Stephen C. Meyer Article: The
Biological Information and the Higher Taxonomic
CategoriesProceedings of the
Society of WashingtonJanuary 26,
4th, 2004 an
extensive review essay by Dr. Stephen C. Meyer, Director of Discovery
Institute's Center for Science & Culture appeared in the
the Biological Society of Washington (volume 117, no. 2, pp.
Proceedings is a peer-reviewed biology journal published at the
Museum of Natural History at the Smithsonian Institution in Washington
In the article, entitledThe Origin of Biological Information
Higher Taxonomic Categories, Dr. Meyer argues that no current
theory of evolution can account for the origin of the information
build novel animal forms. He proposes intelligent design as an
explanation for the origin of biological information and the higher
Due to an unusual number of inquiries about the article, Dr.
copyright holder, has decided to make the article available now in HTML
on this website. (Off prints are also available from Discovery Institute
writing to Keith Pennock at [email protected] Please provide your
address and we will dispatch a copy).
PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF
The origin of
information and the higher taxonomic categories
In a recent volume of
Vienna Series in a Theoretical Biology (2003), Gerd B. Muller and Stuart
argue that what they call theorigination of organismal form
unsolved problem. In making this claim, Muller and Newman (2003:3-10)
distinguish two distinct issues, namely, (1) the causes of form
the individual organism during embryological development and (2) the
responsible for the production of novel organismal forms in the first
during the history of life. To distinguish the latter case (phylogeny)
former (ontogeny), Muller and Newman use the termorigination to
causal processes by which biological form first arose during the
life. They insist thatthe molecular mechanisms that bring about
form in modern day embryos should not be confused with the causes
for the origin (ororigination) of novel biological forms during
of life (p.3). They further argue that we know more about the causes of
ontogenesis, due to advances in molecular biology, molecular genetics
developmental biology, than we do about the causes of phylogenesis--the
origination of new biological forms during the remote past.
this claim, Muller and Newman are careful to affirm that evolutionary
has succeeded in explaining how preexisting forms diversify under the
influences of natural selection and variation of genetic traits.
mathematically-based models of population genetics have proven adequate
mapping and understanding quantitative variability and populational
organisms. Yet Muller and Newman insist that population genetics, and
evolutionary biology, has not identified a specifically causal
the origin of true morphological novelty during the history of life.
their concern is what they see as the inadequacy of the variation of
traits as a source of new form and structure. They note, following
himself, that the sources of new form and structure must precede the
natural selection (2003:3)--that selection must act on what already
in their view, thegenocentricity andincrementalism of the
mechanism has meant that an adequate source of new form and structure
has yet to
be identified by theoretical biologists. Instead, Muller and Newman see
to identify epigenetic sources of morphological innovation during the
of life. In the meantime, however, they insist neo-Darwinism lacks any
of the generative (p. 7).
As it happens, Muller and Newman are
in this judgment. In the last decade or so a host of scientific essays
have questioned the efficacy of selection and mutation as a mechanism
generating morphological novelty, as even a brief literature survey will
establish. Thomson (1992:107) expressed doubt that large-scale
changes could accumulate via minor phenotypic changes at the population
level. Miklos (19:29) argued that neo-Darwinism fails to provide a
that can produce large-scale innovations in form and complexity. Gilbert
(1996) attempted to develop a new theory of evolutionary mechanisms to
supplement classical neo-Darwinism, which, they argued, could not
explain macroevolution. As they put it in a memorable summary of the
starting in the 1970s, many biologists began questioning its
adequacy in explaining evolution. Genetics might be adequate for
microevolution, but microevolutionary changes in gene frequency were not
able to turn a reptile into a mammal or to convert a fish into an
Microevolution looks at adaptations that concern the survival of the
not the arrival of the fittest. As Goodwin (1995) points out, 'the
species--Darwin's problem--remains unsolved' (p. 361). Though Gilbert
(1996) attempted to solve the problem of the origin of form by proposing
greater role for developmental genetics within an otherwise
numerous recent authors have continued to raise questions about the
that framework itself or about the problem of the origination of form
(Webster & Goodwin 1996; Shubin & Marshall 2000; Erwin 2000;
Morris 2000, 2003b; Carroll 2000; Wagner 2001; Becker & Lonnig 2001;
et al. 2001; Lonnig & Saedler 2002; Wagner & Stadler 2003;
What lies behind this skepticism? Is it warranted?
new and specifically causal theory needed to explain the origination of
This review will address these questions. It
will do so
by analyzing the problem of the origination of organismal form (and the
corresponding emergence of higher taxa) from a particular theoretical
standpoint. Specifically, it will treat the problem of the origination
higher taxonomic groups as a manifestation of a deeper problem, namely,
problem of the origin of the information (whether genetic or epigenetic)
as it will be argued, is necessary to generate morphological
order to perform this analysis, and to make it relevant and tractable to
systematists and paleontologists, this paper will examine a paradigmatic
of the origin of biological form and information during the history of
Cambrian explosion. During the Cambrian, many novel animal forms and
(representing new phyla, subphyla and classes) arose in a geologically
period of time. The following information-based analysis of the Cambrian
explosion will support the claim of recent authors such as Muller and
that the mechanism of selection and genetic mutation does not constitute
adequate causal explanation of the origination of biological form in the
taxonomic groups. It will also suggest the need to explore other
factors for the origin of form and information during the evolution of
will examine some other possibilities that have been
TheCambrian explosion refers to the
geologically sudden appearance of many new animal body plans about 530
years ago. At this time, at least nineteen, and perhaps as many as
phyla of forty total (Meyer et al. 2003), made their first appearance on
within a narrow five- to ten-million-year window of geologic time
al. 19, 1998a:1, 1998b:40; Kerr 19; Monastersky 19; Aris-Brosou
2003). Many new subphyla, between 32 and 48 of 56 total (Meyer et al.
classes of animals also arose at this time with representatives of these
higher taxa manifesting significant morphological innovations. The
explosion thus marked a major episode of morphogenesis in which many new
disparate organismal forms arose in a geologically brief period of
To say that the fauna of the Cambrian period appeared in a
geologically sudden manner also implies the absence of clear
intermediate forms connecting Cambrian animals with simpler pre-Cambrian
And, indeed, in almost all cases, the Cambrian animals have no clear
morphological antecedents in earlier Vendian or Precambrian fauna
Erwin et al. 1997:132, Steiner & Reitner 2001, Conway Morris
Valentine et al. 2003:519-520). Further, several recent discoveries and
suggest that these morphological gaps may not be merely an artifact of
incomplete sampling of the fossil record (Foote 1997, Foote et al. 1999,
& Ayala 2003, Meyer et al. 2003), suggesting that the fossil record
least approximately reliable (Conway Morris 2003b:505).
debate now exists about the extent to which this pattern of evidence
with a strictly monophyletic view of evolution (Conway Morris 1998a,
2003b:510; Willmer 1990, 2003). Further, among those who accept a
view of the history of life, debate exists about whether to privilege
molecular data and analyses. Those who think the fossil data provide a
reliable picture of the origin of the Metazoan tend to think these
relatively quickly--that the Cambrian explosion had ashort fuse.
Morris 2003b:505-506, Valentine & Jablonski 2003). Some (Wray et al.
but not all (Ayala et al. 1998), who think that molecular phylogenies
reliable divergence times from pre-Cambrian ancestors think that the
animals evolved over a very long period of time--that the Cambrian
along fuse. This review will not address these questions of
pattern. Instead, it will analyze whether the neo-Darwinian process of
and selection, or other processes of evolutionary change, can generate
and information necessary to produce the animals that arise in the
This analysis will, for the most part, 2
therefore, not depend upon assumptions of either a long or short fuse
Cambrian explosion, or upon a monophyletic or polyphyletic view of the
history of life.
