Micro vs. macro

As usual, I’m way behind in my comment reading (I’m up to Feb. 27th in my backlog), but I’m seeing references to micro vs. macro evolution in the comments, and since I’ve come across this sort of discussion before, I thought I might step in and clarify my point a little.

The behavior of rivers is, broadly speaking, fairly easy to explain: water flows downhill. If your specialty is the study of rivers, however, you might want to dispute the claim that all rivers work in essentially the same way. You might want to point out different mechanisms of erosion and silt deposition, and how that interacts with the river to produce variations in the rate of flow due to changes in the riverbed. You might further study how the river affects the climate, possibly inducing changes in rainfall that in turn have an impact on the water flowing into the river. And yet, when you have delved down into all the technical hydrological details, all rivers still consist of water flowing downhill.

It was in that sense that I alluded to microevolution and macroevolution being the same basic process. Evolution is a process of change in the distribution of alleles, coupled with natural variations within the pool of available alleles and with the influence of environmental conditions on the selection of which alleles, if any, come to predominate within the population. Biologists are interested in breaking down this overall process into specialized submechanisms, and studying the factors and processes that produce certain specific types of variation under certain specific sets of conditions, and yes, in that particular technical discussion, you can make a technical distinction between microevolutionary processes and macroevolutionary processes. Such distinctions are of no use to evolution-deniers, however, because even here, we’re not talking about the kind of difference that would make microevolution possible while ruling out macroevolution.

In order to deny that macroevolution is possible (as Geisler and Turek attempt to do), creationists need at least one of two things: either a distinct mechanism for macroevolutionary changes, and/or a standardization mechanism which would triple the amount of genetic information required for each inheritable characteristic. Let’s take these one at a time.

Natural changes are the raw material of evolution. Mutations are the most famous source of natural variations, but there are others, which I’m not going to delve into here. The point is that these variations are all microvariations. There is no macrovariation that would allow, say, a cat to give birth to a horse. There may be subsequent specific processes that operate on these microvariations to produce macroevolutionary changes in the population(s) as a whole, but the fundamental basis for these changes necessarily involves the accumulation of microvariations passed from one generation to the next. Hence, even macroevolution is necessarily the accumulation of microevolutionary changes.

Failing a separate and distinct mechanism for macrovariations, the creationist can turn to the idea of genetic “barriers”—some kind of genetic standard that defines what the limits for a “kind” are, plus some sort of mechanism for enforcing those limits. The problem with this approach (apart from the fact that there is absolutely no scientific evidence or hypothetical mechanism for it) is that it requires each inheritable characteristic to have triple the genetic information required to describe the characteristic.

If a kind is allowed to have only a certain range of skin colors, for instance, the “skin color” gene must have not only the value of the current individual’s color, but also the minimum and maximum ranges that the kind is allowed to have. And even then, what happens if a mutation moves the skin color outside that range? You also need a mechanism for detecting the violation, and repairing it.

That’s a vastly oversimplified description, of course, but I think you get my drift. You could reduce the requirements somewhat by not allowing any variation at all, and requiring each characteristic to be an exact clone of the ancestral characteristic, but what about mutations? And even if you had a mechanism for detecting and repairing variations from the standard, what’s to prevent the mechanism itself from mutating? And even if you could propose a hypothetical self-repairing mechanism for maintaining an independent set of standards, where is there any evidence that any such mechanism exists and operates the way creationists need it to? And why, incidentally, would a wise Creator deliberately afflict His creatures with mechanisms designed to make them less adaptable and thus more fragile and liable to extinction in a hostile and changing environment?

The “barrier” against macroevolution is simply wishful thinking on the part of creationists. It just one more ramification of God’s failure to show up in real life: believers who are looking for evidence of His existence have to go all the way back to ancient prehistory to try and find something technical enough and obscure enough that they can say foolish things about it in order to create a pretext for claiming that divine intervention is necessary. That’s why so many devout believers (myself included) begin their journey away from Christian faith by taking a hard, honest look at creationism.

