A lot of creationists believe that mutations can’t “create information”, they can only destroy it. They like to imagine making random changes to a book – it always ends up making random gibberish – thus, random mutations must do the same thing to the genome, right? Wrong. This misconception is so widespread, I thought I’d go ahead and prove that random mutations can create information.
First, I should say that creationists use a rather subjective definition of information. They aren’t talking about Shannon information or anything like that. Instead, “genetic information” is synonymous with “useful genetic sequences”. It’s not something that can be measured, and it’s highly contextual (a useful sequence in one creature might be completely useless in another creature). Despite the subjectiveness of the definition, we can all agree that genes do something useful in the body, that the genome contains a high concentration of useful genetic sequences (in comparison to say, a randomly generated DNA sequence).
So, let’s use the creationist’s definition of genetic information. Let’s say that we have a small sequence of DNA consisting of 90 nucleotides. We’ll call this Sequence A.
Let’s also say that we have another DNA sequence which is identical to Sequence A except that it is different in just one codon. We’ll call this Sequence B. There are three possibilities for the Sequence B: it does something better, equally well, or worse (perhaps not at all) than the Sequence A. (In creationist language, it contains more information, the same information, or less information than Sequence A.)
Now, if a point mutation happens to occur to Sequence A or Sequence B, it will alter it at one codon. Given the number of nucleotides (90) and the fact that there are three possible other codons at each location, the odds of a point-mutation turning Sequence A will turn it into Sequence B is 1 in 270. Similarly, the odds that a point-mutation will turn Sequence B into Sequence A is 1 in 270. So, both sequences can be converted into each other. But, we said earlier, that we don’t know if Sequence B is more useful, equally useful, or less useful to the creature than Sequence A. If Sequence B is more useful than Sequence A, then the mutation changing Sequence A into Sequence B (1 in 270 odds) is an increase in information. If Sequence B is less useful than Sequence A, then the mutation changing Sequence B into Sequence A (1 in 270 odds) is an increase in information. Thus, if A > B or A < B, we can prove that information can increase.
Once the mutation exists, natural selection either drives it into extinction – if harmful, or causes it to proliferate in the species – if useful.
Counterargument 1: A creationist once counterargued that, since the sequences can be inter-converted, that both sequences must have the same amount of information. Because I haven’t even told you what the actual sequences are, then his “equal information” argument must be true for all possible sequences A and B. In order for his argument to work, this means all possible 90 nucleotide sequences must have the exact same amount of information. (This is because it’s possible to convert any sequence X into any other sequence Y via a finite number of single-codon changes. If each single-codon change results in 0 information change, then all sequences X and Y have equal information, no matter how different they are.) Since there is nothing special about 90 nucleotides – he has to argue the absurd position that all possible sequences of N nucleotides contain the same amount of information. And since insertion and deletion mutations can alter the number of nucleotides, then (by his logic) all DNA sequences containing any number of nucleotides must contain the same amount of information.
Counterargument 2: “But evolution can’t explain complex systems”. I typically interpret this response as “I don’t want to admit you’re right. So, I’ll bring up a related – but different – topic.” This example does show an increase in information, and there’s not much sense in moving-on to other topics if creationists aren’t willing to admit it when it’s made obvious. Besides, if they can’t admit that mutations can produce “new information” when it’s made plain, then talking about other topics are unlikely to be fruitful.
Counterargument 3: “The second law of thermodynamics prevents an increase of information.” First of all, creationists are misapplying the second law of thermodynamics to make it say something that it doesn’t say. Second, what if it were really true that mutations can’t accidentally produce an increase in information? In order for mutations to never create information, you have to accept a whole bunch of absurd conclusions. First of all, the random mutation would have to understand how that gene functions in order to avoid causing an accidental improvement. They have to argue that a mutation can turn a fully functional gene into a weaker version, but once that weaker version exists, mutations will explicitly avoid any change that would convert it back to it’s original form (in spite of the mathematics). Additionally, it would have to understand how that gene works within each specific creature. Because the sequences are context specific (i.e. depending on the creature’s biology), then it’s possible that Sequence A will function better in Creature A, but Sequence B functions better in Creature B. Do mutations “know” to allow and avoid the specific mutations based on creature type? In Creature A, a mutation can turn Sequence A into Sequence B, but never the Sequence B into Sequence A? And vice-versa in Creature B? Of course not. The sequences and mutations are completely blind about what effects the mutations have, and that means that they can accidentally increase the information.
