We are delighted to offer an excerpt from Father Martin Hilbert’s new book for Discovery Institute Press, A Catholic Case for Intelligent Design. This article is adapted from Chapter 2.

The tree of life is the only picture in Darwin’s Origin of Species, and it is a well-known icon of evolutionary theory. But we will consider Ernst Haeckel’s version because it makes clearer some of the notions that Darwin wanted to illustrate. The vertical axis, the height, represents the time elapsed since the serendipitous arrival of the first self-replicating life-form in some warm pond eons ago. This single-celled life-form is the base of the tree. As time progresses, we move up the page, seeing what looks like a trunk. Then we start to see branching when two population groups get separated and each adapts to the local conditions. Each of these then gets split up, causing more branching. As we go higher up the tree and do a horizontal cut, we get progressively more species, with the differences between them being proportional to the horizontal distance along the cut. But is there evidence for this tree?

The obvious way to check to see what happened in the past is to examine the fossil record. If Darwin was right, we should be able to find fossils leading from one species to another by almost imperceptibly small steps, so that if we took a picture of each of them and then quickly projected these pictures one after another, we should get a video showing the transformation, in the same way that time-lapse photography can show us a budding plant transform into a blooming flower in a manner of seconds. Darwin knew that the fossils gave little support to his theory, but he could console himself by appeals to the incompleteness of the fossil record. He hoped that in the future these gaps would be filled by new fossil discoveries. But these hopes have not been realized; on the contrary, the evidence against a slow gradual transformation of species has grown.

Smooth Transitions?

What about the series of horses, from a fox-sized animal to the modern horse? Do these not show smooth transitions? Perhaps there is a progression. But there are two points to keep in mind. First, does the progression prove descent? Imagine lining up the skeletons of the least weasel, mink, ferret, marten, otter, badger, and wolverine: all members of the Mustelidae family. Would that prove that the wolverine descended from the least weasel? In the case of the horse fossils, the fossils get bigger as they get more recent, so the evidence of descent is better. But if Darwinism were true, one would expect many more such sequences. And the fact that we keep seeing the horse sequence recycled time and time again tells us that such sequences are rare. The second point to keep in mind is that this sequence may indeed be an argument for Darwinian evolution, but it is fairly limited. In the case of the Mustelidae, Darwinian evolution, if real, does not transcend the level of family. Something much more is needed for the grand claims of Darwinism.

One body of fossil evidence that is particularly telling against Darwin comes from the fossils in and before the Cambrian era, and especially from a very narrow five million years within the Cambrian era, from 530 to 525 million years ago (Mya). Darwin was aware that this era gave rise to a great variety of fossils for which there were no antecedents in earlier layers. As time went on, much richer sources of Cambrian fossils were discovered. The first major find was the Burgess shale deposits in British Columbia, discovered in 1909. Since then another rich source was discovered in Chengjiang, China, in 1984. In a very short geological span, some 0.1 percent of the time since the earth was formed 4.5 billion years ago, a menagerie of life-forms arrived on the scene, without warning. This is known as the Cambrian explosion.

Running Into Opposition

It is hard to say anything about this explosion without running into some opposition. The Darwinists instinctively know that it is powerful evidence against them, so they have circled the wagons. In Darwin’s Doubt, Stephen Meyer describes the antics surrounding the showing of a documentary film, Darwin’s Dilemma, at the University of Oklahoma. He and Jonathan Wells, from Discovery Institute, were the presenters. Since the public funding policies of the University did not permit it to deny a forum to groups such as Discovery Institute, the administration had to go into damage control mode. They issued a disclaimer saying that the university did “not support unscientific views masquerading as science.” A lecture was scheduled by one of the professors to mock the Cambrian “explosion,” which ended just before the film was to start. The question-and-answer period after the film was packed with a hostile crowd of experts insisting the Cambrian fossils posed no problem because their precursors had been found.

