Classification of a Hierarchy — No Ancestral Lines of Connection
Questions:
- Do all of life's creatures fit today's commonly used classification system?
- Are there clues to refining biological classification by looking at the way organisms appear over time and the way in which their characteristics make unique groups?
- Might there be an alternate approach where organisms are classified by types? (the term 'type' is described below)
- If not by a branching tree, what else organizes the hierarchy of life forms (microbes, plants, animals)?
Short Answer:
A quite different type of classification system is termed hierarchic, in which there are no overlapping or partially inclusive classes, but only classes inclusive or exclusive of other classes. Such schemes exhibit, therefore, an orderly "groups within groups" arrangement in which class boundaries are distinct and the divisions in the system increase in a systematic manner as the hierarchy is ascended. The absence of any overlapping classes implies the absence of any sort of natural sequential relationships among the objects grouped by the scheme. Denton (ETC) Page 119
There is more than one way to organize a classification for the diversity of life. The typical [taxonomic] approach may in fact be inappropriate. A branching tree diagram is commonly used to represent the appearance of organisms over time. But problems arise where there is no evidence to make the branches! There is little evidence clearly supporting transitions implied by the branches. This calls into question the production of unique phyla by gradual change and development over time (see: Cambrian explosion, fossils, and macroevolution).
If life's origin requires careful review, as noted elsewhere (see: fossils, lineage, macroevolution, microevolution), then life's classification scheme requires review.
What alternatives are there to the branching tree? To consider another perspective, we first offer the illustration below. Note how the tree diagram uses dashed lines as 'branches' to link solid lines. The dashed lines are associations placed between known species or phyla that have existed over time. This is one approach based on macroevolution and the idea of life's descent from a common ancestor.
The dashed lines (see diagram below) represent a special case for (presumed) jumps in appearances (the term for this is 'punctuated evolution'). The reason for such a diagram began when biologists found no clear evidence for intermediate life forms that would make the dashed lines into solid branches (such a branching pattern leads to the tree illustrations like the one below). So, there are no intermediate forms here, just a presumed association between lines of life forms.
If one removes the dashed lines and then projects the lines upward onto another plane, we then get a 'map' that plots life forms in a more hierarchical fashion. (This is illustrated in the top part of the diagram above) The result is a polyphyletic diagram in that each larger group is a phyla that may contain one or more groups within, but there is no tracing back in time to a presumed common ancestor (as implied by the tree illustrated here). The groups here are all associated by similar common characteristics.
Let's look at this from another perspective. The data clearly show multiple phyla come along at various points in time (i.e., polyphyletic origin; not requiring a common ancestor). Each phyla may show some differentiation over time, within limits, including new species arising within, but each phyla does not go beyond the 'rectangle' that uniquely describes its group within the overall hierarchy.
To be sure, there are other technical ways to describe what is summarized in this Short Answer. And we know alternatives to macroevolution run contrary to naturalism. The point is that until other perspectives are examined, we have limited room to consider anything other than assumptions applied to evolution theory. By digging into the hierarchical view, we become critical thinkers. Once an alternative clicks into place, you'll have added a new perspective to your view.
The issue for now is that no clear classification scheme is universally agreed upon. To many scientists, that's a revolutionary idea! And that alone is a telling fact. But moreover, the objections as to why the tree diagram does not hold true makes for a most interesting study. And the following section illustrates why!
Consider This:
As noted previously without the linking branches of the 'tree of life,' a tree diagram fails to capture the hierarchy> that life forms exhibit. Life's historical and present evidence reveals separate distinct groups of organisms. Yes, species do evolve and evidence for changes at the species level can be documented, but at levels above this a "typological model holds almost universally." (Denton (ETC) Page 105)
And as far as the individual defining characteristics are concerned, one could continue citing almost ad infinitum complex defining characteristics of particular classes or organisms which are without analogy or precedent in any other part of the living kingdom and are not led up to in any way through a series of transitional structures. Denton (ETC) Page 107
This statement alone effectively dismisses the tree illustration. This separates branches from the tree. By Darwin's time, the study of anatomy was nearly complete and to that point provided adequate information to consider life as organized into groups within groups (as illustrated above in the line diagram) and further that: "The scheme expresses succinctly the pre-evolutionary belief that nature's order was fundamentally non-sequential."(Denton (ETC) Page 124)
Remember, if evolution is an unfolding of a sequence, then a common ancestral life form would logically reside at the base of the tree. But what one sees is not a best fit with organisms developing new organisms in such a manner. The concept of a sequence is an assumption. Seeing that one does not have to fit life to a sequence opens new avenues of thinking.