Second, if Sequence A contained more information than Sequence B, then we could take a million copies of Sequence B, expose them to mutagens until each of them had a single point-mutation, then look at those million mutated copies, and (against all laws of probability) none of them would have been turned into Sequence A. If true, it would allow scientists to accurately produce a hierarchy of genetic sequences sorted from “contains more information” to “contains less information”, defying all logic about how the universe works. If true, it would allow scientists to perform all kinds of miracles – because the mutation would explicitly avoid any increase in information – biological or otherwise. You could learn secret information by looking at what sequences it seems to avoid. Take a billion copies of the human hemoglobin gene, and expose it to a mutagen. Any sequences which never appear in the results would be stronger versions of the hemoglobin gene. Of course, the universe doesn’t work that way.
Counterargument 4: “Your example shows an increase in information in one case out of 270. What about the other 269 cases? If some of them are negative, then the average result is a decrease in information.” That’s true. The average case probably is a decrease in information. But, that’s where natural selection steps in. Natural selection drives the negative mutations out of the gene pool (because the creatures that have the negative mutation are less likely to survive or reproduce than the rest of the population). Natural selection also promotes the spread of positive mutations throughout the gene pool. This gives the (rare) positive mutations a huge boost over the (more common) negative mutations.
Counterargument 5: If mutations can be positive, then why do our bodies have mechanisms to prevent and reverse mutations? Mutations are a mixed-bag. Some are positive, some are neutral, and some are negative. There a probably a lot more negative mutations than positive ones. This means it’s critical to keep the number of mutations low – so that positive and negative mutations can be sorted by natural selection. Here’s an example: let’s say that you are playing a game. You pickup a random card from a deck, and whenever you get an Ace, you win. Whenever you pickup an 6 or less, you automatically lose. All other cards are a draw. Clearly, the game is stacked against you – 1 out of every 13 cards is a winner, but 5 out every 13 cards is a loser. Except there is one additional rule: you can bet between $1 and $10 on each round, and you get to decide how much to bet after you see your card. Of course, whenever you pull an Ace (1 in 13 odds), you bet $10. Whenever you pickup a 6 or less (5 in 13 odds), you bet $1. (This resembles the way natural selection magnifies the value of positive mutations, and minimizes the damage of negative mutations to the gene pool.) The result is that the game is now in your favor. Now, imagine if the rules were changed slightly: instead of picking up one card, you have to pickup two cards at a the same time (i.e. an increase in the number of mutations). In a few cases, you’ll pickup two Aces or an Ace + 7 or higher, and you win $10. But, in other cases, you’ll pickup an Ace and a 6 or less (resulting in a loss). In this example, the result of this change is that players win 15% more frequently, but get a losing hand 60% more frequently – because the losing cards are more likely to show up. If we pickup three or four cards at the same time, it gets even worse. When we calculate the average winnings per hand:
Single-card rules: (0.077*$10) – (0.385*$1) = +$0.385 per hand
Two-card rules: (0.089*$10) – (0.621*$1) = +$0.269 per hand
Three-card rules: (0.077*$10) – (0.767*$1) = +$0.003 per hand
Four-card rules: (0.059*$10) – (0.856*$1) = -$0.263 per hand
The same thing with mutations: high rates of mutation means more positive mutations, but it also means more negative mutations. If you happen to get a positive mutation and negative mutation at the same time, then the creature might be dead – preventing the spread of that one positive mutation. In the end, the best solution is to keep the number of mutations low – and that makes anti-mutation mechanisms useful.
Saying “creatures have mechanisms to prevent mutations – therefore mutations must always be bad” is a little bit like saying “animals have mechanisms to prevent swallowing too much food at one time – therefore food must be bad”.