A Question for those that doubt Common Descent

Recent posts by Sal remind me that there are some intelligent educated people who doubt Common Descent.  What I don’t understand what they think the alternative is. Put simply I take Common Descent as the position that :

* At one time there was only very simple unicellular life on earth (this is not a debate about how that unicellular life originated)

* Complex life forms (eukaryotes) are created by slight modifications from other life forms (which are their parents). We have never observed them being created any other way!

* All complex life forms are the descended from a very small number of simple life forms – quite possibly just one.

The alternatives I can imagine are:

* Complex life descended many different times from simple life forms – so e.g. mammals descended from a different simple life form from fish. This flies in the face of the fossil record and the hierarchical nature of complex life but I can sort of understand it.

* Complex life from time to time gives birth to wholly different species – massively implausible.

* Complex life is created anew by some process never imagined or observed – even more implausible but presumably what Young Earth creationists believe.

But maybe there is another option?

If Sal or someone could explain I would be interested.

92 thoughts on “A Question for those that doubt Common Descent

  1. Perhaps you could cite some examples from the history of science where the god hypothesis has been a useful heuristic .

    Physics? Geology? Astronomy?

  2. “FWIW, even though it is speculative, and many physicists will disagree, the notion of a Creator is not formally excluded as a possibility from what we know of the natural world, even though it could be an unprovable hypothesis.” – Salvador T. Cordova

    This is not news. Anyone who has given their attention to discourse involving ‘science, philosophy and theology/worldview’ over the last 30+ years knows this. It is the weakness of ‘Intelligent Design Theory’ that it has been able to do little more than simply repeat this, e.g. founding ‘father’ Phillip Johnson’s ‘Wedge’ strategy (which is now mainly pushed aside by Dembski, Behe, Meyer, et al. who have heard enough legitimate criticism by fellow theists to abondon it).

    Salvador T. Cordova has not taken his negative denial a step further in planting IDEA networks with Luskin, promoting ARN, etc. It is a sad American emptiness in Philosophy of Science that is demonstrated, as if ‘wisdom’ doesn’t really matter, just pragmatism, PR, legal teams for school boards and funding channels based on neo-evangelicalism and neo-creationism (and Salvador still, still, still considers himself a ‘creationist’!).

    “I found peace framing the argument in terms of payoff” – Cordova

    Salvador, let’s face it; you’re a gambler at heart. You work in finance, after all!

    “a possible mechanism (God)” – Salvador T. Cordova

    Ouch. Yeah, that sounds just reductively like Thaxton’s ‘engineer God.’ Sadly, typically of the IDM, its a surprisingly far cry from the supra-design Father-Creator of the Abrahamic faiths, which IDists deny because of their scientism at almost any opportunity.

    Salvador likely won’t promote ‘Common Design’ here, even though he obviously ‘believes’ in it, because he has no ‘scientific’ credibility or proof to present. Because he is still a self-labelled ideological ‘creationist,’ worthy of rebuke by theists and atheists alike.

  3. So let’s look at how the OP defines “common descent.”

    Put simply I take Common Descent as the position that :

    At one time there was only very simple unicellular life on earth (this is not a debate about how that unicellular life originated)

    A statement, not a definition. So apparently someone who believes in “common descent” accepts that at one time there was only very simple unicellular life on earth.

    This position does not in any way conflict with Intelligent Design. In fact, it doesn’t even seem to reject the position that this first “unicellular life on earth” was the product of Intelligent Design.

    So how is it even distinguishable from Intelligent Design?

  4. So let’s look at how the OP defines “common descent.”

    Put simply I take Common Descent as the position that :

    Complex life forms (eukaryotes) are created by slight modifications from other life forms (which are their parents). We have never observed them being created any other way!

    I agree. We’ve never observed complex life forms created. Why does that conflict with ID? We’ve never seen complex life forms which don’t have a parent. Why does that conflict with ID?

    Where is the defense of the implied premise that eukaryotes are complex life forms while non-eukaryotes are not complex live forms?

    Where is the defense of the implied claim that eukaryotes had parents which were not eukaryotes?

    If it is a definition of “common descent” that eukaryotes are more complex than non-eukaryotes and that eukaryotes had as parents life forms which were not eukaryotes, why is that claim not made expilcitly?>

  5. So let’s continue our look at how the OP defines “common descent.”

    Put simply I take Common Descent as the position that :

    * All complex life forms are the descended from a very small number of simple life forms – quite possibly just one.