 
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Posted in Science. 12 Comments »

12 Responses to “Micro vs. macro”

  1. Freidenker Says:

    Funny thing you mention this. I was just finishing Carl Zimmer’s “At The Water’s Edge” (if you’re interested, I’ve written a short review about it on my blog) – and I remember reading this one bit that immediately reminded me of ER:

    Zimmer wrote that basically, macroevolution can be regarded as cumulative microevolution, but if you disregard the obstacles that bind evolutionary change, you’re missing a great deal of the picture and this gross oversimplification is nothing more than a layman-friendly inaccuracy, which is actually far from the truth in many occasions.

    I realize that your original post wasn’t about evolution, so obviously you weren’t under any obligation to start writing theses on the subject.

  2. cl Says:

    The “barrier” against macroevolution is simply wishful thinking on the part of creationists. It just one more ramification of God’s failure to show up in real life: believers who are looking for evidence of His existence have to go all the way back to ancient prehistory to try and find something technical enough and obscure enough that they can say foolish things about it in order to create a pretext for claiming that divine intervention is necessary. That’s why so many devout believers (myself included) begin their journey away from Christian faith by taking a hard, honest look at creationism.

    I agree, and I am commenting on this post at all only to dispel the notion that I am a creationist who denies the possibility of macroevolution – and to state that this post has absolutely nothing to do with my arguments in the other thread – arguments I would not have had to vehemently defend had certain people chosen to focus on my 10+ points of agreement with DD about main subject matter, instead of choosing to insult my science education almost near-exclusively on a single point of sub-contention that had only peripheral relevance to the OP. Funny that a Senior Lecturer in Biology Studies at Cornell, a Professor in the Biochemistry Dept. at Univ. of Toronto, a biology undergrad, and jim’s own source all happened to agree with the stupid sophist with a < high-school-level science education. For the record, I said it there and and I’ll say it here: Creationists did not “invent” the “macro/micro” issue, and the sufficiency of microevolution is a matter of legitimate scientific debate. No more canards.

  3. ThatOtherGuy Says:

    “Creationists did not ‘invent’ the ‘macro/micro’ issue, and the sufficiency of microevolution is a matter of legitimate scientific debate. ”

    And I’ll say what I said again: creationists DID invent THEIR version of the macro/micro issue, as they misunderstand and misuse the scientific terminology.

    http://creationwiki.org/Macroevolution

    They call macroevolution “large changes” and microevolution “small changes,” completely misunderstanding the nuances of the scientific terms. They then attempt to use what scientists say about the ACTUAL macro- and micro- evolution with their own flawed definitions. Creationist macro- and micro- evolution ARE akin to my example of macro- and micro- addition, whether you want to grant it or not, and THAT is what I was talking about.

    Once again you willfully ignore what’s ACTUALLY being said and then act like you’re the big saint for defending science.

  4. cl Says:

    ThatOtherGuy,

    How can you know my will? How would you know that I “willfully ignored” what you actually said? What if you assumed I was talking about you when I wasn’t? Surely that’s reasonable, right? Did you happen to notice that I did not attribute those words to you? I didn’t. Your comments here *might* have value had I so much as even mentioned your name, but Arthur is who that particular part of my comment referred to, and Arthur and I have cleared our misunderstandings up. So, whatever you call it when you jump the gun and think someone’s talking about you when they’re not – that’s what you just did.

    Incidentally, yes – creationists do misuse scientific terminology, and they do have their own fabricated macro / micro issue. I’ve never denied that, and speaking of ignoring things, this isn’t the first time I’ve said that, either. Next, I never denounced your claim because it was false, so please, quit echoing yourself. I denounced it because it is irrelevant to my original argument, and can only serve to take this thing even further off course. Creationists and their claims have nothing to do with you and the rest of my opponents oversimplifying complex biological terms. I’m not a creationist, and as Dan also seems to agree, I don’t advance oversimplified misuses of the terms.

