Why I Don’t Debate Evolution

My sometimes co-blogger Ken and I often discuss the whole evolution-v.s.-creationism issue, and I’ve tried a few times to explain to him why I don’t write about it much here. I occasionally discuss or speculate about some basic evolutionary science, and I’ve slammed some really idiotic creationist nonsense, but I just don’t want to get into a debate about it.

I got to thinking about it again when I heard that Bill Nye (“The Science Guy”) was apparently going to debate Ken Ham, who is the founder of something called the Creation Museum (now with Zip Lines!).

This strikes me as a bad idea. Bill Nye is famous for explaining science, but not for debating it, and debating evolution v.s. creation (or intelligent design) is hard.

To give you an idea why, let’s start with a simple challenge that might be offered by an opponent of evolution: The second law of thermodynamics says that entropy must always increase, that is, things become disordered. Yet evolution implies an increases in order as things evolve into more complex forms. Therefore evolution would violate the second law of thermodynamics.

This is a simple misunderstanding of the basic science. The second law of thermodynamics applies only to closed systems, and the Earth is not a closed system because it receives energy from the Sun. That energy powers the biological processes of evolution. Considering the combined system of the Sun and Earth, entropy still increases because the decrease in entropy implied by evolutionary processes on Earth is more than made up for by the increasing entropy in the furiously churning heart of the Sun.

As creation v.s. evolution questions go, that was a fairly easy one for me to answer. It doesn’t really even require any knowledge of evolution, just a basic understanding of thermodynamics.

To handle more difficult challenges, some understanding of evolution is necessary. My own knowledge is strictly amateur level, but I think I can respond to a slightly harder challenge, such as If species evolve to survive, how come we still kill cattle in slaughterhouses? Shouldn’t cattle have evolved to prevent us from doing that?

I can think of three answers to that question, depending on your point of view:

1. Cattle are at an evolutionary dead end. Evolution happens through small changes. But can you imagine any property of cattle as a species — height, weight, speed, intelligence, digestion — where a small change would allow them to escape the ranch or the slaughterhouse? If not, then evolution won’t help them get away.
2. It’s already happened. That is, the question is misleading because it focuses on a single species. But if you look at the larger Bovidae family, which contains cattle (Bos primigenius), Wikipedia tells us it includes 145 distinct species, including yak, several types of antelope and oryx, bison, anoa, several types of buffalo, zebu, nyalas, elands, many types of duiker and gazelle, a variety of goats, several types of reedbucks, impala, wildebeest, several hartebeest, and muskox. Humans may eat some of those creatures now and again, but how many of them have you seen at the butcher shop? Cattle are an unusual case in a part of the animal kingdom where most species have followed evolutionary paths that escaped humanity’s hunger.
3. The cattle species is actually very successful. Cattle’s survival “strategy” is to make themselves valuable to humans. As individuals, they may die by the hundreds of millions, but as a species, they are thriving: By becoming a tasty food source, they’ve given humans an incentive to protect and nurture a worldwide herd of a billion cattle. Measured as a fraction of the mass of all living things on Earth, the cattle species has managed to garnered a larger portion of the organic matter of this planet than any other single land-dwelling species. (Humans are a close second.)

That was a lot more evolution-specific, and I had to look a few things up on the web to get the details about the Bovidae family and biomass proportions, but it’s still basic science. And while I find it a convincing response, I can’t be sure that it would convince anyone else.

Now lets move on to a harder challenge: If evolution does move in small steps, how could something as complex as an eye evolve? It seems to be a structure of irreducible complexity — until you’ve got the whole thing, you’ve got nothing useful — so what good would evolving 1% of an eye’s structure do for a species’ survival?

This is at the limits of my knowledge, and I only know the basic outline of an answer: To a blind organism swimming in the ocean, even a slight ability to sense light will give it useful information, such as how close it is to the surface. Then, once any sort of photosensitive patch has formed, any ability to detect the direction of incident light is an improvement, and one of the easiest way to increase directionality is to recess the photosensitive patch into the body a bit, so light has to strike it from within a narrow angle. The more the photosensitive patch recesses, the more directional it becomes, until it reaches the point of being a photosensitive pit with a tiny viewing hole. Then it works like a pinhole camera and images form on the photosensitive surface, so it becomes advantageous to evolve brain structures for interpreting those images — edge detection, motion detection, and so on.

And that’s about all I know. I can only describe the basic idea. To respond effectively in a debate, I’d have to be able to offer evidence that anything like this actually happens. It’s my understanding that you can find examples of all major stages of eye evolution in nature if you know where to look, but I haven’t got a clue.

I’ll bet that many biologists can’t give a high-quality answer this challenge either, unless they just happen to have researched eye formation. Creationists also assert that other things have irreducible complexity, such certain cellular internal structures and the mechanism by which blood clots. To survive in a debate, you’d have to have researched the answers ahead of time, which means knowing the creationist challenges ahead of time.

There are still harder kinds of challenges. They tend to sound something like this: If the theory of evolution is correct, how do you explain Professor Robert Schuster’s 1992 paper in which he reports finding Cathayornis yandica fossils in the sedimentary deposits of the Chusovaya River Basin at levels beneath where he found Castorocauda lutrasimilis?