Defining Biological Form and
Form, like life itself, is easy to recognize but
hard to define precisely. Yet, a reasonable working definition of form
suffice for our present purposes. Form can be defined as the
topological relations of anatomical parts. This means that one can
form as a unified arrangement of body parts or material components in a
shape or pattern (topology)--one that exists in three spatial dimensions
which arises in time during ontogeny.
Insofar as any particular
biological form constitutes something like a distinct arrangement of
body parts, form can be seen as arising from constraints that limit the
arrangements of matter. Specifically, organismal form arises (both in
and ontogeny) as possible arrangements of material parts are constrained
establish a specific or particular arrangement with an identifiable
dimensional topography--one that we would recognize as a particular
cell type, organ, body plan or organism. A particularform,
represents a highly specific and constrained arrangement of material
(among a much larger set of possible arrangements).
in this way suggests a connection to the notion of information in its
theoretically general sense. When Shannon (1948) first developed a
theory of information he equated the amount of information transmitted
amount of uncertainty reduced or eliminated in a series of symbols or
characters. Information, in Shannon's theory, is thus imparted as some
are excluded and others are actualized. The greater the number of
excluded, the greater the amount of information conveyed. Further,
a set of possible material arrangements by whatever process or means
excluding some options and actualizing others. Thus, to constrain a set
possible material states is to generate information in Shannon's sense.
follows that the constraints that produce biological form also imparted
information. Or conversely, one might say that producing
by definition requires the generation of information.
Shannon information theory, the amount of information in a system is
inversely related to the probability of the arrangement of constituents
system or the characters along a communication channel (Shannon 1948).
improbable (or complex) the arrangement, the more Shannon information,
information-carrying capacity, a string or system
1960s, mathematical biologists have realized that Shannon's theory could
applied to the analysis of DNA and proteins to measure the
capacity of these macromolecules. Since DNA contains the assembly
for building proteins, the information-processing system in the cell
a kind of communication channel (Yockey 1992:110). Further, DNA conveys
information via specifically arranged sequences of nucleotide bases.
of the four bases has a roughly equal chance of occurring at each site
spine of the DNA molecule, biologists can calculate the probability, and
the information-carrying capacity, of any particular sequence n
The ease with which information theory applies to molecular
has created confusion about the type of information that DNA and
possess. Sequences of nucleotide bases in DNA, or amino acids in a
highly improbable and thus have large information-carrying capacities.
meaningful sentences or lines of computer code, genes and proteins are
specified with respect to function. Just as the meaning of a
depends upon the specific arrangement of the letters in a sentence, so
the function of a gene sequence depend upon the specific arrangement of
nucleotide bases in a gene. Thus, molecular biologists beginning with
equated information not only with complexity but also with
wherespecificity orspecified has meantnecessary to
1958:144, 153; Sarkar, 1996:191).3
Molecular biologists such as Monod and Crick understood biological
information--the information stored in DNA and proteins--as something
mere complexity (or improbability). Their notion of information
biochemical contingency and combinatorial complexity with DNA sequences
(allowing DNA's carrying capacity to be calculated), but it also
sequences of nucleotides and amino acids in functioning macromolecules
a high degree of specificity relative to the maintenance of
The ease with which information theory applies to
biology has also created confusion about the location of information in
organisms. Perhaps because the information carrying capacity of the gene
be so easily measured, it has been easy to treat DNA, RNA and proteins
sole repositories of biological information. Neo-Darwinists in
assumed that the origination of biological form could be explained by
to processes of genetic variation and mutation alone (Levinton
1988:485). Yet if
one understands organismal form as resulting from constraints on the
arrangements of matter at many levels in the biological hierarchy--from
and proteins to cell types and tissues to organs and body plans--then
biological organisms exhibit many levels of information-rich
Thus, we can pose a question, not only about the
genetic information, but also about the origin of the information
generate form and structure at levels higher than that present in
proteins. We must also ask about the origin of thespecified
opposed to mere complexity, that characterizes the new genes, proteins,
types and body plans that arose in the Cambrian explosion. Dembski
used the termcomplex specified information (CSI) as a synonym for
complexity to help distinguish functional biological information from
Shannon information--that is, specified complexity from mere complexity.
review will use this term as well.
The Cambrian Information
The Cambrian explosion represents a remarkable jump
specified complexity orcomplex specified information (CSI) of the
world. For over three billions years, the biological realm included
than bacteria and algae (Brocks et al. 1999). Then, beginning about
million years ago (mya), the first complex multicellular organisms
the rock strata, including sponges, cnidarians, and the peculiar
(Grotzinger et al. 1995). Forty million years later, the Cambrian
occurred (Bowring et al. 19). The emergence of the Ediacaran biota
and then to a much greater extent the Cambrian explosion (530 mya),
steep climbs up the biological complexity gradient.
One way to
the amount of new CSI that appeared with the Cambrian animals is to
number of new cell types that emerged with them (Valentine 1995:91-).
of modern animals suggest that the sponges that appeared in the late
Precambrian, for example, would have required five cell types, whereas
complex animals that appeared in the Cambrian (e.g., arthropods) would
required fifty or more cell types. Functionally more complex animals
more cell types to perform their more diverse functions. New cell types
many new and specialized proteins. New proteins, in turn, require new
information. Thus an increase in the number of cell types implies (at a
a considerable increase in the amount of specified genetic information.
Molecular biologists have recently estimated that a minimally complex
single-celled organism would require between 318 and 562 kilobase pairs
to produce the proteins necessary to maintain life (Koonin 2000). More
single cells might require upward of a million base pairs. Yet to build
proteins necessary to sustain a complex arthropod such as a trilobite
require orders of magnitude more coding instructions. The genome size of
modern arthropod, the fruitfly Drosophila melanogaster, is
180 million base pairs (Gerhart & Kirschner 1997:121, Adams et al.
Transitions from a single cell to colonies of cells to complex animals
significant (and, in principle, measurable) increases in
new animal from a single-celled organism requires a vast amount of new
information. It also requires a way of arranging gene
higher levels of organization. New proteins are required to service new
types. But new proteins must be organized into new systems within the
cell types must be organized into new tissues, organs, and body parts.
turn, must be organized to form body plans. New animals, therefore,
hierarchically organized systems of lower-level parts within a
Such hierarchical organization itself represents a type of information,
body plans comprise both highly improbable and functionally specified
arrangements of lower-level parts. The specified complexity of new body
requires explanation in any account of the Cambrian
neo-Darwinism explain the discontinuous increase in CSI that appears in
Cambrian explosion--either in the form of new genetic information or in
of hierarchically organized systems of parts? We will now examine the
of this question.
Novel Genes and Proteins
and mathematicians have questioned the ability of mutation and selection
generate information in the form of novel genes and proteins. Such
often derives from consideration of the extreme improbability (and
of functional genes and proteins.
