Transitional Forms

(Copyright Creation Matters, Vol. 6, No. 2, March/April, 2001.)

Few terms in the origins debate are as confusing or as often misconstrued as the term “transitional form.” Yet this concept is fundamental to characterizing the distribution of organisms in the record of life. Creationists and some evolutionists claim that transitional or intermediate forms are rare. For example, Gould states, “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 nods of their branches; the rest is inference, however reasonable, not the evidence of fossils.” (Gould, Stephen J. The Pandas Thumb, 1980, p. 181.) Many evolutionary specialists, on the other hand, declare that intermediate forms are abundant. Cracraft claims: “Each species, then is intermediate in some sense of the word; all species possess primitive and derived characters.” (Cracraft, Joel, “The Scientific Response to Creationism,” in LaFollette (editor), Creationism, Science and the Law: The Arkansas Case, 1983, p. 146.)

The public interprets the word “transitional” or “intermediate” in an uncomplicated, straightforward way, to indicate an organism along a clearly identified lineage between two different organisms.

Webster’s defines, “transition: passage from one state, stage, or place to another: a movement, development, or evolution from one form, stage, or style to another.” (Woolf, Henry B. editor,Webster’s New Collegiate Dictionary, 1977, p. 1241.)

Yet Darwinists misconstrue the term to create illusions of ancestry. Let us review some of these various usages, then we can better understand what actually constitutes a “transitional form” such that it is evidence for common descent.

In recent years many evolutionary biologists have shifted attention to cladograms (a branching diagram that is used to depict the hierarchical distribution of shared characters). Walter ReMine comments on this usage: “…a species is intermediate to other species if they all have a pattern of nested similarities, as displayed on a cladogram.” This meaning is often used, even if there is no plausible ancestral evidence, and phylogeny (a lineage) is never clarified. (ReMine, Walter, The Biotic Message, 1993, p. 295.)

On other occasions, evolutionists commonly define a transitional form as one containing character traits from two separate groups. Strahler notes, “A transitional form, then, is judged to be an intermediate when its morphological features, or characters, are a combination of those of two distinct taxa.” (Strahler, Arthur, Science and Earth History,1999, p. 420.) That is not a lineage, despite the fact that the public perceives it as such. This is the primary reason that this term causes so much confusion.

Some scenarios focus upon the supposed evolution of certain body parts. Anti-creationist authors like Arthur Strahler and Philip Kitcher are notorious for zeroing in on just a single trait of supposed intermediates, such as dentition or locomotion, while ignoring many other characteristics that are not “transitional.” Their reason for this is predictable: “Given the vicissitudes of fossilization, there is no reason to expect a sequence of fossils showing continuous modification of any characteristic we choose, even if that characteristic was continuously modified. Paleontologists think themselves lucky to be able to trace the continuous emergence of some characteristics.” (Kitcher, Philip, Abusing Science, 1998 p. 110.) Here Kitcher offers up excuses for the pattern of gradual change, being absent. Yet it is important to note that a lineage does not require a “continuous modification of any characteristic.” Rather, it requires a clear-cut trajectory through morphology space, with a void or absence of organisms orthogonal to that trajectory. But both the pattern of gradual change and the evidence of a lineage are systematically missing in the fossil record.

Supraspecific groups
The Classic Darwinians expected evolution to create lineages with clear-cut ancestors and descendants. When they couldn’t find them, they began misusing words to create the illusion theyhad found them. If the various species in question plotted along a clear morphological trajectory, this would have been evidence for a lineage. The problem for Darwinists, however, is that there is a scattering of data points. Evolutionists can hide this paucity of supporting data by citing only the supraspecific (higher than the species level) groups or taxa. Kitcher declares: “About 180 million years ago, different groups of reptiles gave rise to the mammals and the birds.” (Kitcher, 1998, p.28.) Such a statement makes it appear as if there are only a few data points (reptiles, mammals and birds), when in fact there are wide morphological gaps that remain to be filled in and a vast diversity within each of these groups. These higher taxa do not exist as data points and do not reproduce. This linearization of the evolutionary “process” makes transitions seem more plausible by obscuring the diversity contained within these groups.

Nested hierarchy
Nested hierarchy can become a source of confusion. For example, one might make the statement: “amniotes gave rise to the mammals, from which arose humans.” The statement is trivially true in the sense that, your grandparents were amniotes, your parents are mammals, and you are human. As humans, we are simultaneously classified as amniotes and mammals. The statement says nothing about evolutionary ancestry.

Paraphyletic groups 
Some taxonomic groups can be readily identified by certain common, narrowly-defined characteristics. For example, birds can be described as animals having feathers, and mammals are distinguished as animals having hair, mammary glands, etc. On the other hand, there are groups of organisms, with a broad degree of diversity, that are united only by the absence of certain characteristics. For instance, invertebrates share no common feature other than their lack of a spinal column. And reptiles comprise a group which is joined by nothing but the fact that they are amniotes that lack hair and feathers.

