The Lessons of Tiktaalik

THE last time we mentioned Tiktaalik, the fossil of a transitional species midway between finned fish and four-footed land animals, was in this post: Creationism and Science, where we were pointing out the foolishness of the creationist claim that the past is scientifically unknowable because it can’t be observed or re-created in the lab.

We’re going to repeat some of what we said then, but we’re also going to elaborate a bit, because the discovery of Tiktaalik illustrates — and rebuts — many of the fallacies of creationism. In fact, we think the story of Tiktaalik should be told every time you find yourself in a conversation with a creationist.

When creationists address the subject of transitional fossils, they are in full denial mode. This is because of their dogmatic insistence that one species can’t evolve into another. They acknowledge what they call “micro-evolution” (observed changes due to mutation and selection, as with Darwin’s finches) but they insist that what they call “macro-evolution” (the result of cumulative changes over time) is impossible. Therefore they flatly assert that there are no transitional fossils, despite the abundant evidence to the contrary. See: list of transitional fossils.

They also claim that a transitional creature is impossible, because — and here they regurgitate comic-book creationism — such a creature would have one fin and one leg, or one lung and one gill, or half an eyeball, or some other ridiculous and impossible set of features. No creature like the creationists’ caricatures ever existed, and no biologist thinks otherwise. Gross genetic deformities sometimes occur, but are rarely viable. What we now recognize as transitional creatures were fully-functional and fully-formed members of a breeding population of similar creatures, entirely capable of surviving in their environment. Except for lines that suffered extinction, each ancient species was a link in the long chain of life between its ancestors and its descendants.

In one sense, every creature that produces offspring is transitional, but in a brief time-span there are no visible evolutionary effects. For example, your father is obviously transitional between you and your grandfather, but you’re all clearly the same species. However, if we find a fossil from the middle of a long evolutionary chain that stretches over millions of generations, changes that have occurred over that time span become evident.

The fossil will have some characteristics that were common to its early ancestors but which are absent in its modern descendants. It will possess other characteristics that its ancestors didn’t have, but which are common to its distant descendants. That’s the value of the fossil record — with enough specimens, each is like a single frame in time-lapse photography, or a page in a flip-book.

But still, how can we explain (or try to explain) to a creationist that the scientific approach to learning about the past has actual scientific value — the results of which are far more “true” (i.e., objectively verifiable) than some account that rests upon mere assumptions? There’s probably little to be gained from a philosophical lecture about the relative merits of natural versus supernatural explanations, because creationists are programmed to reject the former and prefer the latter. However, there is yet another method of explaining the merit of a scientific explanation of the past — cross-confirmation by independent lines of evidence.

A splendid instructional example is the discovery of Tiktaalik. Interestingly, Tiktaalik has its own website. One of the principal scientists involved in the discovery was Neil Shubin, author of Your Inner Fish (Amazon listing).

That fossil wasn’t an accidental discovery. It was found by predicting that a transition occurred approximately 360 to 380 million years ago, before which, according to the fossil record, there were no four-legged vertebrates living on land. Relying on geology, an appropriately aged and conveniently exposed rock stratum was located in the Canadian Arctic that had once been an ancient shoreline. That’s where the search commenced.

Bear in mind that the fossil search was based on two independent theories about the past — first, that the fossil record tells a reliable history of the development of life on earth, so the scientists knew when to search; and second, that geologists have developed reliable methods for determining the age of various rock strata, so the scientists knew where to search. The fossil hunt was a test of both theories.

This article in New Scientist, First fossil of fish that crawled onto land discovered, is from April of 2006, the time of the discovery. It says:

Palaeontologists didn’t previously have a decent fossil representing the intermediate between finned fish and four-footed land animals, or tetrapods. The new animal has been named Tiktaalik after suggestions from Inuit elders in the northern Canadian territory of Nunavut, where the fossil was found.

[...]

“We describe this as a ‘fishopod': part fish, part tetrapod,” says Neil Shubin, a palaeontologist at the University of Chicago, and a member of the team that discovered Tiktaalik.

[...]

Tetrapods evolved from lobe-finned fishes between 380 and 365 million years ago.

[...]

Hoping to understand this key period better, Shubin and his colleague Ted Daeschler of the Academy of Natural Sciences in Philadelphia, together with Farish Jenkins of Harvard, began searching for fossil-bearing sediments of the right age. After five years of digging on Ellesmere Island, in the far north of Nunavut, they hit pay dirt …

There’s much more information in that article, and also at the Tiktaalik website to which we linked above. At that site, click on the “Discovery” tab. It’s worth the visit.