    No one believes this, no one. Not Darwinists, not ID’ists.

  6. Mung:

    This position does not in any way conflict with Intelligent Design. In fact, it doesn’t even seem to reject the position that this first “unicellular life on earth” was the product of Intelligent Design.

    So how is it even distinguishable from Intelligent Design?

    Mung,

    You’re a bit slow on the uptake.

    Mark is asking those people who doubt common descent to explain their position to those of us who don’t. He is not excluding IDers from the latter category.

  7. I do.

    (Let us not debate the various meanings of ‘believe’, here. I mean, I accept this as the best interpretation of the data: following all lines of ancestry back from any modern form coalesces upon a single individual cell – one of many alive at the time, all coalescing yet further back, but only one of whose descendants are not yet extinct).

  8. keiths:

    Mark is asking those people who doubt common descent to explain their position to those of us who don’t.

    That’s all well and good. I would suggest starting out with a coherent definition of “common descent.” Wouldn’t you?

    A definition of “common descent” that fails to exclude anyone isn’t very useful in the current context. Wouldn’t you agree?

    Given his so broad and vague definition of “common descent,” what’s to disagree with? That’s my point.

    keiths:

    He is not excluding IDers from the latter category.

    He’s not excluding ANYONE that I can tell.

    Even Young Earth Creationists believe that all life presently on earth descended from the animals on the ark. If that’s not a belief in common descent, what is?

  9. petrushka:

    Perhaps you could cite some examples from the history of science where the god hypothesis has been a useful heuristic.

    And perhaps you could actually go and study the history of science.

  10. Mung:

    Why on earth do people here at TSZ claim that ID proponents deny common descent?

    keiths:

    Mark is asking those people who doubt common descent to explain their position to those of us who don’t. He is not excluding IDers from the latter category.

    Joe Felsenstein:

    Because you deny all the interesting common descent.

    You people can’t even get your stories straight.

    Did the OP set out the distinction between “interesting common descent” and “uninteresting common descent” or did I just miss that?

  11. Over at UD Elizabeth declared that the evidence for common descent is “vast”!

    I disagreed and she failed to respond. Anyone here want to take up the cause for her?

  12. Elizabeth Liddle:

    The evidence is vast for Universal Common Descent.

    You don’t need faith to think that all known terrestrial organisms have a common ancestor.

    here

  13. Mung:
    So let’s continue our look at how the OP defines “common descent.”

    Put simply I take Common Descent as the position that :

    No one believes this, no one. Not Darwinists, not ID’ists.

    Like Allan Miller, So do I “believe” it.

  14. Mung:
    Even Young Earth Creationists believe that all life presently on earth descended from the animals on the ark. If that’s not a belief in common descent, what is?

    Yeah, but they obviously don’t believe that these animals on the ark shared ancenstry. And they most certainly don’t believe that that ancestry goes back 3.5 billion years and have evolving into the diversity of life we see today. That’s the difference.

  15. Mung:
    Over at UD Elizabeth declared that the evidence for common descent is “vast”!

    I disagreed and she failed to respond. Anyone here want to take up the cause for her?

    What are you looking for specifically? Someone to detail all the existing evidence for common descent for you?
    Or how about we just start with the basics, like:
    Genetics and molecular phylogenies. You accept paternity tests can be used to determine degree of relatedness I assume? It’s the same principle really, only applied to even longer timescales.

    Or is there something in particular you think requires going over that casts doubt on the whole thing? Or maybe it’s not that you doubt there’s a large amount of relatedness (say, like all mammals are related), maybe you doubt, for example, that prokaryotes and eukaryotes share ancestry?

    Where do you want to go?

  16. Mung: I disagreed and she failed to respond.

    I suspect that says more about you then anyone else Mung.

  17. Mung: And perhaps you could actually go and study the history of science.

    Interesting how you can then say

    I disagreed and she failed to respond.

    So when somebody disagrees with you and asks you to support your claim you tell them to go study the history of science. Yet when the same happens to you it’s now a problem that somebody “failed to respond”.

    Go read a book Mung. It’s overdue. And try not to do the thing you are complaining about other people doing two posts later.

  18. keiths:

    Mung,

    You’re a bit slow on the uptake.

    Mark is asking those people who doubt common descent to explain their position to those of us who don’t. He is not excluding IDers from the latter category.