A typical gene contains over
thousand precisely arranged bases. For any specific arrangement of four
nucleotide bases of length n, there is a corresponding number of
arrangements of bases, 4n. For any protein, there are
20n possible arrangements of protein-forming amino
gene 999 bases in length represents one of 4999 possible
sequences; a protein of 333 amino acids is one of 20333
Since the 1960s, some biologists have thought
proteins to be rare among the set of possible amino acid sequences. Some
used an analogy with human language to illustrate why this should be the
Denton (1986, 309-311), for example, has shown that meaningful words and
sentences are extremely rare among the set of possible combinations of
letters, especially as sequence length grows. (The ratio of meaningful
words to 12-letter sequences is 1/1014, the ratio of
sentences to possible 100-letter strings is 1/10100.) Further, Denton
most meaningful sentences are highly isolated from one another in
space of possible combinations, so that random substitutions of letters
after a very few changes, inevitably degrade meaning. Apart from a few
clustered sentences accessible by random substitution, the overwhelming
of meaningful sentences lie, probabilistically speaking, beyond the
Denton (1986:301-324) and others have argued that
constraints apply to genes and proteins. They have questioned whether an
undirected search via mutation and selection would have a reasonable
locating new islands of function--representing fundamentally new genes
proteins--within the time available (Eden 1967, Shutzenberger 1967,
1979). Some have also argued that alterations in sequencing would likely
in loss of protein function before fundamentally new function could
1967, Denton 1986). Nevertheless, neither the extent to which genes and
are sensitive to functional loss as a result of sequence change, nor the
to which functional proteins are isolated within sequence space, has
Recently, experiments in molecular biology have shed light
these questions. A variety of mutagenesis techniques have shown that
(and thus the genes that produce them) are indeed highly specified
biological function (Bowie & Sauer 1989, Reidhaar-Olson & Sauer
Taylor et al. 2001). Mutagenesis research tests the sensitivity of
(and, by implication, DNA) to functional loss as a result of alterations
sequencing. Studies of proteins have long shown that amino acid residues
active positions cannot vary without functional loss (Perutz &
1968). More recent protein studies (often using mutagenesis experiments)
shown that functional requirements place significant constraints on
even at non-active site positions (Bowie & Sauer 1989,
Sauer 1990, Chothia et al. 1998, Axe 2000, Taylor et al. 2001). In
Axe (2000) has shown that multiple as opposed to single position amino
substitutions inevitably result in loss of protein function, even when
changes occur at sites that allow variation when altered in isolation.
Cumulatively, these constraints imply that proteins are highly sensitive
functional loss as a result of alterations in sequencing, and that
proteins represent highly isolated and improbable arrangements of amino
-arrangements that are far more improbable, in fact, than would be
arise by chance alone in the time available (Reidhaar-Olson & Sauer
Behe 1992; Kauffman 1995:44; Dembski 1998:175-223; Axe 2000, 2004). (See
the discussion of the neutral theory of evolution for a precise
Of course, neo-Darwinists do not envision a
random search through the set of all possible nucleotide
sequence space. They envision natural selection acting to preserve
advantageous variations in genetic sequences and their corresponding
products. Dawkins (1996), for example, likens an organism to a high
peak. He compares climbing the sheer precipice up the front side of the
to building a new organism by chance. He acknowledges that his approach
Mount Improbable will not succeed. Nevertheless, he suggests that
there is a
gradual slope up the backside of the mountain that could be climbed in
incremental steps. In his analogy, the backside climb upMount
corresponds to the process of natural selection acting on random changes
genetic text. What chance alone cannot accomplish blindly or in one
selection (acting on mutations) can accomplish through the cumulative
many slight successive steps.
Yet the extreme specificity and
of proteins presents a difficulty, not only for the chance origin of
biological information (i.e., for random mutations acting alone), but
selection and mutation acting in concert. Indeed, mutagenesis
doubt on each of the two scenarios by which neo-Darwinists envisioned
information arising from the mutation/selection mechanism (for review,
Lonnig 2001). For neo-Darwinism, new functional genes either arise from
non-coding sections in the genome or from preexisting genes. Both
In the first scenario, neo-Darwinists envision new
information arising from those sections of the genetic text that can
vary freely without consequence to the organism. According to this
non-coding sections of the genome, or duplicated sections of coding
experience a protracted period ofneutral evolution (Kimura 1983)
alterations in nucleotide sequences have no discernible effect on the
of the organism. Eventually, however, a new gene sequence will arise
code for a novel protein. At that point, natural selection can favor the
gene and its functional protein product, thus securing the preservation
heritability of both.
This scenario has the advantage of allowing
genome to vary through many generations, as mutationssearch the
possible base sequences. The scenario has an overriding problem,
size of the combinatorial space (i.e., the number of possible amino acid
sequences) and the extreme rarity and isolation of the functional
within that space of possibilities. Since natural selection can do
help generate new functional sequences, but rather can only
sequences once they have arisen, chance alone--random variation--must do
work of information generation--that is, of finding the exceedingly rare
functional sequences within the set of combinatorial possibilities. Yet
probability of randomly assembling (orfinding, in the previous
functional sequence is extremely small.
performed during the early 1990s suggest that the probability of
random) the correct sequencing for a short protein 100 amino acids long
1 in 1065 (Reidhaar-Olson & Sauer 1990, Behe 1992:65-69).
result agreed closely with earlier calculations that Yockey (1978) had
based upon the known sequence variability of cytochrome c in different
and other theoretical considerations. More recent mutagenesis research
provided additional support for the conclusion that functional proteins
exceedingly rare among possible amino acid sequences (Axe 2000, 2004).
(2004) has performed site directed mutagenesis experiments on a
protein-folding domain within a B-lactamase enzyme. His experimental
improves upon earlier mutagenesis techniques and corrects for several
possible estimation error inherent in them. On the basis of these
Axe has estimated the ratio of (a) proteins of typical size (150
perform a specified function via any folded structure to (b) the whole
possible amino acids sequences of that size. Based on his experiments,
estimated his ratio to be 1 to 1077. Thus, the probability of
a functional protein among the possible amino acid sequences
corresponding to a
150-residue protein is similarly 1 in 1077.
considerations imply additional improbabilities. First, new Cambrian
would require proteins much longer than 100 residues to perform many
specialized functions. Ohno (1996) has noted that Cambrian animals would
required complex proteins such as lysyl oxidase in order to support
body structures. Lysyl oxidase molecules in extant organisms comprise
amino acids. These molecules are both highly complex (non-repetitive)
functionally specified. Reasonable extrapolation from mutagenesis
done on shorter protein molecules suggests that the probability of
functionally sequenced proteins of this length at random is so small as
appeals to chance absurd, even granting the duration of the entire
(See Dembski 1998:175-223 for a rigorous calculation of this
Probability Bound; See also Axe 2004.) Yet, second, fossil data
(Bowring et al.
19, 1998a:1, 1998b:40; Kerr 19; Monatersky 19), and even molecular
analyses supporting deep divergence (Wray et al. 1996), suggest that the
duration of the Cambrian explosion (between 5-10 x 106 and,
7 x 107 years) is far smaller than that of the entire
x 1010 years). Third, DNA mutation rates are far too low to
the novel genes and proteins necessary to building the Cambrian animals,
the most probable duration of the explosion as determined by fossil
(Conway Morris 1998b). As Ohno (1996:8475) notes, even a mutation rate
10-9 per base pair per year results in only a 1% change in
sequence of a given section of DNA in 10 million years. Thus, he argues
mutational divergence of preexisting genes cannot explain the origin of
Cambrian forms in that time.4
selection/mutation mechanism faces another probabilistic obstacle. The
that arise in the Cambrian exhibit structures that would have required
types of cells, each of which would have required many novel
perform their specialized functions. Further, new cell types require
Asystems of proteins that must, as a condition of functioning,
close coordination with one another. The unit of selection in such
ascends to the system as a whole. Natural selection selects for
advantage. But new cell types require whole systems of proteins to
distinctive functions. In such cases, natural selection cannot
contribute to the
process of information generation until after the information
to build the requisite system of proteins has arisen. Thus random
variations must, again, do the work of information generation--and now
simply for one protein, but for many proteins arising at nearly the same
Yet the odds of this occurring by chance alone are, of course, far
the odds of the chance origin of a single gene or protein--so small in
to render the chance origin of the genetic information necessary to
build a new
cell type (a necessary but not sufficient condition of building a new
problematic given even the most optimistic estimates for the duration of
Dawkins (1986:139) has noted that scientific
can rely on only so muchluck before they cease to be credible.
theory of evolution, which, by its own logic, prevents natural selection
playing a role in generating genetic information until after the fact,
entirely too much luck. The sensitivity of proteins to functional loss,
for long proteins to build new cell types and animals, the need for
systems of proteins to service new cell types, the probable
the Cambrian explosion relative to mutation rates--all suggest the
improbability (and implausibility) of any scenario for the origination
Cambrian genetic information that relies upon random variation alone
by natural selection.
