Friday, April 22, 2016

Don't call it "The Theory of Evolution"

By now, we all know that a "theory" in science is much more than idle speculation, a point that has been made repeatedly over the past century. With respect to evolution, the most famous essay is by Stephen Jay Gould: "Evolution as Fact and Theory" and the latest explanation is an article in the New York Times by Carl Zimmer: In Science, It’s Never ‘Just a Theory’.

Unfortunately, it's not that simple and there are many scientists who use "theory" in the sense of hypothesis or speculation [see Facts and theories of evolution according to Dawkins and Coyne]. That's not what I want to talk about today.

What do scientists really mean when they refer to "The Theory of Evolution"? There is no single theory of evolution that covers all the mechanisms of evolution. There's the Theory of Natural Selection, and Neutral Theory, and the Theory of Random Genetic Drift, and a lot of theoretical population genetics. Sometimes you can lump them all together by referring to the Modern Synthesis or Neo-Darwinism. These terms are much more accurate than simply saying "The Theory of Evolution" as long as we all understand what those theories mean.

The problem with "The Theory of Evolution" is not only that it's ambiguous but it's misleading. It implies that there's only one theory to explain evolution. Another problem is that it sounds too much like we're talking about the history of life and saying that it's a "theory" that can be explained by evolution.

Instead of using the phrase "The Theory of Evolution," I think we should be referring to "evolutionary theory," which may come in different flavors. The term "evolutionary theory" encompasses a bunch of different ideas about the mechanisms of evolution and conveys a much more accurate description of the theoretical basis behind evolution. Douglas Futuyma prefers "evolutionary theory" in his textbook Evolution and I think he's right. It allows him to devote individual chapters to "The Theory of Random Genetic Drift" and "The Theory Natural Selection."

Here's how Futuyma explains the concept of theory in his book Evolution 2nd ed. p. 613.
So is evolution a fact or a theory? In light of these definitions, evolution is a scientific fact. That is, descent of all species, with modification, from common ancestors is a hypothesis that in the past 150 years or so has been supported by so much evidence, and so successfully resisted all challenges, that it has become a fact. But this history of evolutionary change is explained by evolutionary theory, the body of statements (about mutation, selection, genetic drift, developmental constraints, and so forth) that together account for the various changes that organisms have undergone. [my emphasis ... LAM]
He makes the same point in the opening pages of his book where he uses both terms when discussing the history of evolutionary theory. (Note that when Darwin used the word "theory" to describe natural selection he was not using it in the same sense as Gould and Zimmer to describe a modern scientific theory. That's why Futuyma uses "hypothesis" in the quote below.)
We now know that Darwin's hypothesis of natural selection on hereditary variation was correct, but we also know that there are more causes of evolution than Darwin realized, and that natural selection and hereditary variation themselves are more complex than he imagined. A body of ideas about the causes of evolution, including mutation, recombination, gene flow, isolation, random genetic drift, the many forms of natural selection, and other factors, constitute our current theory of evolution, or "evolutionary theory." Like all theories in science, it is a work in progress, for we do not yet know the causes of all of evolution, or all the biological phenomena that evolutionary biology will have to explain. Indeed, some details may turn out to be wrong. But the main tenets of the theory, as far as it goes, are so well supported that most biologists confidently accept evolutionary theory as the foundation of the science of life. p. 14 [my emphasis ... LAM]
When you're talking about the mechanisms of evolution, please use "evolutionary theory" instead of "the theory of evolution."

I wish the proponents of the Extended Evolutionary Synthesis would agree that the version of evolutionary theory they wish to extend is the one described by Douglas Futuyma. This would make it easier for them to explain what's wrong with that version and why their proposals are an improvement [see Templeton gives $8 million to prove that there's more to evolution than natural selection].


  1. "Don't tell people what not to do, tell them what to do."

    - someone

  2. Call it "evolutionary theory."

    Someone isn't always right. Don't vote for Trump. :-)

  3. I know I'm going to get called pedantic again, but I think the correct term is "theoretical evolutionary biology". It's a field of study concerned with working out the consequences of different evolutionary theories (in singular I would only use that term to describe a particular theory: The near-neutral theory of molecular evolution is an evolutioanry theory).

  4. Where to star? At the finish.
    Evolution is not a fact in explaining the complexity, diversity, origin of biology.
    Its just a hypothesis that tries to deal with new research that threatens it .

    It doesn't matter if 150 years has gone by. time has no effect on evidence claims. Darwin, I read, said it was settled by the timne of his book on expressions. He said it was a fact then especially by the people who mattered. All 76 of them.

    It then or since did not get serious challenges in the small circles that decided if it was true. Who was challenging in the 150 yesrs in 'scientific" circles.
    it was accepted right away without much thoughtfulness in reality.
    Only now do scientists take it on and increasingly.
    In order to challenge a 'theory' one must already be knowledgable about it. Who was when Darwin came on the scence and since/ By definition kids studying for these things already would agree with evolutionary conclusions.
    I say its never been actually challenged and in fact thats happening now. this blog exists because now is the days of serious challenge.

