October 14, 2008 | David F. Coppedge

Tooth Evolution Theory Lacks Bite

The hardest substance in your body is your teeth.  The varieties of teeth among vertebrates is astounding, from the tiny incisors in a mole to the bone-crushing scimitars on a T. rex.  Many fossils are known only from their teeth.  One would think teeth are the best-studied objects in evolutionary theory, but a recent paper uncovers a near absence of explanation about how they arose.
    Soukup et al started the confession with a paper in Nature that essentially falsified the two leading theories for the origin of teeth.1  Georgy Koentges (U of Warwick) followed up in the News and Views section of Nature by almost throwing his hands up.2  First, he said that the development of teeth in the embryo is a “contentious question” about which “we know too little”.  It might be surprising to layman that something observable in the lab – the development of teeth in the embryo – remains obscure.  The subjects of tooth embryology and tooth evolution are related, because evolutionists look where teeth develop for clues about tissues that natural selection might have co-opted for the first teeth.  But if tooth development is obscure, theories of tooth evolution stand on shaky gums.

In evolutionary terms, tooth-like structures – such as the denticles that appear as a ubiquitous feature on the body armour of early vertebrates – might have preceded the advent of jaws proper.  The staggering histological diversity of such structures has led to byzantine systems of classification of vertebrate hard tissues, and in turn to serious differences of opinion.  The acrimony of these debates has scaled linearly with the lack of experimental embryological evidence about the underlying process.

Debate has squared off over two opposite opinions that were either coming or going:

The presence of denticles on the body of early jawed vertebrates led to speculation that, early in vertebrate evolution, embryonic ectoderm moved into the mouth and initiated organized tooth rows there.  In contrast to this ‘outside-in’ view of events is the ‘inside-out’ theory.  This theory holds that the evolutionary origins of teeth started in the mouth or pharynx and are linked to the presence of embryonic endoderm.  An outward migration of cells, or a co-option of a pharyngeal tooth-forming program in a part of the outer body surface, would have to occur to explain the presence of denticles on the outer covering of sharks and other more basal vertebrates.
    Both theories hinge on the idea that there is an inherent difference in the inductive power of ectoderm and endoderm, and that migration of one or the other is the crucial factor in tooth formation.  Implicit in this is the notion that tooth and denticle anatomy reflects embryonic origins – that is, that actual tooth or denticle histology can reveal which embryonic tissue was the key source.

Well, that “notion” has been shot down, Koentges continues: “Soukup et al. now provide experimental grounds to debunk such ideas by testing the spatial distribution of ectoderm and endoderm in relation to erupting teeth.”  They found in certain amphibians that it doesn’t matter whether the teeth emerge from mesoderm or ectoderm: somehow the resulting teeth end up just the same.  Notice the evolutionary implications of this “dramatic finding” –

….the authors show that there is no relationship between ectodermal and endodermal origin and the shape or nature of the resulting teeth – at least at the point when such teeth become visible.  The enamel of teeth can be of ectodermal, endodermal or mixed origin.  This is a dramatic finding.  It means that one cannot infer relative distributions of ectoderm and endoderm from tooth or denticle anatomy even in a living species, let alone in a fossil.

Did he have any good news to come to the rescue?  If so, it’s in future tense.  All he left were a pile of more questions:

Nonetheless, Soukup and colleagues’ study removes the basis for theories depending on ‘co-option’ processes that would require migration of epithelial cells, and redirects future research.  We need to study the molecular co-option of tooth or denticle genetic programs, a process that might have occurred several times independently in the history of jawed vertebrates.  Which gene-regulatory regions are involved in switching on key regulators of tooth or denticle initiation in both epithelial and mesenchymal tissue?  How, where and when did these genomic regions evolve?  Are the same regions driving expression in ectoderm and endoderm?  Are the regions involved in patterning denticle fields also used for organizing feathers and hair?  And where are the ‘atoms of information’ that initiate, position and shape a tooth or denticle, and make its internal structure different from that of a dermal bone?

There won’t be any simple answers, he continued: only combinations of factors.  That concept of information cropped up again: finding the answer will require “new experimental and bioinformatics approaches.”
    Koentges ended by distracting attention from his embarrassment with a few mixed metaphors: “Cracking such hard technical nuts will require strong intellectual teeth as well as robust body armour, given the vigour of opinion on this subject.


1.  Soukup et al, “Dual epithelial origin of vertebrate oral teeth,” Nature 455, 795-798 (9 October 2008)| doi:10.1038/nature07304.
2.  Georgy Koentges, “Developmental biology: Teeth in double trouble,” Nature 455, 747-748 (9 October 2008) | doi:10.1038/455747a.

