Wednesday, August 6, 2008

Evolution 101

Among popular misconceptions of scientific theories, evolution is by far the worst. It astounds me how horribly evolution is framed in popular culture and how maligned it is in public discourse. It is no doubt a result of the Christian-Republican campaign to stifle the teaching of evolution and inject religious dogma straight into the science classroom.

Firstly, among creationists it's abundantly clear that few (if any) of them even understand the scientific theory in the first place. I can't count how many times they have considered "proof" of evolution to be a cat giving birth to a dog or an individual chimpanzee spontaneously metamorphosing into a human overnight. The ignorance is baffling, but unsurprising - these people have been told that evolution is a direct threat to God, so it makes sense to manufacture such self-deceits in a misguided attempt to protect their beliefs.

Not once do they hit on the remarkably simple real idea - that evolution is simply accumulated genetic change from one generation to another. Instead, they attack a strawman of their own devising in an attempt to justify their beliefs.

The process of evolution, pulled from an actual "creation science for kids"-type site.

[Editor's note: finally tracked down the site, it's from our good friend Harun Yahya/Adna Oktar

Straight-line evolution

Like the horribly bad starfish-->fish example, people sometimes think of evolution as a one-way ticket, with a single species "improving" up to a radically different form. The seductive thing about this misconception is that it's partially true - you can trace a current species lineage from its more humble ancestors, but that's only part of the picture. In reality, speciation involves lots of daughter species and many extinctions. It's a messy affair. And the notion of "progress" in evolution is mistaken - fitness is all about surviving in the current environment, and adaptions always have their disadvantages. Examples in nature abound - pangolins have forelimbs so well adjusted to digging that they're no longer very good for walking, leaving pangolins with a hobbling gait. Also, every once and a while, a species seems to "devolve" and go against our vaunted notions of progress - for example, cave fish that no longer have functioning eyes.


Also like the starfish example, creationists seem to think that evolution operates by species launching from their branch in the nested hierarchy to another branch - what was once an echinoderm is now a full-fledged chordate! Sorry, it doesn't work that way; species form a nested hierarchy and continue to evolve, but a mammal species is never going to become a bird species, no matter how much time elapses, their common ancestors have long ago diverged from each other, never to reunite. If they did, that would pose serious problems for the theory of evolution.

Common objections to evolution:

But it's just a theory!

That's true, it is a theory. Heliocentrism is also a theory. Scientific theories are models used to explain facts and scientific laws are mathematical relationships. There's no hierarchy of accuracy - theories don't graduate to law status, no matter how well supported they are by the evidence.

It's morally wrong

A favorite tactic amongst creationists is to throw out irrelevancies - changing the topic from whether or not evolution happens to whether or not evolution is "bad". It's an absurd ploy - no matter how distasteful the facts are, they don't stop existing merely because one doesn't like them - I can't close my eyes and make the world disappear.

It's atheistic

This is the mother lode of objections. I love it because it betrays the motivations of the speaker so well - the main gripe against evolution isn't on factual grounds at all, but on theological grounds.

Well, it's true that the theory of evolution doesn't have much to do with God. Neither does any other scientific theory. Science itself is agnostic on the subject.

But the intent of this objection is to label evolution an "atheistic science" and therefore make it anathema to all theists.

Once again, it's an irrelevant objection - evolution either happens or it doesn't, theological quandaries need not apply.

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