First of all, you’d have to know that Cathayornis yandica is a Cretaceous bird and Castorocauda lutrasimilis is Jurassic mammal, which means you’d expect to find the Castorocauda fossils deposited in the older sedimentary layers beneath the Cathayornis fossils. Finding them higher up seems to imply a problem with our understanding of the fossil record or with the technology used to date fossils, possibly allowing for a younger earth in which all the supposedly ancient extinct species actually lived quite recently, justifying creationists’ depictions of dinosaurs and humans living together.

To respond to this, you’d have to know if Professor Schuster really exists, and if so, did he publish his findings in a peer-reviewed journal or is he some kind of crackpot? Then you’d want to know if his paper actually says what your debating opponent claims it says. And if so, does it mean what it seems to mean? Or would Professor Schuster be shocked to discover that anyone thought his paper disproved the theory of evolution? Is the explanation for the layer inversion actually a geological phenomenon that is a well-understood by anyone who studies the Chusovaya River zone? Could it be that scientists study this area precisely because the well-known inversion gives them easy access to older fossils without digging so much?

For the record, I completely made up this question, so no one could possibly answer it. But when you go up against a sophisticated creationist debater without anticipating his questions and researching your responses, every challenge is going to feel made-up.

Finally, there questions my mother would ask, such as How could the random changes of evolution result in human beings?

The basic answer is that they couldn’t and they don’t and that’s not how evolution works. It’s true that mutations can cause organisms to develop random traits that are different from the parent organism, but whether the organism passes that trait to its own offspring is dependent on whether the organism survives and reproduces. That too is a matter of some random chance, but what’s not random is the differential survival rates between organisms with and without the mutation.

It works a bit like the house odds in a casino. Games like roulette, craps, and keno are all games of random chance, which means individual players could randomly come out ahead or behind after a short playing session. But on average, over time, the house is guaranteed to make money. In the long run — and evolution is always about the long run — that house edge will always wear down the players’ bankrolls until the casino has all the money. There’s nothing random about that result.

Similarly, if a new trait improves the chance of an organism’s survival by even a small amount compared with other members of its species, then the number of organisms carrying that trait will increase as a percentage of the species in every generation until all organisms exhibit the trait.

(I spent a few minutes trying to simulate this, and if I did it right, then if one organism in a colony of a million develops a trait that improves its chance of survival into the next generation by 1%, then that trait will spread to the entire population in less than 3000 generations. That’s tens of thousands of years for a large mammal species, a few decades for houseflies, and about two months for a colony of E. Coli bacteria.)

The thing is, no matter how hard I tried to explain this, I could never find a way to convince my mother. She just couldn’t seem to wrap her mind around the concept. Maybe she was simply unwilling to accept evolution, or maybe I just never found the right way to explain it to her. I had answers that convinced me, but they didn’t convince an evolution skeptic.

This is why I don’t debate the theory of evolution here, and why I think it’s a bad mistake for Bill Nye to try to debate it at the Creation Museum. In order to debate the theory of evolution with a creationist like Ken Ham, it’s not good enough to just learn about the theory of evolution. You also have to learn answers to the kinds of questions creationists raise about evolution, such as my cattle example, or the more specific question about the evolution of the structures of the eye.

That stuff’s not actually so bad, especially if you’re fascinated by evolution, as I am, but then you also have to learn about all the papers and studies and conjectures that creationists have used to attack evolution over the years. For each one of those, you have to learn what creationists say about it, what it actually said, what it meant, whether it was legitimate research, and what legitimate evolutionary scientists say about the issue.

Finally, once you’ve learned about all these challenges you’re going to get from creationists, you have to figure out how to respond to them. That’s harder than it sounds because, as my last example illustrates, it’s not good enough that your responses convince you. A really good response has to convince your opponents, or at least it has to convince listeners who are skeptical about your position.

In other words, in order to debate the subject of evolution, it’s not enough to learn all about evolution. You also have to learn all about creationism, and how creationists think about evolution. You have to be familiar with things like Jonathan Wells’s anti-evolution Icons of Evolution and Alan Gishlick’s explanation of why it’s wrong. You have to absorb the creationists’ way of thinking about evolution in order to explain your point to them in a way they will understand.

And that’s just not something I’m willing to spend a lot of my time on. And unless Bill Nye has been secretly setting up Ken Ham for this debate for months, it’s not something he’s spent a lot of time on either. Which is why I expect it to go something like Greg Laden’s parody of a debate:

Scientist: “If there’s one thing you should take away from this discussion, it’s…

Denialist [interrupting]: Thing one, thing two, thing three, thing four, thing five.

Scientist: “Actually, that thing four you said, that’s not really true ..

Denialist [interrupting]: Thing six, thing seven, thing eight, thing nine, thing ten.

Scientist: We can’t be sure of everything but one thing we are pretty sure of is…

Denialist [interrupting]: I’m sure of thing eleven, thing twelve, thing thirteen thing fourteen.

Greg Laden also discusses some other reasons this debate is a bad idea. I don’t agree with everything he says, but like him, I don’t expect it to go well for the science guy.