    If evolutionary conclusions have become facts then let them show the facts.
    Where are they? why are they not persuasive to so many and not overwhelming to those who seriously listen to both sides?
    Why is evolutionary biology so framed on biology, comparative anatomy and genetics, biogeography,even embryology, etc??
    Why is actual biology not the bulk of the evidence?
    Is a theory of biology a scientific theory if biology occupys a tiny fraction of the evidence??
    Thats why evolution ideas are not scientific facts or theory!! Its a unsupported hypothesis still. I don't mean proven wrong but unsupported by biological evidence to cross a threshold of a scientific theory/fact.
    its studied speculation in small circles about invisible process and results that happened in the past.
    We all deal with the invisible here. Its not like working physics.

  5. descent of all species, with modification, from common ancestors is a hypothesis that in the past 150 years or so has been supported by so much evidence, and so successfully resisted all challenges, that it has become a fact. ///

    What a blatant lie. There is tons of evidence that refutes common ancestry.

    there is no independent evidence that the natural order is an inclusive hierarchy, and incorporation of prokaryotes into the TOL is especially problematic. The only data sets from which we might construct a universal hierarchy including prokaryotes, the sequences of genes, often disagree and can seldom be proven to agree. Hierarchical structure can always be imposed on or extracted from such data sets by algorithms designed to do so, but at its base the universal TOL rests on an unproven assumption about pattern that, given what we know about process, is unlikely to be broadly true. This is not to say that similarities and differences between organisms are not to be accounted for by evolutionary mechanisms, but descent with modification is only one of these mechanisms, and a single tree-like pattern is not the necessary (or expected) result of their collective operation.

    There is more to evolution than will fit on any tree. For understanding major transitions in early evolution, we might not need a tree of life at all.

    If similarity is evidence for common ancestry, then does its opposite – dissimilarity – provide evidence against common ancestry?

    There is, of course, much dissimilarity between living organisms, some of these at a very fundamental level. For example, the standard system of genetic code used by humans is not universal. Eighteen different genetic codes have been found in various species. Many scientists see this as evidence that all life does not come from a single common ancestor.

    i could go on and on.....


    The tree of life, common descent, common ancestry, a failed hypothesis

    1. "There is tons of evidence that refutes common ancestry. "

      You didn't bring any. The papers you reference don't say what you think they do.

    2. They're about whether the tree of life-metaphor is exactly correct (and the primary area of concern is the earliest stages of single-celled life), not whether common decent is true. You idiot.

      "If similarity is evidence for common ancestry, then does its opposite – dissimilarity – provide evidence against common ancestry?"

      Mere similarity isn't evidence for common descent, nobody claims that. You have been thoroughly schooled on this several times already. Will you ever get it?

    3. Mikkel

      you have NEVER schooled me on anything. Your arrogance is telling. All you have, is name calling and personal attacks. I have not yet seen you promote, defend and propagate good science. Your blinkers are the problem.

    4. ElShamah777 is correct. Nobody has EVER schooled him on anything. He has religion. He is unschoolable.

    5. Larry,

      what schools me, is the scientific evidence, which points in a OVERWHELMING WAY to the requirement of intelligence and supernatural power to set up a fine tuned universe, solar system and earth, and the high information content irreducible complex and interdependent biological systems like cells, photosynthesis, nitrogenase enzymes, Rubisco, the human body etc. I do not need Religion to come to this conclusion. When people point their fingers towards others in a acusing manner, its not rare that they actually talk about themself... Your religion is naturalism, and no evidence apparently can convince you on the contrary, since, as it seems, you have a emotional commitment. God deniars are UNEXCUSABLE.

      Romans 1 says : For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse. If that was the case for people that had not access to such a vast insight of how nature works, imagine today....

    6. ElShamah777,

      "The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts."---Bertrand Russell

    7. 1 Cor 1:19-21

      "For it is written, "I WILL DESTROY THE WISDOM OF THE WISE, AND THE CLEVERNESS OF THE CLEVER I WILL SET ASIDE." 20 Where is the wise man? Where is the scribe? Where is the debater of this age? Has not God made foolish the wisdom of the world? 21 For since in the wisdom of God the world through its wisdom did not come to know God, God was well-pleased through the foolishness of the message preached to save those who believe.…"

    8. @ Eric

      "The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts."---Bertrand Russell

      I think you need your irony meter checked.

    9. You could go on and on, El, but nothing you reference is a refutation of evolution. Modern evolutionary theory does not predict a strictly bifurcating tree of all life.

      So what is your problem here? Do any of your references indicate that we must resort to a supernatural being somewhere?

    10. not paper but logic. we know th)at a motor need a designer. therefore a flagellum( motor)need one.even if it have a self replicating syste,

    11. Ah, so faulty analogies with no evidence masquerade under the name of "logic" now?

  6. What does this statement mean above? "It allows him to devote individual chapters to "The Theory of Natural Selection" and "The Theory Natural Selection.""

    1. It was a typo. I meant separate chapters on the theory of random genetic drift and the theory of natural selection.

  7. Perhaps the simplest thing would be to abolish the word evolution, replacing it with two terms. One should just be population genetics, and it would be understood that this is the genuinely scientific part of the old field of evolutionary biology. Perhaps it might be possible to call this evolutionary theory, to emphasize the fundamental importance of the field. After all, genes are everything.

    The other part of the old field of evolution devoted to the multiplication of species is far too hopelessly historical. As fundamentally a non-science it can be safely ignored by the larger number of biologists who are still practicing science, left to the lesser talents seeking soft targets.

    1. I can't tell if that was intended ironically or not.