What is the case against Evolution?

Discussion in 'Biology & Genetics' started by Seattle, Jun 15, 2019.

  1. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    After aptitude

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  3. TheFrogger Banned Valued Senior Member

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    What about longitude?
     
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  5. Yazata Valued Senior Member

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    Why not?

    I'm inclined to imagine simple chemical replicators appearing... somehow. Short RNA strands conceivably, or something else. Molecules able to make more of themselves in a suitable environment.

    Once you have that, natural selection would seem to apply. The more efficient replicators would have a selective advantage.

    Not only would you see more and more effective replicators, you would see other mods appearing that facilitate the replication. Perhaps the ability to synthesize a protective membrane, with suitable permeability, where necessary reactants can gather to facilitate the replicators always having a suitable environment in which to replicate. Stuff like that.

    I imagine the first bacterial-like cells appearing at the end of a long succession of those kind of steps. Steps in which basic cellular anatomy is hammered out, the genetic code, protein synthesis, energy metabolism and all that.

    What I have trouble imagining is fully-formed cells just popping out of some "primordial soup". Anyone who has studied cellular biology would recognize the unlikelihood of that.

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    Last edited: Jul 17, 2019
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  7. exchemist Valued Senior Member

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    I presume what Dave means is that abiogenesis can usefully be regarded as the prebiotic processes that led to the first replicator.

    Since a replicator is required before evolution by natural selection can work, evolution by natural selection cannot include this earlier process.

    However if you widen the meaning of evolution beyond this, then I suppose you could say that these prebiotic processes are part of that broader development.
     
  8. globali Registered Senior Member

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    I agree. People often confuse evolution with evolution by natural selection. My understanding is that evolution refers to anything that changes over time. Other examples of evolution include:
    The process of creating life from simple chemistry is called abiogenesis by chemical evolution.
    The history of my haircuts are called: the evolution of my hairstyling.
    The way the Universe changed since the bb is called the evolution of the Universe.

    By the way, the primordial soup must have been a good source of aminoacids as well
     
  9. DaveC426913 Valued Senior Member

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    To be clear - this isn't my opinion; it's a fact. The theory of Darwinian evolution does not have anything to say about abiogenesis. Both Darwin himself, and the science that sprang from his theory are clear on this.

    References on this are easy to find, based on your source preference.

    "... creationists have appropriated it to refer to the origin of life, and it has even been applied to concepts of cosmic evolution, both of which have no connection to Darwin's work."
    https://en.wikipedia.org/wiki/Darwinism

    "When Charles Darwin published The Origin of Species 150 years ago he consciously avoided discussing the origin of life. ...
    Although he favored the possibility that life could appear by natural processes from simple inorganic compounds, his reluctance to discuss the issue resulted from his recognition that at the time it was possible to undertake the experimental study of the emergence of life."
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2745620/


    "Darwinian evolution is an attempt to explain how living things change and become more complex over time by slow uniform changes that happen solely by natural causes.
    ...
    Darwinian evolution is based on observations of changes within species.
    ...
    These observable changes within species are then extrapolated to non observable changes from one type of species to another type of species. Abiogenesis is not based on any observations but purely on extrapolation from Darwinian evolution based on the assumption that everything must happen by natural cause."
    https://socratic.org/questions/what...theory-of-evolution-and-the-hypothesis-of-abi
     
  10. billvon Valued Senior Member

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    You are talking about two different things.

    One is the theory of evolution, a theory that mutations cause random heritable changes in organisms, and natural selection retains those traits that aid in survival and reproduction. It cannot function until an organism has a mechanism to inherit traits from a progenitor.

    The second is the word evolution. That's just a word that has a lot of meanings, like "change."

    But everyone here is talking about the THEORY of evolution.
     
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  11. globali Registered Senior Member

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    Something like that. Everyone is thinking along these lines (e.g RNA first, metabolism first hypotheses, etc).

    The problem is that all proposed scenaria so far are not consistent, even on a theoretical level (to reach the state of a credible scientific hypothesis). My opinion is that the creation of the replicators is not that difficult to happen. You only need a strand of nucleic acids, or a chain, something like a stable RNA (RNA is unstable) that will attract free nucleic acids through complementary base bonds. One strand will be the template and the other one the newly formed chain. If they brake, the process can go on again. The problem is why will these strands be selected after all. Why will the most efficient replicators be selected? Its their products (aminoacids, etc) that can make them succesful. By themselves they are nothing, powerless. But in order to make their products, a super complicated network of other stuff is needed (ribosomes, endoplasmic reticulum, etc), which in turn are made by DNA. Its like a chain of truly irreducible complexity and if you remove one element, the whole thing gets destroyed, even theoretically. A problem of egg and chicken times thousand.

    Even in cellular membranes. Lipid bilayers can be easily formed, but its the proteins and the other stuff inside them that make them meaningfull (connect cytoskeleton, maintain shape, etc). Without them, they will collapse in tiny balls.
     
  12. globali Registered Senior Member

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    Of course i am talking about 2 different things. The problem is that some people don't even understand their difference and tend to equate them.
     
