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Probe Ministries > Faith and Science > Origins > The Natural Limits to Biological Change


The Natural Limits to Biological Change Print E-mail
Dr. Ray Bohlin

Written by Dr. Ray Bohlin

One of the most significant questions in the origins debate concerns the nature of biological change. Can organisms change into an infinite array of creatures? Or are there genetically imposed limits to the amount of change which can take place? There are two major theories of evolutionary change: neo-Darwinism and punctuated equilibrium. As creationists, Lane Lester and I proposed in 1984 that indeed there are limits to change in our book, The Natural Limits to Biological Change. Theoretically, it may seem difficult to propose that immense variety may occur within a group of organisms yet this variety is constrained within certain genetically induced limits. It may seem contradictory even. But in the intervening ten years, my confidence in the proposal has only strengthened, and my confidence in any evolutionary mechanism to accomplish any significant adaptational change has waned considerably.

The arguments against neo-Darwinism center around four topics: mutation, natural selection, population genetics, and paleontology. Our major objection to the role of mutations in evolutionary change is the clear lack of data to indicate that mutations really accomplish anything new. While some weird-looking fruit flies have been created in the laboratory, they are still fruit flies. Bacteria are still bacteria. We quoted from Pierre-Paul Grasse', the great French evolutionist. When commenting on the mutations of bacteria he said:

What is the use of their unceasing mutations if they do not change? In sum, the mutations of bacteria and viruses are merely hereditary fluctuations around a median position; a swing to the right, a swing to the left, but no final evolutionary effect.

A mechanism for the creation of new genetic material is also sadly inadequate. Sometimes, an extra copy of a gene arises due to a DNA duplication error. Evolutionists suggest that this extra gene can accumulate mutations and eventually code for a new gene with a different function. In reality, however, this fails to explain how an old gene takes on a new function and new regulation pathways by the introduction of genetic mistakes into the gene and the regulatory apparatus.

Natural selection is a conservative process, not a creative one. The famous example of peppered moths teaches us how a species survives in a changing environment by possessing two varieties adapted to different conditions. Antibiotic resistance in bacteria only instructed us in the ingenious mechanisms of different bacteria to share the already existing genes for antibiotic resistance among themselves.

Decades of research in the science of population genetics has not helped the neo-Darwinist position. The data from protein and gene variation shed only a dim light on the major problem of evolution-- the appearance of novel adaptations. The major significance of population genetics has been helping to understand how an organism responds to minor environmental fluctuations. And even this can be clouded in fundamental differences in theory.

The data of paleontology have been elaborated at length elsewhere. Gradual, neo-Darwinian evolution is not observable in the fossil record. The rarity of transitional forms has been called the trade secret of paleontology. Mutations, natural selection, genetics, and paleontology have all proved to be dead ends for Darwinism.

Obstacles to the Theory of Punctuated Equilibrium

The coelacanth is a fish that has existed for hundreds of millions of years according to evolutionists and was thought to resemble the ancestors of modern amphibians. However, research into their anatomy, physiology, and life history since their rediscovery off Madagascar in 1938 have revealed no clues to their possible preadaptation to a terrestrial existence. The coelacanth is an example of stasis--the long-term stability of new species--the first cornerstone of evolution. A second is the sudden appearance of new species. One doesn't have to look very far for statements by paleontologists pointing to the fact that transitional forms are traditionally absent.

Introduced in 1972 by Niles Eldredge and Stephen Gould as a description of the pattern in the fossil record, punctuated equilibrium centers on the claims of stasis and sudden appearance. The major vehicle of evolutionary change becomes speciation, a process which gives rise to new species. Eldredge and Gould suggested that where there is lots of speciation, there should be lots of morphological differences. Where there is little speciation, there will be few morphological differences.

Morphological Change Becomes Associated with Speciation

If morphological change is supposed to be associated with speciation, then groups of organism that contain large numbers of species should also display large morphological differences within the group. But there are numerous examples of specific groups of related organisms that contain large numbers of species, like the minnows (Notropis), which show very little morphological divergence. This is exactly the opposite of their prediction. Sunfishes (Lepomis), however, a group with relatively few species, show just as much morphological divergence as the minnows. This is one more contradiction of punctuated equilibrium because here there is little speciation but a lot of differences.

Another tricky aspect of the claims of punctuated equilibrium is that a new species of fossil can only be recognized because of observable differences, usually in the skeletal structure. Biological species, however, are designated by many criteria (chromosome structure, etc.,) that cannot be detected in a fossil. Therefore, trying to extend a paleontological description of species and speciation will be very difficult.

