Wednesday, December 21, 2005

Resistance is evolution; resistance is futile

It's one thing to not understand evolution, and another (though related) thing to disbelieve it. It's quite spectacular to be a public front against evolution where nearly every word you speak or write demonstrates your continued failure to understand it in the first place... like this AiG article.

In engagements with creationism, it's quite frequent to see examples of antibiotic or pesticide resistance trotted out as examples of evolution. Indeed, they are examples of the action of natural selection in changing the genetic 'make-up' of organsims. Generally, the examples are pests or microbes. So, how do creationists respond to this? The AiG article states:
But in this example, it was known that this resistance to the antibiotic was already in the bacterial population right from the beginning of the experiment. In other words, some bacteria already had the information in their genes to be resistant. The bacteria had inherited information; so the resistance has nothing to do with evolution.

After having read this paragraph, I was geared-up for how they were going to explain that this is not evolution. However, this is how I've always understood the mechanism of evolution by natural selection: variation among members of the population will cause a variation in how well individuals can reproduce. When these variations are heritable the net effect is that the advantageous variations become more widely represented in the population. Over many generations, there is a growth and eventual take-over of this heritable variation. If this process is continued and accumulated, then continued change will occur. Very simple.

The statement that this was "inherited" information and "has nothing to do with evolution" is downright laughable. I would like to know how the folks at AiG would explain evolution without inheritance.

Lest they should explain their assertions, they follow it up with this classic canard:
Now, what about those experiments where some bacteria developed a resistance to substances over time due to mutations in their genes? Such mutations, which are mistakes in the genes, result from a loss of information (such as the loss of a control gene which regulates the pumping of the substance into the cell). Again, this is the opposite of evolution, which requires an increase in information if it were to occur.

Ah yes - good ol' loss of information. It's never really explained what is meant by a loss of information. A loss of gene sequence? 'Overwriting' the old code? I'm not really clear on what is meant. I can only suspect this options. At the risk of putting words in their mouths, I'll focus on these options until such time as a creationist defines what they mean by 'information'.

The loss of gene sequence: Quite ofthen the case with resistance evolution. Pesticides and antimicrobials often work by 'plugging' into a key protein pathway such as to block biologically necessary reactions. A loss of a certain 'non-vital' part of a protein in a pathway may change that protein's conformation and therefore render the pathogenic agent useless.

The problem is that nobody would disagree that this type of event cannot explain how you get from, say, a self-replicating RNA to a single-celled organism. Well, not by itself (it would be naïve to think that such events never would have happened during that transformation). However, the point is irrelevant because it is wholly wrong that novel traits caused by mutations always evolve this way. Gene duplications are a common source of new adaptive capacities by microbial populations. Given that nearly all our developmental genes represent duplicate/divergent copies of the exact same genes in other animals, duplication events are precisely the type of thing we need to explain major transformations in evolutionary history.

The 'overprinting' of old information. Simply stated: this is not a loss but a changing of information. It's essential for evolution to proceed. Granted, evolution to new environments (say, those containing an anti-microbial substance) will carry antagonistic consequences for adaptations to the old environment. However, this has no effect on the acceptability of evolution. Evolution does not state that organisms are Swiss Army knives becoming infinitely large with gadgets for all environments (would sound more like something an omnipotent creator could do though). No, evolution is far from omnipotent. It is limited, imperfect, and often struggling. It can make the descendents of a fish capable of living on land, but it can't make it a universal fish/tetrapod. It loses some aquatic adaptations for life on the land. Even amphibians carry a cost of their terrestriality (such as dessication, the need to return to water). Aquatic reptiles, on the other hand, must surface to breathe. There's always a cost in evolution. The loss of adaptedness in the old environment in order to cope with a new one is not contra evolution.

The other problem is bias-laden terminology: referring to mutations as "mistakes in the genes". Indeed, they are errors in copying fidelity. Whether or not they are "mistakes" depends entirely on what their effects are. Our genomes are peppered with old genes that don't work anymore. That aside (because even creationists will challenge the 'pseudo' in 'pseudogenes'), a 'mistake' can only be interpreted in light of what effect that copying error actually has - not whether or not it changes the old sequence we're accustomed to.

So to creationists, I say that efforts to undermine evolution through the use of loaded semantics and jargon buzz-wording ('information') are futile. This is a question about data and evidence. As AiG themselves point out, observations can be interpreted different ways. However, some interpretations can be shown to be unacceptable or otherwise useless. Citing difference in interpretation does not permit using demonstrably misleading or deliberately vague interpretation.

2 comments:

c. lopez said...

It seems to me that you are not understanding the creationist argument about inherited information as opposed to spontaneous mutation starting a new line of inheritance. Has their been an observed gene sequence change in a specific bacterium that resulted in that specific bacterium becoming resostant to the antibiotic in question.

Martin Brazeau said...

c. lopez,

Alright, what then is the "creationist argument about inherited information as opposed to spontaneous mutation"?

As far as I'm concerned, it's a moot point. Yes, resistance has been shown to arise from novel mutation. It's very simple: grow your experimental lines from a single cell. The variation that arises will therefore be the product of mutation. End of story.

It's a rather simple experiment, too. We did similar ones in one of my undergraduate labs at McGill. In fact, the lead author on that paper is a good friend of mine and we took that lab together. It's partly how he got involved in the research.