Paper View:  Cambrian Explosion Damage Control

Like some federal official holding a press conference after a disaster, a Harvard paleontologist has tackled the unenviable job of explaining what Darwin called the most severe challenge that could be levied against his theory: the fossil record.  The challenge starts with a bang.  Right near the beginning, virtually all animal phyla appear abruptly without ancestors: the so-called Cambrian explosion.  An evolutionist, devoted to a theory expecting to find slow and gradual change, has no small challenge explaining this event.  It’s made all the more difficult by critics of evolutionary theory, like angry reporters asking tough questions, pointing out what the Darwin administration said vs. what the cameras show.  This is no job for a junior spin doctor.

Dr. Charles R. Marshall has the credentials to be a good press secretary: Department of Earth and Planetary Sciences, Department of Organismic and Evolutionary Biology, and Department of Invertebrate Paleontology, Museum of Comparative Zoology at Harvard.  Writing in the May issue of the Annual Review of Earth and Planetary Sciences,¹ he gives what amounts to a State of the Cambrian Explosion address.  Will he be the man of the hour, the master of disaster?

Many in the audience have not been happy with the Darwin administration.  As evidence of the need for regime change, they point to the failure to explain the sudden appearance of virtually all animal body plans in the Cambrian, the lowest layers of fossil-bearing strata.  Duane Gish and Henry Morris pounded evolutionists on this point in their decades of debates.  It was the subject of Stephen Meyer’s notorious exposè (09/24/2004) that made the Darwin administration look like censors.  It was one of the Icons of Evolution defaced by Jonathan Wells.  From the earliest criticisms of Darwin’s book to the cover of Time magazine in recent years, “Biology’s Big Bang” has been one of evolutionary theory’s biggest embarrassments.

Enquiring minds want to know; can Darwinian scientists deal with this?  Aware of the opposition (as he must be), will Marshall describe the problem honestly and accurately?  Will his presentation confirm the viability of the ruling party’s program?  Will the applause be hearty or tepid?  Stepping up to the journal podium, he begins his paper:

The Cambrian “explosion,” or radiation, is perhaps the most significant evolutionary transition seen in the fossil record.  Essentially all of the readily fossilizable animal body plans first appear in the fossil record during this interval (Valentine 2002).  We move from the depths of the Precambrian world, where the sedimentary record is essentially devoid of animal fossils, to the Phanerozoic, where animal life leaves pervasive evidence of its existence, both as body fossils and as disturbers of the sediment.
Numerous explanations for the Cambrian “explosion” have been posited (note here that I am not considering here in any detail explanations for the precursor to the Cambrian “explosion,” the Ediacaran radiation).  Classification of this rich panoply of explanations is somewhat arbitrary but typically explanations center on one of the following factors: (a) changes in the abiotic environment, (b) changes in the genetic or developmental capacity of the taxa involved, or (c) changes in the biotic environment, i.e., in ecology.  All of these factors must have played a role, but how important was each?  To what extent did the Cambrian “explosion” flow from an interaction between them?  How might we develop a conceptual framework for understanding that interaction?  Developing a coherent explanation for the Cambrian “explosion” faces several challenges….   (Emphasis added in all quotes.)

And thus he dives right in.  One notices right off the bat his habit of putting “explosion” in quotes.  This is “because, while the Cambrian radiation occurred quickly compared with the time between the Cambrian and the present, it still extended over some 20 million years of the earliest Cambrian, or longer if you add in the last 30 million years of the Ediacaran and the entire 55 million year duration of the Cambrian.”  This attempt to downplay the seriousness of the damage would surely elicit some boos from the gallery.  One of Marshall’s authorities, Dr. James Valentine, whom Marshall admits did a “masterly treatment of the origin of phyla” (see 07/29/2004) said it was 10 million years, or maybe even 5 million, when interviewed for the film Icons of Evolution.²  But even given the widest latitude of time, Marshall’s own diagram in the paper shows new phyla appearing abruptly without ancestors at various points within the timeline.  Trilobites, for instance, show up at about 525 million years, and no pre-trilobites have ever been found.