Yet the neutral theory requires novel genes
proteins to arise--essentially--by random mutation alone. Adaptive
accrues after the generation of new functional genes and
natural selection cannot play a role until new
molecules have independently arisen. Thus neutral theorists envisioned
to scale the steep face of a Dawkins-style precipice of which there is
gradually sloping backside--a situation that, by Dawkins' own logic, is
In the second scenario,
envisioned novel genes and proteins arising by numerous successive
the preexisting genetic text that codes for proteins. To adapt Dawkins's
metaphor, this scenario envisions gradually climbing down one functional
and then ascending another. Yet mutagenesis experiments again suggest a
difficulty. Recent experiments show that, even when exploring a region
sequence space populated by proteins of a single fold and function, most
multiple-position changes quickly lead to loss of function (Axe 2000).
turn one protein into another with a completely novel structure and
requires specified changes at many sites. Indeed, the number of changes
necessary to produce a new protein greatly exceeds the number of changes
will typically produce functional losses. Given this, the probability of
escaping total functional loss during a random search for the changes
produce a new function is extremely small--and this probability
exponentially with each additional requisite change (Axe 2000). Thus,
results imply that, in all probability, random searches for novel
(through sequence space) will result in functional loss long before any
functional protein will emerge.
Blanco et al. have come to a
conclusion. Using directed mutagenesis, they have determined that
both the hydrophobic core and on the surface of the protein play
in determining protein structure. By sampling intermediate sequences
naturally occurring sequences that adopt different folds, they found
intermediate sequenceslack a well defined three-dimensional
they conclude that it is unlikely that a new protein fold via a series
intermediates sequences (Blanco et al. 1999:741).
second neo-Darwinian scenario has the advantage of starting with
genes and proteins, it also has a lethal disadvantage: any process of
mutation or rearrangement in the genome would in all probability
nonfunctional intermediate sequences before fundamentally new functional
or proteins would arise. Clearly, nonfunctional intermediate sequences
survival advantage on their host organisms. Natural selection favors
functional advantage. It cannot select or favor nucleotide sequences or
polypeptide chains that do not yet perform biological functions, and
will it favor sequences that efface or destroy preexisting
Evolving genes and proteins will range through a series
nonfunctional intermediate sequences that natural selection will not
preserve but will, in all probability, eliminate (Blanco et al. 1999,
When this happens, selection-driven evolution will cease. At this point,
evolution of the genome (unhinged from selective pressure) may ensue,
but, as we
have seen, such a process must overcome immense probabilistic hurdles,
granting cosmic time.
Thus, whether one envisions the
process beginning with a noncoding region of the genome or a preexisting
functional gene, the functional specificity and complexity of proteins
very stringent limitations on the efficacy of mutation and selection. In
first case, function must arise first, before natural selection can act
a novel variation. In the second case, function must be continuously
in order to prevent deleterious (or lethal) consequences to the organism
allow further evolution. Yet the complexity and functional specificity
proteins implies that both these conditions will be extremely difficult
Therefore, the neo-Darwinian mechanism appears to be inadequate to
new information present in the novel genes and proteins that arise with
Novel Body Plans
neo-Darwinian mechanism run deeper still. In order to explain the origin
Cambrian animals, one must account not only for new proteins and cell
also for the origin of new body plans. Within the past decade,
biology has dramatically advanced our understanding of how body plans
during ontogeny. In the process, it has also uncovered a profound
Significant morphological change in organisms
attention to timing. Mutations in genes that are expressed late in the
development of an organism will not affect the body plan. Mutations
early in development, however, could conceivably produce significant
morphological change (Arthur 1997:21). Thus, events expressed early in
development of organisms have the only realistic chance of producing
macroevolutionary change (Thomson 1992). As John and Miklos (1988:309)
macroevolutionary change requires alterations in the very early stages
Yet recent studies in developmental biology make
mutations expressed early in development typically have deleterious
(Arthur 1997:21). For example, when early-acting body plan molecules, or
morphogens such as bicoid (which helps to set up the
head-to-tail axis in Drosophila), are perturbed, development
(Nusslein-Volhard & Wieschaus 1980, Lawrence & Struhl 1996,
The resulting embryos die. Moreover, there is a good reason for this. If
engineer modifies the length of the piston rods in an internal
without modifying the crankshaft accordingly, the engine won't start.
processes of development are tightly integrated spatially and temporally
that changes early in development will require a host of other
changes in separate but functionally interrelated developmental
downstream. For this reason, mutations will be much more likely to be
they disrupt a functionally deeply-embedded structure such as a spinal
than if they affect more isolated anatomical features such as fingers
This problem has led to what McDonald (1983) has
great Darwinian paradox (p. ). McDonald notes that genes that are
vary within natural populations do not lead to major adaptive changes,
genes that could cause major changes--the very stuff of
macroevolution--apparently do not vary. In other words, mutations of the
that macroevolution doesn't need (namely, viable genetic mutations in
expressed late in development) do occur, but those that it does need
beneficial body plan mutations expressed early in development)
According to Darwin (1859:108) natural selection cannot act until
variations arise in a population. Yet there is no evidence from
genetics that the kind of variations required by neo-Darwinism--namely,
favorable body plan mutations--ever occur.
raised another formidable problem for the mutation/selection mechanism.
Embryological evidence has long shown that DNA does not wholly determine
morphological form (Goodwin 1985, Nijhout 1990, Sapp 1987, Muller &
2003), suggesting that mutations in DNA alone cannot account for the
morphological changes required to build a new body plan.
It also helps to regulate the timing and expression of the synthesis of
proteins within cells. Yet, DNA alone does not determine how individual
assemble themselves into larger systems of proteins; still less does it
determine how cell types, tissue types, and organs arrange themselves
plans (Harold 1995:2774, Moss 2004). Instead, other factors--such as the
three-dimensional structure and organization of the cell membrane and
cytoskeleton and the spatial architecture of the fertilized egg--play
roles in determining body plan formation during
example, the structure and location of the cytoskeleton influence the
of embryos. Arrays of microtubules help to distribute the essential
used during development to their correct locations in the cell. Of
microtubules themselves are made of many protein subunits. Nevertheless,
bricks that can be used to assemble many different structures, the
subunits in the cell's microtubules are identical to one another. Thus,
the tubulin subunits nor the genes that produce them account for the
shape of microtubule arrays that distinguish different kinds of embryos
developmental pathways. Instead, the structure of the microtubule array
is determined by the location and arrangement of its subunits, not the
properties of the subunits themselves. For this reason, it is not
predict the structure of the cytoskeleton of the cell from the
of the protein constituents that form that structure (Harold
Two analogies may help further clarify the point. At a
building site, builders will make use of many materials: lumber, wires,
drywall, piping, and windows. Yet building materials do not determine
plan of the house, or the arrangement of houses in a neighborhood.
electronic circuits are composed of many components, such as resistors,
capacitors, and transistors. But such lower-level components do not
their own arrangement in an integrated circuit. Biological symptoms also
on hierarchical arrangements of parts. Genes and proteins are made from
building blocks--nucleotide bases and amino acids--arranged in specific
Cell types are made of, among other things, systems of specialized
Organs are made of specialized arrangements of cell types and tissues.
plans comprise specific arrangements of specialized organs. Yet,
properties of individual proteins (or, indeed, the lower-level parts in
hierarchy generally) do not fully determine the organization of the
structures and organizational patterns (Harold 2001:125). It follows
genetic information that codes for proteins does not determine these
higher-level structures either.
