Why Evolution Needs Mutations

I stopped by the Freethinkers table at my school’s activity fair recently. They had a number of tracts on their table. When I spotted one on Evolution, I picked it up. I’ve been writing about evolution for a while and tracts are quick to read. The title: “Evolution in a Nutshell”.

It was a quick read. It was mostly a theoretical explanation of the theory of evolution. It first explained artificial selection, then explained Natural selection and Niches – all things that should be reasonable simple and uncontroversial (at least at the basic level). Then, it proceeded to contrast micro and macro evolution.

Some critics of evolution assert that this only describes “micro-evolution”. They say that “macro-evolution”, where creatures change to form a new “kind” has never been observed. This is like saying that 1 + 1 may equal 2, but no one has ever counted to a million, so it is impossible to get to a million by starting at 1. Or, I can walk to the corner store, but it is impossible to walk across the country.

The answer is the same in each case is the same. Yes you can. All you need is enough time.

ladderThe Case of the ladders

Look at ladder A on the right of the page. Can you climb to the top of the first ladder? Of course. You can climb to the first rung, from the first rung, you can climb to the second, and then to the third and so on. Can you climb to the top of ladder B? Not unless you have extremely long legs. You can climb to the fourth rung, but that’s as far as you get. What then would you say to the writer of the above paragraph when he says

That’s like saying 1 + 1 = 2, but you can’t count from 1 to a million. Yes, you can. All you need is enough time.

Obviously, that person is missing one crucial fact. You don’t need just time to get to a million, you need a path. The reason you can get from 1 to a million is that from any point, you can always add 1 and get to the next number. The reason you can climb to the top of ladder A is that from any one rung, you can always get to the next rung. The reason you can’t climb to the top of ladder B is that there is no path to the top that you can take.

Why am I picking on this one inaccuracy? Because natural selection is the only evidence presented for Evolution in the text. Furthermore, the text asserts that Evolution isn’t blind chance, or random because natural selection isn’t random. They practically argue against the idea that mutations are necessary in the Darwinian theory of evolution. So, their case stands or falls on the efficacy of natural selection. In the tradition of encouraging knowledge and fighting ignorance, I felt obliged to point out their error. OK, you got me. I hate missing a chance to tell someone how wrong they are.

Why are Mutations Necessary?

Point 1: Natural selection, as the term implies, works by selecting from things that are already present. For instance, if you have a basket of fruit, you can select from them based on color, type of fruit, weight, etc. But if there is nothing in the basket, or all the fruits have the same characteristics, selection (natural or artificial) is useless.

Point 2: natural selection works by eliminating characteristics from the pool. Imagine a basket containing red apples, green apples, carrots, bananas, oranges and grapes. Let these be my species. Now, I am the representing the forces of nature, selecting members of a species (fruit from the basket). Any fruit that I like, I eat. Those I hate remain.

Stage 1: I like fruits that aren’t roughly spherical. So, I’m going to eat them out of the basket. This gets rid of the carrots and bananas.

Stage 2: I like fruits that are cool in color, so I eat the grapes and green apples.

Stage 3: I like fruits that are not red, so I eat all the fruits except the red apples.

At this point, I have little to select. I can select the apples based on weight and such, but due to the homogeneous nature of my fruits, I’m not going to get any basket different from what I have. This is what is called a limit to natural selection. It is like the fourth rung on ladder B in the example above. There is no where to go from there.

643px-Explanation of Evolution v2.1
643px-Explanation of Evolution v2.1 (Photo credit: Wikipedia)

Point 3: Natural selection produces a mostly homogeneous collection of a species.  See point 2. Also note the increasing uniformity in the picture on the right.

Point 4: Natural selection often makes species less likely to survive when their environment changes. How do I know this? Imagine my sister shows us and she likes only sugary fruits. Having lost the variety of fruits in my basket, how many of them would she eat? A lot. Imagine my brother then shows up and he loves apples. I now have a total of zero fruits in my basket. Note that if the forces of natural selection (aka me) had not done the selection, my sister would have eaten everything except the green apples, carrots, and bananas. My brother would have eaten only the green apples, and my species wouldn’t be extinct.

The larger the variety in the species, the more resilient it is. The more natural selection that occurs, the less resilient it is.

In conclusion

Natural selection does not create diversity. It depends on diversity being already present. It does not preserve or increase this diversity; it reduces it. It does not make a species more likely to survive. The loss in diversity it produces reduces the viability of the species. So, how exactly does such a process create a progression of species from less complex to more complex and from less diversity to more diversity as the Darwinian theory of evolution requires?

It doesn’t. Mutation does. Mutation is what changes the genetic structure of a species. Mutation can create diversity. Mutation can lead to a more complex species arising from a less complex one. But (and here’s the rub), mutations are the thing that make evolution very improbable and reliant on chance. Don’t take it from me. Take it from this online pro-evolution textbook.

The Secular Student Alliance should not have published that tract.


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I’m Tracy

16 thoughts on “Why Evolution Needs Mutations”

  1. I appreciate the pingback on the article I wrote for Atheonomy. That being said, there are better resources that should be cited; Understanding Evolution (created by University of California Museum of Paleontology), Why Evolution is True (created by Jerry A. Coyne, Ph.D with the Department of Ecology and Evolution at the University of Chicago), and Pharyngula, (created by PZ Mters, Ph.D a biologist at University of Minnesota Morris). I’ll link them below. Most of the content in my comment that follows was culled directly from the Understanding Evolution website.