Marshall provides some background and a timeline of the Cambrian radiation (as it is also called).  He delves into the Precambrian looking for ancestors.  He discusses the strange Ediacaran creatures (see 08/19/2004); no one is sure, however, if these are even animals, and even if they were, they seem to have gone extinct before the explosion, without having any relationship to the complex animals that followed.  Marshall portrays a sequence (but not necessarily a phylogeny) of the explosion in slo-mo.  Traces in the rock, first 2-dimensional then 3-dimensional, appear right before the Cambrian boundary.  Next, some small shelly things appear which might be either new animals or broken bits of molluscs and brachiopods.  Then, boom: “large, morphologically diverse taxa.”  These include the trilobites and echinoderms, and all the wondrously diverse organisms found in the Chengjiang biota of China.  By the time of the Burgess Shale formation (Canada), less than 10 million years later, the “Cambrian explosion is all but spent.”  (He forgot to add the quotes that time).  We’ll abbreviate it CE from here on.

Can we trust the fossil record, though?  Could the CE just be a selection effect, an artifact of what animals happened to get fossilized?  He seems to agree with Valentine and colleagues (1991) who, in “the only quantitative treatment of the suddenness of the Cambrian ‘explosion,’ conclude that the suddenness of the adaptive radiation is real, even when the incompleteness of the fossil and rock records is taken into account.”  But he speculates that “it is likely that evolutionary lineages have their origins in rocks older than their first observed occurrences in the fossil record.”  The only evidence he offers is that “attempts to use molecular clocks to estimate the time of origin of the animal phyla” (what he calls a “subtle and difficult art” because different clades may “evolve at different rates”) have led to “much larger estimates of the incompleteness of the fossil record” (see 04/20/2004).  Strangely, he brings these two conflicting data sets into accord – without evidence: first, by asserting “the fact that the divergence times of lineages (which molecular clocks estimate) may significantly predate the time of emergence of diagnosable morphologies (which the fossil record estimates),” and second, by stating flatly that “all agree that the phyla have at least some Precambrian history.”  Both these assertions assume evolution.

To set up the problem of the Cambrian “explosion” (quote marks or not), Marshall outlines the aspects that need explaining:

There are five major components of the Cambrian “explosion” that need to be explained: (a) the spectacular increase in animal disparity, (b) the rise in animal diversity,³ (c) why the time of onset of the explosion was some 543�542 mya, (d) why the duration of the explosion was some tens of million years long, and (e) why the event appears unique.
There are also two problems that emerge once we begin to examine the fossil record in some detail: (f) Where are the (largely) missing fossils of the bilaterian stem-groups, and (g) What are the phylogenetic affinities of the Ediacaran biota?

Marshall mentions that the CE is not the only spectacular radiation in the record.  He mentions the large increases in diversity in the Ordovician, Paleozoic, Mesozoic and Cenozoic; “there are many other major events in the history of animal life other than the Cambrian ‘explosion,” he reminds the reader.  The unique thing about the CE is that all the later radiations are variations on body plans already established in the Cambrian.  (It is also puzzling why he would point to more explosions to help explain this one.)

The remainder of Marshall’s paper can be divided roughly into two parts.  The first examines all the proposed explanations for the CE, including their relative strengths in explaining all seven aspects listed above.  These he shows to be inadequate.  The second part gives his own personal explanation.  We now summarize part one: here is why, in his opinion, the other explanations fail in one way or another (although, he suggests, each might contribute partial explanations):