These considerations pose another
challenge to the sufficiency of the neo-Darwinian mechanism.
to explain the origin of new information, form, and structure as a
selection acting on randomly arising variation at a very low level
biological hierarchy, namely, within the genetic text. Yet major
innovations depend on a specificity of arrangement at a much higher
level of the
organizational hierarchy, a level that DNA alone does not determine. Yet
is not wholly responsible for body plan morphogenesis, then DNA
mutate indefinitely, without regard to realistic probabilistic limits,
not produce a new body plan. Thus, the mechanism of natural selection
random mutations in DNA cannot in principle generate novel body
including those that first arose in the Cambrian explosion.
could be argued that, while many single proteins do not by themselves
cellular structures and/or body plans, proteins acting in concert with
proteins or suites of proteins could determine such higher-level form.
example, it might be pointed out that the tubulin subunits (cited above)
assembled by other helper proteins--gene products--called Microtubule
Proteins (MAPS). This might seem to suggest that genes and gene products
do suffice to determine the development of the three-dimensional
Yet MAPS, and indeed many other necessary
only part of the story. The location of specified target sites on the
of the cell membrane also helps to determine the shape of the
Similarly, so does the position and structure of the centrosome which
the microtubules that form the cytoskeleton. While both the membrane
the centrosomes are made of proteins, the location and form of these
is not wholly determined by the proteins that form them. Indeed,
structure and membrane patterns as a whole convey
structural information that helps determine the structure of the
and the location of its subunits (McNiven & Porter 1992:313-329).
the centrioles that compose the centrosomes replicate independently of
replication (Lange et al. 2000:235-249, Marshall & Rosenbaum
The daughter centriole receives its form from the overall structure of
mother centriole, not from the individual gene products that constitute
(Lange et al. 2000). In ciliates, microsurgery on cell membranes can
heritable changes in membrane patterns, even though the DNA of the
not been altered (Sonneborn 1970:1-13, Frankel 1980:607-623; Nanney
1983:163-170). This suggests that membrane patterns (as opposed to
constituents) are impressed directly on daughter cells. In both cases,
transmitted from parent three-dimensional structures to daughter
three-dimensional structures directly and is not wholly contained in
proteins or genetic information (Moss 2004).
Thus, in each new
generation, the form and structure of the cell arises as the result of
both gene products and preexisting three-dimensional structure
organization. Cellular structures are built from proteins, but proteins
their way to correct locations in part because of preexisting
patterns and organization inherent in cellular structures. Preexisting
three-dimensional form present in the preceding generation (whether
the cell membrane, the centrosomes, the cytoskeleton or other features
fertilized egg) contributes to the production of form in the next
Neither structural proteins alone, nor the genes that code for them, are
sufficient to determine the three-dimensional shape and structure of the
entities they form. Gene products provide necessary, but not sufficient
conditions, for the development of three-dimensional structure within
organs and body plans (Harold 1995:2767). But if this is so, then
selection acting on genetic variation alone cannot produce the new forms
arise in history of life.
course, neo-Darwinism is not the only evolutionary theory for explaining
origin of novel biological form. Kauffman (1995) doubts the efficacy of
mutation/selection mechanism. Nevertheless, he has advanced a
self-organizational theory to account for the emergence of new form, and
presumably the information necessary to generate it. Whereas
attempts to explain new form as the consequence of selection acting on
mutation, Kauffman suggests that selection acts, not mainly on random
variations, but on emergent patterns of order that self-organize via the
Kauffman (1995:47-92) illustrates how this might work
various model systems in a computer environment. In one, he conceives a
of buttons connected by strings. Buttons represent novel genes or gene
strings represent the law-like forces of interaction that obtain between
products-i.e., proteins. Kauffman suggests that when the complexity of
system (as represented by the number of buttons and strings) reaches a
threshold, new modes of organization can arise in the systemfor
is, naturally and spontaneously--after the manner of a phase transition
Another model that Kauffman develops is a system of
interconnected lights. Each light can flash in a variety of states--on,
twinkling, etc. Since there is more than one possible state for each
many lights, there are a vast number of possible states that the system
adopt. Further, in his system, rules determine how past states will
future states. Kauffman asserts that, as a result of these rules, the
will, if properly tuned, eventually produce a kind of order in which a
patterns of light activity recur with greater-than-random frequency.
actual patterns of light activity represent a small portion of the total
of possible states in which the system can reside, Kauffman seems to
self-organizational laws might similarly result in highly improbable
outcomes--perhaps even sequences (of bases or amino acids) within a much
sequence space of possibilities.
Do these simulations of
self-organizational processes accurately model the origin of novel
information? It is hard to think so.
First, in both examples,
presupposes but does not explain significant sources of preexisting
In his buttons-and-strings system, the buttons represent proteins,
packets of CSI, and the result of preexisting genetic information. Where
this information come from? Kauffman (1995) doesn't say, but the origin
information is an essential part of what needs to be explained in the
life. Similarly, in his light system, the order that allegedly arises
free actually arises only if the programmer of the model system
tunes it in
such a way as to keep it from either (a) generating an excessively rigid
or (b) developing into chaos (pp. 86-88). Yet this necessary tuning
intelligent programmer selecting certain parameters and excluding
is, inputting information.
Second, Kauffman's model systems are
constrained by functional considerations and thus are not analogous to
biological systems. A system of interconnected lights governed by
rules may well settle into a small number of patterns within a much
of possibilities. But because these patterns have no function, and need
any functional requirements, they have no specificity analogous to that
in actual organisms. Instead, examination of Kauffman's (1995) model
shows that they do not produce sequences or systems characterized by
specified complexity, but instead by large amounts of symmetrical
or internal redundancy interspersed with aperiodicity or (mere)
53, 89, 102). Getting a law-governed system to generate repetitive
flashing lights, even with a certain amount of variation, is clearly
interesting, but not biologically relevant. On the other hand, a system
lights flashing the title of a Broadway play would model a biologically
self-organizational process, at least if such a meaningful or
specified sequence arose without intelligent agents previously
system with equivalent amounts of CSI. In any case, Kauffman's systems
produce specified complexity, and thus do not offer promising
explaining the new genes and proteins that arose in the
so, Kauffman suggests that his self-organizational models can
elucidate aspects of the Cambrian explosion. According to Kauffman
(1995:199-201), new Cambrian animals emerged as the result oflong
mutations that established new body plans in a discrete rather than
fashion. He also recognizes that mutations affecting early development
almost inevitably harmful. Thus, he concludes that body plans, once
will not change, and that any subsequent evolution must occur within an
established body plan (Kauffman 1995:201). And indeed, the fossil record
show a curious (from a neo-Darwinian point of view) top-down pattern of
appearance, in which higher taxa (and the body plans they represent)
first, only later to be followed by the multiplication of lower taxa
representing variations within those original body designs (Erwin et al.
Lewin 1988, Valentine & Jablonski 2003:518). Further, as Kauffman
body plans appear suddenly and persist without significant modification
But here, again, Kauffman begs the most important question,
is: what produces the new Cambrian body plans in the first place?
invokeslong jump mutations to explain this, but he identifies no
self-organizational process that can produce such mutations. Moreover,
concedes a principle that undermines the plausibility of his own
Kauffman acknowledges that mutations that occur early in development are
inevitably deleterious. Yet developmental biologists know that these are
only kind of mutations that have a realistic chance of producing
evolutionary change--i.e., the big jumps that Kauffman invokes. Though
repudiates the neo-Darwinian reliance upon random mutations in favor of
self-organizing order, in the end, he must invoke the most implausible
random mutation in order to provide a self-organizational account of the
Cambrian body plans. Clearly, his model is not
Of course, still other causal explanations have
proposed. During the 1970s, the paleontologists Eldredge and Gould
proposed the theory of evolution by punctuated equilibrium in order to
for a pervasive pattern ofsudden appearance andstasis in
record. Though advocates of punctuated equilibrium were mainly seeking
describe the fossil record more accurately than earlier gradualist
models had done, they did also propose a mechanism--known as species
selection--by which the large morphological jumps evident in fossil
have been produced. According to punctuationalists, natural selection
more as a mechanism for selecting the fittest species rather than the
individual among a species. Accordingly, on this model, morphological
should occur in larger, more discrete intervals than it would given a
traditional neo-Darwinian understanding.