Even today zoologists find it impossible to relate the major groups of organisms in any sort of lineal or sequential arrangement. Denton (ETC) Page 125
[ For Further Study Note: Dr. Denton follows the statement quoted above with four illustrations of evolutionary trees that place groups in very different positions. (See Denton (ETC) pages 126-127) To get the full benefit of broadening the view on how one might illustrate relationships between life forms, we encourage your personal study of these illustrations. ]
TYPES, TYPOLOGY, HIERARCHY
Keeping in mind the diagram above, here are a few words that provide another perspective on the relationships between life forms ...
A quite different type of classification system is termed hierarchic, ... an orderly "groups within groups" arrangement in which class boundaries are distinct and the divisions in the system increase in a systematic manner as the hierarchy is ascended. The absence of any overlapping classes implies the absence of any sort of natural sequential relationships among the objects grouped by the scheme. Denton (ETC) Page 119 (See sidebar above for longer quotation)
The absence of sequences moves us to consider the term 'typology' ... which recognizes organisms reveal 'types' which in turn are unique to their grouping. A 'fixity' within a type could explain why living fossil species remain so much like their ancient predecessors (i.e., fixity meaning "stay the same over time;" see examples in fossil article). Evolution theory does not explain how these separate types arose, nor to explain the origin of unique characteristics that do not fit the concept of a common ancestor.
If the hierarchy suggests any model of nature it is typology and not evolution. How much easier it would be to argue that the case for evolution if all nature's divisions were blurred and indistinct, if the systema naturae was largely made up of overlapping classes indicative of sequence and continuity. Denton (ETC) Page 137
Blurred here implies an array of forms with all the intermediate stages indicating how an ancient form lead, stepwise, to a modern form (phyla to phyla). Why is this blurring not evident today? The presence of types seems more evident than a 'blur' of forms, that before our eyes today, would confirm evolution theory! But it's not there!
In other words, if there was a fuzzy connection with intermediate forms making a tell tale trail, then a tree of life would be an ideal illustration. But given the evidence as it is, unbranched lines of life forms ascend (geological) time to the present (see diagram below). Types don't always fit a tree because some of their traits appear in a presumed lineage that the traits themselves do not fit. So, why did biologists [taxonomists] place them there? Furthermore, these lines arise at various points in time, but all lines stand relatively independent of one another. This point is illustrated below in simplest terms (time plotted versus variation in types).
The
vertical lines represent separate body plans. That
is, each plan is like a design platform with a common
set of core features. These features persist over
time even with and through development of species
from the core body type.
Restated, in other words, body plans that are distinct—species
spin off from these basic plans—but the framework
remains uniquely isolated and unlinked.
OTHERS WHO RECOGNIZED THE TYPOLOGICAL MODEL
The
idea behind types is not new. Types, clades (see definition below), or other
concepts have merit. They broaden the discussion and tell us why some scientists
have been compelled by the data to move beyond basic assumptions ascribed
to evolution theory.>
The
following quotations really ask why have we been
in a rut!
Agassiz, in common with the great majority of leading biologists in the nineteenth century, adhered to a philosophy of nature referred> to as typological which was completely antithetical to the concept of organic evolution and which denied absolutely the existence of any sort of sequential order to the pattern of nature.
According to the typological model of nature all the variation exhibited by the individual members of a particular class was merely variation on an underlying theme or design which was fundamentally invariant and immutable. Each individual member of a class conformed absolutely in all the essential details to the theme or archetype of its Class.
