You can bring a Rhipidistid to land but you can’t make it walk

6 08 2007

Background reading:
Combating Creationism With History
Why Fight Creationism?

Steven Berven of the blog Tattered Bits of Brain was kind enough to respond to my post “Why Fight Creationism?” (see link above) in a new post called “It’s alive (or, yet another creationism post).” I don’t mean to be unkind, but there is a bit of goal-post-shifting, reductio ad absurdum, and other “classic” rhetorical devices used throughout, suggesting that evolution is every bit as much as “just-so story” as creationism is.

Steven starts off with a disclaimer;

If I haven’t made it clear before, let me reiterate: I don’t in any way mean to suggest that creationist views and religious ideology should supplant the scientific method. I enjoy science. I love learning about the way our world works and the amazing complexity and interdependence of the life and natural processes of this world.

I just don’t happen to think it within the realms of possibility that it could all just ”happen” through a series of random accidents and fortuitous spontaneous breakthroughs.

I never suggested Steve was a YEC, only that YEC arguments are not only unscientific, they’re simply ill-founded assertions that find their roots in devotion to Biblical authority. Steve seems to fall along the theistic evolution/intelligent design section of the continuum, and while Steve is more than welcome to have whatever beliefs he wants regarding the origin and evolution of life, I feel that both theistic evolution and intelligent design require at least some amount of special pleading and a requirement to bend a bit to spiritual/religious notions.

Anyway, on to the meat of the argument. In the last post in this series, I gave a summation of early tetrapod evolution in non-technical terms (see “Why Fight Creationism?“, and also “Taking in the Carboniferous Atmosphere“). Steve has some problems with my explanations/use of rhetoric language, however;

An external change gave the tetrapods a “good reason to develop their lungs.” Okay, so they’ve got the reason. Now what? Do they think to themselves, “Hmm, guess it’s probably a good time to develop lungs. Ready…..GO!“

Clearly a silly example; or is it? Examples such as these seem so suggest that species respond in an almost cognitive fashion, and that this somehow results in a kind of genetic memory that is imprinted on their DNA. What’s the real answer? “Evolution,” (as in the proper noun) was kind enough to “pre-adapt” species (and by that I take to mean “build in?”) the capability to exploit a new niche? So Evolution pre-engineered in capabilities? Tetrapods were given a reason to developed their lungs? Lobe-finned fish responded to selective pressure, pushed up on their arms, and “decided” to leave the water in order to avoid death? The water murks up, the plants move in, and you have a choice: adapt or die. So you adapt. Huh?


In this little discourse Steve is trying to paint my summation in an anthropomorphic or vitalistic light, something I myself have spoken against before. If one looks back at the original post we’re discussing, I try to take an ecological approach to tetrapod evolution, showing how selective pressures would have favored those animals better able to survive and reproduce in plant-clogged swamps near the edge of insect-filled forests. I did not suggest some vitalistic force, driving the animals on internally, nor the early tetrapods thinking “I want to have some bugs for lunch, so I’m going to develop lungs and do away with my gills.” This is clearly absurd, and perhaps I could have chosen my words better when I said that tetrapods had “good reason” to become more developed to land. I had assumed that there was a basic understanding that those early tetrapods that were better able to exploit the changing environment would be more successful, leaving more offspring which would have their own variations, and the duel pressures to develop lungs and to take advantage of new food sources provided plenty of selective pressures for populations of these animals to change.

