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Thread: Common ancestor?

  1. #1

    Default Common ancestor?

    One of the theories under the umbrella of "The Theory of Evolution" is that all living things today evolved from a common ancestor. If this turns out to be true I think it would be strong evidence pointing to the existence of a creator. I don't see the logic in this theory if we are to assume life started and evolved according to the mechanics of nature.

    Nature tends to do things in a big way. When conditions are right for a snow storm it will produce billions of snow flakes. Why would we assume that if conditons were right for the formation of life on earth there would only be one species of microscopic creaures appearing at only one point on the planet at only one point in time in the history of the planet? Wouldn't it be far more likely that billions of creatures were produced over some unkown length of time? If 99% of those creatures died that would still leave millions to evolve, and I see no reason to believe they would have all evolved in exactly the same way. In a relatively short time many more species would evolve. Some would disappear, but others would survive and start multiple lines of evolution.

    We have this image of evolution in the form of a tree with a single trunk supporting all the branches of life but, in reality, isn't it far more likely that there were many trunks? And even the branches would be multiple lines of evolution in the same manner as the trunks.

    The common ancestor would be the "trunk" of the tree of evolution, however, I believe if it was left up to nature there would not have been just a single tree, but a forest.

  2. #2

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    Well the first single-celled organism didn't just pop into existence. If you read the second chapter of The Selfish Gene by Richard Dawkins, it explains the theory of how life began quite well. I'll try and summarize it to the best of my ability below.

    A very very very long time ago, there was just a large soup of organic material, nothing necessarily "living" at all. Just a lot of organic molecules. Different molecules would form out of the molecules that had different properties. These molecules were more stable than their predecessors, causing them to grow in number (more stable refers to a lower energy state, which is favorable by nature). Some of these molecules were able to spontaneously form replications of themselves. This isn't because they "wanted" to replicate, it simply happened because the process formed a more stable molecule (Dawkins says "By ordinary processes of chemistry and physics"). Now there may have only been one type of molecule like this, or there could have been many. But due to limitations of resources, one of them had to win out. We know which one won, because of the presence of DNA in almost every form of life.

    Eventually these predecessors of DNA would mutate, causing different features to be exhibited by different molecules. Some of these molecules allowed to development of a "membrane" around them, while still letting replication exist. This mutation eventually eliminated the others, as we can see by the presence of cells. It's not because they necessarily wanted to "kill" the other DNA molecules (can you really consider it life at this point?), but rather these replicators found a way to disassemble the other molecules and use their atoms to replicate more molecules like them. At this point, there was no conscious fight for continuation of elongation of your "species".

    Each successive mutation either further increased chances of replication or decreased them, causing the mutation to continue or be demolished. Only the mutations that best allowed the cells to replicate survived further. At some point, these cells developed a mutation allowing them to work together, and this gave them a favorable advantage over other cells. This created the first multi-cellular organisms.

    From this point of view, animals are just walking vehicles for the survival of DNA, hence the title of his book The Selfish Gene.

    Again, this is a very rough outline of the chapter, you can read it online here: http://www.arvindguptatoys.com/arvin...ne-dowkins.pdf (hit ctrl+F and type "In the beginning" and you should find the beginning of the chapter)

    It answers your argument quite well. Nature does tend to do things in a big way, but nature did not just precipitate several different cells. It precipitated different compounds, which through precipitation (amongst other natural phenomena) created the first molecules. This led to the first cells, then the first creatures. Really the "common ancestor" is DNA. While there may have been more than one type of initial replicator, DNA won out amongst them.

  3. #3

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    Quote Originally Posted by nothingusual View Post
    Different molecules would form out of the molecules that had different properties. These molecules were more stable than their predecessors, causing them to grow in number (more stable refers to a lower energy state, which is favorable by nature).
    Stating that molecules had 'predecessors' presupposes that these molecules evolved from these predecessors, yet he doesn't go onto say how, or describe the mechanism for this evolution at all.

    There is a very distorted view concerning the 'first single celled organisms', that we are all supposed to ultimately have evolved from.

