Evolution in Theory

Discovering the means of mutation
Discovering the means of mutation (Photo credit: Noah Sussman)

I know someone who is a deist, but looks on the Darwinian theory of evolution with disdain. To put it mildly, he doesn’t believe in evolution. He frequently posts article on the facebook page that he believes undermine the theory even if those articles are written by people who accept evolution and do not posit that their findings contradict the theory. For instance: Widespread horizontal transfer of retrotransposons and Bacteria May Readily Swap Beneficial Genes: Microbes Trade Genetic Coding for Antibiotic Resistance and More. I say that to say this: in my previous post on evolution, I criticized its supporters’ chronic lack of civility, from insisting that those who reject evolution do so because of their religion to calling them stupid, ignorant, and wicked. I’m newly short tempered so anyone who issues such responses on this post is in for a surprise (no, you will not be banned).

Evolution in Theory

One can explore the theory of evolution in two ways. Firstly, by thinking about it and evaluating its plausibility and possibility and secondly by exploring the physical evidence to see if it really did happen. This is an important distinction because it is perfectly possible for a theory to be both plausible and possible, but not be the case. By way of illustration, it is possible that I cheated on my JSCE. It is also plausible because I, being human, often do wrong things. But it did not happen. On the other hand, if an idea is possible but not plausible, one can rationally reject it in the absence of very strong evidence in its favor.

Is Evolution Possible?

Diagram of mutation and selection in evolution.
Diagram of mutation and selection in evolution. (Photo credit: Wikipedia)

The theory of evolution goes something like this: Organisms adapt to their environment. Organisms of the say type often vary in specific ways. If one of those organisms is different from others in a manner that benefits it, it is more likely than its peers to survive to maturity and pass on its genes. This creates a slow shift in which said characteristic becomes dominant in that species. If this goes on long enough, you eventually get a type of animal very different from the original. This process of change as a result of natural selection is referred to as evolution. Note that in order for this to work, those traits being selected must be genetic or they could not be passed to offspring.

Of course, natural selection won’t work on its own because you need the group of organism to possess genetic characteristics different from each other. Or there will be nothing to select. Think of the very first living cell. It produced offspring and passed its characteristics to them. How then did those offspring become different from each other? That would only happen if the organism failed to pass on its genes faithfully to its offspring.

So the theory of evolution can be summarized thus: Genes can be mutated, creating diversity in the offspring of a particular organism. Those organisms are then selected by their environment because those best able to reproduce do better than the rest. If this process goes on long enough, we get a huge array of living organisms.

I have told a story that sounds possible. It could happen. So did it?

Is Evolution Plausible?

PhotonQ-Homer' s Evolution Theory
PhotonQ-Homer’ s Evolution Theory (Photo credit: PhOtOnQuAnTiQuE)

The whole bulk of evolution hinges on the issue of mutation. Without that, there would be nothing to select. If the first species was terribly unsuited for its environment, it would simply die out. Even already existing species could not change into new ones. Each species would have to be built from scratch. I don’t know anyone who thinks that humans could be built from scratch with no guiding intelligence. We haven’t even been able to build a single cell with guiding intelligence. So, even if that was possible, it would take a damned long time for the diversity we see to  appear; probably longer than the earth has existed.

So, is it plausible that millions of mutations produced the diversity of life on earth? Let’s first get something out of the way: mutations happen. That said,

1. Most mutations are harmful: To make that obvious, consider this example from the University of Utah’s genetics program

Thesunwashotbuttheoldmandidnotgethishat.

Dividing the string into three letter words produces a sensible sentence: “The sun was hot but the old man did not get his hat.” You can try to mutate the sentence, but you’re more likely to get a nonsense statement than a sensible one. For instance, let’s pick a letter to mutate. The ‘b’ in ‘bat’. If we mutated the ‘b’ to ‘h’, we would get ‘hat’ and the sentence would still make sense (somewhat. It wouldn’t get a good grade). However, most of the letters of the alphabet won’t have the same effect. If you picked a letter of the alphabet at random, you would most likely get something like an ‘e’ or a ‘g’, which when substituted for the ‘b’ in ‘bat’, completely ruins the sentence. So going on blind chance only, it is pretty darn unlikely that a mutation would produce a good result.

This ‘bad luck’ can be worked around. As this source makes clear, if the organism accidentally gets two copies of the same gene, one copy can be mutated while the other remains the same. That way, as long as the mutated gene doesn’t dominate the other, work can be done on the other one without killing the organism. Remember that these mutations are all happening by pure chance. Don’t imagine that there are some intelligent choices are being made.

