Microevolution

I get really confused and depressed when people misunderstand evolution badly enough to use the word microevolution. Creationists often love to fall back on the old “microevolution is real, but macroevolution is a lie!” trope. I don’t get it.

Microevolution is macroevolution. Evolution is evolution! What creationists call macroevolution is just evolution taking place over relatively long periods of time. What does that mean, “relatively long?” It means “long enough for populations to deviate enough from one another that we perceive them as different species.” The only part of that definition that differs from what they call microevolution is time.

Whoa there, I’d best back up a bit. What is microevolution? Well, according to biologists, it’s a bullshit word made up by ignorant creationists. According to those ignorant creationists, it describes changes that occur within a species, such as different breeds of dog. The reason I call these creationists ignorant is that this is evidence for, not against, the theory of evolution.

* * *

Reading Richard Dawkins changed my life. Unlike so many of my fellow atheists, I actually discovered him first through his work in biology. I was aimlessly browsing my local library one day when I came across The Ancestor’s Tale. It’s a book describing evolution from a modernity-centric, backward-looking viewpoint, essentially beginning with humans and following the tree of life back in time to the “source.” It carries itself as a sort of narrative and describes key concepts in biology and evolution throughout in a way that I found easily understandable. (And I am not a biologist.) It was eye-opening for me because prior to reading it, the only significant experience I’d had studying inheritance was doing Punnett squares in seventh grade. (Seriously, that’s it. PS: They suck.)

The way most people think about evolution is entirely backwards. If you think evolution is any sort of active process that takes place in the background to drive a species towards being more capable of thriving in its environment, you’re suffering from the same misapprehension I was under. There is no guiding force. Evolution does not steer a species toward any goal. “Survival of the fittest” does not operate by making some individuals better at reproducing per se—it’s called “survival” because everything dies, but individuals with beneficial mutations die slightly slower. Organisms that lack these beneficial mutations (or that carry harmful mutations) are more likely to die off.

Another common misconception about evolution is that individuals evolve. They don’t. We don’t. You don’t. Once you’re born into the world, that’s it. There is no evolving for you. Pokémon is a damned lie. Only groups evolve—individuals may only bear mutations. When a group is isolated and enough of these mutations have spread throughout it, it is possible for that group to become a subspecies (like a dog’s breed: it has obvious traits that the main group does not—just for the record, no, skin color is not sufficient to classify people into different subspecies). Given enough time, these mutations will slowly create a scenario in which members of that group will no longer be able to produce viable offspring with the original population in the wild. When this happens, we say speciation has occurred. You know what that means? Speciation is just microevolution plus time. Thus, microevolution is macroevolution. Both are just plain-ol’ evolution. It’s the same damn thing. And at no point can a lizard ever give birth to a bird.

But what about transitional forms?

Oh yes, that question. Transitional forms indeed. The analogy that best helps me understand this idea is that of a clock. If you watch a clock, you will see the second-hand spinning, spinning, spinning, and the minute-hand sloooowly creeping along. Unless you stare at it for quite some time, you will fail to see the hour-hand moving at all. Yet the hour-hand is moving; it does not stop. What we call species represent positions on the clock—they’re the hour marks on the clock. Individual genetic mutations are the changes that take place on the second-hand. Mutations becoming predominant are the changes taking place on the minute-hand. They’re largely arbitrary designations.

You bear genetic material from both of your parents, but odds are high that your genetic code also carries with it mutations— essentially DNA that neither of your parents have. (But don’t worry, most mutations are harmless. You wouldn’t even notice ’em.) You exist as a fraction of a fraction of a second different from your parents. This is how it has always been; every child has always been of the same species as its mother. In truth, every organism is a transitional form between its parents and its offspring.

But your children are the same species as you!

This is true in exactly the same sense that 5:03:00000000002 PM  is the same time as 5:03:00000000003 PM. We live in a world measured in seconds, but each second is broken up into smaller fractions. There is a point at which these fractions are so small that we cannot perceive them—the resolution of our minds is not precise enough to perceive this scale. So too with most evolution.

Most? Yes, only most. Evolution seems so slow for us because mutations take place on the generational level. The shorter a species’s life cycle, the more quickly we can perceive the effects of evolution. Genetic change in fruit flies is much more rapidly visible because their short lifespan means their evolutionary clock runs faster than our own. (This is why scientists often use them in genetic experiments.)

This observation’s most threatening implication is seen at the bacterial level. The discovery of antibiotics allowed us to fight diseases with never before seen effectiveness. Indeed, some diseases, such as smallpox, were entirely eradicated because the little critters that caused them had no defense against our superior antibacterial weaponry. Things are no longer so clear-cut; stories of the so-called superbug, MRSA, abound. Our application of antibiotics has become somewhat less than judicious, which is where natural selection comes back into play.

