Common Descent Munged

I come from the Michael Behe school if ID. I accept common descent, by which I mean universal common ancestry. It seems to be the consensus view in science, it seems reasonable to me, and I don’t have any compelling reasons to doubt it.

But could I actually defend my belief in common ancestry if asked? All living organisms share certain features in common. Organisms leave offspring. Therefore, universal common ancestry. That sounds pretty weak, I admit. I need to do better.

I don’t believe that new organisms appear out of thin air, so to speak. I accept that the organisms of today are the offspring of prior organisms. Even young earth creationists accept common descent prior to the flood and common decent after the flood, though they resist the idea of universal common ancestry. I still haven’t figured out how and where they draw the lines though, so why should I draw a line that I cannot defend. Therefore common ancestry. That still sounds pretty weak, I admit. I still need to do better.

So time to hit the books. What are the arguments for universal common ancestry in the books on evolution that I have. Erm… Halp!

Why do folks believe in universal common ancestry and what is the best book on “the evidence for evolution” to refer to in order to find the best arguments in favor of universal common ancestry?

What if it’s not the evidence for the theory of common descent per se that leads people to accept it, but rather how the theory of common descent provides an explanatory framework. Does its explanatory power outweigh the need for evidence for it and do people confuse what it can explain with what constitutes evidence for the theory?

What is the evidence for universal common ancestry and why is it considered evidence for universal common ancestry?

263 Replies to “Common Descent Munged”

  1. GlenDavidson
    Ignored
    says:

    Erik: That which you think doesn’t mean anything and what you find nonsensical is the historical record of the fact that languages change. When I say “what languages are” I mean the observed reality that languages are changeable and there is a long record of observations of how the changes occur. Those observations serve to justify that languages with scant historical record can be treated in a similar manner – that they are changeable and there are certain rules to how they change. Because in other cases it’s been observed that that’s how languages behave and that’s what they are.

    Empirical reality seems to be too much over your head. That’s way too sad.

    So if we didn’t have those records, you couldn’t properly infer anything from their nested hierarchies? You’d have no idea what could have caused the nested hierarchies? And you wouldn’t be able to recognize from language evolution and its nested patterns that species and manuscripts would have similar (but not identical) patterns had they, too, happened to undergo common descent?

    Principles. They’re available for use, to those who understand what they mean.

    Glen Davidson

  2. Alan Fox Alan Fox
    Ignored
    says:

    Erik:
    Alan Fox,

    Whatever happened to “NotA implies NotB = B implies A”? If the criteria that are known to determine relatedness between languages fail to determine relatedness between some given languages, it should be legitimate to conclude that those given languages are demonstrably unrelated.

    I dunno. Seems to me human language is so intimately linked to human evolution and that humans are descended from earlier ancestors already showing the adaptations necessary for speech production and processing that to rule out any relatedness for the Basque language with any other, purely on the absence of evidence, is a bit premature.

    And I see that a fairly recent study on DNA from modern Basques and skeletons found in the Basque country and comparisons with other peoples does indicate when, where and how the Basques became isolated. You could make an analogy with genetic drift here. Here is the Science article.

    ETA The original paper

  3. Alan Fox Alan Fox
    Ignored
    says:

    Allan Miller: The evidence available in books of ‘observation’ of language evolution mirror pretty closely those of ‘observation’ of genetic evolution. You dismiss one, you dismiss ’em both. Accept one, accept ’em both. Some of your co-religionists would have it that languages were all ‘created’ anyway, Tower of Babel style.

    Indeed. The analogies one can come up with!

    One working well for me is human communities migrating into new territory, say the Pyrenees, where there are fertile valleys ripe for exploitation physically separated by impassable ridges. The tribe is too large for one valley, so a group finds another one. The two groups don’t mix much after that. Lifestyle is similar in both valleys, people cooperate and talk to each other, initially all in one language. But with no mixing, differences can creep in till those differences accumulate to the extent that mutually intelligible conversation is now impossible. It could happen without any selective pressure, just different choices for favourite words, phrases and constructions.

    Anything like genetic drift?

  4. John Harshman John Harshman
    Ignored
    says:

    Erik: If you want to teach me logic, then why not do it by filling in what you meant by A and B above?

    This is the actual conversation:

    Me: If they [languages] were not related, you couldn’t draw a consistent tree.

    You: Right, but the fact the you can draw a consistent tree, does NOT in itself show that the languages are related.

    A: Languages are related. B: You can draw a consistent tree.
    NotA implies NotB: (Languages are not related) implies (You can’t draw a consistent tree).
    B implies A: (You can draw a consistent tree) implies (Languages are related).

    See? You explicitly accepted the first and denied the second.

    And if you agree that you are not in position to teach me linguistics, then why do you keep doing it?

    I’m actually teaching you how science works.

    In contrast, I am in position to teach you linguistics just fine and here it comes again.

    You have evidently never seen how it works. It’s done by lists of cognates (words with their meanings) with their historical reconstruction by internal and comparative analysis. That’s tables.

    Are those binary tables, or do the entries in the tables have treelike structure? Is all you’re doing saying “these languages are related” or are you saying “these languages are related in this specific way”, i.e. organizing them into a language phylogeny?

    So according to you there are two kinds of languages: Demonstrably related and undemonstrably related. How very Darwinian of you. How about the theory (fact rather) that, even though e.g. French and HIndi share a common history, they don’t seem to have anything much in common now.

