Darwinism and its Discontents (part 2)

So I promised to take a look at some of the popular ideas opposed to Neo-Darwinian evolutionary theory.

“Young earth creationism” or other schools of thought that try to read the creation stories of Genesis (there are two) as scientific texts just aren’t serious. I’ve only met one adult who believed in it so I can’t think it is as popular as people say. It also is important to point out that in the history of Christianity Biblical literalism has rarely been a mainstream phenomena. For about 1500 years the common opinion among Christian theologians was that some bits of the Bible are meant to be taken literally, others as history, others as poetry, others as homilies, etc. Literalism has become more popular since the Reformation, in part as a reaction against modernity, in part as an expression of modern man’s quest for clear and certain knowledge. Modern man had a hard time understanding that truth is a many-layered thing, and this seems to have rubbed off on some Christians. Enough about Biblical literalism.

The other, more serious option tossed around is Intelligent Design Theory (ID Theory). ID Theory has a harsh critique of neo-Darwinism that goes something like this: a single life form is composed of several interdependent systems which cannot exist apart from one another, and each of these systems is composed of various interdependent parts. This is called irreducible complexity: each part serves a purpose only in reference to the others. Therefore no one of the parts can evolve on its own, they all have to evolve together. But evolving together implies that they evolve, not by chance, but with a purpose.

For example: An eye is a system (lens, muscles, retina, nerves…). Take away a piece, and it stops working; it does not help the animal survive, and the animal will not  reproduce. So either the elements of the eye evolved all at once or they never evolved at all. A snail with a lens but no retina will not pass the lens onto the next generation, so retinas and lenses could not have evolved at all. The eye is part of a larger system called sight, by which electromagnetic waves reflecting off objects are translated into electro-chemical impulses which the brain uses to reconstruct a 3-D image of the surrounding world by which we can walk around without bumping into things. An eye is useless without reference to this larger system.* It cannot randomly come about through mutation and the survival of the fittest.

Where the wheels fall off the ID bus, however,  is when they propose to save the theory of evolution by trotting in God. I’m not saying that God can’t be an intelligent designer, but that is not a scientific answer to a scientific problem. What ID does is point out that a scientific theory is inadequate, but then   re-proposes the same inadequate theory + God. It would be like Galileo correcting Aristotle’s notion that objects with greater mass fall faster by saying “They do fall faster, but little angels slow down the big objects so the little objects don’t feel bad and everyone wins the race.”

I think that when faced with the question “how does an irreducibly complex system like sight, which to this day we do not really understand, evolve into existence”, the only honest answer is to say: “We don’t know.”*

If neo-Darwinian theory cannot answer the ID critique, there is nothing wrong with scrapping the theory and trying to come up with another one that explains how wolves and dingoes are members of the same species, but not foxes. It will not be necessary to dump what we know about paleontology, comparative biology and genetics, but to reinterpret it. That is what used to be called “scientific progress.

* The eye example and “We don’t know” answer is lifted from The Deniable Darwin, an article by David Berlinski in Commentary Magazine, 1996. I have mixed feelings about the article, but between it and letters to the editor it caused you can get a good all around view on the popular debate.

Next time: Which side will you choose? Order or Chaos?



  1. Billy Maiden · · Reply

    Hello David, I am one of Maureen’s kids. I really enjoy reading your blog, as it always makes me think afterwards. I would like to interject on one point, however. We actually know quite a bit about the eye and its evolution. The article in question proposes the eye evolved from the front to the back, which is obviously absurd. As the writer correctly points out, there would be no need for a lens if there was nothing behind it to interpret the light.

    However, the eye evolved from “back to front,” if you will. Our most basic organisms have little organization, but do possess some photoreceptors throughout their bodies. These photoreceptors are not specific like the eye, but they can interpret light, dark, and movement around them. As we move into more complex organisms, these photoreceptors become concentrated in areas; these areas then invaginate to protect the photoreceptors; these invaginations are covered with aqueous humors for additional protection, which then are covered with crystallin lenses, which finally are given muscles to control light focus so ocular vision can actively control its ability to see clearly at different lengths! It’s an incredible evolutionary process that is not a hypothesis, but can actually be seen and studied by actively following genetic code to construct an evolutionary tree out of living organisms and look at the light-sensing structures within those organisms. This is excellent news to the snail, as he can in fact still see without our complex eyes to get in the way, and us, as we need a much clearer vision than what eyestalks can provide in order to survive.

