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Maybe random mutation isn’t the sole engine of evolution after all

by Greg Krehbiel on 19 February 2012

If you listen to the rhetoric on the so-called “science blogs,” you’re a heretic, a creationist and a moron if you so much as question the idea that random mutation provides sufficient material for natural selection to bring about the kind of evolutionary changes we see in the fossil record. (At least that’s how it seems to me.)

If someone were to say, “I don’t think random mutation is enough to get the job done. The odds are just too small.” Wouldn’t it be reasonable for a scientist to say, “It’s possible you’re right. There are other sources of genetic variation that we know of, and there might be more we haven’t discovered yet.”

But that’s not what usually happens. The idea that some other force may be necessary to provide the required changes is mocked and scorned. This is not because anybody has proven that random mutation does all the work. (How could they?) It’s simply because they’re scared to death that opening the door to some other factor may leave room for that guy upstairs.

The reaction prompts religious people to think that what’s really going on here isn’t science, but hatred of God. And they have a point. It often seems that’s the real motivation. But the similar reaction against any hint of Lamarchism undercuts that argument. It seems it’s really more of a “circle the wagons” kind of thing. Probably combined with poor social skills.

I find the Spanish Inquisition-like reactions self-defeating and unscientific. The first step in the quest for knowledge is to say “I don’t know.” Insisting that random mutation is good enough, and there’s no need to look for any other mechanisms, is at least as counterproductive as that cartoon where the guy inserts “then a miracle occurs” in his equation.

How do we know that the environment never affects heritable characteristics? How could we possibly know it?

The truth is that scientists have not ignored the possibility of other mechanisms. What I see repeatedly is that when they’re talking about science, they’re open to other ideas. Maybe the environment can affect heritable traits. Maybe the randomness of mutations goes beyond stuff like transcription errors. Sometimes other weird things are going on, like horizontal gene transfer.

I don’t pretend to understand everything being discussed in this article — A Biochemical Mechanism for Nonrandom Mutations and Evolution — but it’s clear that the author is trying to understand what’s going on, not trying to Defend Doctrine.

In the last couple decades some really cool stuff has surfaced. As you might expect, life is far more interesting and complicated than we thought. I’m convinced that in the next decade or two we’ll find mechanisms going on in our DNA that make all the theories from 30 years ago seem like medieval nonsense.

It seems inevitable. Scientists used to regard cells as little more than puddles of goo in a balloon. They had no concept of transcription errors, recombination, repair, or any of the stuff that’s common knowledge today, including the incredible molecular machinery. Scientists are only beginning to understand all the wacky stuff that goes on in there. I think it’s very unlikely that the old theories will remain unchanged.

Which is one of the reasons I have a hard time reading the science blogs. They need to add a double espresso dose of intellectual humility to their daily routine.

-- 2012-02-19  »  Greg Krehbiel

Talkback x 8

  1. John Krehbiel John K
    19 February 2012 @ 11:20 am


    Good grief! Sorry about the all caps, but I really, really get tired of repeating myself on this one.

  2. John Krehbiel John K
    19 February 2012 @ 11:22 am

    How do we know that the environment never affects heritable characteristics? How could we possibly know it?

    You’re kidding, right. Three words; nutrition affects height.

  3. Greg Krehbiel Greg Krehbiel
    19 February 2012 @ 12:22 pm

    And I’m tired of repeating myself on this.


    John, I went to a science and tech high school. I have a science degree. I have been involved in science debates for years. I have watched these issues, read countless books and articles, for many, many years.

    I am not saying that serious scientists say that random mutation is the only driving force of evolution. I am saying that the popularizers, the debaters, the science teachers, the bloggers, etc., often say this.

  4. Greg Krehbiel Greg Krehbiel
    19 February 2012 @ 12:40 pm

    Here is an article attempting to reply to the “there isn’t enough time for evolution” article. The point of the article is to say there is enough time, but it doesn’t attack the fundamental premise — that the creative material all comes from random changes. (Pharyngula’s blog post on the study does the same.)

    Here is a very short article on “misconceptions” that addresses randomness. It says the non-random part is selection. IOW, it does not admit that there may be some non-randomness in the generation of new material for selection to work on.

    It took me all of five minutes to find this. It’s all over the place.

    If somebody doubts evolution because they don’t believe random changes are good enough to cause it (i.e., to create all the new material for selection to work on), the correct response is, “okay. Random mutation can do some things, but it’s also possible something else is going on.”

  5. John Krehbiel John K
    19 February 2012 @ 2:29 pm

    Neither of those is relevant.

    You said that random mutation isn’t enough to cause evolution. Neither of those articles addresses that question. Your argument is a straw man because NOBODY except creationists claim that random mutation is the only cause of evolution.

    There certainly are cases where certain kinds of mutations are made more likely by environmental factors. But mutations are “random” in the sense that they are not a response of the need of an organism to get a particular new mutation. A few interesting counterexamples don’t change that general fact any more than some guy correctly predicting 12 consecutive coin tosses on one occasion makes coin tosses nonrandom.

  6. Greg Krehbiel Greg Krehbiel
    19 February 2012 @ 2:49 pm

    It astonishes me that you continue to make claims like this.

    … NOBODY except creationists claim that random mutation is the only cause of evolution.

    How long do you think it would take to refute that?

    Here. This took about a minute.

    This conception of genetic changes as accidental and unique, about which no laws may be formulated, is fundamentally flawed, for all that it reappears in a number of influential works on evolution. Causes of genetic change are being uncovered routinely, and they involve better or worse understood mechanisms that are very far from random, in the sense that there are very clear causes for the changes, and that they can be specified in detail over general cases.


    This is from a site dedicated to explaining the “mainstream scientific perspective,” and it admits exactly what I’m saying.

  7. RootCzar
    20 February 2012 @ 11:04 pm

    Why are multitudes of internet articles of whatever origin ok to substantiate your point on the ‘theory’ of evolution, but not ok to substantiate climate change?

  8. Greg Krehbiel Greg Krehbiel
    21 February 2012 @ 7:20 am

    If the question is for me, the issue is what it is you’re trying to establish.

    I’m not trying to establish any fact about evolution other than that people have taught and advocated a particular perspective on it (i.e., that random mutation is the sole source of new raw material). IOW, I’m not trying to demonstrate something about evolution, but about the way it is presented.

    When it comes to global warming, I’m not talking about how it’s presented, but the reality.

    And before you start, my position is not out of the mainstream and it does not deny any “scientific consensus.” The consensus — to the extent there is one — is that CO2 is a greenhouse gas and that human action is affecting the climate. I’m okay with that. There is no consensus, so far as I can tell, on how much human action is affecting the climate, or whether it’s possible or even worthwhile for us to try to reverse it.