... all the members of any defined class are equidistant from the members of other classes as well as being equirepresentative of the archetype of their class. Denton (ETC) Page 94>
We can only speculate about the motives that led scientists to accept the concept of common ancestry so uncritically. The triumph of Darwinism clearly contributed to a rise in the prestige of professional scientists, and of the idea of automatic progress so fit the spirit of the age that the theory even attracted a surprising amount of support from religious leaders. In any case, scientists did accept the theory before it was rigorously tested, and thereafter used all their authority to convince the public that a naturalistic processes are sufficient to produce a human from a bacterium, and a bacterium from a mix of chemicals. Evolutionary science became the search for confirming evidence, and the explaining away of negative evidence. Johnson (DOT) Page 152
Again, remove the tree's branches and we are left with the occurrence of unique, equidistant, basic body plans. The body plan maintains a set of common features that hold within the group over time. To that core plan can be added features or variations to make unique species. But the core plan stays steady over time. A clade is another term used in relation to hierarchic patterns.
clade n. A group of organisms, such as a species, whose members share homologous features derived from a common ancestor. [From Greek klados, branch.] (American Heritage Dictionary, 1994)
One clade can be compared relative to traits, features, or characteristics exhibited by other clades (such examination is referred to below as a cladastic procedure):
Like many other approaches to classification, yet again, cladastic procedures invariably result in strikingly hierarchic patterns.
... it is significant that since the time of Aristotle the living world has been generally perceived by taxonamists as conforming to a highly ordered hierarchical system of clearly differentiated classes.
... as biological knowledge has grown, the tendency to perceive nature's order in terms of orderly hierarchic systems of clearly defined classes has grown increasingly intense. Denton (ETC) Page 131
Again, the concept here is groups are separated by "stand alone" sets of characteristics.
The hierarchy has a structure, not like a tree, but illustrated by groups.
By its very nature a cladogram draws attention to the fact that all the species grouped in under> one node possess to the same degree those unique defining characters of their class, so that they are all equally representative of their class and a equidistant from all other organisms in terms of these fundamental characteristics. Denton (ETC) Page 137
There is no longer any need to read between the lines to see a form of typology re-emerging in the thinking of many leading zoologists taxonomists today. Denton (ETC) Page 138
So, if at the root of each phyla or type there is a unique body plan with nothing leading to that plan, then we have evidence for a unique appearance. When would the separate body plans emerge? Do we have any examples? There are in fact examples! The fossil record is witness to sudden appearances of life forms at a number of points in geologic time. The Cambrian explosion is one such example.
SUDDEN APPEARANCES MAKES GROUPS SEPARATE
The Cambrian explosion is getting serious attention due to new data from China. Dr. Denton wrote the following words some time before the recent work. The fossil finds in China strengthen Denton's commentary:
Curiously, the problem is compounded by the fact that the earliest representatives of most of the major invertebrate phyla appear in the fossil record over a relatively short space of geological time, about six hundred million years ago in the Cambrian era. The strata lain down over the hundreds of millions of years before the Cambrian era, which might have contained the connecting links between the major phyla, are almost completely empty of animal fossils. If transitional types between the major phyla ever existed then it is in these pre-Cambrian strata that their fossils should be found. Denton (ETC) Page 163
Meyer and coworkers look at all this from an informational point of view. Where does the information come from? It's a big jump in biological information to fill the gaps noted here:
Quoting Simpson:
"but the appearance of a new genus in the record is usually more abrupt than the appearance of a new species; the gaps involved are generally larger, that is, when a new genus appears in the record it is usually well separated morphologically from the most nearly similar other known genera. This phenomenon becomes more universal and more intense as the hierarchy of categories is ascended. Gaps among known species are sporadic and often small. Gaps among known orders, classes, and phyla are systematic and almost always large. Denton (ETC) Page 165
[Simpson, G. G. (1960) "The History of Life," in The Evolution of Life, ed Sol Tax, University of Chicago Press, Chicago, p 149.]
With respect to huge jumps in information and diagrams that illustrate points made by Meyer, et al., we refer you to our brief article on the Cambrian overview.
Polyphyletic versus monophyletic origin of basic types
All basic types are thought to share a common ancestor that is more primitive than its descendants. Accordingly specific biological data available should fit mechanistic evolutionary models in and should demonstrate transitions between fossil groups of forms that may be considered as basic types.
Alternatively basic types might have originated by design. If this assumption shall be taken seriously, biological data must make sense when interpreted within a such an idea. Furthermore, predictions must be derivable from such a hypothesis, which can be tested by further experimental work.
Basic type biology implies a polyphyletic origin in the sense that each basic type originated, phylogeneticly, independent from other basic types.