Steve also mentions my explanation that tetrapods were pre-adapted to evolve in that they already possessed rudimentary lungs and a locomotor system that could easily be modified. I was not suggesting that evolution “knew what was coming” or acted like some spiritual guiding force, urging on the animals. Rather the previous evolution of the tetrapods gave them an advantage when things started to change, and if the early tetrapods did not have lungs or fleshy fins with strong-enough bone structure, the vertebrate “invasion” of the land would likely have had to wait. The point I was attempting to get across is that as ecology changes, some animals are favored over others, natural selection (and other factors) working on variations and systems already present in animals, further modifying them into new forms. It is no accident that all living tetrapods share the same basic body plan; it was inherited from our early ancestors, and it has proved efficient enough that it only need be modified through evolution rather than constructed from scratch every few hundred million years. In any event, in case it was not already clear, evolution does not work like some abstract supernatural force, like some natural toolkit of “Mother Nature”; organisms change together in ecologies, and there is no prediction of what is going to happen next, so changes in ecology favor some and not others, those that were pre-adapted to do better in a different world allowing natural selection and other mechanisms to further adapt the organisms.

Steve continues along with a similar absurd argument, implying that early tetrapods just didn’t know they could breathe air until they were forced to, somehow then realizing their opportunities. As I’ve just described, this is an attempt to ridicule a straw-man argument so much as to make the position of the opposing side seem untenable, but I said nothing of fish as prescient as the ones Steven describes. Steve continues;

This is exactly the kind of intellectual sleight of hand that causes me the most trouble with much of the current evolutionist theories. To vaguely suggest that “Nature” did it or “Evolution” did it is NO DIFFERENT than saying that “God” did it! Do you see what I’m trying to get at here?

Again, this is creating a straw-man argument via reductio ad absurdum. The whole point of my last entry, taking special care to mention Romer’s “drying pond hypothesis” was to present the best model we now have, even though the model may change. It’s a good hypothesis, but we don’t have all the information as yet (there’d be no work to do if we did), and part of the major difference between evolutionary science and ID/creationism is that evolutionary scientists actually make hypotheses and modify them as better evidence becomes available. Trying to ascribe a belief in the God of Evolution like that of creationists in the Judeo/Christian God is a poor argument at best, and as I’ve already shown, has little to do with what I actually described. Then Steve shifts the goalpost down the field;

What I want evolutionary theory to provide me, to provide us, to provide science the world over, is reproducible evidence of the the internal, bio-chemical mechanism whereby RNA and DNA, all those little peptides and amino acids are re-arranged or reprogrammed, how from one generation to the next they are imparted with new replication data that results in a different species, one now better suited to live on land, rather than water. How does “Nature” pre-adapt a species to a range of potential changes? And on a wide enough scale to ensure viability?

This is quite a different aim than wanting to know how tetrapods crawled out of plant-choked swamps onto land, involving the sciences of inheritance, genetics, biochemistry, and many others. Indeed, science has made great strides in figuring out the genetic code and how mutations come to be expressed in future generations, but such explanations would be a book in and of themselves, and fortunately, other authors have already carried this subject. For those unfamiliar with such sciences, a good place to start would be Futuyma’s textbook Evolution and Sean B. Carroll’s Endless Forms Most Beautiful and The Making of the Fittest. As always, there’s still plenty of work to be done, but evolutionary science isn’t merely playing connect-the-dots with fossils, either.

Steve leaves us with this;

I’ll readily admit that much of my data on evolution might be a bit dated, as I’ve kind of been out of the “fight” for a few years. However, from what I’ve been able to gather, evolutionary theory is still long on what happened, and a little short on the how it happened. And to me, if you continue to insist on the what, without being able to provide the how, well then my friends, you are operating in faith as surely as that Bible-thumping creationist.

Again, this reflects a bit of goal-shifting. The “what” and the “how” can vary greatly depending on what level of organization we’re talking about, even though it’s all connected together. Lines of research intertwine and support each other, and scientists are not obligated to agree whatever is new or just seems to “make sense.” A recent example of a smaller-scale evolutionary change involved male butterflies decimated by bacteria, only to bounce back within a few generations. I’ve already covered the story here, and it provides a good example of scientists looking into researching evolutionary changes. Still, as far as fossils go, some information is just not available to us; we’re probably never going to find any genetic material from early tetrapods or be able to study it directly. Does this mean that everything scientists say is therefore “junk”? Of course not, and studying ancient ecosytems as a whole through time can give us some great information about changes in ecology working on individuals and populations of animals. In the end, however, those who would prefer to subscribe agency to a deity or other supernatural force will continue to do so and continue to disagree with me, and that’s fine, but I utterly reject the idea that evolutionary science is merely a new form of religion that seeks to design it’s own creation mythology than learn about how life came to be on this planet.



