A Biophysicist Responds

January 18th, 2006 by Potato

Orson Scott Card recently wrote an opinion piece on Intelligent Design vs. Darwinism. He made some good points, but I also think that he skimmed over some of the issues in reaching his conclusion.

First off, he did a good job of distinguishing Creationism, Intelligent Design, and Darwinism. Creationism is not quite the same as Intelligent Design: while they both contain appeals to a Higher Being to explain gaps in the evidence, Creationism is significantly more dogmatic and, well, silly. Creationism essentially says that the story of creation in genesis is literal truth. God really did create the earth out of nothing in 6 days, and all the species were placed there in their final, complete, and perfect forms. Any fossils or extinct species we may find today (such as dinosaurs) were simply those species that were not carried by Noah on the arc, and saw mass extinction in the Flood, or alternatively, placed there on purpose by God when He created the world to, as proclaimed by the (non-canonical) prophet Biff, “Fuck with our heads.”

Intelligent Design, by contrast, is… somewhat… scientific. It agrees with Darwinism on a number of important points, including that evolution occurs (species change and diverge over time), and that natural selection may, in some cases, be involved. But where it differs is in the nitty-gritty: rather than relying on the mechanics of random chance and mutation to generate the differences upon which natural selection acts, ID instead invokes the actions of the “Designer” (generally, the Christian/Judaic God). ID (and OSC) argue that the appeals to a Designer are only made in the areas of the Theory of Evolution that are not fully understood, and so are no more religious than the Darwanist appeals to fortune and chance. By that argument, both theories break down into dogma at some point, and so neither should be taught in the schools. Instead, the Theory of Evolution should be taught, but only up to the point where it is well-supported by the evidence (namely, that species change over time, and that selection of the fittest and descent of traits over time is invovled. No mention of why these changes occur, what generates the variance for selection to act on, nor what else might be involved in addition to natural selection).

I’d like to make a few points of my own though (realizing the danger of trying to debate someone as talented as OSC, I’m not going to post a copy of this on his forums :)

He says that ID only exists because it explains the “holes” in Darwinism. I’m not sure that there are holes in Darwinism.

Let’s start with a few quick definitions and some common ground. We agree that evolution occurs, and that natural selection plays a role. This is the basis of the Theory of Evolution — notice that I capitalized Theory, this is because I wish to distinguish it from the word “theory”. You see, we have “theories”, which are our best guesses as to what is going on, stories that explain the facts as we know them, but which aren’t necessarily solid yet. Then we have Theories, where I’ve reserved the capitalization for those special theories that have been proven over and over and which form a fairly fundamental basis of our body of knowledge. So by this, I mean things like the Theory of Gravity, the Theory of Evolution, etc.

So, the Theory of Evolution covers the fact that species change over time, and that natural selection is the engine of that change. If, for example, two subpopulations of a species have different traits, the one with the trait that is more advantageous to survival will survive longer to breed more, and in the next generation that subpopulation will make up a larger portion of the species as a whole, until virtually the entire species has changed to contain the trait.

I would say that it also covers other important aspects of the process, tying into the inheritance of traits (the theory doesn’t work very well if those who survive due to their traits can’t pass them on), which ties into genetics. It doesn’t strictly rely upon another theory explaining where the variance that natural selection acts on comes from (mutation, or divine fiddling), and it doesn’t necessarily get into explaining other problems that I’ll get into (rather, the theories explaining those problems are based on the Theory of Evolution).

First off, we have the “problem” of explaining where the variance comes from that natural selection acts on to cause evolution. We know that inheritance occurs via genes encoded in DNA, and we know about copying errors and other mutations that can change those genes, which produces variation. The problem, as the ID people see it, is that by far most of the mutations we’ve observed have been harmful. Our bodies appear to be finely tuned organic machines, and futzing with the blueprint, even in relatively minor ways, can have disastrous results. So, they cite this as a shortcoming of the theory, and make their first call to the Designer, to put in beneficial mutations on purpose (for how else could something with such a low probability get in there?).

