birds came from dinosaurs, (currently well accepted, especially after feathers were found on a dinosaur like creature in China.) they may have come from the "warm-blooded sub set" of all dinosaurs. Flying takes a very high metabolic rate, so non soring birds all have body temperature well above mamals, like humans. Surely the flyng dinosaurs were warm blooded. If not, they with their clumbsy wings on ground on a cold day would be easy prey.

    Often special features like wings or eyes have developed independantly more than once. (bat's wing are not at all related to bird wings) Humans and most creatures vaguely related got the less efficient eye design - the photo sensitive retina cells are behind at at least two distint layers of processing nerves (mainly doing data compression to find the contrast boundaries, as there are nearly 100 retinal receptors for every "output wire" (optical nerve fiber). These receptors are also behind all the blood vessels - that is handy if you need laser photo coagulation of a leaking vesel, but some how I don't think either "God" or "evolution" was thinking that far ahead when our type eyes were designed. The octopus and many marine creatures got the good design - photo recepters in front of all this trash light coming to ours must pass.

    Who said Zuse was more powerful than Neptune? God Neptune at least knew what he was doing. Zuse was too busy seducing women to think much about how things should be done "top side".
     
    Last edited by a moderator: Oct 7, 2005
  17. kenworth dude...**** it,lets go bowling Registered Senior Member

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    velociraptors-balance when running fast.eventually start gliding short distances etc etc etc
     
  18. root Registered Senior Member

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    Thanks for the reply. If not "Survival of the fittest" then what is the driving force behind "sexual selection". In some cases, like the beetle you mention, there may be a slight advantage but consider the following:

    1. An animal with four legs (possibly walking upright on its hind legs) bears offspring with deformed front legs - the first step towards development of wings.
    2. The first generation have a very slight deformation and there is absolutely no reason why these should have a better chance at survival than ones with healthy front legs.
    3. Now, for thousands or millions of years offspring are born with successive more advanced deformations until eventually the wings are perfect for flying.
    4. While this is happening not only are the front legs changing, the whole body of the animal also has to change into a form that would allow it to fly.
    5. Each and every step through this development, although it still cant fly, (through thousands of generations) these deformed animals are (each generation) somehow better equipped for survival than healthy ones without deformations. In other words: every step of the development somehow provides it with an advantage over the normal animal although this advantage is not "flying".

    This is just too much for me to swallow. To me it seems that "Life" has knowledge of possibilities in development and that it develops with a purpose in a certain direction. Natural Selection and Survival of the Fittest is just not an adequate explanation.
     
  19. spuriousmonkey Banned Banned

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    It seems that the main problem here is that you don't want to accept evolution under any circumstances. We have given perfectly reasonable scenarios, but you 'can't believe' in those. You don't have to believe them, but you can deny that the evolution of flight can be explained in a reasonable manner.

    Instead you make a ridiculous scenario and then claim it can't have happened like that. Obviously not.
     
  20. root Registered Senior Member

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    I have no problem with evolution as such and I never said I had. What I have a problem with is the proclaimed driving force. Please explain: why is my scenario so ridiculous?
     
  21. spuriousmonkey Banned Banned

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    You say it yourself actually.
     
  22. root Registered Senior Member

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    I will take this to mean: "I don't know!".
     
  23. spuriousmonkey Banned Banned

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    You are taking it wrong.

    You mention a scenario (made up by yourself). You then claim it can't be like that.

    Logical deduction:

    your own scenario is not reasonable.
     

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