I submit that basic type biology helps to define microevolution and macroevolution more clearly, providing a test for the macroevolution concept. Scherer (MC) Page 201
Microevolution:
variation within basic types. [Scherer (MC) Page 201]
... Generally it is acknowledged that taxonomical hypotheses below the family level are most controversial. Furthermore, speciation is a known phenomenon. Since the genomes of the species within the basic type must be very similar in terms of the regulation of morphogenetic processes, we tentatively suggest that the processes of variation observed within basic types may be termed microevolution.
Macroevolution: Descent of different basic types from a common ancestor.
I submit that the term macroevolution be used to describe the formation of different basic types descending from a common ancestor. In contrast I suggest using the term microevolution for processes leading to the formation of species and genera within a basic type. It is postulated that species belonging to the same basic type form a monophyletic group.
Macroevolution at the molecular level.
My conclusion is that no molecular mechanisms accountable for macroevolutionary processes are known.
Polyvalent ancestral populations?
Evolutionary biology usually assumes that this ancestral population was more primitive than the species that descended from it. In other words, the direction of evolution is from a more primitive state to a more complex state. Scherer (MC) Page 202
When the results of the different basic types analyzed in Scherer (1993) are reviewed, some common features emerged that are found across the different groups of animals and plants. For this purpose we need to change levels and get back to the realm of real biology.
A related observation concerns species within basic types that are impossible to classify. ...these species are termed aberrant types, displaying a mosaic of characters ...
A large number of such problematic species or genera are known. Scherer (MC) Page 203
This does not mean that all characters of extant species were expressed in the ancestral population but that the genetic potential for such variation was hidden in the ancestral polyvalent gene pool.
... obviously the genetic balance of a species that results in a continuous expression of species-specific features becomes disturbed upon hybridization, revealing an astonishing potential for variability.
It is found throughout the basic types described so far (Scherer 1993c) that it seems impossible to construct a phylogenetic tree of all members of a particular basic type without numerous contradictions. Different characters yield different phylogenetic trees; ...
In the latter basic type, primitive characters are found regularly together with advanced characters (heterbathmy). However, there is no objective way to know which character is ancestral and which one is derived. Any such decisions are usually disputed. Characters therefore seem to form a network rather than a tree when species of a basic type are compared.
The evolution of different species from complex ancestors would scatter different characters and character combinations throughout the descendant species, the process being influenced by, for example, size of the descendant populations, migration pattern of populations, chance effects and the action of selective forces on random character combinations. Such a process might explain the network of characters without involving unknown as selective pressures. Scherer (MC) Page 204
Speciation itself would therefore appear to support the concept of ancestral populations with a large hidden potential for variation. Scherer (MC) Page 205
Interpretation of the fossil record
Is it possible that generally no fossil links can be demonstrated that would unequivocally connect two clearly delineated basic types? However, paleontological data have yet to be related to basic type taxonomy.
Basic type biology predicts that major discontinuities between basic types will continue to emerge at different levels of comparative biology. Scherer (MC) Page 205
Evidence for design?
What is evidence for design? ...
Walter ReMine (1993) suggested that biological data may be understood with respect to the message a hypothetical designer wanted to transmit via life. He submitted that the system of life was constructed to make it clear that life originated from a single source. The hypothesis that all life forms come from a single source is convincingly demonstrated by the overall similarity of life at all biological levels. Evolutionary biology uses these data to support a monophyletic history of life. Similarity, however, may likewise be used as an argument in favor of a single designer. It is not possible, using empirical arguments, to decide these two worldviews. Overall similarity of life forms as such can therefore not be used as a final evidence for design or for evolution but can be interpreted within both frameworks.
Much more provocative is the idea of ReMine that the very peculiar pattern of diversity underlying life was designed to send the message that it did not result from a naturalistic process.
How could basic type biology contribute to the discussion that a message is transmitted by organisms?
Polyvalent ancestors?
If the species and general constituting a basic type descended from a polyvalent ancestral population, the existence of such ancestral populations is very unexpected and their origin difficult to explain within an evolutionary framework. A polyvalent (complex) ancestral population would, however, fit into a theory of design. Scherer (MC) Page 205
Gaps between basic types
If it can be demonstrated that the existence of gaps between basic types is a general feature of extant life forms, such a feature would seem to be quite unexpected and difficult to explain within an evolutionary framework. It would, however, fit into a theory of design. The fossil record has to be analyzed accordingly.