My response to this is that it’s not really necessary. True, getting hit by a cosmic ray and mutating in such a way to improve your odds of survival is like winning the lottery (or even worse!), but we have two things that make this system work. The first is sheer numbers. When dealing with whole populations as long as any one member gets a beneficial mutation and survives to pass it on, it’s gravy, even if millions of others suffered negative mutations and were culled (or even failed to gestate). The other is time. Evolution, particularly drastic speciation, can take place on very long timescales, which gives us lots of opportunities for a beneficial mutation to come along. Keep in mind that the whole time natural selection is also acting on the deleterious mutations, preventing them from becoming too problematic.

Closely related to this is that mutation rates for different genes vary. The genes that are critical to survival, such as the ones that encode the proteins that digest sugar or heat shock proteins (my own topic of study), hardly change at all over billions of years, with just a few trivial basepair substitutions accrued in the divergence of yeast to humans. While other less critical genes, such as those for various pigments, are more open to variation. The arguments over this are difficult for both sides. One one hand, it seems like exactly the sort of thing a Designer who did not wish to meddle too much would put in place, while at the same time, since it offers such a high increase to survival, it would be “strongly selected for” by natural selection. How it got there may be something we may never be able to answer one way or the other, but in my opinion, since it’s there now, it gives a mechanism for “undirected” Darwinism to take place.

The next argument, and perhaps the strongest in the ID arsenal, is the issue of complexity. There are two facets of the argument. The first one, and in my opinion the only valid one, concerns the intermediate steps. A valuable adaptation, such as an eye, or a bat wing, does not spring out of whole cloth in a single generation (though if it did, that would practically scream out the existence of a Designer!), there’s a lot of complexity involved there, and the intermediate steps on the way might not necessarily confer an evolutionary advantage. So if we consider a “fitness quotient”, the base organism might have a value of 100, and the “evolved” organism (with a complete wing or eye) might have a value of 125, but in-between, it has to pass through the “half-finished” stage, where it might be less survivable, with say a value of only 80. Our Theory tells us, then, that barring the outside influence of a Designer, the less-survivable “half-finished” version sould be selected against in favour of keeping the original.

There are a few responses to this. It’s not necessarily true to assume that the intermediate steps hold no value. This has been demonstrated with the eye: if you break it down into more logical steps, you wouldn’t start with an unseeing globe on your face, you’d start with a simple light receptor. All it could do is sense the presence or absence of light. And you can immediately see the use in that: you can more reliably determine what time of day it is, or if the weather is really terrible out (blocking out the sun). If you’re a pond-dwelling organism, you can then decide when to move out into the sun, or when to move away from the fresh-water slick formed on the surface during the rain. Then you can proceed to the next step: an array of photoreceptors to determine direction of light as well. From there, you can enclose them in a globe behind an aperature like a pin-hole camera. Useful both for protection and forming images on the photoreceptor array. Then, you can develop a lens that allows you to better focus the image, to look at specific things in detail. I tried to do the same for the bat wing as a school project, and it was a little harder to go through each step, but there I was helped by the fact that it requires fewer steps. If, for instance, you want to start with something like a flying squirrel (so you already have the soaring behaviour and the flaps of skin), it only takes a single mutation to make one finger freaky long to really stretch the skin out and glide like crazy. One other complication is that selection pressure is not equal through time. Selection pressures change depending on the climate, the relationship with other species and other factors. While unlikely, it is possible that a species could experience next to no selection pressure for a time. For example, let’s say that a group of rats swam to a previously uninhabited island. There would be abundant food for several generations before they had to compete amongst themselves, and predators were completely absent for a time. In those sorts of conditions, all sorts of “experimental” evolutionary off-shoots could take place, regardless of their usual survival value. A few generations of these sorts of conditions could allow a new change (like a bat wing) to progress through those poorly adaptive intermediate stages to form the basis of a fully-functional subspecies.