Despite its virtues as a
descriptive model of the history of life, punctuated equilibrium has
criticized for failing to provide a mechanism sufficient to produce the
form characteristic of higher taxonomic groups. For one thing, critics
noted that the proposed mechanism of punctuated evolutionary change
lacked the raw material upon which to work. As Valentine and Erwin
the fossil record fails to document a large pool of species prior to the
Cambrian. Yet the proposed mechanism of species selection requires just
pool of species upon which to act. Thus, they conclude that the
species selection probably does not resolve the problem of the origin of
higher taxonomic groups (p. 96).8
Further, punctuated equilibrium has not addressed the more specific and
fundamental problem of explaining the origin of the new biological
(whether genetic or epigenetic) necessary to produce novel biological
Advocates of punctuated equilibrium might assume that the new species
which natural selection acts) arise by known microevolutionary processes
speciation (such as founder effect, genetic drift or bottleneck effect)
not necessarily depend upon mutations to produce adaptive changes. But,
case, the theory lacks an account of how the specifically higher
arise. Species selection will only produce more fit species. On the
if punctuationalists assume that processes of genetic mutation can
fundamental morphological changes and variations, then their model
subject to the same problems as neo-Darwinism (see above). This dilemma
evident in Gould (2002:710) insofar as his attempts to explain adaptive
complexity inevitably employ classical neo-Darwinian modes of
attempt to explain the origin of form has been proposed by the
such as Gerry Webster and Brian Goodwin (1984, 1996). These biologists,
on the earlier work of D'Arcy Thompson (1942), view biological form as
result of structural constraints imposed upon matter by morphogenetic
laws. For reasons similar to those discussed above, the structuralists
insisted that these generative or morphogenetic rules do not reside in
level building materials of organisms, whether in genes or proteins.
Goodwin (1984:510-511) further envisioned morphogenetic rules or laws
ahistorically, similar to the way in which gravitational or
operate. For this reason, structuralists see phylogeny as of secondary
importance in understanding the origin of the higher taxa, though they
that transformations of form can occur. For structuralists, constraints
arrangement of matter arise not mainly as the result of historical
contingencies--such as environmental changes or genetic mutations--but
because of the continuous ahistorical operation of fundamental laws of
form--laws that organize or inform matter.
While this approach
many of the difficulties currently afflicting neo-Darwinism (in
associated with itsgenocentricity), critics (such as Maynard
Smith 1986) of
structuralism have argued that the structuralist explanation of form
specificity. They note that structuralists have been unable to say just
laws of form reside--whether in the universe, or in every possible
world, or in
organisms as a whole, or in just some part of organisms. Further,
structuralists, morphogenetic laws are mathematical in character. Yet,
structuralists have yet to specify the mathematical formulae that
Others (Yockey 1992; Polanyi 1967, 1968; Meyer
have questioned whether physical laws could in principle generate the
complexity that characterizes biological systems. Structuralists
existence of biological laws that produce form in much the same way that
physical laws produce form. Yet the forms that physicists regard as
manifestations of underlying laws are characterized by large amounts of
symmetric or redundant order, by relatively simple patterns such as
gravitational fields or magnetic lines of force. Indeed, physical laws
typically expressed as differential equations (or algorithms) that
definition describe recurring phenomena--patterns of compressible
complexity as defined by algorithmic information theory (Yockey
Biological forms, by contrast, manifest greater complexity and derive in
ontogeny from highly complex initial conditions--i.e., non-redundant
of nucleotide bases in the genome and other forms of information
the complex and irregular three-dimensional topography of the organism
fertilized egg. Thus, the kind of form that physical laws produce is not
analogous to biological form--at least not when compared from the
(algorithmic) complexity. Further, physical laws lack the information
specify biology systems. As Polyanyi (1967, 1968) and Yockey (1992:290)
shown, the laws of physics and chemistry allow, but do not determine,
distinctively biological modes of organization. In other words, living
are consistent with, but not deducible, from physical-chemical laws
Of course, biological systems do manifest some
patterns, processes and behaviors. The same type of organism develops
from similar ontogenetic processes in the same species. Similar
cell division reoccur in many organisms. Thus, one might describe
biological processes as law-governed. Even so, the existence of such
regularities does not solve the problem of the origin of form and
since the recurring processes described by such biological laws (if
such laws) only occur as the result of preexisting stores of (genetic
epigenetic) information and these information-rich initial conditions
constraints that produce the recurring behavior in biological systems.
example, processes of cell division recur with great frequency in
depend upon information-rich DNA and proteins molecules.) In other
distinctively biological regularities depend upon preexisting biological
information. Thus, appeals to higher-level biological laws presuppose,
not explain, the origination of the information necessary to
Thus, structuralism faces a difficult in principle
dilemma. On the one hand, physical laws produce very simple redundant
that lack the complexity characteristic of biological systems. On the
hand, distinctively biological laws--if there are such laws--depend upon
preexisting information-rich structures. In either case, laws are not
candidates for explaining the origination of biological form or the
necessary to produce it.
Cladism: An Artifact of
Some cladists have advanced another approach
problem of the origin of form, specifically as it arises in the
have argued that the problem of the origin of the phyla is an artifact
classification system, and therefore, does not require explanation. Budd
Jensen (2000), for example, argue that the problem of the Cambrian
resolves itself if one keeps in mind the cladistic distinction between
andcrown groups. Since crown groups arise whenever new characters
to simpler more ancestral stem groups during the evolutionary process,
will inevitably arise once a new stem group has arisen. Thus, for Budd
Jensen what requires explanation is not the crown groups corresponding
new Cambrian phyla, but the earlier more primitive stem groups that
arose deep in the Proterozoic. Yet since these earlier stem groups are
definition less derived, explaining them will be considerably easier
explaining the origin of the Cambrian animals de novo. In any
Budd and Jensen the explosion of new phyla in the Cambrian does not
explanation. As they put it,given that the early branching points of
clades is an inevitable result of clade diversification, the alleged
of the phyla appearing early and remaining morphologically static is not
require particular explanation (Budd & Jensen
superficially plausible, perhaps, Budd and Jensen's attempt to explain
Cambrian explosion begs crucial questions. Granted, as new characters
to existing forms, novels morphology and greater morphological disparity
likely result. But what causes new characters to arise? And how does the
information necessary to produce new characters originate? Budd and
not specify. Nor can they say how derived the ancestral forms are likely
been, and what processes, might have been sufficient to produce them.
they simply assume the sufficiency of known neo-Darwinian mechanisms
Jensen 2000:288). Yet, as shown above, this assumption is now
any case, Budd and Jensen do not explain what causes the origination of
biological form and information.
Convergence and Teleological
More recently, Conway Morris (2000, 2003c) has
another possible explanation based on the tendency for evolution to
the same structural forms during the history of life. Conway Morris
numerous examples of organisms that possess very similar forms and
even though such structures are often built from different material
and arise (in ontogeny) by the expression of very different genes. Given
extreme improbability of the same structures arising by random mutation
selection in disparate phylogenies, Conway Morris argues that the
of convergent structures suggests that evolution may be in some way
toward similar functional and/or structural endpoints. Such an
understanding of evolution, he admits, raises the controversial prospect
teleological or purposive element in the history of life. For this
argues that the phenomenon of convergence has received less attention
might have otherwise. Nevertheless, he argues that just as physicists
reopened the question of design in their discussions of anthropic
the ubiquity of convergent structures in the history of life has led
biologists (Denton 1998) to consider extending teleological thinking to
And, indeed, Conway Morris himself intimates that the evolutionary
beunderpinned by a purpose (2000:8, 2003b:511).
