Posts Tagged Natural Selection
Warning: the following contains high levels of derision, for which Qu apologises. He is apparently not the biggest fan of the Intelligent Design movement. Either that or he’s just grumpy today.
LIKE HELL THEY DON’T
Another fun argument from the antievolutionists who fancy themselves smarter than your average bear, this one has become much more common since the rise and subsequent fall of the Intelligent Design movement and the release of Nazi propaganda film Expelled: No Intelligence Allowed*. It’s patently absurd on the very face of it, but that doesn’t stop it from getting about. Here’s a quick, dirty refutation:
AGCT => point mutation => ACCT
This mutation could have all sorts of effects, but it has clearly changed the information content. Of course, how it has changed the information content depends on how you define “information” (something the anti-evolutionists are very careful never to do). There are fewer characters used, so it’s got less information (by one definition). But it’s now more ordered, and it could replace the word “Act” and be legible to an English-reading person, so it’s got more information (by another definition). And there’s still the same number of digits, so it’s got the same amount of information (by yet another definition). But that’s not particularly important for the argument. What is important, is this:
ACCT => point mutation => AGCT
The above can be applied to almost any mutation. Point mutations can be undone by new point mutations, addition and copy mutations can be undone by deletions, deletions can be undone by additions and copies.
Mutations can be undone by subsequent mutations. This is a fact, an observation, a truth, something indisputable. It happens. So if an anti-evolutionist claims that mutations can decrease total information content, then they’re also claiming the inverse: that mutations can increase it.
There is a second even more patently absurd variant of this argument that says “mutations can’t be beneficial”, and usually cites things like sterility and cancer. Yes, cancer. The mutation that causes individual cells to reproduce very rapidly. I would hope I didn’t have to explain that a multicellular organisms “cancer” is a single-celled organisms “beneficial mutation”, but I’ve long since stopped being that naive. The moment you assume a certain level of minimum-intelligence amongst others, one of them will go out of their way to prove you wrong.
“There are two things in the universe that are infinite: the universe, and human stupidity, and I’m not sure about the former.”
– Albert Einstein
Now, for the sake of fairness, I should point out that the people making this argument do have a glimmering of a smidgeon of a speck of a fraction of a gram of an interesting point, though it’s highly doubtful they actually noticed it. The point in question is this: most mutations are indeed harmful or neutral. Very few are beneficial.
Now for an denialist, that’s enough. Case closed, end of story, entire theory of evolution completely disproven because we found some small problem and didn’t bother/didn’t want to/aren’t capable of thinking about it in any depth. For a scientist, it’s a challenge. Why are most mutations harmful? Why doesn’t this stop anything from evolving?
The answer to the first question is a combination of factors, but the primary one is this: we’re already using most of the beneficial mutations for our environment. We’ve stabilised and plateau’d, at least in comparison to the rapid evolution associated with population explosions. I’m actually seeing this in action with Species right now: creatures will very quickly develop simple legs and features, but evolution will then slow down significantly.
The second question, ”Why doesn’t this stop anything from evolving?” can be answered with two words: natural selection. Natural selection works as a ratchet: allowing movement to the left, but not the right. If a beneficial mutation occurs, it will help its host survive and result in it being kept and propagated throughout the population. The hundreds of negative mutations that also occurred were not kept: their hosts didn’t survive, so they were culled from the population.
Not that any of this means anything to the propaganda artists. “Mutation doesn’t increase information” is a useful soundbite because, as I’ve just demonstrated, it needs quite some time to demonstrate to be false. In the time it takes a scientist to refute it, the denialist can have repeated it and other soundbites like it to hundreds of people.
After all, why drop a perfectly good persuasive soundbite just because it’s dishonest?
So… yeah… meh, I dunno… this post kinda got out of hand… whatever…
*footnote: Oh dear, I’m sorry. Expelled features lots of images and references to nazi’s and is a propoganda film. These two things are not connected in any way. Well, okay, they are, but not in the way my wording implied. I apologise for any confusion my completely accidental wording may have caused, which is more than the films producers have done.
Uh oh… he got through an entire post without referencing time travel, eldritch abominations, zombie armies, orbital weapons platforms or the end of the world. That’s a bad sign. I’d better go check the cynical bastards not about to do something stupid, like join a secret society or a cult or a political party or all three…