  13. exchemist Valued Senior Member

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    Yes indeed. What globali and I have been exploring is that "evolution", as a word, can have broader meanings.

    You yourself qualify it, in relation to the context in which you intended it, by adding "Darwinian" - which is what I meant by evolution "by natural selection". As I understand it there are now additional change mechanisms in evolutionary theory, that are not strictly due to natural selection (e.g. genetic drift). But all of them relate to inheritable traits and thus assume the presence of a mechanism of replication, so even if one includes these, abiogenesis is something that has to happen before any of this can work.

    I quite agree one has to be careful not to let people with an agenda blur the scientific meaning of the Theory of Evolution, for rhetorical purposes.

    But I see I am late to the party and others have made the same point already.....

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  14. Write4U Valued Senior Member

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    What about the evolution of an existing pattern like a river. Is the gradual change of a river due to erosion a form of evolution?
    How about the formation of the solar system, a spiral galaxy? Evolution?
     
  15. globali Registered Senior Member

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    My only concern is that i am over simplifying the process, and a knowledgable biochemist might laugh and think that i am talking bs. This process is carried by super complex enzymes called polymerases, not to mention ligases, helicases, etc. Their activity is dictated by their spatial structure that in turn is determined by the sequence of aminoacids (see pic)

    However, i guessed that maybe the job can be partly (approximately) done by simpler processes. Maybe i am talking bs though.

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  16. globali Registered Senior Member

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    Of course its evolution. Like the evolution of my hair styling. It was influenced by several external and internal factors during the years.
     
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  17. Write4U Valued Senior Member

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    If you want to avoid getting tangled up in "irreducible complexity", you cannot propose a process that already has complexity in its parts to start with.

    The whole point is that all complexity can be reduced to individual parts, until you arrive at the very elementary particles from which everything is made.

    Pattern forming started from the ground up, one piece at a time. Once a pattern has formed it may be used in other patterns where it has functionality. But then there still is no irreducible complexity, only complexity.
     
    Last edited: Jul 17, 2019
  18. globali Registered Senior Member

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    thats what i did. You think you are saying something deep, while in fact you are trying to catch up with the obvious. You think you have a solution because you don't understand in depth what the problem is. You are viewing it superficially.
     
  19. Write4U Valued Senior Member

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    Apparently it is one of the most common occurrences in nature. We can observe naturally formed cells everywhere.

    The self-organizing feature is found in the polar ends of molecules.
    One end likes water the other repels water.

    Put a clump of this bi-polar substance in water and the molecules will line up with the water attractive side out and the water repellent side inward. Presto, a cell has formed.

    Pour some oil in water and you will immediately get a buch of cellular oil droplets floating in the water.
    https://www.dictionary.com/browse/chemical-evolution
     
    Last edited: Jul 17, 2019
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  20. Write4U Valued Senior Member

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    Hmmmm....and the above is an example of something deep you are saying?
    Here is something deep; "Take an enema"!

    I have given you no offense. I would suggest you don't give me offense.
     
    Last edited: Jul 17, 2019
  21. Yazata Valued Senior Member

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    I agree that Darwin himself avoided addressing the problem of the origin of life. But obviously science today is addressing it. (If you want to disagree about that, take it up with Paddoboy. He's the "abiogenesis" guy.)

    I interpret the phrase "Darwinian evolution" to basically mean natural selection. I think that's how it's generally understood in biology today.

    It can't refer exclusively to what Darwin wrote in his 1859 Origin of Species, since Darwin was clueless about today's molecular genetics. He didn't even know about Gregor Mendel's roughly contemporary work establishing some of the foundations of genetics. Yet Darwin's (and Wallace's) idea of natural selection remains fundamental to what biology is doing today.

    Right. Just go to Google Scholar and do a search for "prebiotic evolution" and "natural selection".

    https://scholar.google.com/scholar?hl=en&as_sdt=0,5&q="prebiotic evolution" "natural selection"&oq="

    Bottom line: Whether we choose to call it "Darwinian" or not (I see no harm in doing that), I think that the idea of natural selection is probably very applicable to understanding the appearance of life prior to the appearance of the first cells. Though like Exchemist says, this kind of "Darwinian" natural selection wouldn't have been applicable until the first self-reproducing chemical replicators had made their appearance. Natural selection does seem to help us make the leap from simple chemical self-replicators to cells though.
     
  22. globali Registered Senior Member

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    ok i will try not to be offending!!

    er......I disagree

    And so are iron particles around a magnet. Are they self-organizing?

    I don't think so (that a cell has formed)

    Cellular? I disagree! Water or oil droplets are not cellular according to my personal opinion.
     
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  23. billvon Valued Senior Member

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    Well - no. Oil is hydrophobic. Oil and water do not mix well. No "cells" - just areas of oil and water.

    You are thinking of a bilayer formed by molecules that have the characteristic you mention above. These will often form bilayers in water - layers where the hydrophilic end is outside and the hydrophobic layer is inside. These will sometimes spontaneously form cell-like structures but they are NOT simple compounds like oils - they are more complex molecules like phospholipids.
     
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