Thursday, March 13, 2014

What is "macroevolution"?

Denyse O'Leary on Uncommon Descent wonders Is “macroevolution” even a meaningful term? It’s time to ask.

Here's the problem as creationists see it ...
The evolution that Darwin’s theory accounts for (natural selection acting on random mutation) is, in the real world, small changes that don’t add up to much over the long term.

That is why the term "macroevolution" had to be invented. It was a leap of faith to assume that Darwinian "microevolution" would become "macroevolution" instead of just being washed out by other types of change (what usually really happens).

But gradually scientists are becoming less afraid to talk about this: Macroevolution apparently happens, but not by Darwinian means.

G’bye, Darwin. We packed the crumpets for ya.

Will it soon be: So long, Darwin-in-the-schools pressure groups? Gee, how they’ll be missed in the legislatures and courts.

No, wait, we’ll all be too busy figuring out what really happens in the history of life. It’s a fascinating story and now – for once – we might get to read it without all the interruptions.
I can't tell you how frustrating it is to see this kind of crap over, and over, and over. We have been trying to teach evolutionary biology to the IDiots for decades but they seem to be totally incapable of listening.

True, there was a time when biologists thought that Darwinian natural selection was all there is in evolution. They even thought that all of evolution, from changes within populations to the evolution of new phyla, could be explained solely by natural selection acting on allele frequencies within populations (Darwinism).

Most evolutionary biologists have moved on in the past half century and they now realize that macroevolution is a separate field that combines genetics, population genetics, geology, ecology and a host of other fields in order to explain the history of life. So, Denyse, it's true that macroevolution happens by means other than Darwinism even though natural selection is an important component of macroevolutionary explanations.

The only news here is that it takes IDiots so long to catch up with evolutionary biologists.

Back in the days of talk.origins, this topic (macroevolution) came up so frequently that I wrote a little essay to explain it in a way that even the most profound IDiot could understand. The latest version is from 2006: Macroevolution.

Wouldn't it be nice if the creationists could make an attempt to understand modern evolutionary theory instead of just repeating the same old tired arguments that they used 50 years ago?
The suggestion that macroevolution should be divorced from microevolution provides Creationists only with a debating point. It allows Creationists to say that there are some evolutonary theorists who distinguish the mechanisms studied in classical population genetics from those they take to be involved in large-scale evolutionary change ... But this is not to suppose that the distinction drawn by heterodox evolutionists is that favored by the Creationists.
                                                               Philip Kitcher (1982) p.150


17 comments :

  1. I can't tell you how frustrating it is to see this kind of crap over, and over, and over. We have been trying to teach evolutionary biology to the IDiots for decades but they seem to be totally incapable of listening.

    Trying to teach numbskulls like O'Leary anything is an exercise in futility. Like the French Bourbons, she has learned nothing and forgotten nothing.

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  2. Thanks for linking that essay - a great summary. I take it you are still recommending Gould's book as the starting point for reading on this topic?

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  3. macroevolution is a separate field that combines genetics, population genetics, geology, ecology and a host of other fields in order to explain the history of life.

    I think the confusion is that some see it as a field of research, and others see it as a process distinct from the process of microevolution. And it is not only creationists who do the latter, at least implicitly. I know a systematist who argues against phylogenetic systematics as follows (paraphrasing):

    Macroevolution is taxa turning into other taxa, e.g. a new genus evolving out of an ancestral genus. Phylogenetic systematics does not allow supraspecific taxa to be ancestral to other supraspecific taxa (at the same or higher rank). Therefore, phylogenetic systematics is unevolutionary.

    Yes, that first sentence in the previous paragraph does appear to be his definition of macroevolution.

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    1. That's one weird, or perhaps just very old, systematist you have there. Is he claiming that a genus doesn't begin as a single species? And is he claiming that "genus" is an objectively defined rank, distinct from "species" or "family"?

      However, you don't have to be weird or very old or against phylogenetic systematics to think that there are macroevolutionary processes that don't reduce to microevolutionary processes. I don't even think it helps.

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    2. > And is he claiming that "genus" is an objectively defined rank, distinct from "species" or "family"?

      Sadly, yes. Mostly he starts from the conclusion that paraphyletic taxa should be allowed and rationalizes from there.

      I am still not sure that the distinction between micro- and macroevolutionary processes is really that helpful. Yes, a species diversifying into two species is a different level than observing allele frequencies in a population under selection, but well, there is no level at which the latter is not the underlying driver.

      It is the same with other high and low level processes. What happens in a flood does not simply reduce to what happens at the level of hydrogen bonds between individual water molecules, but saying that the flood "happens by processes other than" hydrogen bonds is not entirely the best way of putting it either because yes, they are still there as one of the factors.