1. Environmental Explanations:  These look for geological or atmospheric changes that created environments suitable for change.  He says, “There has been a resurgence in this class of explanation, partly owing to increased interest in the Cambrian ‘explosion’ within the wider geoscience community.”  (Who, in particular is interested, and why, is not detailed.)
   1. Increased oxygen?  Were oxygen levels too low for large animals?  Probably not.  Some Ediacarans were large.  Hard to test: we don’t know the minimum oxygen requirements of the first animals, and we don’t know how much oxygen there was.
   2. Snowball Earth?  Did biology’s big bang after the Earth emerged from a deep freeze?  Unlikely; too early.  More importantly, “It is also hard to see how a major environmental catastrophe could have lead [sic] to fundamentally new levels of developmental and morphological organization.”
   3. Carbon shock?  Maybe the Earth underwent some catastrophe at the time, as suggested by carbon isotope anomalies found at the beginning of the Cambrian.  Some compare this with the presumed extinction of the dinosaurs, followed by the rapid radiation of mammals.  Marshall does not feel this comparison is appropriate.  Both dinosaurs and mammals were vertebrates.  The CE, by contrast, saw “a dramatic increase in both disparity and diversity.”  Worse, even though “We have much to understand” about such things, this suffers from the same objection: “it is hard to see how a simple (even if large) environmental disturbance can lead to an increase in disparity.”
   4. Continental shakeup?  Maybe polar wanderings of continents caused “methane burps” that altered Earth’s temperature.  Same flaw: “No explanation is offered as to why an increase in diversity, per se, should have led to new levels of disparity.”  He tries not to be too hard on these suggestions.  “This remains an intriguing hypothesis,” he grants.

   In summary, each of these sets the table but doesn’t invite the guests.  “While it is clear that the environment needs to have been conducive to the evolution of large animals for the Cambrian ‘explosion’ to proceed,” he explains, “none of the environmental explanations address why an environment permissive of complex animal life should necessarily lead to the evolution of complex animal life, and especially why we should see a shift from diploblastic-grade organisms to complex triploblasts.”⁴

2. Developmental Explanations:  These look for developmental or genetic reasons for the sudden onset of evolutionary innovation.  Marshall mentions a key point: “Animals cannot evolve if the genes for making them are not yet in place.”
   1. Bilateral Development?  While the discovery of Hox genes began a “revolution in our understanding of the genetic basis of morphological form,” Marshall admits we still “understand little of how and when the system originated,” but perhaps gene duplication was involved.  But here he uses his first exclamation point.  Noting that all animal groups share the same developmental program, we can make inferences about their common origins: “While we only have detailed genetic data from a very few species (the so-called model systems), the last common ancestor of these species also happens to be the last common ancestor of all the bilaterian phyla!” he announces triumphantly.  This allows us “to make quite powerful inferences about the genetic capacities of animals that lived at the Precambrian/Cambrian transition.”  Disparate animals may look as different as apples and oranges on the outside, but are “genetically comparable” on the inside.  Maybe these developmental programs originated even farther back in time.  Time for a reality check:
      

      However, the significance of the presence of these shared genes is still an open question (Erwin & Davidson 2002).  Does the presence of the tinman/NK2.5 gene in the last common ancestor of the bilaterians indicate the presence of a heart and circulatory system in that ancestor, or does the gene simply mark a special type of muscle that was later and independently co-opted to initiate the development of fully developed circulatory systems in different lineages (Erwin & Davidson 2002)?  If the latter view is correct then there must have been considerable developmental sophistication on route from the last common ancestor of the bilaterians to the living phyla.

   2. Code Shuffling?  Since genes are combinatorial, like Lego blocks, maybe complexity can arise as an “emergent property” (i.e., an unforeseen level of complexity independent of the building blocks).  He refers to Stephen Wolfram, who wrote about this controversial idea in A New Kind of Science (08/18/2003).  More on this later.
   3. Entrenchment?  This is the “appealing idea” that the first members of a clade are the most plastic, but later on, they become entrenched (canalized) and resistant to change (11/02/2005, 06/25/2002)    Marshall does not think this idea is a winner, either; he thinks it more plausible that “ecological/functional constraints, not entrenchment” led to the fossil patterns seen.