    You've got 'random organic matter' being organised into a 'single celled organism'

    While this single celled organism (SCO)is a lot less complex than other beings/organisms/etc, it is still in it's own right extremely complex. Logically, those SCOs must have been at least able to reproduce (a necessity for evolution) and take in energy (a necessity for reproduction)

    So Dawkins would have us beleive, that magically, random matter formed itself into a fairly complex, self replicating, energy consuming SCO, but fails to say why or how. .

    Yet another untestable, unprovable, unclassifiable pseudo scientific theory from someone who hasn't actually practised science or seen the inside of a laboratory for a couple of decades.

    Richard Dawkins must be one of the greatest con artists of our age.

  4. #4

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    "We do not know what chemical raw materials were abundant on earth before the coming of life, but among the plausible possibilities are water, carbon dioxide, methane, and ammonia: all simple compounds known to be present on at least some of the other planets in our solar system. Chemists have tried to imitate the chemical conditions of the young earth. They have put these simple substances in a flask and supplied a source of energy such as ultraviolet light or electric sparks—artificial simulation of primordial lightning. After a few weeks of this, something interesting is usually found inside the flask: a weak brown soup containing a large number of molecules more complex than the ones originally put in. In particular, amino acids have been found—the building blocks of proteins, one of the two great classes of biological molecules." - Richard Dawkins.

    Just read the chapter, it's MUCH better at explaining than I am.

  5. #5

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    There is a ton of assertions going on in here that have little to do with scientific discovery and more metaphysics. So lets go through those as one would need to take an upper level biology course or buy a textbook to accurately understand everything that I'm saying on a greater level, which I think the OP will understand better on that point. I'll do laymens terms as best I can.



    Quote Originally Posted by Drifter
    One of the theories under the umbrella of "The Theory of Evolution" is that all living things today evolved from a common ancestor. If this turns out to be true I think it would be strong evidence pointing to the existence of a creator. I don't see the logic in this theory if we are to assume life started and evolved according to the mechanics of nature.
    Actually no it wouldn't. Do you know what a "common ancestor" means in the concept of evolution? Something did not magically pop out of thin air. The theory of Abiogenesis explains how these first "proto-cells" came to after rather simple chemical interactions. Did you know I can make a plasma membrane in a lab with a concentration gradient with a a couple simple channel proteins? The chemical mechanisms that cause the molecules of the lipids (the membrane molecules) form a sphere. This process took place a few billion years ago.

    Mechanics of nature? Please explain what you think the mechanics of nature are in more specific terms. When you use the word "logic" you imply nature has a logical why it goes about it's process and something is behind that. We need to address that later.



    Nature tends to do things in a big way. When conditions are right for a snow storm it will produce billions of snow flakes. Why would we assume that if conditons were right for the formation of life on earth there would only be one species of microscopic creaures appearing at only one point on the planet at only one point in time in the history of the planet? Wouldn't it be far more likely that billions of creatures were produced over some unkown length of time? If 99% of those creatures died that would still leave millions to evolve, and I see no reason to believe they would have all evolved in exactly the same way. In a relatively short time many more species would evolve. Some would disappear, but others would survive and start multiple lines of evolution.
    Ah now we're getting somewhere. So according to what you see as the "mechanics of nature" things must be done in a "go big or go home" type deal? Okay.



    Why would we assume that if conditons were right for the formation of life on earth there would only be one species of microscopic creaures appearing at only one point on the planet at only one point in time in the history of the planet? Wouldn't it be far more likely that billions of creatures were produced over some unkown length of time?
    No disrespect intended, but here's where your lack of understanding on cellular biology and evolutionary processes comes into play.

    Here's a pretty decent modern example. Let's say I have a species of bacteria in a hospital that has somehow absorbed a plasmid (circular section of DNA) that allowed them to survive a strong anti-biotic. This plasmid also gives the bacteria new cellular features and becomes distinct from the same bacterial species before it absorbed the plasmid. The one with the plasmid and the other no longer can "recognize" each other for say methods of pili-reproduction (exchanges DNA). You now have two distinct species of bacterial organisms from a purely random process. In a sort of way your asserting "well why aren't there more of these types of super bugs appearing in hospitals across the world!?" Because the conditions in this particular environment where just right, and now any bacterial strains that form have a common ancestor of this bacteria.