17 responses

6 08 2007
Zach Miller

Well, honestly Brian, that’s exactly how evolution works. The giraffe looks up at a tree with all its tasty fruit and says, “You know what? I think I’ll grow a bigger neck.” And so, using all his willpower, he grows a bigger neck. Just like that. And now he can reach the food. And this trait is of course passed on to his kids. Evolution = Decision-making. Duh!


Now, on a serious note, there’s a new field of genetics called eugenetics which has shown that stresses put on many animals in their environment over their lifetimes actually influence their offspring, in some cases for many, many generations. Exactly how this works, I have no idea, but it was in Scientific American a few months back. It’s a fairly new field, but they’re rewriting how heredity works–at least, it’s a whole lot more complicated than just dad’s chromosomes plus mom’s chromosomes.

6 08 2007
Chris Harrison

Zach, I think you’re talking about epigenetics.

6 08 2007

Zach; Chris is right, the emerging field is called epigenetics, and I actually mentioned it a few weeks ago in contemplating the book Survival of the Sickest. The effect of nutrition and other environmental constrains definitely seems to affect evolution, but for the case of argument here I wanted to keep things simple (since a lab mouse is a bit removed from rhipidistids). Some have heralded the new science as Neo-Lamarckism, but I don’t really see it that way; it’s more of an integrated approach, recognizing that animals are affected by ecological change in much more subtle ways. I definitely think epigenetics and evodevo will show us a lot about how evolution works in the future, but since I can’t really prove any epigenetic link with the evolution of tetrapods, I decided to omit it (although the heightened oxygen levels mentioned earlier might have helped early tetrapods get out onto land and make the switch from gills to lungs as the adult breathing apparatus). In any case, epigenetics is definitely something I plan on learning more about.

6 08 2007
Steve B

Thanks for the response (I think :~)). Some of my examples were intentionally hyperbole, rather than inadvertent chest beating.

The crux of my point was that it is very difficult to address causality without using some sort of anthropomorphic languange, exactly because they are still some significant gaps in our understanding of the mechanisms responsible for “driving” the changes in species.

I think, at it’s core, my biggest issue is with the way evolutionary theory is presented as not just the “prevailing” theory, but the only allowable theory in intellectual circles. As such, evidence is only examined within that context.

It’s difficult to “prove” a creative or designing influence. Yet, based on the evidence, it is my opinion that it is intellectually dishonest to completely dismiss the possibility. IMHO.

And therein lies the fundamental philopophical disconnect between the two camps. Not sure when that’ll change, if ever.

6 08 2007

Steve, thank you for your reply. I too want to avoid any rabid chest-beating, and despite our disagreements this has been an overall pleasant/enlightening exchange for me.

In terms of there being a supernatural designer, the problem I have with entertaining the notion is not that it = religion; I have no problem with considering it as a hypothesis. The problem I have is that no positive scientific evidence is given for the intervention of such a designer. Intelligent Design advocates continually skirt the question of who the designer probably is, when they acted, why the did so, etc. In other words, they make no hypothesis to test, merely say “life looks too complex to have evolved.” Life is indeed complex, but an argument from incredulity isn’t scientific and doesn’t advance our understanding. Creationism/ID aren’t rejected by many scientists because it’s inherently religious, but rather because advocates refuse to engage in scientific discourse or really commit to putting forth a hypothesis. Even if they’re wrong, wouldn’t it help refine science and bring us closer to the truth?

You’re right in that this problem will be unlikely to go away anytime soon, however, although I do hope that scientists can use the popularity of the debate to enhance the general understanding of science. Again, thanks for your comments and calm discourse.