   Like the environmental explanations, this class also comes up short of the dynamite needed for the CE:

   The developmental class of explanation, per se, does not address the question of why the origin of such a system should, ipso facto, lead to increased diversity or disparity.  In fact, if at least one Ediacaran is a bilaterian (Kimberella, Spriggina, Dickinsonia, or Arkarua, for example), then the bilaterian developmental system existed at least a few tens of millions of years prior to the Cambrian “explosion,” suggesting something more than just developmental innovation might be needed to account for the “explosion.”

3. Ecological Explanations:  Suppose some Precambrian animal develops an eye or a mouth (trilobites, after all, already had complex eyes)  Suddenly, the lucky winner is like a burglar with a gun in a supermarket.  To cope, all the other animals all must develop defenses, like shells and armor.  The world is divided into predators and prey.  An evolutionary arms race is on.  Marshall quotes Valentine and others who invented “niche space” models (i.e., the pace of evolution is rapid till all available niches fill up), but doesn’t feel that these ecological explanations explain why the CE was unique, or why it lasted as long (or short) as it did.  What does he think of those who suggest that macroscopic eyes and color perception triggered the CE?  Not much; there are other ways to find food, “so there almost certainly would have been some sort of radiation even if large compound eyes had not evolved in the Cambrian.”
4. Theoretical Explanations:  Marshall considers Stewart Kauffman’s idea about “fitness landscapes” and the emergence of evolutionary innovation: “the rate of evolution dramatically slows as the landscape is explored.”  So we should expect to see an explosion, followed by a rapid decline in evolutionary innovations, “simply as a consequence of the time it takes to find progressively more optimal solutions.”  Nice math, but we must get real, Marshall reminds us:
   

   The challenge for this class of explanation is understanding how the theoretical constructs related the real world.  In the case of Kauffman’s NK models, the roughness of the landscape is controlled by K, the number of interactions between the N genes.  However, it is difficult to meaningfully assign a value of K to a set of genes, and it is even more difficult to interpret these landscapes in morphological terms; i.e., the NK model does not explicitly incorporate the phenotype into the calculation of the fitnesses.

In short, though each might contribute factors, none of these classes of explanation have a total answer for the Cambrian explosion and its seven puzzles.  What they have done, however, is contribute to our understanding of the necessary preconditions for a valid explanation:

It is clear that the environment must be permissive of animals before they could have evolved.  It is also clear that the genetic machinery for making animals must have been in place, at least in a rudimentary way, before they could have evolved.  And finally, organisms must be able to leave viable offspring to survive and evolve, so ecology had to be important too.

Now to the climax.  Marshall embarks on a five-page description of his own explanation.  Surprisingly, however, he says very little about actual fossils – only one paragraph about where the Ediacaran biota might fit in.  His “framework for integrating environmental, ecological and developmental data” is almost completely theoretical.  He launches off from Sewell Wright’s concept of the fitness landscape, on which peaks represent higher evolutionary fitness, and valleys lower fitness.  Here’s a new word for you: “Fitness Landscapes (of the Morphogenetic Kind).”  Knowing that morpho- refers to body or structure, and -genetic refers to origin or begetting, is Marshall suggesting that a fitness landscape can invent a body?  Apparently so.  Watch carefully:

Following the rich tradition begun by Sewell Wright (1931, 1932), fitness landscapes provide a fruitful way of thinking about the interaction between developmental potential and evolutionary success, the ability to pass one’s genes on to the next generation.  The coordinate system in most fitness landscapes is based on genes and their alleles.  However, the Cambrian “explosion” finds its expression in the fossil record morphologically, so it is more appropriate to use a morphogenetic rather than a genic coordinate system.  Hence, theoretical morphospaces (McGhee 1999), where each axis of the landscape represents a distinct morphogenetic rule and where the position along each axis corresponds to a particular variant of the rule, is appropriate here.  Every point in the space corresponds to a unique morphology that arises from the morphogenetic rules.

