Science Sundays: The Random Nature of Mutations (or why we won't ever turn into the X-men)

By: Meradeth Houston on 11:18 AM

Okay, so for today's Science Sunday post I thought I'd hit on a topic that seems to be regularly misrepresented in general science stuff on TV and in books. Just this week I saw it messed up in a book I was reading (I won't get into which one, but I've already reviewed it here) and in an episode of the X Files (yeah, I love that show and watch reruns all the time, but sometimes Mulder gets a little jacked up when it comes to basic evolutionary theory).

So, here's the low-down: mutations are random. This means new adaptations that are based on the changes that these mutations create are random. And just because we NEED something to happen in order to survive, well, we can't make that happen just because we want it to. Confused? Let me give an example:

Le sigh, this is just dumb....

Say there's a massive change in the environment that happens really fast, such as Climate Change melts all the ice caps and drowns most of the world's landmasses (yeah, there's been a few movies about this). Well, humans would all do a whole lot better if we could breathe under water, right? It might allow our species to survive. We really *need* that mutation that allows us to have access to our vestigial gills. But just because we need it doesn't mean we're ever going to have a mutation occur that's going to allow us to access those bad boys, a la Waterworld.

In reality, the only way humans would survive this kind of situation would be if someone, somewhere had already had this random mutation (or was born with it in time to make use of it) and this random event allowed them to survive, have offspring, and pass along that mutation for gills (something that was probably pretty hard, seeing as how A. they're probably the only one on earth with gills, and B. human "gills" aren't really gills in the sense that work that way, but whatever, it's just an example).

Hopefully that makes sense :)

Just because we need, want, or would find a particular ability totally useful doesn't mean we're going to get it.  We are constrained by the random nature of whatever mutations occur in our DNA that produce a different phenotype (or outward expression of the genes or genotype) and the right kind of situation that will allow for selection of that phenotype, so that it becomes more common in the population through natural selection.

There has been some recent research into this using bacteria and mutations that allow them to process types of food that were usually harmful or poisonous to them, and finding ways to survive, but the underlying principle is the same: the mutation that allows for the bacteria to feed off something new is still random and not exactly "induced" by the environment.

If we *were* hypothetically able to induce mutations due to need, you can bet your bucks that someone, somewhere would have figured out how to induce mutations for superpowers (probably through lots of radiation, which in reality would just kill you...). Or, induce mutations to change haircolor or texture, or anything along those lines. Right? I mean, if I really, really needed to fly (and I've give a whole lot of money to be able to do so) I'd find some way to induce that kind of mutation. But that's just not how it works.

Bummer, really.

In reality, most mutations that occur and create changes in our DNA, and then in our phenotype, are usually crappy. They lead to things like cancer and a host of other unpleasant genetic diseases. No fun. So, the next time you hear about genetic mutations, think less about the X-men, and more about cancer.

Next time maybe I'll go into the awesome world of Punctuated Equilibrium, another topic that Mulder clearly needs some schooling on... :)