    Mung:

    He’s not excluding ANYONE that I can tell.

    Poor Mung. After more than ten years as an antievolutionist, he still has no idea what his fellow travelers believe.

    If he’s this incurious about anti-evo, it’s no suprise that he knows nothing about evolution.

  19. Ah, late to the party.

    Hi, mung.

    Left you some comments at UD but if you want to continue discussion here that would be much better.

    I see you want a resumé of the evidence for common descent. Would you like us to rewrite Theobold? I’d first be interested in whether there is anything in that list that you find persuasive.

  20. Lizzie’s blog – Lizzie’s rules!

    Please try and address issues and avoid personal attacks! Thanks for your consideration.

  21. I have studied the history of science. The closest thing to ID in science is Deism or its modern equivalent, fine tuning.

    Neither of which are inconsistent with abiogenesis or evolution.

  22. Mung: He’s not excluding ANYONE that I can tell.

    Even Young Earth Creationists believe that all life presently on earth descended from the animals on the ark. If that’s not a belief in common descent, what is?

    I defined Common Descent as the belief that

    * At one time there was only very simple unicellular life on earth

    * Complex life forms (eukaryotes) are created by slight modifications from other life forms (which are their parents).

    * All complex life forms are the descended from a very small number of simple life forms – quite possibly just one.

    Do YEC’s believe that life on the ark was descended from a very small number of simpler life forms?

    Do YEC’s believe that fish and other water based complex life was descended from the animals on the Ark?

  23. Mark Frank:

    * At one time there was only very simple unicellular life on earth

    A YEC may or may not believe this. The book of Genesis does not distinguish “simple” life from “complex” life and does not mention unicellular life.

    * Complex life forms (eukaryotes) are created by slight modifications from other life forms (which are their parents).

    Even the most ardent YEC would not deny that all life forms were created 🙂

    If God chose to “create” eukaryotes from unicelluar life then that is what God chose to do. Are there no unicellular eukaryotes?

    Of course there are:
    Unicellular Eukaryotes

    * At one time there was only very simple unicellular life on earth

    Only Simple Unicellular Eukaryotes?

    I’ve no doubt that there are scientists who believe and have argued in published peer-reviewed papers, that eukaryotic life preceded prokaryotic life.

    What say you?

  24. keiths:

    Poor Mung. After more than ten years as an antievolutionist, he still has no idea what his fellow travelers believe.

    If he’s this incurious about anti-evo, it’s no suprise that he knows nothing about evolution.

    Does keiths have any actual evidence he would care to present that I am anti-evolution? Or is he just lying again.

    keiths declares that I have no idea what my “fellow-travellers” believe. He is even more ignorant than I ever imagined.

    keiths declares I know nothing about evolution. He is either ignorant or a liar.

    More than 10 years? Really? That’s the best that you can do?

    keiths, no facts.

  25. “MungJanuary 30, 2013 at 6:36 pm
    How is anyone supposed to learn how wrong evolution is if they can’t read about it!?”

  26. “MungJanuary 17, 2013 at 6:28 pm
    It seems to me that a great deal of evolving had to take place after the flood.”

  27. Rumraket:

    Or how about we just start with the basics, like:
    Genetics and molecular phylogenies. You accept paternity tests can be used to determine degree of relatedness I assume? It’s the same principle really, only applied to even longer timescales.

    How accurate are paternity tests? Do you even know?

    How far back in time do paternity tests extend?

    10 generations? 20 generations?

    1?

    l o l

    http://en.wikipedia.org/wiki/Parental_testing

    Would you like to explain for all us ignorant ID’ists how paternity tests determine “degree of relatedness”?

    So if a paternity test comes back that I am 50% “degree of relatedness” (what nonsense) does that make me a father, mother, brother, sister, uncle, aunt, cousin, monkey, or what?

    And this is what you base your belief in “common descent” upon? I pity you.

  28. Mung,

    Well if a YEC believes that

    * At one time there was only very simple unicellular life on earth

    * Complex life forms (eukaryotes) are created by slight modifications from other life forms (which are their parents).

    Then they believe in Common (although absurdly rapid) Descent. Do you seriously think that many YECs hold these beliefs?

    I am not quite sure why it relevant but I guess it is possible that there are scientists who believe and have argued in published peer-reviewed papers, that eukaryotic life preceded prokaryotic life. There are all sorts of strange scientists with crackpot opinions – although this would be a very weird one.

