Another Failed Evolutionary Prediction

A common fruit fly, Drosophila melanogaster (click for credit)

The acid test of a scientific theory is whether or not it can make testable predictions about things that are not known. If it can’t, it isn’t really a scientific theory. If it can, those predictions should be tested by observation or experiment. If the results of the test confirm the predictions, you can have more faith in the theory. If they do not, you must either alter your theory or abandon it. One of the main reasons I am a creationist is that creationism has made many testable predictions, and many of those predictions have been confirmed. In fact, creationism has a much better track record when it comes to confirmed predictions than does evolution (see here and here).

Recently, I ran across another study that demonstrates another failed prediction of evolutionary theory. It studied the alcohol dehydrogenase protein (ADH) as made by fruit flies. Fruit flies often consume alcohol because they feed on rotting materials, and the ADH they make allows them to do that. How do they make ADH? They have a gene that gives the necessary instructions to the cell. That gene is, in effect, a “recipe” for ADH.

Studies have already shown that the common fruit fly (Drosophila melanogaster) tends to feed on alcohol-rich things (like rotting fruit) more than a similar fruit fly, Drosophila simulans. The evolutionary explanation that has always been given for this fact is that these two fruit flies had a common ancestor, and that ancestor had a gene that made less efficient ADH. As a result, the common ancestor didn’t eat alcohol-rich things.

The evolutionary line that led to the common fruit fly experienced mutations in the ADH gene, and those mutations ended up making the ADH more efficient. Natural selection then caused those fruit flies to survive, because they could now survive by eating a lot of rotting fruit, while the other flies could eat only a little rotting fruit. That process continued over time, eventually leading to the common fruit fly we see today, which eats a lot of rotting fruit. In evolutionary biology lingo, we would say that the common fruit fly underwent “positive selection” in its ADH gene, while the other fruit fly did not.

While this explanation makes a whole lot of sense, four biologists decided to actually test whether or not it is correct. First, they looked at the differences in the ADH gene between the two species of fruit flies and came up with what they thought would be the “ancestral” gene – the one that was in the most recent common ancestor of the two fruit flies. They then compared the alcohol-digesting ability of the ADH made from that “ancestral” gene and the ADH made from the common fruit fly gene. The evolutionary prediction would be that the ancestral ADH would be less efficient at digesting alcohol than the common fruit fly’s ADH. In a laboratory setting (biologists call that in vitro), there was no difference in the alcohol-digesting ability of the ADH produced by the two different genes.

Of course, an organism isn’t a lab, so they decided to test the ancestral gene in actual fruit flies (biologists call that in vivo). They edited some common fruit fly DNA so that its ADH gene was the “ancestral” one, and they then measured how efficiently those fruit flies digested alcohol. Once again, the evolutionary prediction would be that the common fruit flies with this edited DNA would be less efficient at digesting alcohol than common fruit flies whose DNA had not been edited. Once again, however, that prediction was falsified. Both digested alcohol at the same efficiency.

Well, the efficiency of digestion may not be the key to survival, so the biologists actually did tests measuring how well the fruit flies with the edited DNA survived in the presence of a lot of alcohol. The evolutionary prediction would be that they shouldn’t survive as well as common fruit flies with unedited DNA. Once again, that was falsified. There was no detectable difference between the survivability of the two different fruit flies! The authors therefore conclude that the evolutionary explanation for the difference between ADH genes in Drosophila melanogaster and Drosophila simulans is wrong.

In addition to falsifying an evolutionary prediction that has been stated as fact to many unsuspecting students, the authors have some words of wisdom for evolutionary biologists:

We tested a widely held hypothesis of molecular adaptation — that changes in the alcohol dehydrogenase protein (ADH) along the lineage leading to Drosophila melanogaster increased the catalytic activity of the enzyme and thereby contributed to the ethanol tolerance and adaptation of the species to its ethanol-rich ecological niche. Our experiments strongly refute the predictions of the adaptive ADH hypothesis and caution against accepting intuitively appealing accounts of historical molecular adaptation that are based on correlative evidence.

Many biologists accept evolutionary predictions as fact simply because they “make sense” (are intuitively appealing). As these biologists warn, that should not be the practice of any serious scientist. I tell my students all of the time that science doesn’t have to make sense. It simply has to be confirmed by the data. This is just one of the many, many examples of how evolutionary explanations are not confirmed by the data.