    Do not believe the author when he asserts that the eye, or any structure, is so complex that humans cannot understand how it works or where it came from. Not only do we have an excellent understanding of the human eye and how it works, we also understand how we got it.

    Keep up the good work!

    1. Wow! So what are you studying?
      Anyway, thanks for the correction Billy. I’ll be more wary of Berlinski in the future.
      The problem is this though: While a slug with more concentrated photoreceptors can survive better than a slug without and pass this trait onto its offspring, the lens coming from nowhere is problematic (a slug covered with translucent scales, maybe?). Worse, it now grows muscles “to” control… but no, growing muscles in order to do something implies finality, and that is not allowed in mainstream evolutionary theory.
      Now I suppose we could think around this and come up with a narrative that does not imply finality, but then it is still just a narrative. And you can see the pitfalls that ID theory tries to exploit. Their point is that if you have parts of organisms developing independently of one another which serve no purpose until they are developed and working together, then the neo-Darwinian school is falsified and we need a new evolutionary theory driven by something other than survival of the fittest + random mutation.
      I’m not ready to jump on the ID bandwagon yet, but this strikes me as a serious challenge.

      1. Billy Maiden · ·

        It’s a good point. The very idea of evolutionary theory is, after all, based on the fact that over time, random mutations will provide organisms to be more well-adapted to their environments. After doing some research, however, I think I can at least address how the lens came to be in place, or at least its position in an evolutionary fashion. In 1996, a paper was published in BioEssays on a gene region known as Pax-6. Pax-6 was found to be an essential gene in coding for crystallin, the protein that makes up the lens. The authors studied Pax-6’s expression across many different species, and looked for overexpression or absence of the gene in question. In humans, a mutation in this region causes serious eye defects. In mosquitoes, an overexpression of the gene causes too many of its compound eyes to be produced. The gene itself is also highly conserved, meaning the DNA code across species is remarkably similar. This hints somewhat of its necessity to the role in eye formation, and that it is something we should be able to find in the genetic code of organisms who do not express a lens. The authors mentioned that ubiquitous crystallins, which are common to all vertebrates and invertebrates, also function as thermoregulators in some invertebrates that express no crystallin lens, with other functions as well in other organisms that do.

        This is an important point in how evolutionary theory functions. Often, enzymes are repurposed or reused for other areas of the body, even when the organism is using those enzymes for other body functions. The ability to create crystallin has had its place in DNA for a long time as an enzyme that had nothing whatsoever to do with vision. Because a mutation occurred where crystallin was recruited to serve another function (the lens), it served as an important evolutionary milestone in eye formation. ID says that parts evolving without purpose and independently of each can’t work, and evolution agrees. Evolution’s response is to use the organism’s own existing genetic material with some mutations to provide a more well-adapted organism in the long run. When an organism could use a clear protein to protect the eye, evolution does not suddenly create an offspring with entirely new DNA that perfectly codes for such a protein.Rather, by way of essentially random functioning, DNA is mutated in hopefully a way that benefits the organism (say, by sending a clear thermoregulating protein to the front of the photoreceptors!) It functions as more of a long-term guiding principle: over time (and I mean looong periods of time) organisms will accumulate mutations that will help it better survive within its environment. The ones that don’t work are eventually removed from the population. There is never an endpoint (unless you consider extinction by natural causes an end). A narrative is indeed probably the best way to think in evolutionary terms, as long as you include some guidelines on how your narrative is shaped!

        Enough with the science, however. I’m in year 4 of 6 of pharmacy school up at Ohio Northern University. I’m having a wonderful time, and we’ve finally finished with the background science and we’re diving right into the medicinal stuff. Thanks for the response! Again, I like reading your blog, and I look forward to more posts.

        PS Here is the study that I reference:

      2. Thanks, Billy, for the clarification and for bringing genetics more fully into the conversation, which isn’t complete without a discussion of the genetic code.
        I’ll have to let you have the last word on the theme since I’m getting close to exhausting what I recall from Biology 101! And please feel free to post here more often, you lift the level of conversation.
        Say hi to your grandparents for me next time you see them.

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