course, considers this possibility in relation to a very specific aspect
problem of organismal form, namely, the problem of explaining why the
arise repeatedly in so many disparate lines of decent. But this raises a
question. Could a similar approach shed explanatory light on the more
causal question that has been addressed in this review? Could the notion
purposive design help provide a more adequate explanation for the origin
organismal form generally? Are there reasons to consider design as an
explanation for the origin of the biological information necessary to
the higher taxa and their corresponding morphological
remainder of this review will suggest that there are such reasons. In so
it may also help explain why the issue of teleology or design has
within the scientific discussion of biological origins (Denton 1986,
Thaxton et al. 1992; Kenyon & Mills 1996: Behe 1996, 2004; Dembski
2002, 2004; Conway Morris 2000, 2003a, 2003b, Lonnig 2001; Lonnig &
2002; Nelson & Wells 2003; Meyer 2003, 2004; Bradley 2004) and why
scientists and philosophers of science have considered teleological
for the origin of form and information despite strong methodological
prohibitions against design as a scientific hypothesis (Gillespie 1979,
First, the possibility of design as an explanation
logically from a consideration of the deficiencies of neo-Darwinism and
current theories as explanations for some of the more striking
design in biological systems. Neo-Darwinists such as Ayala (1994:5),
(1986:1), Mayr (1982:xi-xii) and Lewontin (1978) have long acknowledged
organisms appear to have been designed. Of course, neo-Darwinists assert
what Ayala (1994:5) calls theobvious design of living things is
since the selection/mutation mechanism can explain the origin of complex
and organization in living systems without an appeal to a designing
Indeed, neo-Darwinists affirm that mutation and selection--and perhaps
similarly undirected mechanisms--are fully sufficient to explain the
of design in biology. Self-organizational theorists and
this claim, but affirm its essential tenet. Self-organization theorists
that natural selection acting on self organizing order can explain the
complexity of living things--again, without any appeal to design.
Punctuationalists similarly envision natural selection acting on newly
species with no actual design involved.
And clearly, the
mechanism does explain many appearances of design, such as the
organisms to specialized environments that attracted the interest of
century biologists. More specifically, known microevolutionary processes
quite sufficient to account for changes in the size of Galapagos finch
that have occurred in response to variations in annual rainfall and
food supplies (Weiner 1994, Grant 1999).
But does neo-Darwinism,
other fully materialistic model, explain all appearances of design in
including the body plans and information that characterize living
Arguably, biological forms--such as the structure of a chambered
organization of a trilobite, the functional integration of parts in an
molecular machine--attract our attention in part because the organized
complexity of such systems seems reminiscent of our own designs. Yet,
review has argued that neo-Darwinism does not adequately account for the
of all appearances of design, especially if one considers animal body
the information necessary to construct them, as especially striking
the appearance of design in living systems. Indeed, Dawkins (1995:11)
(1996:228) have noted that genetic information bears an uncanny
computer software or machine code. For this reason, the presence of CSI
living organisms, and the discontinuous increases of CSI that occurred
events such as the Cambrian explosion, appears at least suggestive of
Does neo-Darwinism or any other purely materialistic
morphogenesis account for the origin of the genetic and other forms of
necessary to produce novel organismal form? If not, as this review has
could the emergence of novel information-rich genes, proteins, cell
body plans have resulted from actual design, rather than a purposeless
that merely mimics the powers of a designing intelligence? The logic of
neo-Darwinism, with its specific claim to have accounted for the
design, would itself seem to open the door to this possibility. Indeed,
historical formulation of Darwinism in dialectical opposition to the
hypothesis (Gillespie 1979), coupled with the neo-Darwinism's inability
account for many salient appearances of design including the emergence
and information, would seem logically to reopen the possibility of
opposed to apparent) design in the history of life.
considering design as an explanation for these phenomena follows from
importance of explanatory power to scientific theory evaluation and from
consideration of the potential explanatory power of the design
Studies in the methodology and philosophy of science have shown that
scientific theories, particularly in the historical sciences, are
justified as inferences to the best explanation (Lipton 1991:32-88,
1989:1124-1129, Sober 2000:44). Historical scientists, in particular,
test competing hypotheses by evaluating which hypothesis would, if true,
the best explanation for some set of relevant data (Meyer 1991, 2002;
Those with greater explanatory power are typically judged to be better,
probably true, theories. Darwin (1896:437) used this method of reasoning
defending his theory of universal common descent. Moreover, contemporary
on the method ofinference to the best explanation have shown that
which among a set of competing possible explanations constitutes the
depends upon judgments about the causal adequacy, orcausal
competing explanatory entities (Lipton 1991:32-88). In the historical
uniformitarian and/or actualistic (Gould 1965, Simpson 1970, Rutten
Hooykaas 1975) canons of method suggest that judgments about causal
should derive from our present knowledge of cause and effect
historical scientists,the present is the key to the past means
experience-based knowledge of cause and effect relationships typically
the assessment of the plausibility of proposed causes of past
it is precisely for this reason that current advocates of the design
want to reconsider design as an explanation for the origin of biological
and information. This review, and much of the literature it has
suggests that four of the most prominent models for explaining the
biological form fail to provide adequate causal explanations for the
discontinuous increases of CSI that are required to produce novel
Yet, we have repeated experience of rational and conscious agents--in
ourselves--generating or causing increases in complex specified
both in the form of sequence-specific lines of code and in the form of
hierarchically arranged systems of parts.
In the first place,
human agents--in virtue of their rationality and consciousness--have
demonstrated the power to produce information in the form of linear
sequence-specific arrangements of characters. Indeed, experience affirms
information of this type routinely arises from the activity of
agents. A computer user who traces the information on a screen back to
source invariably comes to a mind--that of a software engineer or
programmer. The information in a book or inscriptions ultimately derives
writer or scribe--from a mental, rather than a strictly material, cause.
experience-based knowledge of information-flow confirms that systems
amounts of specified complexity (especially codes and languages)
originate from an intelligent source from a mind or personal agent. As
(1964) put it, thecreation of new information is habitually
conscious activity (p. 16). Experience teaches this obvious
Further, the highly specified hierarchical arrangements of
in animal body plans also suggest design, again because of our
of the kinds of features and systems that designers can and do produce.
level of the biological hierarchy, organisms require specified and
improbable arrangements of lower-level constituents in order to maintain
form and function. Genes require specified arrangements of nucleotide
proteins require specified arrangements of amino acids; new cell types
specified arrangements of systems of proteins; body plans require
arrangements of cell types and organs. Organisms not only contain
information-rich components (such as proteins and genes), but they
information-rich arrangements of those components and the systems that
them. Yet we know, based on our present experience of cause and effect
relationships, that design engineers--possessing purposive intelligence
rationality--have the ability to produce information-rich hierarchies in
both individual modules and the arrangements of those modules exhibit
and specificity--information so defined. Individual transistors,
capacitors exhibit considerable complexity and specificity of design; at
higher level of organization, their specific arrangement within an
circuit represents additional information and reflects further design.
and rational agents have, as part of their powers of purposive
capacity to design information-rich parts and to organize those parts
functional information-rich systems and hierarchies. Further, we know of
other causal entity or process that has this capacity. Clearly, we have
reason to doubt that mutation and selection, self-organizational
laws of nature, can produce the information-rich components, systems,
plans necessary to explain the origination of morphological novelty such
which arises in the Cambrian period.
There is a third reason to
purpose or design as an explanation for the origin of biological form
information: purposive agents have just those necessary powers that
selection lacks as a condition of its causal adequacy. At several points
previous analysis, we saw that natural selection lacked the ability to
novel information precisely because it can only act after new
CSI has arisen. Natural selection can favor new proteins, and genes, but
after they perform some function. The job of generating new functional
proteins and systems of proteins therefore falls entirely to random
Yet without functional criteria to guide a search through the space of
sequences, random variation is probabilistically doomed. What is needed
just a source of variation (i.e., the freedom to search a space of
possibilities) or a mode of selection that can operate after the fact of
successful search, but instead a means of selection that (a) operates
search--before success--and that (b) is guided by information about, or
knowledge of, a functional target.