Marshall seems to be saying that a morphogenetic rule – some kind of body-building principle in nature – will automatically give rise to new animals (given a rudimentary genetic toolkit), just from the existence of needs.  In his words, “if we assign a fitness value” to a morphology (roughly, a body plan), “evolution” will “explore” the fitness landscape to deliver the body.  Not only that, the fitness landscape itself evolves!  Clearly, to Marshall, this is a situation pregnant with possibilities.

He is quick to explain that the fitness landscape metaphor has limitations.  “First, movement [in the fitness space] is measured in terms of change in the morphogenetic rules, several steps removed from the genetic changes that are responsible for those rules,”  he explains.  That is, there needs to be a connection between the outside environment and the inside coded instructions.  However, “we are still profoundly ignorant of how changes in the genome translate into changes in morphology, despite the spectacular advances we have made in understanding the genetic basis of morphogenesis.”  Somehow, it must happen; the information required to live on the outside must get coded on the inside.  That’s somebody else’s problem.

For the remainder of the discussion, Marshall lets computer models work the miracles.  Borrowing on computer models by Karl Niklas, he postulates that, if the fitness landscape can become “roughened” (i.e., with more and smaller fitness peaks closer together), interesting things can happen: “increases in diversity and disparity may also be achieved… without the need for new genes and morphogenetic potentials.”

While that thought sinks in, let us ask, what factors can roughen the landscape?  Here’s the short answer: “the number of needs the organism must satisfy.”  Plants, for instance, might need “to perform realistic ecological tasks, including the ability to produce and disperse seeds, harvest light, avoid mechanical breakage of its branches, and minimize the risk of desiccation through minimizing its surface area.”  Necessity is the mother of invention.

If you feel frustrated by this line of argument, Marshall turns that, too, to his advantage.  He introduces the “Principle of Frustration” – a thought so profound, he says, “I have elevated its importance by labeling it a principle.”  What, you ask, is the principle of frustration?  It “captures the notion that different needs will often have (partially) conflicting solutions, so that the overall optimal design for an organism will rarely be optimal for any of the specific tasks it needs to perform (i.e., there are trade-offs).”  In other words, it’s the old engineering principle of constrained optimality.  Consider a laptop computer, for instance.⁵  A big screen is good, but conflicts with the need for compactness and light weight.  Heavy-duty peripherals are good, but conflict with the need for long battery life.  So in Marshall’s context, a plant or animal is going to have conflicting needs in order to survive, so “evolution” will explore the fitness landscape, and produce the morphology that provides the best trade-offs in order to ensure survival.⁶

The main point Marshall wants to get across is that the rougher the landscape, the better.  Rough landscapes are evolutionary playgrounds.  In his words,

The key point is that when all tasks need to be performed, the trade-offs combine to produce a wide range of local optima, given the rules for making the plants.  Thus, it is frustration that leads to an increase in the roughness of a fitness landscape as the number of needs increase (Figure 3).  While the number of local optima in a fitness landscape will clearly depend on the specific morphogenetic system (e.g., whether we are dealing with plants or animals, etc.) and on the range of environments that system finds itself in (e.g., terrestrial, aquatic, polar, tropical, etc.), the roughness of the landscape will also usually depend on the number of needs that must be met, or tasks that need to be performed.

More small peaks, therefore, yield more diverse and disparate inhabitants sitting on them.  Yet how can a peak, large or small, produce an optimally-engineered creature sitting on top?  The sherpa, the engineer, the innovator, the outfitter, the creator is: EVOLUTION.  That is the hero of the story: evolution actualizes the body plans that the real world constrains.  Is that not echoed in the end of the “Devonian, the period of greatest gross morphological innovation in the terrestrial invasion by plants”?  It must be.  The Niklas computer model showed it could be so.