    Now imagine somewhere on primordial earth the conditions were just right for the formation of a proto-cell to propagate itself. I mean it is sort of logical to say that there might have been a couple proto-cells that formed somewhere but these ones made it with the right set of stuff. Statiscally, it was almost a one a in a million chance this happened, that's why there weren't "billions of different proto-cells everywhere." DNA evidence and other cellular process point to the common ancestor as specific evidence to be true and "logical."

    Evolution takes millions of years. It's a random, non-directed process with little logic behind it. Though we can predict because there are various evolutionary mechanisms in DNA and the environment.



    We have this image of evolution in the form of a tree with a single trunk supporting all the branches of life but, in reality, isn't it far more likely that there were many trunks? And even the branches would be multiple lines of evolution in the same manner as the trunks.

    The common ancestor would be the "trunk" of the tree of evolution, however, I believe if it was left up to nature there would not have been just a single tree, but a forest.
    Ummm....from the common ancestor we already have a "forest" of biological diversity on planet earth from evolutionary processes. You are probably on the line of thinking there would be non DNA or say silicon based life walking around too. The problem with that is, again, conditions were not right, or it was chemically not feasible. Science fiction buffs like to think silicon based life exists, but the way the silicon atom binds and it's overall atomic size, makes it nearly impossible.

    You are actually correct in a way. There are many different trunks for different organisms. Animals cells have a very distinct "trunk" from those of plant cells. But it boils down back billions of years ago to that first proto-cell that used the first DNA molecule.



    Quote Originally Posted by Coodie
    While this single celled organism (SCO)is a lot less complex than other beings/organisms/etc, it is still in it's own right extremely complex. Logically, those SCOs must have been at least able to reproduce (a necessity for evolution) and take in energy (a necessity for reproduction)
    Not exactly. You now what the smallest cells needs and how simple it proteins need to be? Extremely simple. I can create membranes in a lab. SCO's actually are the product of a simple chemical processes in proto-cells that took quite some time to form. We've been able to replicate said processes in a lab already.

    Dawkins isn't the greatest source of scientific knowledge and his stance in New Atheism makes him a not a great source for this conversation. Keep it to peer-reviewed journals or textbooks or other more appropriate examples.

    I'm a cell and molecular biology major, it's still pretty amazing how it works.
    Last edited by Geno; 03-Feb-2013 at 15:37.

  6. #6

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    Quote Originally Posted by nothingusual View Post
    " After a few weeks of this, something interesting is usually found inside the flask: a weak brown soup containing a large number of molecules more complex than the ones originally put in. " - Richard Dawkins.
    Exactly my point. Thankyou Mr. Dawkins!

    If a "large number" of complex molecules formed in such a short period of time in such a tiny environment inside a flask wouldn't it be natural to assume that, over a period of millions of years, an environment as large as the world itself would produce an infinitely larger number of such molecules? And if these molecules somehow led to the formation of life why would we assume that only one single, primitive, living, organism was created to become the common ancestor of all life?

    Even if we shift the discussion to "species" rather than individual organisms the numbers still apply. There is no basis for the assumption that only a single species miraculously popped up under these circumstances, but even if it had, all the members of this species would then have been created from the same chemical process and there would be no ancestral relationship among them. We would be facing the same problem as before. In order for there to have been a common ancestor only one individual of that first species could have survived to create this evolutionary line.

  7. #7

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    Quote Originally Posted by Drifter View Post
    We have this image of evolution in the form of a tree with a single trunk supporting all the branches of life but, in reality, isn't it far more likely that there were many trunks? And even the branches would be multiple lines of evolution in the same manner as the trunks.

    The common ancestor would be the "trunk" of the tree of evolution, however, I believe if it was left up to nature there would not have been just a single tree, but a forest.
    the theory of evolution, though often taken to mean all of life that ever occurred on earth, really only applies to our particular lineage (hence, the representation of the tree). it's true that various forms of life have come and gone and that they have no obvious link to ourselves. and many are still with us.

    the story of the origin of life goes beyond biology and delves wholeheartedly into geology. afterall, we're not really much more than giddy mud.

