Friday, August 09, 2013

Evolving Our Understanding of Evolution: A Guest Post by Jill Johnson


by Jill Johnson

When it comes to contentious issues in the North American church, a recurring source of fear and anger is the idea of evolution. I had heard these arguments floating around as I grew up in the church, but when I studied biology, I compartmentalized these ideas quite separately from my studies, for the most part. It wasn't until I casually mentioned to a clergy member, in a church building, that I had a big paper due in my Evolution class, that I realized that some might see my upbringing and my studies as incongruous. I've since given the matter quite a bit of thought, and I have come to believe that this "controversy" is largely, perhaps entirely, based on a reaction to an inaccurate idea of what evolution is and what it claims to do.


(Note: For the purposes of this piece I'll be writing about evolution as though scientists are a monolithic group that has reached a consensus. Of course, science is a mechanism that allows us to explore questions and not a textbook that provides an unchanging list of the answers, so absolute consensus among scholars is an overstatement. However, I hope to do justice in describing how evolutionary theory is applied by the majority of scientists participating in these conversations today.)

The stereotype of Big Bad Evolutionary Teaching that elicits the strongest push-back from some Christians is typically characterized by some of these features:

It requires adherents to believe in a certain beginning-of-the-world narrative;
           
It is solely concerned with the creation of new species (especially humanity); and

It is mutually exclusive with religious beliefs.

I hope to demonstrate that evolutionary science in its present state cannot be characterized by these statements. The version of evolution you may have been taught to distrust is a version that no one is actually advocating. First, let me provide a quick primer (with an example) on how evolution is typically defined.

Simply put, evolution is change in the inherited characteristics of biological populations over successive generations. For evolution to occur, three requirements need to be met:

1. Variability - A trait (colouration, height, the presence of certain enzymes, etc.) must have multiple versions simultaneously present in a population

2. Heritability - That trait can be passed down through generations

3. Differential fitness - Individuals with different versions of the trait go on to produce different numbers of offspring.

Here's a commonly used example: the peppered moth. The peppered moth population contains variability in colouration; some moths are lighter while others are more darkly coloured (Requirement 1).


Moth colouration is also heritable; darkly coloured moths have darkly coloured offspring and vice versa (Requirement 2). Now, before the Industrial Revolution, the most common colouration for a peppered moth was light. These insects spent a lot of time resting on lightly coloured vegetation, and so light colouration provided effective camouflage. Few moths were darkly coloured. 

However, during the early English Industrial Revolution, the trees where the moths rested became covered in soot. Now, lightly coloured moths stood out and were easy targets for predation. Suddenly, darkly coloured moths were much more likely than their pale peers to survive and leave numerous offspring (Requirement 3). The frequency of dark colouration in the population jumped. This change in the frequencies of the two colourations of peppered moths in response to a change in their environment (the pollution) constitutes evolution in this population with respect to colouration.

I want to point out that in this example no new species are created. Evolution is just a mechanism by which the frequency of heritable traits change in a population. A substantial change might warrant labelling the new generation as a new species, but not necessarily. Evolution does feature prominently in many origin-of-life theories, of course, but acceptance of these theories is not mandatory in order to consider how evolution may function over smaller time courses. I think that this point is where some Christians and some scientists really misunderstand each other.


A few common misconceptions about evolution

Claim 1. Evolution designs organisms according to how helpful/awesome/sexy an adaptation would be.

Response. The idea that evolution can just design things willy-nilly works well in comic universes because it mirrors the way that writers write. Unfortunately, evolution cannot say, as a writer can, "Do you know what would be awesome? Spider people!" Evolution can only act on pre-existing variability on a certain trait. In the peppered moth example, darkly coloured moths did not appear ex nihilo; they existed in the initial population.


Claim 2. All scientists believe that humans are descended from monkeys (in fact, the same monkeys you can see in a zoo).