The startling possibility is that evolution has found essentially all the locally optimal ways of being a terrestrial plant (ignoring the fine morphology associated with leaves, reproductive organs, roots, etc., as well as major modifications in the way living plants grow and reproduce compared with these early plants), and that it explored the morphogenetic space in just about one geological period.  The Niklas study opens up the possibility that evolution is able to find essentially all the locally optimal morphologies consistent with a given underlying developmental system on geological timescales.  That is, all the processes associated with variation (point mutation, recombination, hybridization, gene conversion, insertion and deletion, post-transcriptional changes in mRNA processing, etc.) are able to effectively explore fitness landscapes on geological timescales; evolution is able solve [sic] the np–hard problem of exploring the rich combinatorial potential embedded in the genome in the order of 10-20 million years.

What an amazing scout, this evolution. Engineers must be envious.

Marshall has turned the tables.  At the end of a difficult speech, begun facing angry reporters asking tough questions, he is in control.  “Viewing the Cambrian ‘explosion’ in the context of the evolution of fitness landscapes,” he grins, “opens up the possibility that uniqueness of the Cambrian ‘explosion’ may simply represent the exhaustion of ecologically viable alternatives that can be generated by the bilaterian developmental system…”  Simple, isn’t it.  That’s all there is to it.  What’s the problem?  The reporters are writing as fast as they can to get this down.  Once upon a time, the landscape was filled with fitness peaks, and as they got rougher, evolution obliged by filling them.  Good enough for a sound bite.

But what about information in the genes for these new body plans? asks one mythical reporter.  Where did it come from?  No problem, is the confident response; the information was already there: “As discussed above,” Marshall continues, “the phylogenetic distribution of key developmental genes in living species suggests that the basic developmental toolkit, a combinatorial toolkit, for bilaterian animals was already in place prior to the radiation (Carroll et al. 2001), certainly before the end of the Ediacaran.”  Take the Lego blocks, sprinkle them onto a roughened landscape, and the rest is history.  (Where the toolkit came from is thus pushed farther back into the past, as someone else’s problem.)

This calls for a new creation myth.  Here is the new Genesis – or, shall we say, the Book of MorphoGenesis.  Marshall starts a new paragraph entitled, “The Arms Race Roughens the Garden of Ediacara.”  In the beginning, there were peace-loving Ediacaran organisms in paradise; innocent and blind, without knowledge of good and evil.  But a time of testing came.  Instead of a Biblical serpent, some generic predator appeared on the scene, and frustration entered the world:

With the advent of ecological interactions between macroscopic adults (especially interactions associated with predation)… the number of needs each organism had to meet must have increased markedly: Now there were myriad predators to contend with, and a myriad number of ways to avoid them, which in turn led to more specialized ways of predation as different species developed different avoidance strategies, etc.  Even with no changes in the bilaterian developmental system as it existed by the end of the Ediacaran, the diversity and disparity of animals should have risen sharply, as the fitness landscape roughened in response to dramatic increase in the level of frustration (Figure 3).  The combinatoric richness already present in the Ediacaran genome was extracted through the richness of biotic interaction as the Cambrian “explosion” unfolded (Marshall 2003). I offer this as a null hypothesis explanation for the Cambrian explosion.⁷

In fact, Marshall continues, his model can even offer a prediction, as any good scientist should.  Look east, my young disciple:

It suggests that if we replayed the tape of life, with the same developmental programs, we would see similar morphologies each time: In the debate that sprung up across the Atlantic between the importance of contingency (Gould 1989) and inevitability (Conway Morris 1998, 2003) in the history of life (to oversimplify the issue somewhat!), perhaps the truth of the matter lies more to the East than most would be willing to grant.

Exactly how one might test the prediction (replaying the tape of life) is not explained.  Presumably, if there are no planets available for millions of years, one could play SimEarth.

Alas, “There are many issues that remain,” he ends.  How did a rough landscape actually generate new morphologies?  If the principle of frustration worked so well at the Cambrian, why not at the Ordovician?  What controlled the duration of the event?  “Is it simply the time it takes evolution to explore the landscape… or does the roughening occur piecemeal…? he asks.  “That is, is there a steady dance as the fitness landscapes of each of the major clades coevolve?”  And “Why does phylum-level innovation die away as the Cambrian unfolds?”  Why didn’t the explosion occur 100 million years earlier – or later?

