The Evolution Debate: Beneficial Mutations

No, this isn’t actually a mutation, but it does illustrate the point.

In the creationism-evolution debate, one of the most common creationist talking points is that random mutation cannot be the driving force behind evolution, either because it is too unlikely to happen by random chance, or because mutations can’t make any substantive changes to lifeforms. Now, this ignores the fact that evolution doesn’t have a “direction” or “goal” in mind that mutations must fulfill, but that’s really irrelevant. The underlying point, as it is usually formulated, is a very clear assertion that evolution is impossible in principle because random mutation just can’t do it.

This point really comes in two parts:

“There are no beneficial mutations,” AND “Mutations can never add information to the genetic code.”

This topic is moving away from the fossil record for the moment to genetics and laboratory experiments. Of course, the fossil record is still relevant, but we can’t really see individual mutations there like we can in a laboratory.

The basic theory is this: when animals and plants reproduce, with each generation, there is a chance for random mutations to occur in copying their DNA. Many, perhaps most mutations don’t do anything important. They might not even be noticeable. Or they might make some pretty significant changes, like changing color or growing extra toes, without doing serious harm. The point is, they make no difference to survival.

Many mutations will hurt or even kill an organism. There is a long list of birth defects and genetic diseases that are not inherited, but are caused by random mutations in the DNA that slip through the cells’ error-checking functions. Obviously, these organisms rarely survive and reproduce in nature.

But some mutations, evolution says, are beneficial. They will help an organism survive better than the normal version of that gene. A common example is antibiotic resistance or pesticide resistance, where a bacterium or an insect or anything we want to kill mutates to become immune to a particular poison. That certainly makes it easier to survive when we’re spraying poison everywhere, and it’s very important that we understand and account for this immunity.

But if we can see this in the lab or in the wild, why don’t creationists believe it? Well, it’s not quite as cut-and-dry as it looks. Again, a lot of the criticism seems to be based on finding fault with any specific example that’s given. Creationists may say that the mutation is not new information. (“Those bacteria didn’t evolve the ability to digest citrate. That was just repairing a broken gene.” The implication being that it worked when God first created it.) Or they may say there’s insufficient evidence. (“That mutation didn’t create a new gene. You’re just comparing genes that already existed in the wild. You didn’t see them change.”) Or if all else fails, they can say the difference is too small to make the organism a different “kind,” so it’s not evidence for macroevolution. See here and here.

And indeed, it’s harder than you may think to irrefutably prove that a beneficial mutation has been observed. Evolutionists point to a lot of examples, like bacteria developing the ability to eat citrate when that’s the only food available, but I don’t know of any examples of mutations that definitely are (1) beneficial for survival, (2) include new information, i.e. it wasn’t present in either parent, and (3) have been directly observed to change between parent and offspring. I think there may be some demonstrated in a laboratory in the near future, but there aren’t any that are really unassailable.

So how do we change the conversation here? Where are Creationists going wrong in their arguments (intentionally or not)? I think one point that hasn’t been addressed very much is that the whole concept of a “beneficial mutation” isn’t necessarily coherent because the same mutation can be beneficial or harmful in different circumstances.

I’m not exactly talking about the same thing as the famous peppered moths pictured above. That’s a common example because it’s easy to understand, but it is very much about already-existing genes. But the point is, white moths are more likely to survive where trees are light-colored, and black moths are more likely to survive where trees are dark-colored. (This example is also disputed by Creationists as evidence for evolution, but the latest research does support it.)

One example of a mutation that does appear to be new comes from this study, where a population of insects that didn’t have any pesticide resistance before later developed it. This would seem like a beneficial mutation (for the insects), but whether or not it’s a valid example of “new information,” the more important point for this post is that it’s not always beneficial. This study, shows that the gene makes the insects less likely to survive if there are no pesticides around to kill the ones that don’t have it. In a pesticide-free environment, this is a harmful mutation (not lethal, but harmful). In other words, whether or not a mutation is beneficial depends on the context, so you can’t just say that it’s impossible as a blanket statement.

And that is my “Question for Creationists” in this post:

Will you admit that it doesn’t make sense to say that all mutations are neutral or harmful because the same mutation can be either beneficial or harmful in different circumstances?

About Alex R. Howe

I'm a full-time astrophysicist and a part-time science fiction writer.
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