Response. No. Evolutionary biologists do often study how related organisms are to one another (by assessing things like how much genetic material, anatomy, and behaviour are shared by the two groups). However, they do this in order to make hypotheses about how recently the two groups may have shared a common ancestor, not to determine which came first.

It is also important to note that this type of work is not always all about humans or even mammals! Work investigating genetic relatedness can provide insight into all sorts of questions. For example, chickadee population genetics can provide insight into how glaciers may have moved across North America.

Claim 3. Some organisms are "more evolved" or "more highly evolved" than others.

Response. This type of language is often used to support the idea that humans are unique, but is easily co-opted in science fiction or for evil real-life purposes like justifying racist actions. Don't do this. Scientists rarely (if ever) talk about organisms as more or less evolved. Evolution is really all about the fit between an organism and its environment, so really everything that is currently living is equally "evolved."

Now that I’ve provided a quick primer on what evolution is (and is not), I hope it’s clear that evolution as a mechanism is not the all-encompassing worldview that Christians sometimes fear. Saying that evolution forces us to deny the existence of God is like saying, “Because water seems to turn into a gas on its own at a certain temperature we have to deny God’s involvement in the process. Therefore, God can’t exist.” Discomfort with an atheistic origin of humanity, which leads some Christians to reject evolution, actually conflates “evolution” with the way some atheist scientists have used it as proof for the non-existence of God. But evolution itself doesn’t give us that kind of information. In other words, the mechanism of evolution does not make claims about the existence of God one way or the other, so our beliefs about the existence of God should not dictate our acceptance or rejection of evolution.

Returning to my initial list of statements associated with Big Bad Evolutionary Teaching, I hope that I have given a new face to mild-mannered evolution-the-mechanism. It is very possible to engage with the idea of evolution as I have described it without accepting any particular creation narrative. There are numerous examples of fruitful studies of evolution that are not interested in the creation/destruction of new species (much less the origins of humanity). And finally, I want to point out that, while evolution-the-mechanism can be described without including God in the description, it does not require God's non-existence in order to function.

Jill Johnson holds an B.Sc. in Biological Sciences and an M.A. in Psychology. She currently manages a research lab that studies developmental psychology.

7 comments:

  1. I'm sorry but she is completely wrong and, unfortunately, has been misled by whoever taught her. What she's talking about in terms of "evolution isn't that bad" with her examples is in fact "adaptation" not evolution. Adaptation is quite consistent with creation- after all we have so many breeds of dog but conceivably Noah only saved one pair in the Ark. However, evolution is not. Evolution does not deal *simply* with the adaptation of species over short periods of time but in fact posits the change of one species into another over millions of years. For instance, many evolutionists have attempted over the years to prove that humans evolved from apes, that land animals evolved from sea creatures (or vice versa, they really can't make up their minds- some scientists are even saying hyenas and whales came one from the other).
    While Christians can and certainly should make use of adaptation, we cannot make use of evolution as an entire theory. She has been misled by no doubt well-meaning professors into thinking that because a few scientists she knows don't take full-scale evolution and apply it to the world around them, therefore no one does. Richard Dawkins would laugh in her face.
    She IS correct about why evolution can't work the way scientists say it does, but again she's using "evolution" in place of adaptation. It's true that ADAPTATION has to work on pre-existing traits. Evolution supposes at its core ex nihilo genesis, if you follow the rabbit hole all the way down.

    In short: www.creation.com and it's wonderful magazine also disprove her whole thing, but really her problem is just that she's mis-defined her terms and listened to the wrong people. I can assure you that mainstream evolutionists are quite certain about their millions of years, their one species to another evolution (though they've still not proven it), and their lack of the existence of God. Though of course, they can't prove that either- but they'll do their best to say they did.

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    1. Hi Kevin. Thanks for your comments. I appreciate you raising an opposing view, but I would like to remind you that, on Ground Motive, it's not okay to direct criticism at the the author. Please keep your criticism on the level of the ideas discussed. For Ground Motive's comment guidelines, look at the "About the Forum" tab.