What we see is that beyond punctuated equilibrium's ability to describe the fossil record, it is of little use to evolutionary biologists because they cannot imagine a way to make it work with real organisms. Gould and Eldredge admitted as much in their review of punctuated equilibrium's progress in the journal, Nature, in 1993 when they lamented that:

But continuing unhappiness, justified this time, focuses upon claims that speciation causes significant morphological change, for no validation of such a position has emerged.

In addition, punctuationalists offer no new mechanisms for arriving at new genetic information. No new theory of evolutionary change is complete without some workable mechanism for generating new genetic information. There appears to be a general lack of appreciation as to what a mutation is and what its effects on the organism may be. Discussions of regulatory and developmental mutations are carried out with no regard as to the overwhelmingly destructive effect such mutations produce compared to mutations in structural genes. Developmental mutations can cripple an organism or even lead to death. Thus, punctuated equilibrium raises more questions than it answers.

Another Alternative

As I have tried to point out, the two major competing models of evolutionary change are far from being considered accepted facts of nature. Both suffer from serious problems from which, some say, they may never be able to recover. However, if one sits back and views the evidence as a whole, a totally different perspective arises as a possibility.

First, virtually all taxonomic levels, even species appear abruptly in the fossil record. This, it will be remembered, is one of the sharper criticisms of neo-Darwinism, and one of the two cornerstones of punctuated equilibrium. It is relevant not only that the various levels of taxa appear abruptly but also that alongside the higher taxonomic levels there are unique adaptations. This is the key. Unique and highly specialized adaptations usually, if not always, appear fully formed in the fossil record. The origin of the different types of invertebrate animals such as the sponges, mollusks, echinoderms like the starfish, arthropods like crustaceans, and others all appear suddenly, without ancestors, in the Cambrian period.

Second, there is the steady maintenance of the basic body plan of the organism through time. One need only think of the living fossils from paleontology and of bacteria and the Drosophila fruit flies from genetics. The basic body plan does not change whether analyzed through time in the fossil record or through mutations in the laboratory. This conclusion is reinforced by animal and plant breeders through artificial selection. There is much variation, but it can be manipulated only to a limit.

Third, we found that in the few cases where organisms have adapted to new environments, this is predominantly brought about through very ordinary processes utilizing genetic variation that was probably always present in the species. Mutations, when they do play a role, produce defective organisms that survive and thrive only in unusual and unique environments. At best the chances of mutants outcompeting normal or wild-type organisms are minute.

Fourth, we see the apparent inability of mutations to truly contribute to the origin of new structures. The theory of gene duplication in its present form is unsuitable to account for the origin of new genetic information that is a must for any theory of evolutionary mechanism.

Fifth, we observed the amazing complexity and integration of the genetic machinery in every living cell. What we do know of the genetic machinery is impressive; what we have yet to learn staggers the imagination. One's curiosity is aroused as to how mutation, selection, and speciation could ever hope to improve or change the machinery in any substantial way. The cellular machinery poses an even bigger problem. The molecular workings of cilia, electron transport, protein synthesis, cellular targeting, and so many others, are simply astounding.

The sixth and final element involves the big picture. Ecosystems themselves are a marvelous balance of complexity and integration. One can devise schemes of energy flow or biomass flow through an ecosystem as complicated as any biochemical pathway or genetic regulatory scheme. At the center of all this is the wondrous fit of an organism to its own peculiar environment. In the time before Darwin this wondrous fit was the chief evidence of a Supreme Designer.

So, while it is clear that organisms change, there may be a limit to biological change.

The Natural Limits to Biological Change

Has Darwin's theory of natural selection really shown intelligent design in nature to be unreasonable? In view of the failure of evolutionary mechanisms to be convincing, might biological change be a limited affair? Could the limits of biological change arise from the very nature of the genetic code itself, the unique set of structural and regulatory genes present in various groups of organisms and the tight organization and coadapted nature of the entire genome? I believe there are limits to biological change and that these limits are set by the structure and function of the genetic machinery.

Intelligent design is not a new concept. Of course the concept itself, goes back into the previous centuries. Intelligent design, however, is taking on a more sophisticated form. As knowledge of informational codes and information theory grows, the possibility of making predictions of the intricacy of the DNA informational code grow more realistic. If DNA required intelligent preprogramming, the signs should be unmistakable.

The mark of intelligence is not exactly hard to discern. We speak of the genetic code, DNA transcribed into RNA, RNA translated into protein. These are language terms. They are used not just because they are convenient, but because they accurately describe what is going on in the cell. There is a transfer of information. I believe that an application of information theory to the field of genetics will yield a comprehensible theory of limited biological change.