So this is an area where Darwinism has difficulty explaining the evidence, and where the theories become small-t ones, but I really don’t think it’s a “shortcoming” that requires an alternative explanation like Intelligent Design.

The other part of the complexity argument is that for each of the simple changes I’ve described above, there are fairly large biochemical changes. There’s just so much that has to change, that surely it requires divine intervention? This one, I think, is merely a misunderstanding of the problem. True, there are tens of thousands of genes with millions of amino acids, but the thing about our bodies is that they’re based on a very modular blueprint, and the genetic code is not necessarily on a one-to-one basis with phenotype. You can make minor changes to certain genes and get huge changes in body design, while big changes to other genes make very little difference. And because everything is so modular, it’s very easy to just copy a gene and make minor changes. For example, if you wanted to have 4 arms like Goro in Mortal Kombat, you wouldn’t need to find, copy, and alter all of the genes involved in arm construction, such as the ones that encode the nerves, the muscles, the vasculature, the skeletal basis, etc.; all you would need to do is find the protein that during embryogenesis directs all those other genes to form an arm, and alter it so that it instead called for two arms to be made. The already-established set of genes that direct arm formation would handle the rest. (Though if you wanted to use the arms, you might also need to alter the genes that make shoulders).

Far less complexity than one would think…

Anyway, I’ll wrap up my diatribe here. I agree that definitely the Theory of Evolution should be taught in schools, but I don’t think that it is so deficient in certain aspects of the how and why that appeals to a Designer need to be made. While those parts may not deserve a capital-t Theory (yet), I think they have a good enough probability of being true that they should be taught in schools (and that they’re not quite as religious as OSC makes them out to be). While Orson doesn’t think either ID or this extension of Darwinism should be taught in schools since they’re both based on faith at the moment, I’d have to disagree. While we may not know it to be scientific truth yet, these theories on how evolution occurs represent the best idea we have so far, and teaching them to our kids will give them the best foundations to discover what the real story is in the future.

Moreover, this theory has some predictive value, and is useful in that way. Whereas Intelligent Design won’t ever give you predictive powers unless you can speak to the Designer in some meaningful way — and if we could do that, the debate would be over!

Finally, I don’t mean to say in any of this that science or evolution deny the existence of God. It’s just that invoking Him isn’t necessary to make our theories work, and to explain the world around us. However, if it suits your belief pattern any better, God can happily influence any random process, from your rolls at the craps table in Vegas to the pattern of mutations underlying evolution, without ever impacting the science of your theory. Randomness is and perhaps always will remain beyond our control and understanding. It’s in this domain that God can potentially carry out His divine machinations without overtly revealing Himself and thus denying Faith. It is perhaps for this reason that fundamentalist religious types don’t like science. They don’t like the idea that they may just be praying to pure dumb random chance.

Edit 1: Too many “first offs” :)
Edit 2: Last paragraph.

2 Responses to “A Biophysicist Responds”

  1. netbug Says:

    “…it only takes a single mutation to make one finger freaky long to really stretch the skin out and glide like crazy.”

    Love that sentence.

    And ya… I don’t have much to say on this subject… you pretty much summed it up. There was an article in Scientific American a few years back that was arguments for “creationist nonesense”. I really liked that one… and reading the letters that came in the months after. :P

    I think that having 4 arms would improve my game playing… I could have two hands on the keyboard, one on the mouse and one to hold my beer.

  2. Potato Says:

    Forgot the word in the actual post, but when talking about the complexity issue, ID people will often call it “irreducible complexity” implying that you get to a point where you can’t have feasible subunits evolve. This is, of course, an open question and an active area of research in biology, but all the evidence so far indicates that if we look, there often are precursors readily available. It’s where the science is weaker, granted, but I don’t think it’s an area where it breaks down completely.