The one issue I instantly see with this is that the mutated gene cannot be selected if it is not in effect. However, if it is in effect, this particular benefit arising from the duplication would be of no use. So, this requires that all modifications of the gene be mutations and that those successive mutations eventually produce something useful. Then that gene has to become dominant.

Here’s the math*:

P1 = Probability that a gene is duplicated X Probability that one of the genes is mutated beneficially X probability that the mutated gene is not dominant (at all stages of its mutation) X Probability that if and when the gene eventually comes online, the changes it has are beneficial.

You can probably tell that I’m not very optimistic about the chances.

2. It gets worse. After all the trouble necessary to create a working mutation, most mutations affect only a single protein product; a tiny change. So in order to create an organism with phenotypic (visible) differences from its parent, you need a lot of mutations. You need the group of genes responsible for that characteristic to be mutated in specific beneficial ways such that they are still compatible with each other. The previously mentioned article argues that this problem can be made easier. Often, some of the genes in that group have a bigger effect than others. So, the more of the more important genes mutated, the more significant the changes in the phenotype. It’s not a breakthrough but it moves the necessary events from really really really unlikely to about really really unlikely.

The math:

P2 = Probability that all the genes responsible for said trait are mutated (or not) in beneficial and compatible manners.

So, the composite probability that a minuscule change in the characteristics of a species occurs = P1 X  P2. Fat chance, huh? And we haven’t even specified that the change in phenotype be beneficial (note that this is different from the change in the genes being beneficial), nor have we gotten into the details of natural selection.

In Conclusion

I’m a huge believer in chance. If a mail arrives in my box with the name of a high school classmate on it and she doesn’t even know my  address, I’ll chalk it up to chance. However, If I arrive home to find a beautiful intricate house of cards on my dining table, you’d better believe I’d be looking to see who broke in. It’s possible that the cards just fell of a shelf and happened to make that house, but I’ll probably never believe that.

This does not mean that evolution didn’t occur – even a little bit. But it does predispose me to the belief that it is not the sole explanation for the diversity of life on earth. It’s possible, but not plausible. My next post on this topic will explore the question of whether there is evidence for the theory.

______________

* My probability might be rusty. If I made any huge mistakes, please point them out. The calculations are only supposed to be approximate.

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Published by

Tracy

I’m Tracy

7 thoughts on “Evolution in Theory”

    1. If religion is so flawed, why is it a pillar of every society in the world (except the ones that ruined themselves overnight)?

      I don’t know the answer to either of those questions but I’m pretty sure there are lots of reasons why people believe and build intricate structures on false beliefs.

      Like people keep telling me, evolution selects for survival, not truth and the things that we believe to keep us alive need not be true. Maybe the answer to both is evolution or stupidity, or a reluctance to face the truth or aliens playing with our brains.

      But your question is not an argument against my claims. If you’re going to imply that evolutionary theory is strong, respond to my arguments.

      1. Sure, Tracy.

        Evolution is true because it works for everyone everywhere all the time. This actually matters. We build applications, technologies, and therapies based on this explanation. The test results show that the explanation continues to work. And this, too, matters.

        In comparison, religion does no such thing so your counter question is nothing more than a “Quick! Look over there!” tactic. Appealing to a religious vs scientific popularity aspect is hardly a reasonable approach to explain why modern biology accepts evolution to be true. In fact, it’s a really poor diversion.

        I had hoped my question would get you to open your eyes past your own belief about what you assume is a shortcoming in evolutionary theory. For that belief to be reasonable, we must assume that the tens of thousands of working biologists missed the memo you happened to catch on horizontal transfer. Maybe, just maybe, they didn’t miss it at all but and have incorporated this (now widely accepted) mechanism into population genetics. The criticism you raise has been taken seriously, well researched, peer reviewed, and incorporated because the evidence shows that it works. And Lo and Behold! the theory still stands.

        Go figure.

        One might think an educated mind willing and capable of critical thinking would take this fact into serious consideration and find out how what was presumed to be a fatal flaw actually supports the theory in practice… rather than assume it is fatal flaw overlooked and ignored by tens of thousands of professional scientists. To believe the latter shows a pretty strong arrogance to assume a really bad answer rather than a willingness to learn. And the reason why someone might chose a really bad answer can often be directly linked to a desire to accommodate a religious belief.

        Funny, that.