      When you say, "Evolution supposes at its core ex nihilo genesis," I think that's not quite right. I think what might be more accurate is to say, "Some atheist evolutionary theorists presuppose ex nihilo genesis." What this article does, for me, is show us that evolutionary theory just does not have any atheist or nihilist claims built into it. It's a useful scientific theory that describes how adaptation seems to work, but it doesn't tell us anything about the existence or non-existence of God or the meaningfulness or meaninglessness of life.

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    2. Quite right, Matt, but I think it's fair to say that appearance out of nothing (latin be damned!) is entirely compatible with evolution. Evolution readily demonstrates how life as varied and complex as it exists today could have begun with a very simple, single species. In doing so it removes the necessity of a designer-God to explain life as we know it and makes a good downpayment on conceiving life itself as having a purely physical origin. Evolution doesn't include a theory about how the first specie came to exist but for those who have hung their belief in God on the existence of life, it makes the jump to non-belief much easier by making that-which-remains-undiscovered much smaller and more plausible.

      -dz

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    3. Hi All,

      I appreciate your comments!

      @Kevin While I understand what you're getting at in emphasizing the role of adaptation, I think the distinction between adaptation and evolution that you're making is artificial. Adaptation is the mechanism of evolution. I used the term evolution exclusively in this article, which is totally consistent with common usage in mainstream science. (I'm not trying to do something tricky). Adaptation over short periods of time leads to small changes, and over large periods of time leads to large changes. My understanding is that some creationists are comfortable with the former but not the latter. My argument, then, is that if you believe that only small changes have taken place (presumably because you believe the earth is young), that is fine. However, your issue then is not with evolution/adaptation. Instead your issue is with a certain view about the age of the earth. I intentionally did not take a stance on the age of the earth or whether species change because my sole point was to argue that adaptation, the mechanism of evolution, is surprisingly inoffensive to many Christians. In fact, most scientists use the term evolution to refer to processes you would classify as "only adaptation" very frequently. I was hoping to show to the readers that the degree of overlap between their beliefs and much of scientific practice is quite large and to reduce an "us v. them" mentality that I think is often unjustified.

      I would also just like to mention that several statements you made (e.g. "she... has been misled") imply that my opinion was fed to me and that I was passive in that process. I want to challenge this. My position is my own, and is the result of careful thought and study over several years. While I don't want to assume to know your intentions, these statements have the appearance of trying to downplay my expertise on this subject, and I think this is not helpful to the dialogue. That being said, I do appreciate the points you raised and the opportunity to provide clarification.

      @Matt Thanks for your clarification!

      @Anonymous I agree with your comment entirely, and I think you do an excellent job shedding some light on why evolution and non-belief tend to cluster together (though one does not necessitate the other).

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  2. Hi Jill!

    Great post! I think you're right to say that a lot of Christian people who take issue with evolution don't try very hard to understand the theory they're trying to discredit, and it seems to me that you've done a good job clearing up some of the misrepresentations here.

    In the last few years I've grown much more contented with the reasonableness of evolution and with its compatibility to faith than I had been earlier in my life. There are still certain parts of the theory of evolution (or my limited understanding of it) that I find difficult to swallow, though. There appears to be a bit of a gap in your post that corresponds to my principal difficulty.

    I really liked your opening explanation of and example for evolution. To me, that sounds entirely compelling. But when you started talking about "common ancestors," I wished you would have spent more space setting that up. I don't see quite how that grows out of the earlier discussion.

    Let's take a very broad example, just to make the point as clearly as possible: if we go back far enough, we'd find that vertebrates have some common ancestor, some species from which mammals and reptiles and fish and birds have all descended. From what I gather, that ancestor species was not a species made up of mammal-reptile-fish-birds which could fly and live underwater and lay eggs and get pregnant all in one species . . . is that correct? So that means that at some point, some non-bird species begot a bird species (and some non-mammal species a mammal species, etc). That seems different from what you had talked about at the start. And it's not just a difference of degree, it's a difference of kind: variability and heritability and differential fitness don't apply at all to the "common ancestor" idea, as far as I can fathom.