Ha!  This is rich.  Look carefully: did you find any explanatory power for evolution in this story?  No; it was all hand-waving and misdirection.  He waffled: it might be outside-in, it might be inside-out, but whoa!  The paper found both are wrong, so maybe it’s downside-up, upside-down, or over the rainbow.  For all this time, we listened to those grandiose tales of How the T. rex Got Its Teeth and other fables, and they never told us there was nothing empirical to back them up.  They can’t even look down in the mouth and find out what’s going on in a developing salamander right now.  How many years has it been since Charlie proposed natural selection as the explanation of all explanations?  All we see are questions and empty speculations.
    Making up words is not explanation.  Look at what Georgy did.  He’s got miracle-words everywhere.  He spoke of the “advent” of jaws.  That sounds downright churchy.  Jaws became flesh, and dwelt among fish.  It’s surprising the Darwin Party doesn’t celebrate Bite-mas in their Byzantine classification temple.  It must be hard to celebrate when “the acrimony of these debates scales linearly with the lack of experimental embryological evidence about the underlying process” of evolution.  Since the acrimony requires robust armor, you can bet the lack of evidence must be huge.  This is an inverse relationship: less evidence, more acrimony.  Do the new math.  In the set of scientific explanations, this means evolution is the empty set.
    There’s plenty more miracles in their story.  While divining the pudding (10/09/2008), they see the ectoderm moving into the mouth, where “it initiated tooth rows there.”  Well, great.  Who did the initiating?  Did it initiate the program on purpose?  Was it following a master plan?  No; they would say.  It was just another miracle of chance that worked.  Isn’t scientific explanation wonderful; the Stuff Happens Law is always there when you need it.
    Next, we are told that the “evolutionary origins of teeth started in the mouth… and are linked to the presence of embryonic ectoderm”.  It evolved because it evolved.  Then, as part of the hand-waving calisthenics, “An outward migration of cells, or a co-option of a pharyngeal tooth-forming program” would have to occur because, according to the puddingoscopy readout, evolution needs to explain both shark skin and shark teeth.  Tooth-forming program?  Who was the programmer?  Whence come the “atoms of information” that flow into teeth or into denticles?  Does information have any meaning without an observer?
    The workout turns intense with extreme jawboning exercises: “We need to study the molecular co-option of tooth or denticle genetic programs, a process that might have occurred several times independently in the jawed vertebrates.”  Wow; that’s real miracles fer ye, o ye of little faith.  What is co-option, if not a sleight-of-mind personification of intelligent design?  It’s the old the Tinker Bell defense.  The evolution fairy decided that jaw ectoderm needed a little bite, so zap! a tooth was born.  Do you have any idea how complex a mouth full of teeth is?  Each tooth has roots, blood vessels, dentin, enamel, a precise shape for its function, and a matching tooth on the other jaw, to say nothing of genetic programs to assemble them at the right time and replace baby teeth with permanent teeth.  To assume that they will just “occur” (note the miracle word) not once but several times independently is absurd.  Since Georgy needed every trick in the evolutionary explanation cookbook, he even threw in a little Haeckel recapitulation theory for taste: “Implicit in this is the notion that tooth and denticle anatomy reflects embryonic origins – that is, that actual tooth or denticle histology can reveal which embryonic tissue was the key source.”  That’s ontology recapitulates phylogeny, in case you missed it.  But Mr. Scientist, Sir, we’re kind of tired of “notions.”  When are we going to get your scientific explanation?  (Notions are found in fabric stores near the sewing machines.  If you use notions without strong empirical fabric, whatsoever you sew you shall also rip.)
    The real howler of miracle-words was mentioned so surreptitiously you might have missed it.  He spoke of the “inductive power of ectoderm and endoderm”.  Clearly, Georgy was not talking about logical induction here.  He was talking about some mystical power in tissue cells that could induce them to evolve into teeth.  If there is a more blatant case of pulling a rabbit out of a hat (in this case, a hard tooth out of squishy cells), then clap wildly for the magic show.  This is circumlocution pretending to be scientific explanation.  It’s as comical as Moliere’s satire on Aristotelian explanations when the doctor in one of his plays explains why opium induces sleep – because it has a “dormitive virtue.”  In the same way, this Doctor Koentges put his readers to sleep by hypnotizing them to envision tooth evolution occurring as a result of the “inductive power” of ectoderm or endoderm cells.  To put it simply, he is saying, “evolution occurs because of the evolution-inducing power of material substances.”  Pray tell how this improves on animism.
    The Darwinists are so clever.  They hide their miracles in highfalutin words.  They shield their faith with cryptic jargon.  These are the same people who turn around and accuse religious people (especially the dastardly creationists) of using God-of-the-gaps logic whenever they can’t explain something.  Creationists and ID advocates, we are told, bring science to a halt by just appealing to faith and saying, “God did it, I believe it, that settles it.”  Come now.  Let’s play “find the hypocrite.”
    Reality check time.  Turn off the reruns of the Darwin Charade Parade, stop looking at the cheerleaders (09/29/2008 commentary), and examine what’s left.  Speculation.  Dramatic findings that long-held theories are falling by the wayside.  New unanswered questions.  Byzantine systems of classification (is this the Dark Ages?).  A rare honest admission that “one cannot infer relative distributions of ectoderm and endoderm from tooth or denticle anatomy even in a living species, let alone in a fossil,” meaning that any hope of reconstructing the evolution of teeth is doomed from the start.  More vaporware.  More futureware.  This, folks, is the magic of evolutionary explanations: it’s all bombastic oratory about change we can believe in, without a plan or a policy that will work in the hard, cruel world of reality.  That’s why you have to believe in it.  Wishful thinking, if strong enough, eases the pain when you hit bottom.
    When in doubt, look tough.  “Cracking such hard technical nuts will require strong intellectual teeth as well as robust body armour,” Koentges said, “given the vigour of opinion on this subject.”  He hasn’t seen anything yet.  Just when he thought this was only intramural warfare, the Visigoths showed up over the horizon (05/09/2006)  Unlike the obese and lazy Darwin Party animals, they don’t use plastic teeth and cardboard armor.  They look disciplined, determined, and armed to the teeth.  For combat over the truth of the tooth, they’re prepared for a bite to the finish.  General Dawkins rallies his troops out of their drunken stupor, bluffing that the Visigoths are a pushover because they trust in “faith” instead of “science.”  Better have some bite behind the bark; and remember, let not the one who puts his armor on boast like the one who takes it off.

(Visited 28 times, 1 visits today)

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.