To a skilled press secretary, these questions are not difficulties; they are opportunities.  “In summation,” his last sentence announces, “explaining the Cambrian ‘explosion’ of bilaterian animals will remain a rich field of enquiry for quite some time to come!”

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¹Charles R. Marshall, “Explaining the Cambrian ‘Explosion’ of Animals,” Annual Review of Earth and Planetary Sciences, Vol. 34 (Volume publication date May 2006) (doi:10.1146/annurev.earth.33.031504.103001).
²It must be noted that the dating methods of evolutionary paleontologists all assume evolution and long ages.  Creation scientists will argue that the dates are fallacious and falsified by their own research (e.g., see 11/05/2005).  Nevertheless, this writeup will assume the long ages, to give the evolutionists their best possible conditions for explaining the Cambrian explosion.  Even so, Jonathan Wells once remarked that, in geological terms, the event was so sudden and so brief, it would be like walking a football field and having all the animal phyla appear when stepping across the 60-yard line.
³Diversity means the number of species, whereas disparity is degree of difference between them.  There may be a great diversity of trilobite species, for instance, but the disparity between a trilobite and a starfish – or a dinosaur – is much greater.
⁴Diploblasts have two organized cell layers, like corals and jellyfish.  Triploblasts have three, with an outer ectoderm, middle mesoderm, and inner entoderm (which includes the gut).  All the complex animals, (also called Bilateria, or animals with bilateral symmetry), including those appearing in the Cambrian explosion, are triploblasts.
⁵Jay W. Richards used this analogy in the Q&A extras on the film, The Privileged Planet, in discussing how the Earth is optimized for scientific discovery.
⁶This presumes the neo-Darwinian notion that “passing on one’s genes” (survival) is a measure of fitness.  When defined this way, fitness is a tautology: not only do the fit survive, whatever survives, by definition, is fit.
⁷A null hypothesis is a baseline or default explanation, against which other hypotheses can be measured.  A null hypothesis for a new medication, for instance, might be, “this medication has no effect.”  It’s up to an experimenter to prove that it does, contrary to the null hypothesis.

There is a little word, presto, with two meanings appropriate here.  In music, it is a very rapid tempo.  In entertainment, it is a magic word that produces rabbits out of hats and beautiful women out of gunny sacks stuffed into tiny boxes.  Marshall has explained the presto tempo of the Cambrian explosion with a presto magic act.  Discerning readers know it is just a trick.

Theists believe God created the world and life, with good reason: the world looks designed.  We must not be misled by the term Cambrian “explosion.”  We think of explosions as accidents and terror attacks, wreaking havoc and leaving a scene strewn with debris and damage.  The CE was the opposite of this.  It was a sudden, explosive appearance of order and complexity, with tissues, organs, systems and a whole ecology appearing out of nowhere – just as would be expected if it had been created.

Duane Gish, the veteran creationist debater, never appealed to religious or Biblical arguments when standing toe-to-toe with the greatest evolutionists in debates at prestigious universities across America and Europe.  He didn’t need to, because the science was on his side.  Though he believed in the God of Genesis, he hammered on two scientific nails that shut the coffin on evolution.  He would say, (1) the law of entropy shows evolution could not happen, and (2) the fossil record shows it did not happen.

Go to the fossil beds and look.  Strata do not come with dates on them, labeled “545 million years old.”  You can go to Mongolia or southern California and you will find rock layers with fully-formed, complex trilobites, and nothing underneath.  Gish might have believed that the strata are young, but he could grant his opponents the geological column and give them the widest possible time latitude in which to work; the conclusion is the same: the fossil record looks like creation, not like evolution.  Each new animal appears abruptly.  There is not enough time in the best of cases for that much complexity to “arise” without design.  None of the precursors on Marshall’s chart, whether the Ediacaran biota, the trace burrows, or the small shelly animals, are precursors in ancestry.  No matter how much the timeline is stretched, each new body plan appears suddenly, without ancestors.  Face it, evolutionists!  This is not what your theory predicts, and no amount of handwaving is going to make this huge problem go away.  To an unbiased observer, it falsifies evolution.  Only dogmatic adherence to a philosophy pushes evolutionists to imagine their theoretical and highly implausible yarns to explain away the evidence of their senses.