  29. Mung:
    So if a paternity test comes back that I am 50% “degree of relatedness” (what nonsense) does that make me a father, mother, brother, sister, uncle, aunt, cousin, monkey, or what?

    Parent, offspring, or full sibling of the other, but not an identical twin or clone. Not an uncle, aunt, or cousin. Only a monkey if the other sample is from a monkey.

  30. Mung:
    Rumraket:
    How accurate are paternity tests? Do you even know?
    How far back in time do paternity tests extend?
    10 generations? 20 generations?
    1?
    l o l
    http://en.wikipedia.org/wiki/Parental_testing

    You’re missing the point, which is really just the fundamental principle of paternity tests: How similar is some given compared stretch of DNA between the parent and child? This is then used to determine whether the subject in question is a parent or not. There are several different ways to do this. Some don’t actually sequence any DNA, they just cut it into pieces with restriction enzymes and run it through a gel electrophoresis and take a picture of the pattern of the fragments and compare it with another sample.

    Yes, it’s usually only used to determine 1-generation relationships (parent-offspring) in an either/or fashion. But again, the underlying principle is genetic similarity.

    This principle can be extended through generations indefinitely. The less genetically similar you are, the more distantly related you are. We know why this is so, it’s a property of the way inheritance and reproduction works.

    Would you like to explain for all us ignorant ID’ists how paternity tests determine “degree of relatedness”?

    It depends on the type of test used. For example a restriction enzyme digestion of some stretch of DNA will produce a certain pattern of DNA fragments on a gel picture. These pictures can be compared between different people and so on and so forth. Do I really need to explain to you how this works?

    So if a paternity test comes back that I am 50% “degree of relatedness” (what nonsense)

    It’s not nonsense, it’s an observed fact. I’m afraid YOU don’t understand how these tests work. It is pretty easy to generate a similarity score when comparing two restriction-enzyme digested fractions of DNA (for example). The more generations have passed between you, the more dissimilar the pattern of fragments on your gel will be.

    does that make me a father, mother, brother, sister, uncle, aunt, cousin, monkey, or what?

    A mere similarity score drawn from a test like the one i mention above won’t tell you that. You’d need a different kind of test, like actual sequencing of DNA. This is more expensive of course, though it’s got much cheaper recently. I wouldn’t be surprised if at some point whole-genome sequencing will be used for paternity testing eventually.

    What, then, will your argument be? Degree of genetic similarity does NOT imply relationships through common descent? You believe you don’t share alleles and mutations to a higher extent with your siblings and parents than with your cousins and grandparents?

    And this is what you base your belief in “common descent” upon? I pity you.

    Turns out I should be pitying you.

    I also couldn’t help noticing how you refrained from answering or responding to any of the points or questions I asked of you in my post.

  31. Hey Mung, check this out:

    http://en.wikipedia.org/wiki/VNTR

    VNTR Inheritance

    In analyzing VNTR data, two basic genetic principles can be used:

    Identity Matching – both VNTR alleles from a specific location must match. If two samples are from the same individual, they must show the same allele pattern.

    Inheritance Matching – the VNTR alleles must follow the rules of inheritance. In matching an individual with his parents or children, a person must have an allele that matches one from each parent. If the relationship is more distant, such as a grandparent or sibling, then matches must be consistent with the degree of relatedness.

    Your bluff has been called. Oops.

  32. Sal,

    Some of us choose not to support Uncommon Descent by giving them traffic and associated ad revenue. How about answering Mark here?

    While you’re at it, you could answer all the outstanding questions from your last couple of drive bys as well.

  33. Mark Frank:

    Then they believe in Common (although absurdly rapid) Descent. Do you seriously think that many YECs hold these beliefs?

    Yes, I do. But that does not mean that they understand what they are buying in to. And it’s one of my greatest objections to the YEC view. It is self-contradictory. It denies evolution, but demands very rapid evolution.

    If all extant life on earth descended from some few animals preserved on Noah’s Ark, how did that happen? The rate of evolution must have been very high (which they deny) or God must have continued to create new species (which they deny).

    The YEC position is incoherent, which is why I abandoned it.

    (That and the fact that it doesn’t fit the facts.)

  34. Mark Frank:

    I am not quite sure why it relevant but I guess it is possible that there are scientists who believe and have argued in published peer-reviewed papers, that eukaryotic life preceded prokaryotic life. There are all sorts of strange scientists with crackpot opinions – although this would be a very weird one.