6 08 2007
Zach Miller

Yes. Epigenetics. And I mention it only because it’s interesting in the context of how species might go about evolving.

As for a “designer,” I suppose it’s not completely out of the question. The thing about evolutionary “theory” (it’s fact, goddamnit) is that it’s been proven and given strength through every field of biology, and on occassion, astronomy, geology, and even computer sciences have managed to strengthen it.

We should not get irate just because evolution is the “only acceptable theory.” The reason it got that way is through blood, sweat, and tears. And many, many, MANY scientists working many, many, MANY hard hours to try and figure out how it works.

If I start, I’ll never stop, so I’m going to stop there.

Once the Creationists or ID’ists or Bokononisks come up with a theory that has as much data behind IT, then THAT will become the new prevailing theory. A theory is only as good as its scientific support.

6 08 2007

Nice to see the general civility in the debate here, rather unusual for the blogosphere. It’s clear that Steve has some scientific knowledge under his belt and is asking honest, earnest questions, I hope my perspective can help bring him into the ‘fold’ as it were.

1) I do think that there is one critical “leap of faith” at the heart of Evolution, one that is so inherent to science that many people don’t even realize that they are making it. Science requires an acceptance of Naturalism, that the physical universe can be understood in terms of observable/measurable phenomena.

Even at it’s fuzzy margins like quantum mechanics, science provides us with relatively concrete ways to interpret the behavior of the observed universe. IDers, who often claim to be scientific, dwell on abstractions of ‘irreducible complexity’ and ‘statistical improbability’ and offer no engaging interlinked interpretations of genes, fossils, diseases, symbioses, behaviors, physical traits, population trends etc. etc. etc.

I am a decided agnostic, but not a hardcore atheist, but think any meaningful glimpse of a true greater order will be found through only by a concerted examination of physical reality and not through prayer, revelation or divine fiat. Even after all the hallucinogens, I’m really quite happy to put my faith in the hands of my hands, and eyes, and ears and such.

2) Evolution isn’t a theory it’s a phenomenon.

Like gravity, reflection, oxidation, meiosis, weathering etc. Any close look at the fossil record or the biological world shows organisms to share a great deal of their physical character both within and across specific (i.e. breeding) boundaries. We don’t wonder at the similarity within species because they have a shared ancestry. The similarities between species are arranged in a beautiful nested hierarchy, suggesting one of two explanations:

a) species share a common ancestry
b) all life was designed to create an astonishingly elaborate and sophisticated illusion of shared ancestry

Reject natural selection if you’d like, hey, you can even invoke divine intervention at every single codon slip if you’d like, but honest observation of the universe clearly shows all organisms on the planet to be physically connected. And, fossils reveal those connections to extend in curious and amazing ways, deep into the rock record.

3) I respect your request that evolutionary theory provide a full explanation from peptide to primate. In fact, that’s what we’d all like, but we have a lot of work to do and a long way to go. But, try asking a physicist to give you a full explanation of Earth’s orbit starting from quarks…. There is bound to be some inevitable arm-waving simple because these things happen on temporal and spatial scales that make Ur indistinguishable from Studio 54 (sorry if that’s a weirdly esoteric analogy).

4) “Pre-adaptation” is an awful word, and I wish it was never coined. But here’s the idea: take a look at your keyboard. That QWERTY layout is a holdover from old typewriters, an intentional separation of commonly typed letters designed to slow down your typing. People got used to it and now it’s the standard keyboard layout for computers even though we don’t have to worry about mechanical keys getting stuck anymore.

History provides a sort of physical inertia to the operation of the physical universe and often this generates the strange sort of obsolescence as we see in the QWERTY keyboard, wisdom teeth, male nipples etc. But occasionally, instead of shutting a door, sometimes history opens a window…an accumulation of waste products turns out to be a useful shield against a predator or, a thickly boned fin proves to be a useful tool for navigating a marginal environment.