An additional point must be made: Creationists often claim that statements about the age of the earth and of fossils involve circular reasoning, because fossils — presumed to be old — are then used to claim that the rock strata in which they are found must also be old — which is all hogwash because the earth was created only 6,000 years ago. However, as the discovery of Tiktaalik so strikingly demonstrates, the fossil find isn’t what caused the rock stratum to be arbitrarily declared of the proper age, merely to suit the theory of evolution. The geological information was separately developed by geologists, using their own methods, and that information was relied upon as a guide to the proper location for the fossil hunt.

The point to be emphasized is this: Testing a specific prediction based on both evolution and geology, Shubin and his colleagues searched for the fossil of a transitional creature that — according to the theory of evolution — must have once existed in a place and time like the one geologists said they were searching. Their discovery, after five years of effort, spectacularly confirmed the validity of both geology and evolution theory. That is why the past is scientifically knowable, even if it can’t be observed or re-created in the lab.

Will the creationist to whom you explain this be convinced? Alas, probably not. But at least you’ll know you gave it a good try.

Copyright © 2009. The Sensuous Curmudgeon. All rights reserved.

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39 responses to “The Lessons of Tiktaalik

  1. Tiktaalik – a pure example of the predictability of Evolution followed by a discovery of just what was predicted.

    Neat

  2. Curmudgeon wrote: “…the creationist claim that the past is scientifically unknowable because it can’t be observed or re-created in the lab.”

    You “Darwinists” just don’t understand creationism. Creationism does admit that the past is scientifically knowable. At least when it suits the purpose of debunking “Darwinism,” or for the increasingly rare YEC/OEC debates. The “scientifically unknowable past” is just a fallback strategy when the other doesn’t work.

    That’s why you “Darwinists” will never win. You just don’t have as many options as “we” do. You refuse to pick and choose only that data that suits your conclusion. You insist on supporting your theory on its own strengths instead of the much easier fabrication of weaknesses of the alternatives. You foolishly discard obsolete evidence and falsified claims instead of recycling them for another gullible audience. ;-)

  3. Frank J says: “Creationism does admit that the past is scientifically knowable. At least when it suits the purpose …”

    True. I had forgotten how ready they were to accept the results of testing of the Shroud of Turin, but only if the conclusion suited them.

  4. The Curmudgeon claims

    For example, your father is obviously transitional between you and your grandfather

    But my Mama assures me I ain’t no kin to my pappy!

    …Er, wait a minute, hang on…

  5. Gabriel Hanna

    Well, there’s only four “scientific” arguments that creationists have EVER made:

    1) Design implies a designer

    2) Irreducible complexity (cribbed from Darwin! “If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. “)

    3) Evolution violates the 2nd law of thermodynamics (revived by Dembski in the form of complex specified information–when he bothers to calculate anything, it is invariably Shannon information)

    4) Fossils, geology, and radioisotopes don’t tell us EVERYTHING, therefore they tell us NOTHING

    In criticizing Popper’s characterization of the scientific method (conjecture and refutation), people talk about the “auxiliary hypothesis” problem.

    Jupiter’s moons aren’t where you say they are? Well, it’s because the speed of light is finite. Mercury’s orbit isn’t where it’s supposed to be? Okay, there’s another planet between the Sun and Mercury. Can’t find it? Something’s wrong with the telescope.

    This is what creationists would like to characterize “Darwinists” as doing… but the evidence for evolution comes from so many different directions and disciplines, that it strains credulity for so many lines of evidence, pointing to the same thing, to ALL be false, each for a different reason.

    This is what E. O. Wilson calls consilience (I think).

    Me, I hammer on the nuclear plants. If radioisotope dating doesn’t work, neither do nuclear plants, it’s the same law of physics. Creationists usually don’t have much of a response; it is very easy to show them up if you can turn the topic to physics.

    Doesn’t work on the Old Earth ones though.

  6. Gabriel Hanna says: “If radioisotope dating doesn’t work, neither do nuclear plants, it’s the same law of physics.”

    That’s good. I dimly sense that you have a future in the the science trade. Hey, is this you?

  7. Gabriel Hanna

    No, this is me:

    http://physics.wsu.edu/Personnel/Graduates/gradir.htm

    But I too do infrared spectroscopy and condensed matter physics. Difference is, this guy is a physical chemist and I am more of chemical physicist.

    Coincidences are funny.

    I get my Ph. D. in December, deus volent.

  8. Irreducible complexity cribbed from Darwin?

    Further back than that. Check out the Wikipedia article on “Irreducible complexity” under the heading “Forerunners” for a sampling going back a couple of hundred years before Darwin.

  9. Gabriel Hanna

    TomS, they’ve quote mined Darwin, so I assume they are taking it from him. They nearly always do quote him when they use the argument. I don’t give them credit for going back a couple of hundred years.

  10. Oh no, you have been infiltrated by a LaFolette.

    Doomed, doomed!