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    3. Yes, a species diversifying into two species is a different level than observing allele frequencies in a population under selection, but well, there is no level at which the latter is not the underlying driver.

      That's an assertion. I don't think it's true. In particular, extinction is not a change in allele frequency. And I think extinction has a significant influence on evolution.

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    4. Well, if you get a meteorite on the head allele frequencies weren't involved, sure. But if you are out-competed, or eaten... I don't see how they could not be a factor.

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    5. Consider a case of competition in which there is no selectable genetic variation. Or, to put it another way, suppose one species is competitively superior enough that nothing within the range of variation possessed by the other species makes a significant difference in reproductive success. In such a case there would be no change in allele frequencies. You may argue that such cases don't exist if you want, but I don't see another way out. And I think you would have a hard time doing so.

      In general, any environmental change that happened quickly enough so that allele frequencies didn't have time to change, or for which there was no existing selectable variation and not enough time for any to arise, would result in macroevolution without microevolution. Meteorites, rapid climate change, competitors, all could be causes of that sort of extinction.

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    6. Maybe I'm too obtuse but I don't see the point. Even if both species are completely invariant now, they got to where they are now through a couple billion years of microevolution.

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    7. Yes, if you discount any prior macroevolutionary processes; and they also got there through mutation, as long as you discount selection and drift. Microevolutionary processes just weed out products of mutation; one could also say that macroevolutionary processes just weed out products of microevolution. I don't see a big difference. No matter how the species became invariant, extinction affects the composition of the biota independently of changes in allele frequency. I'd call that evolution.

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  4. I think this lady put it very well. evolutionists do teach micro is the evidence for macro claims. The demise of this micro idea puts stress on the macro conclusion.
    There is no evidence for macro evolution on earth. its a line of reasoning from micro evolution claims in special cases.
    As people get smarter and more do more investigation the whole evolutionary biology theory will fall away.
    Geology has no place in biology by the way. Indeed without the geology there is little claim to evolution evidence. Its not on biology because evolution never could cross the boundaries of glorious biology. There is no scientific biological evidence for evolution. Only lines of reasoning or unrelated fields of study trying to back it up.
    Unless I'm missing it?!

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    1. There is no evidence for macro evolution on earth. its a line of reasoning from micro evolution claims in special cases.

      Says someone who seriously believes that rabbits, wolves and groundhogs turned respectively into wallabies, thylacines and wombats during their postdiluvial trek from Mount Ararat to Australia, and that it was a case of microevolution at work.

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    2. My idea is based on observation and investigation as far as these things can be.
      The micro equals macro is not from the same. its just a line of reasoning in its core foundation. Its a WHY NOT passing as evidence of HOW.
      Thats our complaint and well done.
      Its just a hunch with trivial data to back it up.

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  5. Macroevolution, as defined by the Creationists, is evolution on too large a scale to have been directly observed. So that they can then turn round and say that macroevolution has never been observed directly. As if the forks between the boughs of mighty oaks had not once been the branching of twigs in saplings.

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  6. Larry,

    Your best authority and buddy Jerry Coyne totally disagrees with you on this very subject.... Why do you write " We"? Who is "we"? Who?
    Also, like with Coyne, I have found that your claims are often times just very clever bluffs, and nothing else.... For some reason, you think you have most of the scientific community behind you... but the truth could be very, very different Larry.... Your genetic drift shit is just a shifty theory... You can't prove it....

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  7. At least with the Answers In Genesis supporters, I don't think their idea of macroevolution has a component for the events that led to a different taxonomic family. At least superficially they seem to be focused on the idea that 'new information' occurs between Genesis kinds and that this 'new information' or different information is beyond the scope of a series of mutations. By their reasoning if I understand correctly, there is for example, genetic information in a dog (canid) which specifically gives it dog-like qualities and there is genetic information in a cat (felid) that gives it its recognizable cat-like qualities (IIRC their word is 'cognitum'), and they don't think this information could have come from alteration of a common carnivore ancestor's genome by mutation. Whether the process involved selection or drift etc. is not important to them; it is their inability to think that mutation could have taken an ancestral population's genetic makeup to either the canids or the felids. They continually say that mutation cannot generate 'new information'; only an intelligence can do that.

    The history of the idea of macroevolution in the scientific community and what the word means or how it works as a field of study in the scientific community is interesting, and also useful for responding to quote-mining. In my view, it is separate from the argument that the creationists are trying to make when they use the word. I think they are talking about simple genetics.

    At one level I think this is due to a lack of understanding about genes and gene regulation and protein families. I think laypeople use the word 'adaptation' in a fuzzy way, and the creationist organizations exploit that fuzziness rather than try to clarify it.

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