Creationists see the majesty of the forest and swear that it can’t be made of trees. I can understand that, to a point. But I will always be with the folks digging in the dirt going “Woah! Check out the mycorrhiza! Wait, was that a nematode?”. Who’s out of touch?

6 08 2007

Very nice comment Neil! I too don’t especially like the term pre-adaptation, although I have to admit that I couldn’t think of a better replacement at the time. The term somewhat smacks of giving nature/evolution/a designing force agency as if it predicted what was going to happen, even though there’s no sign this is the case at all. I can’t say I’m a fan of the related term “spandrel” as used by Gould either; it makes me think of some small, annoying dogs rather than evolution or architecture (where it gets its root). Coming up with a better/more accurate term for adaptations that come into favor is definitely something I should think more about, although I have the feeling that it is going to defy being condensed into one word (even a hyphenated one).

Anyway, I had a long conversation with someone today about science and he claimed that science was great because it’s so purely objective. I had to disagree; it’s not purely objective, and everyone has their own ideas and pet theories based upon what we’ve come to know so far. The strength of science is that even if someone is subjective to a greater or lesser extent, science as a process requires those views to be reviewed, tested, and discussed (even harshly debated) if they’re going to gain any amount of credence. Even if it takes a while to overturn old ideas (the debate surrounding plate tectonics comes to mind), science as a process of observing, testing, debating, and investigating continually advancing through not only showing ideas to be true, but (you could even say more often) showing hypotheses to be wrong.

In the end my problem with the more “liberal” creationist philosophies is that they offer nothing up to be tested other than an argument from incredulity. If there has been a designer at work, then their handiwork should be visible in nature, something that advocates of strong or weak creationism have failed to show thus far. If someone wants to believe in such design, that is certainly their choice and they are welcome to it, but I become irked when “belief” is converted to science out of preference or comfort rather than having hard research to back it up.

8 08 2007
Steve B

The problem I have is that no positive scientific evidence is given for the intervention of such a designer.

On the contrary. That continues to be the crux of my point. That I examine the evidence, conduct my scientific inquiries, perform my analysis and weigh the options like a right proper scientist might…and I come to what I see as a supportable and sustainable conclusion that the evidence points to a designing influence.

At which point I am summarily dismissed as a creationist and laughed out of the scientists lounge. And just try and get my paper published in a science journal.

After all, what I did wasn’t science, right? Because it didn’t interpret my results in such a way as to conform to the evoutionary mandate.

So, it’s not so much that creationists don’t provide scientific evidence, it’s that their conclusions are not given merit, because “the system” prevents it. So creationism becomes defined as “not science.” And from there you have a classic no-win situation.

8 08 2007

Steve, thank you again for your comment, but I think you’ve missed the point. Positive evidence of a designing influence is not “This is too complex to have been evolved” or “This looks designed”; if design is apparent, then we should be able to say something about the designer. When, where, how, why, and who are all open questions at that point, but these questions are rarely ever entertained by ID advocates; we’re told that they just can’t tell and probably won’t ever know, even their interpretation of design points straight to God (yet there somehow ashamed to say so).

Creationism, on the other hand, is a little more forthright and therefore easier to dismiss. If the hypothesis is that the world is between 10,000 and 6,000 years old, that has been thoroughly refuted, just like that notion that there was a global flood that covered even the highest mountains. The rest of creationist claims (like dinosaurs living alongside humans) are attempts to sneak things that aren’t into the Bible into the book, so I don’t see why they don’t just tack on a few more books to the old testament; it would be far more honest than saying “We know dinosaurs are real, so therefore they would have to have been on the Ark.”

I would actually love to see some scientific proof of a designer; it would be very interesting to know if it was the Greek or Roman gods, Hindu gods, Allah, God, aliens, Urkel, or whomever you like. Again, what is lacking from creationist and ID standpoints is actual POSITIVE evidence of anything, and the religious stance of creationists and ID advocates certainly compromises their positions (I don’t see the Discovery Institute saying “Well, maybe Odin did it”). I am not summarily dismissing your assertions because they are religious, but rather that you’ve offered no positive proof outside a “feeling” you alluded to that you get from understanding science. That sense of wonder is a good thing, and I hope you keep it, but I can’t say that it’s persuasive evidence.