    To contrast, your own comment April 11 reads, “..outside of creationist attempts to discredit science, there are no such things as macroevolution and microevolution.” This is as scientifically inaccurate as the worst of the creationist’s claims. Working biologists have been using the terms with meaningful distinction for what, eighty years now? You told me to go to MacNeill’s blog; are you not even reading any of Dan or MacNeill’s comments? Like the thing with Smith, I’ve supplied all sorts of original arguments and outside source material that counters your claim head-on, yet you take no responsibility for your claim – all the while rudely implying I don’t know what I’m talking about.

    Similarly, my argument is that everyone else on that thread (excepting myself, nal, and Dan) offered arguments about evolution that were anywhere from grossly oversimplified to outright false. Prof. Moran agreed with me, as did Dan and MacNeill by extension – but all the while, DD’s guests were relentless in what Freidenker called “the ad hominem frenzy,” attacking and insulting me when I was representing the situation correctly from my initial comment.

    If you want me to respond to your next response, put it in the other thread. I have nothing further to say about this post or this thread that I already haven’t said.

  5. cl Says:

    Actually, TOG, one more thing:

    Creationist macro- and micro- evolution ARE akin to my example of macro- and micro- addition, whether you want to grant it or not, and THAT is what I was talking about.

    Really…? So then, we can finally agree that macro- and micro- addition is an absurdly naive analogy, like I’ve been saying all along?

  6. ThatOtherGuy Says:

    “How would you know that I ‘willfully ignored’ what you actually said?”

    I’m giving you the benefit of the doubt. You’re either willfully ignorant or incredibly obtuse.

    “Creationists and their claims have nothing to do with you and the rest of my opponents oversimplifying complex biological terms. I’m not a creationist, and as Dan also seems to agree, I don’t advance oversimplified misuses of the terms.”

    But we’re NOT TALKING ABOUT YOU. We’re talking about Geisler and Turek, who DO argue for creationism.

    “To contrast, your own comment April 11 reads, ‘..outside of creationist attempts to discredit science, there are no such things as macroevolution and microevolution.’ This is as scientifically inaccurate as the worst of the creationist’s claims. Working biologists have been using the terms with meaningful distinction for what, eighty years now?”

    Poor wording. Given the horrific twisting of “wording” you’ve managed to continually do, I think I can be forgiven.

    “So then, we can finally agree that macro- and micro- addition is an absurdly naive analogy, like I’ve been saying all along?”

    Again, NO. It shows precisely why Geisler and Turek are wrong, which is WHAT WE WERE TALKING ABOUT.

  7. Arthur Says:

    cl said,

    …Arthur and I have cleared our misunderstandings up.

    and I guess that’s one way of looking at it.

    ThatOtherGuy said,

    …creationists DID invent THEIR version of the macro/micro issue, as they misunderstand and misuse the scientific terminology.

    At the risk of encouraging cl’s defensive posture, I feel obliged to re-assert—again—that this is exactly, and only, what I meant in that postscript (the quotes cl keeps using to indicate bad faith and scholarship) and what I stated explicitly in my far-less-quoted follow-up.

    nal pointed out, for my benefit, that creationists didn’t invent the terms. But that critics of evolution use the terms to refer to an invented issue seems downright obvious (hell, we all here appear to agree on it); and that there may also exist real macro- vs. micro- issues in science is an entirely compatible assertion.

    That the one should get so easily and consistently confused with the other is… too bad.

  8. cl Says:

    Arthur,

    …creationists DID invent THEIR version of the macro/micro issue, as they misunderstand and misuse the scientific terminology. (TOG)

    At the risk of encouraging cl’s defensive posture, I feel obliged to re-assert—again—that this is exactly, and only, what I meant in that postscript (the quotes cl keeps using to indicate bad faith and scholarship) and what I stated explicitly in my far-less-quoted follow-up. (Arthur)

    Again, as I asked TOG – even if that is what you meant, what does any of that have to do with the sufficiency of microevolution argument I introduced into the thread? Nothing. As far as your claims to what you really meant in your postscript, well, I have no way of knowing what you meant – unlike jim, R.C., Morales, TOG and the others, I haven’t yet figured out how to mindread – so I can only go with what you typed:

    I have always been under the impression that the macro- micro- issue was not an actual source of concern for biologists but invented by critics of evolution. I could certainly be wrong, but here is a pretty readable article on why the distinction isn’t a real one.