Demonstration of this
come from an unlikely quarter: genetic algorithms. Genetic algorithms
programs that allegedly simulate the creative power of mutation and
Dawkins and Kuppers, for example, have developed computer programs that
putatively simulate the production of genetic information by mutation
natural selection (Dawkins 1986:47-49, Kuppers 1987:355-369).
shown elsewhere (Meyer 1998:127-128, 2003:247-248), these programs only
by the illicit expedient of providing the computer with atarget
then treating relatively greater proximity to future function
target sequence), not actual present function, as a selection criterion.
Berlinski (2000) has argued, genetic algorithms need something akin to a
forward looking memory in order to succeed. Yet such foresighted
no analogue in nature. In biology, where differential survival depends
maintaining function, selection cannot occur before new functional
arise. Natural selection lacks foresight.
What natural selection
intelligent selection--purposive or goal-directed design--provides.
agents can arrange both matter and symbols with distant goals in mind.
language, the human mind routinelyfinds or generates highly
linguistic sequences to convey an intended or preconceived idea.
process of thought, functional objectives precede and constrain the
words, sounds and symbols to generate functional (and indeed meaningful)
sequences from among a vast ensemble of meaningless alternative
sound or symbol (Denton 1986:309-311). Similarly, the construction of
technological objects and products, such as bridges, circuit boards,
software, result from the application of goal-directed constraints
1967, 1968). Indeed, in all functionally integrated complex systems
cause is known by experience or observation, design engineers or other
intelligent agents applied boundary constraints to limit possibilities
to produce improbable forms, sequences or structures. Rational agents
repeatedly demonstrated the capacity to constrain the possible to
improbable but initially unrealized future functions. Repeated
affirms that intelligent agents (minds) uniquely possess such causal
Analysis of the problem of the origin of biological
therefore, exposes a deficiency in the causal powers of natural
corresponds precisely to powers that agents are uniquely known to
Intelligent agents have foresight. Such agents can select functional
before they exist. They can devise or select material means to
those ends from among an array of possibilities and then actualize those
in accord with a preconceived design plan or set of functional
Rational agents can constrain combinatorial space with distant outcomes
The causal powers that natural selection lacks--almost by
associated with the attributes of consciousness and rationality--with
intelligence. Thus, by invoking design to explain the origin of new
information, contemporary design theorists are not positing an arbitrary
explanatory element unmotivated by a consideration of the evidence.
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powers that the phenomenon in question requires as a condition of its
the causal powers of various explanatory hypotheses suggests purposive
intelligent design as a causally adequate--and perhaps the most causally
adequate--explanation for the origin of the complex specified
required to build the Cambrian animals and the novel forms they
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Specifically, Gilbert et al. (1996) argued that changes in morphogenetic
might produce large-scale changes in the developmental programs and,
body plans of organisms. Yet they offered no evidence that such
indeed they exist--can be altered to produce advantageous variations in
plan, though this is a necessary condition of any successful causal
2 If one takes the
record at face value and assumes that the Cambrian explosion took place
relatively narrow 5-10 million year window, explaining the origin of the
information necessary to produce new proteins, for example, becomes more
in part because mutation rates would not have been sufficient to
number of changes in the genome necessary to build the new proteins for
complex Cambrian animals (Ohno 1996:8475-8478). This review will argue
even if one allows several hundred million years for the origin of the
significant probabilistic and other difficulties remain with the
explanation of the origin of form and information.
3 As Crick put it,information means here the
precise determination of sequence, either of bases in the nucleic
on amino acid residues in the protein (Crick 1958:144,
4 To solve this problem Ohno himself proposes the
of a hypothetical ancestral form that possessed virtually all the
information necessary to produce the new body plans of the Cambrian
asserts that this ancestor and itspananimalian genome might have
several hundred million years before the Cambrian explosion. On this
of the different Cambrian animals would have possessed virtually
genomes, albeit with considerable latent and unexpressed capacity in the
each individual form (Ohno 1996:8475-8478). While this proposal might
explain the origin of the Cambrian animal forms by reference to
genetic information, it does not solve, but instead merely displaces,
problem of the origin of the genetic information necessary to produce
5 Some have suggested that
inmaster regulator Hox genes might provide the raw material for
morphogenesis. Yet there are two problems with this proposal. First, Hox
expression begins only after the foundation of the body plan has been
established in early embryogenesis. (Davidson 2001:66). Second, Hox
highly conserved across many disparate phyla and so cannot account for
morphological differences that exist between the phyla (Valentine
6 Notable differences in
developmental pathways of similar organisms have been observed. For
congeneric species of sea urchins (from genus Heliocidaris)
striking differences in their developmental pathways (Raff
it might be argued that such differences show that early developmental
can in fact be mutated to produce new forms. Nevertheless, there are two
problems with this claim. First, there is no direct evidence that
differences in sea urchin development arose by mutation. Second, the
differences in the developmental programs of different species of sea
not result in new body plans, but instead in highly conserved
Despite differences in developmental patterns, the endpoints are the
even if it can be assumed that mutations produced the differences in
developmental pathways, it must be acknowledged that such changes did
in novel form.
7 Of course, many
post-translation processes of modification also play a role in producing
functional protein. Such processes make it impossible to predict a
final sequencing from its corresponding gene sequence alone (Sarkar
8 Erwin (2004:21),
friendly to the possibility of species selection, argues that Gould
little evidence for its existence.The difficulty writes Erwin of
selection,...is that we must rely on Gould's arguments for
plausibility and sufficient relative frequency. Rarely is a mass of data
presented to justify and support Gould's conclusion. Indeed, Gould
himself admitted that species selection remains largely a hypothetical
construct:I freely admit that well-documented cases of species
not permeate the literature (p. 710).
do not deny either the wonder, or the powerful importance, of organized
complexity. I recognize that we know no mechanism for the origin of such
organismal features other than conventional natural selection at the
level--for the sheer intricacy and elaboration of good biomechanical
surely precludes either random production, or incidental origin as a
consequence of active processes at other levels (Gould 2002:710).
Thus, we do
not challenge the efficacy or the cardinal importance of organismal
As previously discussed, I fully agree with Dawkins (1986) and others
cannot invoke a higher-level force like species selection to explain
that organisms do'--in particular, the stunning panoply of organismic
adaptations that has always motivated our sense of wonder about the
world, and that Darwin (1859) described, in one of his most famous lines
'that perfection of structure and coadaptation which most justly excites
admiration' (Gould 2002:886).
in the historical sciences typically make claims about what happened in
past, or what happened in the past to cause particular events to occur
1991:57-72). For this reason, historical scientific theories are rarely
by making predictions about what will occur under controlled laboratory
conditions (Cleland 2001:987, 2002:474-496). Instead, such theories are
tested by comparing their explanatory power against that of their
with respect to already known facts. Even in the case in which
theories make claims about past causes they usually do so on the basis
preexisting knowledge of cause and effect relationships. Nevertheless,
prediction may play a limited role in testing historical scientific
since such theories may have implications as to what kind of evidence is
to emerge in the future. For example, neo-Darwinism affirms that new
sections of the genome arise by trial and error process of mutation and
subsequent selection. For this reason, historically many neo-Darwinists
or predicted that the large non-coding regions of the genome--so-called
DNA--would lack function altogether (Orgel & Crick 1980). On this
thinking, the nonfunctional sections of the genome represent nature's
experiments that remain in the genome as a kind of artifact of the past
of the mutation and selection process. Advocates of the design
hypotheses on the
other hand, would have predicted that non-coding regions of the genome
well reveal hidden functions, not only because design theorists do not
that new genetic information arises by a trial and error process of
selection, but also because designed systems are often functionally
Even so, as new studies reveal more about the functions performed by the
non-coding regions of the genome (Gibbs 2003), the design hypothesis can
longer be said to make this claim in the form of a specifically
prediction. Instead, the design hypothesis might be said to gain
support from its ability to explain this now known evidence, albeit
fact. Of course, neo Darwinists might also amend their original
various auxiliary hypotheses to explain away the presence of newly
functions in the non-coding regions of DNA. In both cases,
ex post facto explanatory power reemerge as central to assessing
testing competing historical theories.