    But they do seem to have quite a bit in common, and you do have the data that organizes them and other languages into a tree. You can make a consistent tree of Indo-European languages, therefore they are demonstrably related. If you couldn’t, they might be related but you would have no evidence of that.

    Wouldn’t this be even more true of languages that have no demonstrable common history?

    What do you mean by “demonstrable common history” here? What is the demonstrable common history of French and Hindi? And how is this relevant to disagreeing with my point?

    Even though reality is more complicated than that, for example areal convergence without historical organic relation is very common. So there’s grounds to posit more kinds of languages – organically related, areally related and not related in either of the aforementioned ways.

    How do you know two languages for which you have no evidence of relationship are not related in either of the aforementioned ways, if evidence degrades over time?

    You mean those observations don’t exist? Feel like reading a book?

    What observations? Do you have a continuous record of one language changing into another? I’d say you only have discrete samples in a time series that you are assuming are connected. You have, in other words, a fossil record of language. You accept the fossil record of language as evidence but reject the fossil record of life as evidence.

    When I say “what languages are” I mean the observed reality that languages are changeable and there is a long record of observations of how the changes occur.

    Do you indeed have a record of one language changing into another language? What is it?

    Those observations serve to justify that languages with scant historical record can be treated in a similar manner – that they are changeable and there are certain rules to how they change. Because in other cases it’s been observed that that’s how languages behave and that’s what they are.

    How is that not also true to an equal extent of species? We know how populations change, we know how genomes behave, etc.

  5. John Harshman John Harshman
    Ignored
    says:

    Erik:
    Alan Fox,

    Whatever happened to “NotA implies NotB = B implies A”? If the criteria that are known to determine relatedness between languages fail to determine relatedness between some given languages, it should be legitimate to conclude that those given languages are demonstrably unrelated.

    I see I still have to teach you logic. What you have just said is that B implies A = NotB implies NotA. See the difference?

  6. Allan Miller
    Ignored
    says:

    Alan Fox,

    It could happen without any selective pressure, just different choices for favourite words, phrases and constructions.

    Yep. Although the removal of my jocular ‘stylee’ is an example of purifying selection!

  7. Allan Miller
    Ignored
    says:

    GlenDavidson,

    Principles. They’re available for use, to those who understand what they mean.

    “These are my principles, and if you don’t like them… well, I have others.” – Groucho Marx (possibly).

  8. Alan Fox Alan Fox
    Ignored
    says:

    Allan Miller,
    I should have been a faithful copyist! 🙂

  9. GlenDavidson
    Ignored
    says:

    Alan Fox: But with no mixing, differences can creep in till those differences accumulate to the extent that mutually intelligible conversation is now impossible. It could happen without any selective pressure, just different choices for favourite words, phrases and constructions.

    Anything like genetic drift?

    Yes, but one should note that with languages it’s not going to be just accumulation of random changes. Sometimes a word might change on its own, but other changes are coordinated. French is systematically different from Italian, not randomly, even if some of the differences are presumably fairly random (within limits).

    Natural selection will cause enduring changes to be coordinated, but genetic drift alone will not.

    Glen Davidson

  10. GlenDavidson
    Ignored
    says:

    Allan Miller:
    GlenDavidson,

    “These are my principles, and if you don’t like them… well, I have others.” – Groucho Marx (possibly).

    I’m very principled, it’s just that my principles evolve with each situation.

    Glen Davidson

  11. Alan Fox Alan Fox
    Ignored
    says:

    GlenDavidson: Yes, but one should note that with languages it’s not going to be just accumulation of random changes.Sometimes a word might change on its own, but other changes are coordinated.French is systematically different from Italian, not randomly, even if some of the differences are presumably fairly random.

    Natural selection will cause enduring changes to be coordinated, but genetic drift alone will not.

    Glen Davidson

    Oh sure. Drift happens all the while but selection is the real driving force in evolution.

  12. Mung Mung
    Ignored
    says:

    Allan Miller: Of course, not all inferences are created equal.

    Also an inference? 😉

  13. Robert Byers
    Ignored
    says:

    Alan Fox: I dunno. Seems to me human language is so intimately linked to human evolution and that humans are descended from earlier ancestors already showing the adaptations necessary for speech production and processing that to rule out any relatedness for the Basque language with any other, purely on the absence of evidence, is a bit premature.

    And I see that a fairly recent study on DNA from modern Basques and skeletons found in the Basque country and comparisons with other peoples does indicate when, where and how the Basques became isolated. You could make an analogy with genetic drift here. Here is the Science article.

    ETA The original paper

    Of coarse I must disagree that language evolved with us evolving. We never evolved!!
    I think languages change because identities change. I think its on purpose.
    not merely distance. In North america it was noticed Indian tribes spoke the same language though never seeing each other for years while close Indian tribes, didn’t.
    it was the segregation iof identity that iniated the language change.
    In fact Babel was all about that. God mixed the languages to stop a evil plan but it was not confusion but rather fixed segregation from the languages that made people break up.
    It was pride.
    I don’t think this basque thing is that strange. i don’t agree with their ideas.
    i think the basques, i speculate, are simply a extension of migrations from North africa. Actually there were pre indo euro languages in those areas and even in europe.
    I think rather basques might just be Egyptians or Libiyans or some take off of them. Then when Celts migrated they were forced into the far mountains.
    people moved quickly along water routes.slowly in the landscape.

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