  11. If radioisotope dating doesn’t work, neither do nuclear plants…

    And neither would (many) smoke detectors, gun sights, diagnostic medical techniques, dental x-ray machines, weld-checking devices, or deep-space probes. To name a few additional practical applications of a = a(0)*e^(-lambda*t).

  12. Gabriel Hanna

    Oh no, you have been infiltrated by a LaFolette.

    Many of them have their good points.

  13. Very nice synopsis of Shubin et al’s discovery.

    Also, Gabriel, “If radioisotope dating doesn’t work, neither do nuclear plants, it’s the same law of physics” — I’m going to unashamedly steal that line. :)

  14. Phooey, everyone knows that 6000 years ago half lives were different than they are now. Just like the speed of light.

    Oh ye of little faith.

  15. Gabriel Hanna

    I’m going to unashamedly steal that line. :)

    If you are going to steal it, you must it wisely.

    Both the strong force and the weak force are responsible for radioactive decay and nuclear fission reactions. The weak force is responsible for beta radiation and the strong force and electromagnetism for alpha.

    Decay chains are how you go from one element to another, whether it’s uranium to lead, potassium to argon, or carbon to nitrogen.

    Nuclear fission is harnessing the decay products to split atoms. If atoms didn’t go through radioactive decay the way scientists say they do, then nuclear plants and weapons would not work.

  16. Hey, if radioisotope dating doesn’t work, neither does the sun. Or does that thing have its own rules?

  17. It was created that way.

    Get with the program.

  18. Gabriel Hanna

    Hey, if radioisotope dating doesn’t work, neither does the sun. Or does that thing have its own rules?

    Fusion is a different effect. The sun doesn’t need decay products to function. The sun-well, a predecessor sun much like ours–was needed to produce anything more complicated than hydrogen.

    The sun fuses hydrogen to helium. Eventually it uses all the helium, and then fuses that to make something else, getting less efficient every time, until finally you’ve got something that is mostly iron which (I think) then blows up, and if it’s lucky gets agglomerated into a new solar system, eventually.

  19. Gabriel Hanna says: “Fusion is a different effect.”

    Yeah, well … I knew that. [Mumble, grumble ...]

  20. A nice discussion of Tiktaalik. (I recently read Shubin’s book.) The problem, of course, is creationists and their ilk are beyond the reach of rational discourse. However, if you want to drive them crazy, insist the universe was created last night. Insist they were created with memories of yesterday etc as a test. Drives them nuts because it is a supernatural explanation beyond the realm of testibility or falsification.

  21. Thom says: “However, if you want to drive them crazy …”

    Confucius say: Never tease a rabid dog.

  22. Infidel. I’m sure someone has proven from The Bible that the True Number is:

    1/137.035999070…

  23. That number has its own website: 137.

  24. Hey, 69 is in Wikipedia. It’s the atomic number of thulium. Who knew?

  25. retiredsciguy

    Is it just a coincidence that 69 + 69 = 138, which of course is alpha + 1? Does this have deep significance, or am I just diving into uncharted territory?

  26. Gabriel Hanna

    69, diving, uncharted–the joke writes itself.

  27. retiredsciguy asks:

    Is it just a coincidence that 69 + 69 = 138, which of course is alpha + 1? Does this have deep significance, or am I just diving into uncharted territory?

    There are no coincidences. Everything is designed. The more one looks, the more of these relationships one finds. But I advise you to pull back from such explorations. If not, madness awaits. Trust me, for I have been there.

  28. retiredsciguy

    Gabriel Hanna wrote,

    “69, diving, uncharted–the joke writes itself.”

    I know. That’s the only kind I’m capable of writing.

  29. Since you guys know all the answers, please explain the evolution of complex yet perfectly compatible male and female reproductive systems in totally independent organisms, be that man and woman, male and female cats, dogs, etc.

    I suppose we have to apply natural selection . . . “Sorry pal, yours is too big. And yours is too small. Ah, that looks better, but what a shame you haven’t evolved any sperm yet! Come back in a few million years and I’ll give you another go. OK?

    Meanwhile I’m going to accumulate enough DNA copying errors to give me a womb and better tits. By the way, that might help you guys with little ones . . . ”

    No wonder Dawkins avoids the subject.

  30. JT does have a point. Evolutionists have yet to explain this. Of course, this is basically a God of the gaps argument. Just because we don’t know everything now doesn’t mean we won’t know the answer eventually nor does it mean we should throw out what we DO know.

    I presume from JT’s comment that he believes in God or, at least, an intelligent designer. I would ask JT similar questions. Why is there male/female reproduction for some “kinds” but not others. Sexual reproduction is very inefficient. It seems to me that the fact that there is more than one method of reproduction argues more for evolution than the involvement of an intelligent designer. Wouldn’t it be more “intelligent” to just use the best method of reproduction than a variety?