It is true that there are some fossils from before the main event of 530–525 Mya, but they are far from sufficient to explain the astounding variety of forms that emerged during the Cambrian. A second tack is to argue that the Cambrian precursors must have been soft-bodied creatures, and soft-bodied creatures don’t fossilize. But that is clearly not the case, because many of the Cambrian fossils were themselves of soft animals. University of Cambridge paleontologist and evolutionary biologist Simon Conway Morris thinks that to have escaped detection via trace fossils, any such putative ancestors would have had to be less than a millimeter in length, and what traces there are from this period may not even be from an animal, but rather from, say, “strolling protistan ‘slugs,’ analogous to slime-mold Dictyostelium.”

An important point to be clear about: The Cambrian wasn’t merely an explosion of new species. It was an explosion of entirely new phyla or body plans. Phyla are a high-level classification in the Linnaean system. The categories, in order from most general to most specific, are domain, kingdom, phylum, class, order, family, genus, and species. According to Darwinian theory, it takes the evolutionary process much, much longer to create entirely new phyla than it does new species, and yet in the Cambrian more than twenty new phyla seem to appear out of nowhere. There are presently a total of thirty-six phyla in the Linnaean system; three arose in the Precambrian period; twenty or more, in the Cambrian; four, in later geological periods; and nine are represented only by existing forms.

On Classification Schemes

A problem with presenting this evidence is that it runs directly into a debate about classification schemes. Darwin believed there was a natural classification of all life that formed a record of evolution: a family tree. Be that as it may, any actual classification scheme can be challenged as being a human artifact. If, for example, a really strange creature is found that is too different from any other life-form, does that mean that all of a sudden one has to devise a phylum, class, order, family, genus, and species to give it a name? And, if so, what level of reality do any of these categories possess? The classifiers have their own biases. Some are lumpers and some are splitters. These are not going to agree on the number of phyla that arose during the Cambrian era.

To add to the confusion, there are some very strong advocates for a different kind of classification system, usually called cladistics (from the Greek word klados meaning “branch”). This system puts life-forms sharing certain derived characteristics together and tries to determine the evolutionary branching that took place since the last presumed common ancestor. There is no attempt to rank the clades as there is in the Linnaean taxonomy. Fortunately, we need not get dragged into this argument, for, as Meyer summarizes:

The Cambrian explosion presents a puzzle for evolutionary biologists, not just because of the number of phyla that arise, but rather because of the number of unique animal forms and structures that arise (as measured, perhaps, by the number of phyla) — however biologists decided to classify them. Thus, whether scientists decide to use newer rank-free classification schemes [cladistics] or older, more conventional, Linnaean categories, the “evolutionary novelties” — that is, the new anatomical structures and modes of organization — that arise suddenly with the Cambrian animals remain as facts of the fossil record, requiring explanation.

Fodor and Piattelli-Palmarini concur with this assessment. In their criticism of Darwinism, they speak of morphological explosions and conclude, “We can summarize by saying that morphological explosions may well reflect major changes in internal constraints as crucial components in speciation. If so, then the effects of natural selection may well consist largely of post-hoc fine-tuning in the distribution of subspecies and variants: quite a different kind of account from the one of gradual selection of randomly differing small variations.”

The Cambrian Challenge 

Ironically, even the museum at the University of Oklahoma, which was so opposed to the talk by Meyer and Wells, had a display of fossils that illustrated the Cambrian challenge to Darwinism. As Wells describes it, “It showed over a dozen of the Cambrian phyla at the top of a branching tree with a single trunk, but none of the branch points corresponded to a real living thing.”