Evolution of features of ancestral population of basic types
For ancestral populations of basic types to originate, the evolution of biochemical pathways, cellular structures and morphogenetic programs (i.e., macroevolution) must have happened. It is my assertion that no evolutionary mechanisms have been found so far that could have led to the evolution of such traits. It is a prediction of a theory of design that such mechanisms will not be found in the future.
Convergent characters between basic types
Between basic types there are not only differences but also a very peculiar pattern of similarity (conflicting characters) that is not easily predicted by evolutionary theory. This very common pattern of conflicting characters is usually interpreted to be due to convergent evolution. It is one of the most severe problems that renders the construction of unequivocal phylogenetic trees very difficult. Numerous examples could be given. Conflicting character distribution superimposes a networklike similarity over the nested-hierarchy similarity (treelike pattern) that is predicted by evolutionary theory. Scherer (MC) Page 206
[See example of bacteriophage given on page 206 ]
Odd molecular features of life
What is an odd feature of life?
The universal genetic code has been used as a major, very convincing argument for the monophyletic origin of life. The argument reads as follows: Once the genetic code has been established, each evolutionary diversion from that code would have changed the sequence of all proteins encoded by the genome, carrying the triplet that has been changed. However, an increasing number of slightly deviating genetic codes has been reported (Osawa et al. 1992) not only in mitochondria but also in the nucleus from different organisms. According to evolutionary theory, these different codes must have originated from the primary code independently. Again, it cannot be predicted through evolutionary theory why this should have happened or, more important, how this could have happened even once, not to speak from independent lines of origin. Scherer (MC) Page 207
... another odd feature that has been reported for different organisms. In a few cases, genes overlapping in different reading frames were reported.
It was suggested by evolutionists that a selection pressure due to space limitation on plasmids and phage genomes have led to the evolution of these structures. However, most bacteriophage having genomes of a similar size do not show this features, surviving as well as the phage carrying the overlapping genes. Second, the modeling of an evolutionary origin of completely overlapping genes through a series of selectable intermediates seems to be exceedingly difficult and has not yet been reported.
Conclusion
Basic type classification applies to both animals and plants. This classification could comprise three main lower categories: the biospecies concept as a means to describe biodynamical processes, that is, speciation (comprising individuals genetically related through participation in the same gene pool); the genus category as a means to describe overall similarity (comprising morphologically related forms); and the basic type category as a means to describe monophyletic though potentially heterogeneous groups (comprising morphogenetically related forms).
The author then describes a procedure for delineating a basic type ...
It is now necessary to test the basic type concept with as many animal and plant groups as possible. The results of well so far (Scherer 1993c) seem to be encouraging. ... However, further work could also demonstrate that the basic type criterion submitted here will not hold up when it is put to the test of practicing taxonamists.
Basic type biology or something equivalent to this approach will be a prerequisite to develop a theory of design that also accommodates the endless number of observations of microevolutionary processes. If basic type biology turns out to withstand the test of time, it will provide a framework for interpreting a variety of biological observations such as gaps between basic types, character distribution between the species within a basic type, character distribution between species of different basic types and the interpretation of seemingly odd features of life. Scherer (MC) Page 208
Added Perspective:
You are reading one in a series of articles in WindowView's Science Area. The Science Area's plain language narrative provides an overview on life's origins and special qualities that speak to our being here more by design and not by chance. Build a broad field of view by taking in a number of different perspectives—all from within the articles appearing here.
With this information you will gain insights and interesting supporting evidence for the unique experience called life!If not by chance, then by purpose. Once you see life has a special quality to it, then move on to the rest of the window's view to gather in purpose and find a reasonable means to anticipating what is ahead of us in the future.
Quotations from Dr. Michael Denton's "Evolution: A Theory in Crisis" are used by permission of Adler and Adler Publishers Inc., 5530 Wisconsin Ave, Suite 1460, Chevy Chase, MD 20815>
Quotations from "Mere Creation" (MC) edited by William A. Dembski are used by permission of InterVarsity Press, P.O. Box 1400, Downers Grove, IL 60515. www.ivpress.com All rights reserved. No portion of this material may be used without permission from InterVarsity Press.
Writer / Editor: Dr. T. Peterson, Director,
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