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evolution, Religion, science

Design and Transitional Fossils

This is Tiktaalik.  It was discovered by Neil Shubin and several of his colleagues, who had been looking for it for over a decade.  In many ways, Tiktaalik is the scientific equivalent of the Crocoduck.  It really is a transition between two modern forms of life — fish and amphibians.

The details of Tiktaalik‘s “transitional nature” are very interesting, but rather than focus my attention in that direction, I want to instead use the story of its discovery to help dispel a couple of misconceptions about evolution and Intelligent Design.


The first thing that’s important about Tiktaalik’s discovery is that it was not accidental.  Neil Shubin, et al, had been searching for it in very specific locations for many years.  This fact alone highlights one of the major differences between Intelligent Design Theory (sic!) and Evolutionary Theory.  Like all valid scientific theories, evolution is powerful as a predictive tool.  Using what they already knew about evolutionary theory, scientists predicted three crucial facts about Tiktaalik before ever laying eyes on it.

  1. The structure of its fins, neck and head
  2. Its age
  3. The location of its fossils.

This may not seem like much, but in the broad scheme of evolutionary biology, these three factors are crucially important.  The scientists were searching for the secret of the transition between fins and limbs, as well as the origin of necks, which was a huge evolutionary step.  Because of the placement of fossils in the geologic column, scientists were able to say with relative certainty that before the Devonian Period, there simply were no animals with necks or limbs.  Fins there were aplenty, but no limbs or necks.  They were looking for an animal with intermediate qualities between limbs and fins, and they knew that it had lived around 375 million years ago.  They could make this guess based on the fact that there simply are no land animal fossils before a certain date, and after another date, there are fully transitioned limbs.  Therefore, the transition had to have occurred during a specific window.

At this point, let me make one thing abundantly clear.  There has never been one scientific prediction made by a scientist using Intelligent Design Theory.  Using evolutionary theory, scientists boarded a plane and flew to within a couple of miles of where they eventually found the fossil they were looking for — the fossil they knew would have a flat head, a neck, and something in between limbs and fins. Out of all the land on earth, they picked precisely the right location, based entirely on the predictions of evolutionary theory.

The measure of a theory’s validity is its accuracy in making predictions.  Evolutionary theory is used daily to make accurate predictions.  If you have taken medicine from any recent pharmacological discoveries, it’s very likely that you have evolutionary theory to thank.  If you have eaten produce or meat from a grocery store, you have evolutionary theory to thank.  Evolution’s ability to make predictions is unrivaled.  In fact, saying it is unrivaled does not do it justice.  There is simply not a competing theory which has made accurate predictions.

Perfect Design

Tiktaalik’s appendages are neither limbs nor fins.  In fact, they are fins which are en route to becoming limbs.  Even more astonishing, they are rather definitive proof of the falsehood of one of Intelligent Design’s claims — the “perfection of design.”  It is supposed that each plant or animal is “perfectly suited” to its environment, and that this perfection implies a perfect creator.

The truth of the matter is that very few, if any, designs in nature are “perfect.”   What exactly do we mean when we say that a design is perfect?  Perfect in what sense?  Perfect against what template?  The fact that something survives to reproduce doesn’t imply any sort of perfection.  It only indicates enough survival competence to survive.  In the same way, the fact that an appendage performs a task adequately doesn’t mean it’s perfect.  It means it is sufficient.

We can see this clearly in humans.  We have wisdom teeth that need surgical removal.  Our eyesight is generally far less than crystal clear.  Our hearing can indicate the general direction of a sound’s source, but not its precise location.  We can detect seriously spoiled meat by smell, but not the presence of harmful bacteria which will make us sick even though the meat smells fine.

We know from our scientific examination of the rocks in which Tiktaalik was found that it lived in shallow streams and mud flats.  By examining its skeletal structure, we know that it could push itself up on its half-fin-half-limbs.  It could probably also propel itself for short distances on land or in shallow mud.  Unlike fish, its skeletal structure could take the extra gravity.  Is this design perfect?  Hardly.  It surely couldn’t go far out of water, and could only lift itself a short distance, probably for relatively short durations.  (Think of our primate cousins who can walk with difficulty on two legs for short distances, but must resort to their four legged gate relatively quickly.)

The fact is, all life is transitional.  That is, the notion of a transitional species is interesting when a new and relatively unique adaptation appears.  Lungs, necks, shoulders, wings, etc, are all very interesting adaptations, and when we find a creature in an intermediate stage between any of these and their predecessors, it makes all the science journals.  But these evolutionary “leaps” are relatively rare.  Once evolution has stumbled upon something that works, it tends to keep it so long as it’s still sufficient for the task.

As you can see, the basic structure of these two limbs is more or less identical.  One bone, two bones, lots of little bones, then finally, digits.  This is the same for all arms (and wings) in the animal kingdom — not because it’s the “perfect design” but because the essential underlying structure works well enough, and with the right design tweaks, it can be adapted (get it?!  ADAPTED!) to many different tasks and environments.

The big leap from fish to land animal was the development of wrists and shoulders.  Tiktaalik has a shoulder, and it has the one bone base of modern limbs, but the rest of its appendage is a fin.  This is not a perfect design.  It’s a design that works for the time being.  Rather than take its chances against fish twice its size in deeper waters, Tiktaalik found refuge and enough food to survive in shallows.  It was competent.


Evolution is not a journey to a destination.  It’s a run on a treadmill.  In the competition for survival, species must keep a certain pace or they will be left behind.  Complexity and design innovations are not moving towards perfection.  They are simply the discovery (by mathematical chance) of design innovations that work well enough for individuals to survive and reproduce.

We can see this concept clearly in humans, who are even now developing new design innovations to help us cope with our conspicuously high lactose intake as adults, which is a new environmental challenge to overcome.  We are constantly evolving, though most of the changes are too small for us to detect.  Four limbs, two eyes, one nose, one mouth, and one set of genitals works well enough for us to survive admirably, and without a sustained driving pressure for innovation, we will continue to have the same basic design.

Since Tiktaalik or one of its cousins first developed the neck, there hasn’t been a new, better alternative to the neck.  Instead, the basic design has been adapted across literally millions of species, each of whom needed this or that tweak for the neck to be functional enough to facilitate survival in new environmental niches.  Every species with a neck is a transitional species.  The transition is from one environment, in which the “old” neck is sufficient, to a new environment, in which the new, slightly modified neck is sufficient for the tasks a neck must perform, but the old neck either doesn’t work anymore, or works less effectively than the new one.

Perhaps part of the allure of Intelligent Design is the relative rarity of new design innovations.  Perhaps it seems that because arms and legs are nearly ubiquitous among animals, that there is some magical perfect formula suggesting that four limbs, shoulders, and wrists were handed out to all comers.  Evolutionary theory, however, predicts that once the four limb arrangement became fully formed, it became prohibitively unlikely that any design innovations could overtake it.   It is telling that the best design engineers in the world tend not to design self-propelled robots with four limbs.  Instead, they use wheels, or six or eight legs, or tracks.  Our design is not perfect.  It’s just what we happened to get when Tiktaalikneeded to get out of the way of bigger fish, and started doing pushups in the shallows.



3 thoughts on “Design and Transitional Fossils

  1. Good post, Hamby.

    Posted by Watcher | November 16, 2009, 11:30 pm
  2. Great, I like fossils. We can get the evolutions of the creations on earth to draw a picture of earth billions years ago. Fantastic.

    Posted by George | November 17, 2009, 8:50 pm
  3. Occam’s razor still says god loses.

    Posted by Watcher | November 18, 2009, 7:44 pm

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