This is wholly reasonable because information theory concerns itself statistically with the essential characteristics of information and how that information is accurately transmitted or communicated. DNA is an informational code, so the connection is readily apparent. The overwhelming conclusion is that information does not and cannot arise spontaneously by mechanistic processes. Intelligence appears to be a necessity in the origin of any informational code, including the genetic code, no matter how much time is given.

More directly though, our concern was with what happens after the code is in place. Could intelligence be required for the first cell but not afterward? To answer that we must look at the informational content of DNA a little more closely. Similar to what happens in language, there are two fundamental principles involved in the expression of genetic information. First, there is a finite set of words that are essentials of content. In organisms, this is comparable to structural genes. Second, the rules of grammar provide for the richness of expression using the finite set of words. In organisms, these rules or programs consist of the regulatory and developmental mechanisms. In human languages, given a finite set of words and a set of rules, the variety of expression goes on and on. It is conceivable, therefore, that different groups of organisms, maybe bats and whales for example, are characterized by different regulatory mechanisms, i.e., different developmental programs.

There is growing interest in a biological theory of intelligent design around the world. While many still vigorously oppose all such ideas, there is a much greater openness than ever before. Philosophers, mathematicians, chemists, engineers, and biologists are willing to suggest, even demand that a more rigorous study of intelligent design in relation to biological organisms be pursued. A renaissance may be around the corner.

Confirming New Data

It was known ten years ago that much of the information for the early stages of development were contained in the cytoplasm or the cell membrane. This has since been rigorously confirmed. There is information, therefore, that is possibly not contained in the nucleus. So our emphasis on the genetic material was a little too strong. There is at least another source of information to consider. This seems to imply that in order to change the body plan changes are required to be coordinated in perhaps two unrelated sources of information in the embryo. This would make a change in the developmental pathway even more difficult to achieve.

Michael Denton's book, Evolution: A Theory in Crisis, revealed that development through the earliest embryonic stages is vastly different in amphibians, reptiles, and mammals. Supposedly similar early structures arise from non-similar structures and pathways in the embryo. This bears witness to our contention that unique developmental pathways would separate the basic types, even when the structures are thought to be homologous.

The complexity of living things continue to astound the imagination. Michael Behe has introduced the term irreducible complexity. Irreducibly complex systems are systems which must have all molecular components present in order to be functional. He used the molecular machinery of cilia as an example. Cilia contain numerous molecular components such as the proteins nexin, dynein, and microtubules that all need to be present if a cilia is to perform at all. Cilia cannot arise step by step.

But perhaps the most gratifying confirmation of our ideas came about recently in the publication of a book edited by J. P. Moreland, The Creation Hypothesis. The chapter on the origin of human language contained this passage on the complexities of the genetic language.

In order for any organism to be what it is, its genetic program, (DNA) must specify what sort of organism it will be and, within surprisingly narrow limits, what specific characteristics it will assume. Such limits, innately determined, apply as much to a human being or to a Rhesus monkey as to a special variety of fruit fly or yeast or bacterium (p. 252).

Later after discussing the cascade of information from DNA to protein they conclude:

The whole cascading network of relationships must be specified within rather narrowly defined limits in order for any organism whatever to be a viable possibility. Moreover, the problem of biogenesis and the origin of human language capacity are linked at their basis by more than just a remarkable analogy. It turns out that the human genome must include the essential characteristics of the entire conceptual system that we find manifested in the great variety of languages and their uses, but within rather narrow limits, by human beings throughout the world (p. 254).

The use of such phrases as "narrowly defined limits" and "great variety" applying to both human languages and the information content of DNA is promising. If languages require intelligent preprogramming, then so does the genetic code.

It is difficult for me to imagine that that honest men and women could study the immense complexities of even the "simplest" creatures and not marvel, or better yet worship, at the feet of their Creator.

©1994 Probe Ministries


About the Author

Dr. Ray BohlinRaymond G. Bohlin is Vice President of Vision Outreach at Probe Ministries. He is a graduate of the University of Illinois (B.S., zoology), North Texas State University (M.S., population genetics), and the University of Texas at Dallas (M.S., Ph.D., molecular biology). He is the co-author of the book The Natural Limits to Biological Change, served as general editor of Creation, Evolution and Modern Science, co-author of Basic Questions on Genetics, Stem Cell Research and Cloning (The BioBasics Series), and has published numerous journal articles. Dr. Bohlin was named a Research Fellow of the Discovery Institute's Center for the Renewal of Science and Culture in 1997, 2000 and 2012.

What is Probe?

Probe Ministries is a non-profit ministry whose mission is to assist the church in renewing the minds of believers with a Christian worldview and to equip the church to engage the world for Christ. Probe fulfills this mission through our Mind Games conferences for youth and adults, our 3-minute daily radio program, and our extensive Web site at www.probe.org.

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