Marshall’s elaborate fairy tale shows that the materialists cannot extricate themselves from miracles.  Creationists readily admit that God works miracles, and that the creation was miraculous.  Evolutionists despise miracles, but find them very handy.  They shield their miracles in “presto!” words, saying such-and-such a complex animal or organ (even eyes!) just emerged, arose or developed.  If you watched carefully, you saw that was exactly what Marshall did.  Though earlier he criticized other explanations for failing to provide an account for the origin of the genetic information required, he just pushed it offstage, and when needed, had a stage hand ready to sneak it in the hat, so that he could claim the rabbit was there all along.  His “Abracadabra!” was the term morphogenetic rule, some kind of unspecified, miracle-working process that builds complex bodies out of nothing.  With that sleight of mind, he distracted the audience’s attention from the fact he had cheated when we weren’t looking.  Rules imply a Rulemaker, and necessity is the mother of invention only when there are intelligent designers around.

His math is bad, too.  Marshall thinks that a simpler “combinatorial” genetic system in the invisible ancestors is sufficient to produce eyes and circulatory systems and all the rest when the landscape “roughens”.  Any kid can try this with a Lego set.  Scatter them at random all over a trampoline, start bouncing, and see what happens.  The number of useless combinations vastly exceeds anything ordered and functional.  5 million years – 10 million – 20 million – 65 million is pitifully insufficient to hope for anything interesting, and the parts themselves are not sentient beings to care whether they live or die.  No amount of time is going to produce robots and tanks and monsters out of bouncing Lego pieces; but turn a kid loose applying his intelligent design, and you will get all these things prestissimo, along with a complete ecology in which they interact that he will be glad to explain to you.

Marshall even had a magic fairy in the act: the evolutionists’ favorite goddess, Tinker Bell.  Did you catch her brief appearance?  Marshall referred to co-option, a synonym for “tinkering” with tools and materials that are already there, as a suggestion on how hearts and circulatory systems “developed.”  He repeatedly spoke of evolution in personal terms, as if Evolution were some frontier pioneer, capable of exploring the landscape, deciding where to build a town, then with his “toolkit” setting up the bank, general store, blacksmith shop and saloon by calling whatever materials available to order with the word, “Presto!”  With this tale, Marshall gets diverse trilobites with compound eyes; brachiopods, worms, starfish – even chordates and vertebrates.  No matter that each of these animals had many complex tissues and organs and systems with interrelated parts that had to have existed simultaneously to work.  No observational data are needed in this pagan nature religion.  The Spirit of Evolution, guided by Tinker Bell, does the miracles.

If anyone was not convinced before now that Darwin pulled off a massive con job on science, this should clinch it.  He knew about the Cambrian explosion but delegated the solution to the future.  Well, the future is here, and the problem is worse.  In place of the holding to the standard of rigorous proof in science, Darwin introduced the power of imagination, one “long argument” (aka story) to support his own personal myth.  To back it up, he claimed he was invoking purely natural causes that were rational and did not depend on a God of the gaps.  Well, here you have the result: all he did was replace the omnipotent, omniscient, all-wise God of creation with Tinker Bell of the gaps, a blind, deaf, dumb, careless fictional deity that his disciples are free to invoke whenever a miracle is needed to patch up the Big Just-So Story.  Out of this mythology, a hierarchy emerged with a set of traditions that stifles criticism, keeps the peasants ignorant, and persecutes any perceptive lover of truth able to read the book of nature without the “official” interpretation.  It’s time for a protestant reformation.