Given the controversy about the Cambrian explosion, one might think that it is the only major challenge to Darwin’s theory in the fossil record. But it turns out to be one of many sudden bursts of new life-forms. There is, for example, the Great Ordovician Biodiversification Event (GOBE), in which about 300 new families of marine invertebrates appeared between 485 and 460 Mya. There is the Odontode Explosion, in which all major groups of jawed fish with teeth or tooth-like structures arrived on the scene between 425 and 415 Mya. The Carboniferous Insect Explosion occurred between 318 and 300 Mya. The different subgroups of amniote tetrapods arrived on the scene between 251 and 240 Mya. These include the dinosaurs, turtles, lizard relatives, croc relatives, and the first mammal-like animals. Flowering plants appeared and rapidly diversified between 130 and 115 Mya. Modern placental mammal orders appeared between 62 and 49 Mya, without known precursors. Modern bird groups arrived between 65 and 55 Mya. And there are several other explosions that Meyer and Günter Bechly describe.

No Friend of Christianity

Paleontologist Stephen Jay Gould, no friend of Christianity or intelligent design, summarized the awkward situation for him and his fellow evolutionists:

The extreme rarity of transitional forms in the fossil record persists as the trade secret of paleontology. The evolutionary trees that adorn our textbooks have data only at the tips and nodes of their branches; the rest is inference, however reasonable, not the evidence of fossils…. We fancy ourselves as the only true students of life’s history, yet to preserve our favored account of evolution by natural selection we view our data as so bad that we never see the very process we profess to study.

The available fossils, in fact, provide some arresting evidence against Darwinism, beside discontinuity. I think that most of us assume that mimetics are the product of natural selection. We are told that viceroy and monarch butterflies are mimics of each other, each trying to look like the other because each is unpalatable to some predator. It makes good Darwinian sense. Who would think to challenge it? I am not about to get into the debate about these butterflies as to which is mimicking which. Rather, I will share my surprise about another case of what is often passed off as selection-enhanced mimicry: stick insects, which belong to the order of phasmids. Surely these adapted themselves to blend into their background in ecosystems with lots of sticks and slender branches, right? It turns out there is a major problem with that idea. Giuseppe Sermonti explains:

The oldest phasmid fossils (they go back in Baltic amber to the Tertiary — i.e., about 50 million years ago) look identical to present day species, showing that no gradations have occurred. It is thought that those phasmids originated from Chresmodids of the Upper Jurassic in Germany, fossils of which are encountered in deposits dating back some 150 million years. But the oldest fossils of stick or leaf insects (protophasmids) go back to even remoter periods, in the Permian (250 million years ago, in the Paleozoic). One might argue that these insects completed the process of imitating leaves at an extremely gradual rate beginning at a still earlier time. Yet things do not work out this way. Plants with flowers and leaves… appeared no earlier than the Cretaceous — in other words about 100 million years ago, long after the first protophasmids. This chronological anomaly places the imitators earlier in time than the objects of the imitation, leaving entomologists and paleontologists disconcerted.

A Technical Point 

There is one more technical point to keep in mind before we take leave of the fossil evidence. Darwin’s theory requires a bottom-up tree. In his scenario, by the time that we get to something that taxonomists are willing to call a phylum, there should be numerous species, genera, and families all hinting at its eventual arrival. On the Darwinian view, species develop into genera; genera, into families; families, into orders, etc. Instead, the fossil record shows a top-down approach. A small number of life-forms suddenly arrive representing an entirely new body plan, a new phylum. Then, as time goes by, the phylum gets filled in with more and more representative species.

The history of life can perhaps be likened to a collection of different musical themes. In Beethoven’s Fifth Symphony, the four beginning notes are the theme. They are then developed into many variations that still recognizably reflect the same theme. But there is no smooth way to get from the theme in his Fifth Symphony to the theme of the “Ode to Joy” movement of his Ninth Symphony. The fossil record, in other words, fits more the pattern of an artist creating a new theme and then working variations on it. Or to return to Darwin’s proposed picture of an evolutionary tree of life, with all of life’s variations branching out from a single ancestor “trunk,” it seems that the history of life instead is more like a separate collection of bushes than a single tree.

Editor’s note: All references may be found in the published edition of A Catholic Case for Intelligent Design.