    Now I realize that you're simplifying for an audience of non-scientists (like me), and I'm probably fumbling around even in the way I try to talk about it—but I wonder if you'd help me understand the connection between the initial explanation of evolution you provided and your later mention of "common ancestors."

    Thanks for the post! Looking forward to hearing from you!

    Peace.

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    1. Hi John! Thanks for the comment. I'll take a stab at this, and Jill (or someone else) can correct me if I get it wrong.

      The way I understand it, there is no problem talking about common ancestors and variability/fitness in the same breath if we understand that big species changes don't happen overnight. So if we talk about different species sharing common ancestors, we're not talking just a few generations...it's more like thousands or millions of years. It makes a lot of sense to think about how individual members of the same species varying in traits like coloration (e.g. the moths) might be able to reproduce better or worse depending on what variations they exhibit. If this happens through enough generations, it means that the variations that are helpful to survival and reproduction may become more pronounced or specialized to the environment. Eventually it becomes appropriate to call them a different species (the lines between species, I gather, is a whole different complex discussion).

      So what evolutionary theory lets you do is see similarities between different species and examine how two very different species might have evolved from a common ancestor as a result of different environments or survival requirements.

      The key thing is that talking about common ancestors *is* just a difference in degree from talking about variability within a single species, not a difference in kind.

      Does that address your concern a bit?

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  3. A remarkable feat, Jill! You wrote that whole thing without once using the "m" word. :)

    Mutation is obviously not the main thing at work as species adapt to their environments, especially not when they do it quickly, but it sure attracts a lot of attention, and consequently provides a lot of opportunities for misconceptions. (not to mention disappointments for those of us who hoped to be bitten by radioactive spiders)

    As a social phenomenon, denial of evolution exists mostly because evolution undoes the "intelligent design" argument that has been used to support literal interpretation of the biblical creation story and thus as a powerful proof for the existence of God, capable of compelling or at least maintaining belief in God amongst people who require proof. Miracles can be suspected of being frauds, or historical fictions. Personal experiences are subject to confirmation bias. Ancient writings are not videotape evidence. But finding evidence of design embedded in life itself; that's more like coming across an inuksuk whilst trekking through the wilderness: impossible to explain as anything except the work of an intelligent creator. Ironically, until Darwin's work science was actually making the case for intelligent design stronger. By exposing the wondrous complexity of life in ever greater detail science made the miracle demonstrable, a whole village of inuksuk, in effect. The apparently-designed structures found in the living world would have been enough to satisfy even very critical thinkers, or at least make their objections seem implausible. It's not hard to see how the idea of intelligent design was highly valued.

    I disagree somewhat with your view that the controversy is "largely based in reaction to inaccurate ideas about evolution". I would have said "perpetuated by" instead of "based in reaction to". Arguments against evolution are themselves designed. For the most part they don't arise spontaneously in the population as a consequence of misconceptions. Rather, they are brought to public attention by much smaller numbers of people making court challenges, attempting to alter school curricula, making websites, promoting controversy, and so forth. The motivation for these high-profile evolution detractors is revealed by them and their fellow travellers as the necessity of maintaining belief in a literal interpretation of the biblical creation story, not a benign interest in improving the science. Court cases have demonstrated that objections to the science are crafted to have public appeal, not scientific rigour.

    In this light I found your statement that evolution is not the "all-encompassing worldview that Christians sometimes fear" intriguing. Being Christian alone can't be what makes one susceptible to that fear because whole Christian churches have accepted evolution as scientific fact without that fear gripping their memberships. Evolution certainly is not an all-encompassing worldview, but perhaps a sort of "it takes a worldview to replace a worldview" thinking could occur in those who were responding to evolution as a threat to their own closely-held view-for-the-world. I don't know if this is what you were thinking when you crafted that statement, but that's where it sent me.

    Thanks for opening this topic up.

    -dz

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