    It’s relevant because your OP demands simple to more complex.

    But there is plenty of evidence to suggest that simpler things evolve from more complex things. Do you disagree?

  35. Hi Mark,

    Would you be at all interested in a sort of “book of the month” discussion revolving around this subject of Common Descent?

    It would be interesting, I think, to see just how well-read people really are on the subject, both pro and con.

    We could try to agree on a pro ID book (such as Meyer’s latest) or a Pro-Darwin book such s the one by Prothero, or one like Fuller’s book (Dissent Over Descent), or even Sober’s books.

  36. Richardthughes:

    “MungJanuary 17, 2013 at 6:28 pm:
    It seems to me that a great deal of evolving had to take place after the flood.”

    Your point?

    Context.

    It is my belief that anyone who accepts the universal flood and Noah’s Ark (a view typically associated with Young Earth Creationism) must also accept massive and rapid evolution after the flood.

    Yet most YEC’s deny evolution and/or such a rate of evolution. I don’t hesitate to point out this inconsistency even when posting at UD.

    See my response to Mark.

  37. Rumraket:

    Yes, it’s usually only used to determine 1-generation relationships (parent-offspring) in an either/or fashion. But again, the underlying principle is genetic similarity.

    How was it tested? Do you suppose that it was accepted by our courts without testing the hypothesis?

    This principle can be extended through generations indefinitely.

    But how can it be tested?

  38. Mung:
    Rumraket:

    How was it tested? Do you suppose that it was accepted by our courts without testing the hypothesis?

    But how can it be tested?

    Do YOU really suppose that DNA evidence was accepted by courts without anyone testing the claim that DNA evidence actually works like scientists say it does? Really? You really think that appeals courts in the USA or Europe will allow an accused man to be sentenced to death or life imprisonment based on a DNA “hypothesis” that was never tested? Really? Yeah, we know the Federal Gov’t is filled with political hacks, but do you really think the FBI crime solvers use a scientific analysis which was never tested? Really?

    Bullshit.

    Here. A few relevant paragraphs about the legal side

    In general, two standards are used to judge the admissibility of novel scientific evidence – the “Frye standard” and the “Daubert standard.” The Frye standard originates from a 1923 case, Frye v. United States, where the court ruled that, to be admissible, scientific evidence must be “sufficiently established to have gained general acceptance in the particular field in which it belongs.”

    The Daubert standard is more recent, derived from the 1993 case Daubert v. Merrell Dow Pharmaceuticals, where the Supreme Court went beyond Frye to say that evidence must have sufficient scientific validity and reliability to be admitted as relevant “scientific knowledge” that would “assist the trier of fact.”

    In addition to important court cases scrutinizing the reliability of DNA evidence upon review of laboratory methodology and validation processes, the introduction of the Federal Bureau of Investigation’s (FBI) Combined DNA Index System (CODIS) forensic DNA database – mandated by the federal DNA Identification Act of 1994, provided another set of pressures on forensic laboratories to ensure their methodologies were sound and validated.

    All DNA laboratories that are federally operated, receive federal funds, or employ software prepared for the CODIS are required to demonstrate compliance with the standards issued by the FBI.

    (emphasis mine)

    Go read the whole thing at Forensic Magazine

  39. hotshoe,

    Thank you for making my point.

    Do YOU really suppose that DNA evidence was accepted by courts without anyone testing the claim that DNA evidence actually works like scientists say it does? Really? You really think that appeals courts in the USA or Europe will allow an accused man to be sentenced to death or life imprisonment based on a DNA “hypothesis” that was never tested?

    No, I don’t suppose.

    Now if you’ll provide the same with respect to the evidence for common descent of all extant life from a universal common ancestor I’ll become a believer.

    But you won’t, because you cant.

  40. Hi Mark,

    Would you be at all interested in a sort of “book of the month” discussion revolving around this subject of Common Descent?

    Guess not?

  41. Hiya, Mung,

    guess I missed your reply last week.

    Before I try to explain how DNA provides evidence for common descent of all organisms, how about you explain the part you understand about how DNA evidence can identify a criminal in court and prevent us from wrongly convicting their brother or father or cousin or some random guy who happened to live in the same county. If we have a clear base of understanding how that works, it will make the next step so much easier to understand.
    Thanks in advance!

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