  1. Chris Wirth says:

    Dr Wile,
    Thanks again for the great articles and commentary. I have read on of your well thought out article from the archive that gives a very good data based estimate of appx age of the earth. I have been leaning heavily with my opinion toward a very old earth and universe due in large part to some of the writings of Hugh Ross. I am not completely sold on evolution due to the many holes in the theory, many of which that you have discussed. But it does seem completely possible to me that God COULD have used some version of evolution to bring forth his creation as He has, if he so chose.
    What do you think of Hugh Ross, and also of well respected organizations like Biologos?
    I am a bible believer who accepts biblical authority from Genesis to Revelation, but I dont want Believers to look stupid or irrelevant. You are the best source I (an non-academic laymen ) have found that instills confidence in me for a more literal biblical approach to a Creationist/young-earth position. It has been very refreshing and seems to secures more balance in my thinking. But I wonder how and if you find your comfort zone with these issues.

    1. Jay Wile says:

      Hi Chris,

      Sorry I didn’t respond sooner. I am not sure how I approved your comment but at the same time missed it. I agree with you that God COULD have used some version of evolution to create. I just don’t think there is much evidence that He did.

      I like Dr. Ross a lot. I love his emphasis on design, and I love that he and his organization have developed a testable model for old-earth creationism. I don’t agree with him on the age of the earth, of course, and I don’t think progressive creation is consistent with the data, but still, at least he and his group are taking their task seriously. I am not fond of Biologos at all. It’s not because of their evolutionary stance. I actually think that theistic evolution is more consistent with the Bible than old-earth creationism. Any local flood is really hard to square with Genesis 6-9. I know it CAN be done, but I personally think it can’t be done responsibly. Treating the first 11 Chapters in Genesis allegorically seems a lot more reasonable and has a rich history throughout Christendom (long before people were worried about evolution). Of course, I am not anywhere near an expert on the matter, so I could very well be wrong on that point. However, the main message of Biologos seems to be that people should just believe the scientific consensus regardless of how poorly it compares to the data. I consider that to be amazingly anti-science.

  2. Ken says:

    With so many failed predictions, how is evolution is still regarded as science? I know one of its broader meaning is “change over time” but it seems like animals and organism were programmed with the ability to adapt. Speaking of adaption; is there a difference between: evolution, adaption, and natural selection. From what I’ve been reading natural selection seems like the best explanation of what’s been “observed”. The reason I put observed in quotations could be from my ignorance. How do we observe the past? I know forensic scientists can do that on a crime scene, but even then there’s a margin for error. So how do paleontologist observe millions of years in the past with great accuracy? Science is a wonderful tool. Learning how the designer made things is truly amazing. I read a quote on-line “all that it takes to make men stop thinking are the words – “scientist have discovered.” Once, those words have been announced, there’s no room for skepticism, because the scientific consensus is law. If you don’t mind me asking, what are your thoughts on Bioslogo? In my opinion, some of the authors tend to bash young earth creationist.

    Sorry, for this lengthly reply

    1. Jay Wile says:

      Science has a history of clinging to bad theories long after they have been falsified. Evolution (in the flagellate-to-philosopher sense) is just another example. However, it is losing adherents, as you see committed evolutionists moving away from evolution, and many papers in the peer-reviewed literature questioning key tenants of the hypothesis. The authors in this paper actually give you one answer to your question. Scientists like “intuitively appealing” ideas, and while it is clearly wrong, evolution as a creation myth is very intuitively appealing.

      One of the reasons evolutionists can trick unsuspecting students into believing their creation myth is that the definition of the word “evolution” is routinely changed in classes and textbooks. Sometimes, a text will use it to simply mean “change over time.” Later in that same text, it will be used to mean adaption by natural selection. Other times in the same book, it will be used as a creation myth. In its broadest sense, evolution really is just change over time. We observe change over time in the natural world, so we observe evolution in that sense. We can also observe adaptation through natural selection. The cane toads in Australia are an excellent example of how we are seeing adaptation through natural selection (see here and here). So we see the first two “versions” of evolution. Of course, we can’t see the third version (the creation myth). However, since unsuspecting students are subject to the changing definitions of the word, it leads some to believe that we really have observed the third version.

      Paleontologists cannot observe millions of years with accuracy. They can make predictions about the fossils based on their hypothesis and the compare those predictions to the actual fossil evidence. Of course, those predictions are generally falsified, but that’s okay. To protect their “intuitively appealing” hypothesis, they make up stories to explain around the data. That’s another reason evolution is still considered science. As long as the stories used to explain around the falsified predictions are plausible, those who are committed to evolution as a creation myth can continue to believe it and claim they are doing science.

      I am not a fan of Biologos. Their overall message is that everyone should believe the scientific consensus, no matter how much data stacks up against it. That’s a very anti-science view, and I am constantly amazed that anyone who calls himself or herself a scientist would ever promote it!