  31. Gabriel Hanna

    JT does have a point. Evolutionists have yet to explain this.

    This IS explained. Male genes and female genes pass through both sexes. Dawkins puts this explicitly in “The Selfish Gene”; if a man has genes for a long penis, both sons and daughters inherit the genes even though the daughters don’t express the gene.

    JT’s scenario might make sense if penis genes came only from the father and vagina genes only from the mother. But all of us are descended from people whose parts fit together right, and none of us are descended from people whose didn’t, and we all have genes from all of them.

  32. Well Gabriel, that may explain how two sexes continue but it doesn’t explain how two sexes came about in the first place.

  33. RogerE says: “… but it doesn’t explain how two sexes came about in the first place.”

    The two sexes exist in hermaphrodites. Some hermaphrodites cycle back and forth from one to the other. All that needs to happen is that one individual is mutated so that it’s stuck in one sex or the other. This isn’t a reproductive disaster, as that individual can always find a mate. If the “sticky” mutation perseveres, in future generations there will be some individuals that are always one gender or the other. That’s how it begins.

  34. Roger, thanks for your reasoned response. I was expecting abuse.

    I have concluded that it is virtually impossible to prove anything beyond a reasonable doubt. People believe what they want to believe, what they feel happy with, then try to find logical arguments to support it. Isn’t that what Darwin did?

    Once you believe something, you are happy to accept vague supportive statements such as, on the one hand: “God created it that way by a miracle” — or on the other: “They must have invented toolbox genes” as the explanation of the Cambrian Explosion.

    There are a lot of assumptions floating about. Why assume an intelligent designer would do things the way we see as “most efficient”?

    Do you design for minimum cost or maximum speed and comfort? Or do you blend factors to create what the late Edward Matchett called “appropriate design”?

    P.S. Where did the genes come from in the first place Gabriel? I heard a top Cambridge professor of evolution recently say that was “below the Darwinian horizon”. So that explains it!

  35. “Do you design for minimum cost or maximum speed and comfort? Or do you blend factors to create what the late Edward Matchett called “appropriate design”?”

    Its called natural selection. If the organism isn’t as suitable for its environment as another, it won’t be able to breed as much as the more suitable. Thus organisms more suited for the environment become more populous than those who aren’t. It doesn’t stop there, as genetic variation continues so those creatures continue to evolve towards meeting the demands of its environment. This then forces the appearance of the creatures being “designed” for their environment. The reality really is that the environment “designed” them.

    Oh and for genome appearance, please realize exactly how chemically active and patterned based organic chemicals (carbon, oxygen, hydrogen, etc.) really are. They are ferociously reactive, but with only a few ways they can bond to each other, only some patterns can really be formed. This continues even into large molecules of carbohydrates and such and onto proteins. They are large and complex, but only so many reactions are possible and ones that are self-replicating have an advantage of being persistent AND reproducing to add more to the mix. So as of now, the exact sequence of genome emergence isn’t known, the PROCESSES that probably led to it are understood and demonstrable. There isn’t a need to add some designer to the mix to explain things and would in fact lead to more confusion. Who, what, when, where, why, and how come to mind almost immediately.

    And if said professor remarked that genome creation is “below Darwinian horizon” it seems to be a remark that, despite many creationist rantings, where genes came from has NOTHING to do with evolution and is a separate field of study called Abiogenesis.

  36. I cannot believe that every incredible detail of the human body, from hair follicle to the bones of the middle ear, was “designed” by the action of natural selection giving either the thumbs up or down to an endless stream of random DNA copying errors over zillions of years.

    Even devout evolutionist Derek Hough in “Evolution — a case of stating the obvious” admits that such an idea is “preposterous”. He is currently searching for a more credible mechanism.

    As Hough also admits, he still accepts evolution as a “faith” — unable to accept the alternatives, God or magic.

    As regards Abiogenesis, I agree with Darwin that God the Creator “breathed” life into “a few forms or one”. That would include their genes I assume.

  37. Stephen Black

    You evolutionists are stupid. One fossil out of millions of like fossils and you decide it is a transition fossil. Why not a new species you morons? Oh you say…it comes from strata that is millions of years old so it can’t be current with the millions of like fossils. For you convenience it was exposed millions of year old strata in the arctic which by the way was tropical at one time so our whole ecosystem must have been different. Why not talk about that you evolutionary imbeciles. The ruins of Puma Punka disprove evolution(our onward upward progress from cave dwelling) never mind the dearth of transitional fossils anongst the plethora of species extant. I do the best I is, I from come the bush.

  38. Goodbye, Stephen Black.