There are creationists who are scientists and they want desperately to prove that their ideas are true, but everything they do has to go through a mental filter of “This has to fit the Bible.” Even though some carry out research and experiments, sabotaging your own work by dating dinosaur bones with carbon isotopes (which can’t give you the date of anything more than 60,000 years old) isn’t scientific at all. Again and again creationists have failed to come up with any positive proof, and standard positions based upon the Bible have long been shown to be false. If creationism has any life left in it, it is in the area of “intelligent design,” but all of its scientists are so non-committal that they have failed to prove any evidence of anything or even carry out any research (authoring a popular book does not count as actually carrying out science).

8 08 2007
Chris Harrison

On the contrary. That continues to be the crux of my point. That I examine the evidence, conduct my scientific inquiries, perform my analysis and weigh the options like a right proper scientist might…and I come to what I see as a supportable and sustainable conclusion that the evidence points to a designing influence.

Steve, you have an opportunity here to explain your analysis and why you think they lead to design conclusion. If you’ll notice, there haven’t been any personal insults here, and Brian (and myself) are willing to take a look at what’s convinced you of design.

9 08 2007

You need also to look at how evolution is “explained” in elementary and secondary schools. Quite often teachers will phrase explanations in such a way to unintentionally give the impression that living things “intentionally” evolved. Saying that a certain kind of fish evolved lungs to fill a food niche almost implies design. When you consider that most secondary school science teachers are drafted english majors and not scientists, you can see the beginnings of misunderstanding right there. And if you write a book coaching teachers on how to present evolution in the correct terms, the fundies will scream about indoctrination of the young……

9 08 2007

Thanks for stopping by again, O.F. I think I have mentioned the book to you before, but Christopher Toumey’s God’s Own Scientists is a wonderful, non-polemical look at creationists both at the level of major ministries and small, often more-open-minded small study groups. I have to say that outside of merely ignoring evolution in schools and the media doing a piss-poor job of presenting it (like today’s headlines about the new Nature paper on hominids), I agree with Toumey’s assertion that “science” today can exist as a somewhat malleable system of symbols that can easily be co-opted by pseudo-scientists to impress others. He calls this the “trivial model” of science, and it seems that anyone who can tap into the cultural perception of what science should be (old white guys in lab coats, bubbling substances in beakers, microscopes, technical jargon, etc.) can gain some authority even if their ideas are entirely bunk. Take ID, for example; despite clamoring from scientists to actually give us some peer-reviewed research on ID, all they want to do is write popular books about the weakness of “Darwinism.” There seems to be a strategy shift in the ID camp, with books like Behe’s Edge of Evolution and the DI’s Explore Evolution treading light on the intelligent design, expounding heavily about how evolution is full of holes.

In any case, Toumey’s book (and Sagan’s The Demon-Haunted World) are two must-reads for anyone invested in this debate at all, and I think both authors do a good job of respecting the people making odd claims but being ruthless with their hypotheses.

10 08 2007

I couldn’t get that paper, of course, so I looked it up on the internet hoping someone “accidentally” posted it. The first article I saw pretty much debunked the methodology used in the report. The rest of the google page was full of news pieces extolling the conclusions of the report. Sigh……………

10 08 2007

O.F., if you’re talking about the new Nature paper on hominids, I can send it to you.

10 08 2007

Yes – I was talking about that paper but I’m afraid sending it to me would be a waste. I really haven’t the expertise to analyse it properly. (My spelling checker is definitely an American spelling checker – it doesn’t like “analyse” – it likes analyze.) But I would like to read it anyway.

10 08 2007

It is now in your inbox. I don’t understand everything I read in many papers myself, but it’s not hard to get the “big ideas” behind it. Enjoy!

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