Except in this case, it’s artificial selection because we’ve guided it. Through the misuse of medicine, our own bodies occasionally become breeding grounds for new bacteria (and subsequently, new diseases). You know those commercials for products that say “kills 99.9% of bacteria?” Bacteria are living organisms, so what do you suppose happens to that surviving .1%? They breed more copies of themselves. In terms of medicine, if the reason that .1% survived is because they had a genetic mutation that caused them to survive the drug, their children will be equally likely to survive that drug. Through artificial selection, we’ve created various species of bacteria that resist our treatments. Sucks, doesn’t it?

That’s evolution. Anyone who says “Evolution is just a theory—it’s not a fact!” is just ignorant. MRSA is a fact. MRSA is the product of genetic change. This is a fact. The best scientific explanations for facts are called theories. Evolution is the theory that best describes the observed facts of mutation.

And now you know.

Advertisements

9 responses to “Microevolution

  1. Nice summary. I would just like to add something here about your observation that offspring being the same species is “true exactly the same sense that 5:03:00000000002 PM is the same time as 5:03:00000000003 PM.”
    A species can actually be defined pretty exactly. If two organisms of opposite sex can reproduce to produce fertile offspring, then they are the same species; otherwise not. So in this way, no matter how taboo this sounds, offspring can always mate with their parents to produce more fertile individuals of the same species, so that this puts in down in exact, hard terms what being the same species means. Millions of years down the line, however, your descendant might have become such an organism which, if mated with what you are today, would not produce fertile offspring. Thus, speciation has happened. Of course, not suddenly with one of your descendants not being able to mate with their parent, but gradually over this long period of time.

  2. No–what evolutionists call microevolution is simply adaptation with SEVERE LIMITS. All living organisms can adapt to changing environments with LIMITS (i.e., no turning from eukaryotes to prokaryotes. No transforming from fish to land mammals, and no transformation from knuckle-dragging apes to bipedal human beings with higher intelligence.

  3. “what evolutionists call microevolution is simply adaptation with SEVERE LIMITS”
    This is pure nonsense. “Evolutionists” don’t call anything microevolution because this term has nothing to do with science.

  4. Abhra: Then how do you explain dogs and wolves? Different “species,” but able to produce healthy, fertile offspring. Because they are “mixed” and not as inbred as today’s “dogs,” they are in fact healthier and genetically stronger than dogs. This just further proves that you should not blindly worship these classifications–which are often arbitrarily created at a whim by a few, very ordinary, very flawed, very subjective human beings.

  5. “What is microevolution? Well, according to biologists, it’s a bullshit word made up by ignorant creationists.”

    Now, that’s not very charitable. It’s things like that that make the rest of us just want to stay out of this debate. Whatever issues I have with evolution definitely fall into categories different from those you have listed here. As for micro and macro evolution, I don’t think there’s need to argue over the terms. I just think of microevolution as small changes and macroevolution as what happens when those tiny changes accumulate.

  6. Why should I be charitable to a completely malformed idea? You’re welcome to think of evolution on small and large scales and then label them as micro and macro, respectively, but it’s the same process. The addition of micro- and macro- prefixes adds nothing–neither to the science nor the lay conversation. The terms are used only to add confusion and sow ignorance.

  7. Well, Collin, it depends on what your aim is. Being charitable promotes good conversation and helps people understand you. It is also good etiquette. If you’re trying to get someone to see where they’re wrong, it works better than what you’re doing. I never thought I’d see the day when I would quote the Bible to a non-theist, but 1 Peter 3’s call for “gentleness and respect” might be something you want to follow. If, of course, you wish to promote effective and intelligent discourse.

    As for the micro- and macro- evolution, the terms do help me. If someone, for instance, argued that there are limits to the changes which can occur in species, they would make their point by saying that small changes (micro-evolution) happens up till certain limits but are incapable of accumulating and forming big changes (macro-evolution). In that situation, those words are useful for communication.

  8. The problem is the large number of creationists who reject evolution and are either unwilling or incapable of having an “effective and intelligent” conversation about it. If someone has already decided that evolution is a lie (even if they accept “micro” evolution), that’s not something they’ve done in the face of measured evidentiary reasoning; it’s nothing more than motivated reasoning. These people have made up their minds and prefer to tailor the facts to suit their opinions. I refuse to be charitable with these people.

    Maybe that’s not the majority. Indeed, I hope it isn’t. I’m entirely willing to have a rational conversation with normal people, and I will be charitable with them. The crucial difference is that ideas are never worthy of respect; only people are worthy of respect. I can appreciate a person who believes dumb things, but my appreciation for that person doesn’t change the fact that the dumb things they believe are dumb. I refuse to give up the right to viciously mock bad ideas, with the understanding that a person never deserves to be mocked merely for having an inaccurate belief.

    If the terms help you, it seems probable that your understanding of evolution is insufficient. If someone were to argue that small changes are incapable of accumulating into speciation, that person would have a dumb belief. The words are only useful for communication in the context of people who don’t understand what they’re talking about.

Your feedback is welcome and encouraged.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s