  8. #8

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    Quote Originally Posted by Drifter
    If a "large number" of complex molecules formed in such a short period of time in such a tiny environment inside a flask wouldn't it be natural to assume that, over a period of millions of years, an environment as large as the world itself would produce an infinitely larger number of such molecules? And if these molecules somehow led to the formation of life why would we assume that only one single, primitive, living, organism was created to become the common ancestor of all life?
    You are on the right track and so close to the station, and then rear off the track. You assume because there are a large number of complex molecules this automatically means complex life will form everywhere. Conditions, conditions, conditions. Statistically, as I said it was a one in a million chance one particular proto-cell had developed to self propagate as well as utilize DNA. That flask Dawkins is talking about probably would not conceive life in a several million years. In fact, it's molecules may even break down.



    Even if we shift the discussion to "species" rather than individual organisms the numbers still apply. There is no basis for the assumption that only a single species miraculously popped up under these circumstances, but even if it had, all the members of this species would then have been created from the same chemical process and there would be no ancestral relationship among them. We would be facing the same problem as before. In order for there to have been a common ancestor only one individual of that first species could have survived to create this evolutionary line.
    Its' a simple lack of biological understanding on your part. A single progenitor proto-cell gave basis for more complex and different cells. You are actually correct on that last statement in a way, one "species" did survive to create that evolutionary line. Why is that so hard to comprehend? Because nature somehow doesn't work that way?

    I'm exactly sure what your're getting at. You seem to understand, yet can't seem to see the evidence and logic of that. Either your not very clear, or lack complete understanding of biology and evolution all together to where you can't see the connection. I'm going to assume the latter in this case.

    The fact still stands evolutionary evidence points to this conclusion, so in spite of the evidence, you fail to see the connection. That to me is the issue here.
    Last edited by Geno; 03-Feb-2013 at 16:29.

  9. #9

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    Quote Originally Posted by Geno View Post
    There is a ton of assertions going on in here that have little to do with scientific discovery ...
    I agree.



    Mechanics of nature? Please explain what you think the mechanics of nature are in more specific terms.
    At this point I see nothing objectionable in your explanation of how molecular biology works so, for now, we'll assume this is the "mechanics of nature" for our purposes. I don't question your knowledge of molecular biology but I do question some of your assertions.


    You mention "The theory of abiogenesis" as if there is only one such theory. I don't believe this is the case.

    You say this theory explains how the first "proto-cells" come to be and, later, in reference to proto-cells that can propagate themselves, you say " I mean it is sort of logical to say that there might have been a couple proto-cells that formed somewhere but these ones made it with the right set of stuff."

    This raises the question of why it would it be more logical to assume only a couple of proto-cells formed rather than trillions, and you preemptively attempt to answer this question by stating "Statiscally, it was almost a one a in a million chance this happened..." Where did this statistic come from? And even assuming this is true, if there were trillions of candidates for the position of self propagating proto-cells then "million to one odds" would indicate a likelyhood of millions, if not billions, of proto-cells with the "right set of stuff" appearing.

  10. #10

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    Quote Originally Posted by Geno View Post
    Not exactly. You now what the smallest cells needs and how simple it proteins need to be? Extremely simple. I can create membranes in a lab. SCO's actually are the product of a simple chemical processes in proto-cells that took quite some time to form. We've been able to replicate said processes in a lab already.

    Dawkins isn't the greatest source of scientific knowledge and his stance in New Atheism makes him a not a great source for this conversation. Keep it to peer-reviewed journals or textbooks or other more appropriate examples.

    I'm a cell and molecular biology major, it's still pretty amazing how it works.
    I agree that Dawkins isn't the greatest source of scientific knowledge, but one of the first two posts cited him and I was responding to that. Are you agreeing that Dawkins is incorrect though? If so, how?

    For evolution to occur, and correct me if I'm wrong here, but some form of reproduction must occur. So, while the first links on the evolutionary chain may be relatively simple, they must still be complex enough to reproduce or replicate. Do you agree or disagree with this statement?

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