      1. Ken says:

        Thanks for your reply. I really like reading all of your blogs and your replies to our questions. A couple days ago, I was in a debate, and I brought up creationism. My opponent said that creationism isn’t testable. I know that some of the predictions that are made is supported by the data, but how can we really test the universe has a designer? Some OEC consider creationism as pseudoscience that cannot really be tested by natural processes therefore its not science

        1. Jay Wile says:

          The way we test any scientific theory is to compare its predictions to the data. So yes, creationism is testable, as is evolution. If we use either theory to make predictions about something that is unknown, we can then test that prediction. If the theory’s prediction is confirmed by the data, you can have more confidence in the theory. If it is not, then you have less confidence in the theory. Creationism can be tested against evolutionism by finding some aspect of nature that they make different predictions about. The one whose predictions are confirmed by subsequent experiments is superior, at least in that particular test.

          So for example, young-earth creationism makes completely different predictions about planetary magnetic fields than any old-earth model. When those predictions are tested (after they have been made), the young-earth predictions are confirmed and the old-earth predictions falsified. This is one of the many ways young-earth creationism has not only been tested, but has been found to be more successful than other theories.

  3. John D says:

    I recently read this article – and found it really interesting.

    I’ve always leaned towards Lamarckian ideas and felt his theory was “proven wrong” far too early. I remember the example I was given in school as Lamarckian evolution as “if you cut off rats tails generation after generation you will see rats without tails after a million generations.” This is obviously false but I also think it is a bad example. True Lamarckian evolution is a response to environmental pressure. (Not in the same way natural selection is though). I would argue that when climate cools the thicker animal coats start to happen as a direct response (not an indirext). From the organism suggesting to every cell in it’s being “I’m cold!”. Or bird beaks changing due to a starving organism suggesting to every cell “good I wish I could just crack this nut!” Natural selection does help to fix these changes into the population but I doubt it’s the agent of change. I think that’s why Darwin has been so successfull – the element of truth but FAR from the whole picture.

    Lamarck also fits in much more squarely with Goulds punctuated equilibrium theory of evolutionary “leaps”. This is what the fossil record clearly shows. This is also the only way any organism could hope to survive rapid environmental change. All organisms would go extinct if they had to wait around for Darwin’s mechanism to give them a new set of plans. Coping mechanisms have to be swift!

    1. Jay Wile says:

      Epigenetics is incredibly fascinating, and it does show that organisms can change in direct response to environment. It will be interesting to see how much change is, in fact, epigenetic. We have already seen cases (like this one) where epigenetics caused adaptation that was thought to be the result of mutation and natural selection.

  4. benny says:

    Seems to me that their “ancestral” gene experiment is flawed from the start due to how they derived this so-called “ancestral” gene.
    The article states:
    “First, they looked at the differences in the ADH gene between the two species of fruit flies and came up with what they thought would be the “ancestral” gene..”
    This basically says they had to interpret some aspects of the data in order to determine what they thought might be a reasonable estimate of the “ancestral” gene. So the “ancestral” gene is, by the very manner of it’s creation, flawed due to this human intervention and must be viewed as suspicious at a minimum.
    Therefore any conclusions derived thereafter must also be treated as flawed/suspicious.

    Human nature being what it is, I submit that it would likely be more satisfying/rewarding to publish a contradiction to some established notion rather than merely proving that which everyone already believed.

    1. Jay Wile says:

      It’s quite possible that they didn’t come up with the best “ancestral” gene, but I don’t think that changes the main conclusion. The gene they came up with is something in between the two fruit flies’ genes. So if the ADH efficiency were the reason behind the difference between the two fruit flies’ genes, their “ancestral” gene should produce a less efficient ADH, even if it isn’t exactly what the “ancestral” gene might have been

      1. Jerome says:

        Dr Wile if I was a scientist I would put most of my research into what I call epigenetic evolution. That God created the first cell or cells with a conscious ability to recognize their changing needs and the ability to alter the DNA of its offspring. God has put all the information needed to make everything we see today and maybe even some we haven’t yet. It leaves God out of the messiness of life’s creation, explains why it can happen in a really short time frame, gives an explanation of where “new features” come from and leaves room for natural selection. I like it. Any biologists reading this comment interested. Come on you know it’s more interesting than regular old “normal evolution”.

        1. Jay Wile says:

          It would take a lot more than epigenetics to do what you are suggesting, since there are a lot more nucleotide bases in the “higher-evolved” organisms than in the “lower” organisms. Nucleotide base changes are definitely not epigenetic. However, the overall idea that you discuss is the same proposed by Dr. Michael Behe. He believes that God created the first organism, and all the information necessary to produce evolution was “front-loaded” into that genome. After that, a combination of genetic and epigenetic changes that had been programmed into the organism took place to produce what we see today.

  5. Bill McClymonds says:

    Based on the comments about Biologos, I thought anyone who wasn’t aware of the book Theistic Evolution: A Scientific, Philosophical, and Theological Critique edited by Stephen Meyer might like to know about it. I’ll put a link to it on Amazon. The book is about 1000 pages with multiple authors of the various chapters.

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