Such groups, called paraphyletic groups, are really classification leftovers (para-, aside from; phyletic, of a line of descent). However, evolutionists use this term in a way which implies evolutionary ancestry. They commonly define a paraphyletic group as a group that does not contain all of its descendants. For example, they may speak of reptiles being ancestral to a group such as mammals, or invertebrates giving rise to the vertebrates. Colin Patterson concedes, “The mysterious additional element, the extra information that transforms systematics into phylogeny, is extinct paraphyletic groups.” ( Patterson, Colin, “Morphological Characters and Homology,” p. 64, in Josey, K.A. and Friday, A.E. (eds.), Problems of Phylogenetic Reconstruction, Academic Press, 1982.)

Mosaic or chimeric forms are mistakenly called transitional. Here I quote Gould: “At the higher level of evolutionary transition between basic morphological designs, gradualism has always been in trouble, though it remains the ‘official’ position of most Western evolutionists. Smooth intermediates between Bauplane [body plans] are almost impossible to construct, even in thought experiments; there is certainly no evidence for them in the fossil record (curious mosaics like Archaeopteryx do not count).” (Gould & Eldredge, “Punctuated Equilibria: the Tempo and Mode of Evolution Reconsidered,” Paleobiology, 3:147, 1977, p.147).

Occasionally one finds evolutionists presenting “fine grained transitions” as if these were evidence for large-scale evolution. Perhaps a contemporary illustration will help explain the rare example of gradualism found in the fossil record. In mere centuries most of today’s common dog breeds have been selectively bred from original canine stocks. One can only marvel at the breadth of diversity that has been produced! The Greyhound and the English Mastiff are thought to constitute the ancestors of the Great Dane. The English Mastiff might then be termed “intermediate” between an earlier breed (like the Tibetan Mastiff) and the Great Dane.

The problem for the evolutionists is that such variation is merely the expression of preexisting genetic information, sometimes called “microevolution.” It does not link disparate life forms into a lineage. It does not constitute a transitional form that is evidence for common descent.

Evolutionists frequently employ misleading terms like:

        • “simple”
        • “primitive”
        • “early”
        • “convergent characteristics”
        • “lost features”
        • “found lower/higher in the geologic record”
        • “advanced”
        • “derived”
        • “developed”
        • “complex”

These terms are used as if ancestors had actually been identified when, in fact, they have not.

For example, under a commonplace evolutionary misuse of terms a “convergent form,” like a “transitional form,” contains character traits from two separate groups. The only difference is in how the Darwinists explain them. Archaeopteryx, having teeth and a tail, is said to be a transitional form because it fits the common descent story of birds evolving from reptiles. On the other hand, bats, having wings and utilizing echolocation to navigate, just like multiple species of birds, is said to be convergent. One must not say that bats are transitional between birds and mammals because it does not fit the accepted common descent story. Thus, Dawkins asserts, “It follows that the echolocation technology has been independently developed in bats and birds, just as it was independently developed by British, American, and German scientists.” (Dawkins, Richard, The Blind Watchmaker, 1996, p. 96.) Unfortunately for evolutionary theory, convergent forms are abundant, while transitional candidates are rare.

Tying it all together
Evolutionists create the illusion of ancestry by merging together, in rapid fire, these various techniques. (See, for example Cuffey, Roger J., “Paleontologic Evidence and Organic Evolution,” p. 255-281 in Montagu, Ashley, ed., Science and Creationism, Oxford University Press, Oxford, 1984.) The point is that any collection of objects can arbitrarily be placed into a continuum, with some identified as transitional. This, however, is not sufficient to establish actual evidence for common descent. There must, instead, be a discernable pattern of lineages giving the supposed transitionals credibility. The data must occur along a long, narrow trail. The size of the gaps is not as important as the pattern. Once a lineage is determined, the transitional forms are self-evident.

The phylogeny question
While both creationists and evolutionists agree that there is a general pattern of nested hierarchy (which was recognized by Linnaeus long before Darwin’s work), the question for evolutionists remains one of lineage and ancestors. As more fossils have been found, the gaps and the lack of identifiable phylogeny have become more distinct. New discoveries have tended to obscure lineages previously believed by evolutionists to be reliable.

That is the whole point of punctuated equilibrium. Leading evolutionists do not claim that the fossils demonstrate phylogeny or gradual intergradations sufficient to prove large-scale evolution. To the contrary, they admit to the abundance of systematic, large gaps between major groups in the fossil record. Walter ReMine notes, “These absences are huge as measured by the only scientific measuring stick we have – experimental demonstrations. The gaps are so huge they have not remotely been bridged by experimental demonstrations in labs or in the field.” (ReMine, Walter, Private Correspondence, 1999.) This point should not be debatable since there are plentiful statements from punctuationists admitting to the lack of clear ancestors and lineages in the fossil record.