    Okay – if by “macro- micro- issue” you mean the false argument that “macroevolution is impossible and unproven” (i.e., the “macroevolution denial” issue), then no – such nonsense has never been an actual source of concern for biologists – and yes, (to my knowledge) it was invented by critics of evolution. So what? This fact was never being disputed and is completely irrelevant to the sufficiency of microevolution argument as discussed in the thread. Then, did you think we were talking about something else? Misunderstand my original claim perhaps? Misunderstand the subject matter? Or is there a rational reason you introduced a non-sequitur into a discussion over the sufficiency of microevolution?

    Further, even if said fact were relevant to the sufficiency of microevolution argument, that doesn’t mean we can say generically that, “the distinction isn’t a real one.” Your postscript gave zero indication that you are aware of this fact when it easily could have, and same goes from your follow-up. You can’t include the words “macroevolution” and “microevolution” and “the distinction isn’t a real one” in the same sentence without raising legitimate eyebrows from people who know the first thing about evolutionary biology. The reason I didn’t respond in the context you were expecting was because you were entirely in the wrong context. Creationists and their fabrications have no bearing on my disagreement with DD over his point 11, which is why I kept getting confused when you and TOG persisted in bringing them up. That’s why I’ve been getting a disconnect and denouncing those replies as irrelevant – they are.

    But that critics of evolution use the terms to refer to an invented issue seems downright obvious (hell, we all here appear to agree on it);

    Yes, so why re-state the obvious, especially when it’s irrelevant? Again, what do creationists and their fabrications have to do with my claim that DD inaccurately represented the sufficiency of microevolution argument?

    ..and that there may also exist real macro- vs. micro- issues in science is an entirely compatible assertion.

    …may also…? Arthur, a “real” macro / micro issue has existed in science for decades, and strings like “the distinction isn’t a real one” can lead any reasonable observer to believe you intend to suggest otherwise – especially when used in an intended context other than that of the original discussion.

    As far as your follow-up goes, 1) I used it as an example of error because I initially misread it; 2) I already told you that I noticed it; and, 3) I already apologized for misreading you. And, 4) I agree with you that when G&T make their, “no evidence for macroevolution and spontaneous generation” argument, they are “distorting, misrepresenting, or otherwise getting macroevolution wrong.”

  9. Parker Says:

    1) good luck getting caught up on these comments, dd!
    2) I like the explanation that you can’t take walk a mile without taking a single step. that if you do accept micro-evolution, and you do concede the earth and life have been around a mind-boggling long time, that you have* to accept macro-evolution.

  10. Freidenker Says:

    Parker – creationists don’t put it like that. When I first started studying biology, I was stumped at first as to the possibility of “macroevolutionary obstacles” – that is, that microevolution is possible, but certain evolutionary changes required for macroevolution are impossible and this kind of stuff is actually testable. The problem is – it failed – miserably. The ability of known and observed genetic mechanisms to create variation is actually a major overkill. The problem is not whether not genetics can show variation being generated – the problem is that it creates so much variation that it’s sometimes hard to pin down what genetic mechanisms caused evolution to occur.

    There are some really awesome exceptions to that that I’ll eat my hat if they’re disproved, such as SINEs and LINEs.

  11. Andrew @ EC Says:

    I’m paraphrasing someone (probably PZ), but here goes:

    Saying that you believe in microevolution but not macroevolution is like saying you can understand how we can drive a car to the grocery store, but not how someone could drive a car across the entire country.

  12. Kat Says:

    One of the best examples of micro vs. macro I’ve ever read. Well done!