      2. I believe you have mistaken my argument for something else. My argument was that as far as probability is concerned, the idea that all the variety of life on earth was produced by natural selection and random mutations is so improbable as to be laughable. You responded by asking why the theory is widely accepted.

        I responded that I do not know but that such a response is not a criticism of my argument that the odds are strongly against it. and that your response is akin to replying to the statement ‘God’s existence is very improbable’ with ‘why do so many people believe in him, then?’. It’s not an appropriate response.

        This improbability has not been missed by biologists (case in point: Richard Dawkins and the article I got my two criticisms from). And even if it had, so what? God doesn’t exist just because so many people believe he does.

        Now, you’ve responded by saying that evolution is true because (as this is the most charitable explanation of your argument that I can make) it is (a) useful in making stuff and (b) the test results show that it is still useful for making stuff. Did you learn somewhere that something’s usefulness is indicative of its truth or are you simply expressing an idea badly?

        In either case, that’s not the point here. The point is: “If you believe that the theory of evolution is not vastly unlikely to be true by the calculations of probability, I’ve laid out, why do you think so?” That’s the topic here. If you want to talk about something else, by all means talk about it. Just don’t annoy me by insulting my intelligence and willingness to learn because you can’t stay on topic. It’s the height of discourtesy to that that as a guest in someone’s home.

      3. as far as probability is concerned, the idea that all the variety of life on earth was produced by natural selection and random mutations is so improbable as to be laughable.

        But the probability staring you in the face is P=1! Your beliefs do not change this fact one iota. A variety of life does exist here on earth. Now if you try to explain how this came to be without dipping into the god-of-the-gaps argument, what is laughable is your belief that P=1 is just too improbable to be true. And yet it is.

        Bummer, eh? Your belief is wrong. And should have known this before making such a post.

        What we have is a theory of how life changes over time. The use of this scientific term should have immediately alerted you to its overwhelming explanatory power, and that if you disagree with it for some reason you think is important, realize that you stand against the scientific consensus with your opinion alone. This should make you feel (at least somewhat) abashed at your pertinence.

        Of course, you have every opportunity to compete against this consensus as long as you have compelling evidence from reality to substantiate it. This you (and all those who continue to mistakenly call the understanding of evolution to be a belief) clearly do not have or you would produce it and win a Noel prize. This should be a clue why your opinion is wrong.

        The point I raise is that you stand against a scientific theory without compelling evidence, but still feel as if your mathematical model for improbability carries some equivalent weight, which it clearly doesn’t because the probability is 1. This contrary opinion you continue to hold means you elevate your contrary belief to be equivalent to that which has successfully become a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. In other words, reality has arbitrated the hypothesis to be true in all cases, and thus has become a theory… not because a bunch of addled scientists or those dedicated to promoting some dogma have been hoodwinked. The theory has been able to incorporate ALL the evidence into its explanatory framework… in spite of your contrary belief that it is too improbable. This is what you stand against when you proffer an opinion contrary to a scientific theory and this is why I specifically asked you why the theory is a foundation of modern biology… to see if you truly appreciated what the term ‘theory’ actually meant.

        You didn’t. That is lack of education, a lack of literacy needed to understand why your contrary belief is wrong from the beginning. I tried to show on a practical level why we can have great confidence in the theory even if we aren’t sure or don’t know enough about evolution to be as confident as the 95.6% of professional biologists who understand why evolution is true.

        If the theory were not true, then we would see this reflected in reality. In fact, should reality produce such evidence, then and only then would the theory require revision. In spite of huge swaths of misinformed and misguided individuals who believe the theory is in some kind of crisis, reality continues to confirm it as we incorporate it into advancing our knowledge and applications, therapies, and technologies based on it. As many scientifically literate people have stated to the misguided, nothing in biology makes sense outside the evolution paradigm. Nothing. Inserting a god-of-the-gaps argument doesn’t alleviate this problem one bit. Biology makes sense, allows us to successfully predict, to confirm new avenues of practical knowledge, to inform why the stuff you use works to cause a desired effect, within this evolutionary framework you are willing to reject because you believe it is too darned improbable! Your belief alters nothing, and certainly doesn’t alter or effect how and why evolution is true.

      4. You’re talking past me. You didn’t respond to the probability I calculated in my post. All you did was assert that the probability that evolution is true is 1 (really? I had no idea inductive arguments could be so definitive) and declare that because scientists have seen fit to call it a theory, it must be trustworthy and my argument against it fails – even though you haven’t addressed the argument. Of course, scientists have never changed their minds about any theory.

        This is a pointless conversation. Let me know when you want to respond to my post.

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