    There’s more that should be said here about evolution and natural selection. Changes in the genes controlling development can also have major effects on the morphology of the adult organism. Scientists suspect that changes in developmental genes have helped bring about large-scale evolutionary transformations. And natural selection and mutation aren’t the only basic mechanisms of evolution; it ignores migration and genetic drift.

    Migration is any movement of genes from one population to another. Gene flow includes different kinds of events, such as pollen being blown to a new destination or people moving to new cities or countries. If genes are carried to a population where those genes previously did not exist, gene flow can be a very important source of genetic variation. Sex can introduce new gene combinations into a population and is an important source of genetic variation, too.

    Genetic drift is the change in the frequency of an allele in a population based on random sampling. Some particularly fit individuals are just in the wrong place at the wrong time and get eaten, for instance, while other ill-adapted individuals are spared based on sheer luck. Genetic drift affects the genetic makeup of the population but, unlike natural selection, through an entirely random process. So although genetic drift is a mechanism of evolution, it doesn’t work to produce adaptations.

    You were right to point out where the folks at the Freethinkers table simplified perhaps a bit too much, but you could have elaborated more here, also. Thanks again.




    1. I understand. My purpose was not to say everything there is to say about this topic nor was I under the impression that natural selection and mutation are the only factors. The tract also mentioned Biomes and migration. However, while Biomes, migration and genetic drift are not natural selection, they are like it. They require that diversity already be present. They can change the frequency and location of what they already have and they can throw away some of it, but they can’t add. If they alone were it, under no conditions would a do single cell (or even a number of cells) produce the diversity of life around us.

      1. …but they (mechanisms of evolution) can’t add (diversity).

        Au contraire. They can and do and we have compelling evidence for exactly this supported by multiple lines of inquiry.

  2. Tracy, may I suggest that when confronting a scientific theory and believing one’s self justified in criticizing it for what appears to be a problem, look more closely. One will almost always find that it has been successfully addressed already. Don’t walk away thinking the critical observation remains valid; presume the error (or mistake as you say) is yours and this will take you far in gaining not just knowledge but insight.

      1. As hartm242 said, perhaps the problem with the handout was that it tried to be too simple. But you wrote that diversity had to already be present because biomes and genetic drift could not alone cause new information. This is factually wrong as the The problem here is that all genetic change requires change at the genetic level, obviously, so I assumed you meant that change was the only mechanism, a cause, that is to say, to add new information. In fact, genetic changes can be and are a response to environmental interactions, an effect if you will, rather than a cause. I do not think you understood this point but assumed that only genetic change caused evolution, which is clearly not true as the Lenski experiment shows. Evolution demonstrably causes diversity. You seem confused in this matter.

      2. I think we’re on different wavelengths here.
        Darwin’s theory of evolution (aka Evolution): The theory that all life on earth has evolved from less complex, less diverse organisms to the complexity and diversity we see today.

        Evolution: the process by which new and different species arise from already existing ones.

        This evolution is purported to be brought about by various things: genetic drift, mutations and natural selection are examples.

        My point was that of those three factors, only mutations have the ability to create new genetic information. Natural selection selects from what we already have. Genetic drift changes the proportion of what we already have.

        Of course, mutations happen in response to the environment. Of course, evolution involves a change in the diversity of living things but Evolution doesn’t cause the change. Evolution is the change. Natural selection, etc. are what cause the change (evolution).

  3. By the way, I disagree that the publication’s fault was in being too simple. It attributed evolution solely to the powers of natural selection using predator-prey relationships and competitions. It then piggy backed on that assertion to the conclusion that evolution has no randomness to it because natural selection is not random – as if mutations played absolutely no part.

    That’s like attributing the existence of living things solely to water and then arguing that living things exist wherever there is water. It’s not being simplistic. It’s being wrong.

    1. Hang on: what is “it” that is being selected? Obviously, when all is said and done, “it” is a slight genetic variance ‘selected’ by reproductive fitness. You presume to link genetic variation with randomness but that doesn’t matter in action. It’s not genes doing the selecting here for reproductive fitness; it’s a mechanism we call natural – and the opposite of random – selection. So although genetic variation may be randomly produced, the selection of which random genetic variations are passed on is natural and not random selection. Natural selection accounts for what genetic variation is passed on.

  4. Not having seen the publication myself, the thought of arguing over what it included or did not include seems to be a terrible use of our time. So does arguing if and why it is wrong, and if so, to what extent.

    Yes, the ultimate source of genetic variation is mutation.

    Yes, natural selection tends to reduce genetic diversity by eliminating individuals (and the alleles that they carry) from the gene pool.

    Yes, genetic variation is maintained by mutation, migration, and environmental variation.

    Their pamphlet probably sucked. It was made by undergraduate students who don’t have as firm of a grasp on biology as their professors do. Advertise better resources for people to check out.

    1. No, you forget that evolution has attained the highest possible standard in science by becoming a theory. This means it has “all the necessary evidence” and has passed all challenges to it. It is fully supported by all the evidence. All. There is no challenge to it. That’s why it is a foundation of modern biology – without which our applications, technologies, and therapies built on this understanding make no sense.

      Look, you sometimes will have religion without creationism but you will always find creationism linked to religious – and not scientific – belief. It is a lie – plain and simple – that there is any scientific controversy over the explanation we call evolution. The only controversy comes from the contrary religious belief in creationism backed up by zero evidence. So let’s be very clear and honest here: the accusation about having the conclusion before weighing all the evidence lies solely and wholly with the religious who want to support some form of POOF!ism for their belief in creationism. Accusing others who accept the strength of this theory because it has successfully met all challenges from reality to be assuming an a priori position is a major distortion of what’s true.

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