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Evolution Basics: The Cambrian Diversification and Assembling Animal Body Plans, Part 2

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September 13, 2013 Tags: Genetics, History of Life
Evolution Basics: The Cambrian Diversification and Assembling Animal Body Plans, Part 2

Today's entry was written by Dennis Venema. You can read more about what we believe here.

Note: This series of posts is intended as a basic introduction to the science of evolution for non-specialists. You can see the introduction to this series here. In this post we introduce the concepts of “crown groups” and “stem groups” and apply them to Cambrian fauna to reveal the stages that the arthropod lineage progressed through to reach the modern arthropod “body plan”.

In our last post, we introduced the concept that what we define in the present day as a “body plan” or “shared suite of characteristics of a monophyletic group” in fact presents a challenge for classifying organisms from the deep past. The reason, as we discussed, is that any modern-day suite of characteristics is not expected to have arisen all at once, but rather in a step-by-step, piecemeal fashion.

Let’s return to our discussion of arthropods to see how biologists handle this challenge in the face of real data. The general approach is to start with the characteristics of a monophyletic group of species that has at least two species (or more) represented in the present day. These species, their common ancestral species, and all descendants of that common ancestral species form what is known as a “crown group” on a phylogeny (often abbreviated as a triangle to represent numerous species). Accordingly, we can define “crown group” arthropods as the last common ancestral population of all living arthropod species and all of their descendant species (living or not). Other extinct groups that have some, but not all, of the characteristics of the crown group are then classified as “stem group” species:

Velvet worms are living relatives to arthropods that live in tropical
areas and temperate regions of the southern hemisphere. Although
segmented, they lack the specialized appendages and segments
characteristic of crown-group arthropods. (Image source)

The question then arises: is a “stem group” arthropod really an arthropod? Yes and no – such species are not a crown group arthropod, since they do not possess all of the characteristics that define modern-day arthropods (and their common ancestral population, and its descendants). However, they are more closely related to crown-group arthropods than to any other monophyletic group with living representatives, and they possess at least some of the characteristics of the crown group. As such they are arthropods in a sense, but better described as “stem group” species.

Let’s expand this example to include another crown group – velvet worms (Onychophora). Velvet worms share some features in common with arthropods (such as appendages and segmentation) but not others (for example, they lack the complex specialization of segments seen in arthropods).

Phylogenic analyses (using comparative morphology, the fossil record, and DNA sequencing) consistently place velvet worms as a close relative of arthropods. Since velvet worms have living species, we can define a crown group for them as well (as before, the last common ancestral population for all living velvet worm species, and all of its descendant species). As for arthropods, as we look back in the fossil record, we see some extinct species that have some, but not all, of the defining features of crown-group velvet worms. Accordingly, we can place these species on the “stem” of the velvet worm lineage:

What should be obvious from this phylogeny is that the distinction between a stem-group arthropod and a stem-group onychophoran will become blurred as the two lineages converge (moving from the present day backwards towards their common ancestral population). Species that we find in the fossil record can be assigned as a stem to either lineage based on their suite of characteristics, and whether they show closer relatedness to the arthropod or onychophoran lineage.

Stem-group arthropods in the Cambrian 

With this understanding in hand, we can now turn to actual species that we observe in the Cambrian fossil record as examples of stem-group arthropods. One well-known, large Cambrian predator is Anomalocaris (literally, “abnormal shrimp”). Anomalocaris has a number of features that are clearly shared with crown-group arthropods, such as large compound eyes, specialized jointed appendages, specialized segmentation, and other features. What it lacks, however, is a hardened exoskeleton over its entire body (it has hardened appendages only). This suite of characteristics places it as a close relative to crown group arthropods (e.g. we would place Anomalocaris at the “X1” position in the phylogeny above), and also provides information about the state of characteristics present at the time that the lineage leading to Anomalocaris branched away from the lineage leading to crown group arthropods (i.e. that a fully hardened exoskeleton was one of the last characteristics that the ancestral population leading to crown-group arthropods acquired).

Other species in the Cambrian show even fewer characteristics of crown-group arthropods, but yet still exhibit at least some features in common. The bizarre group of species known as Hallucigenia is an example.  Features that Hallucigenia share in common with common with crown-group arthropods are specialized appendages and specialized segmentation – but other features, such as a hardened exoskeleton (on either appendages or the body as a whole), are absent. In other words, these species are stem arthropods that are more like what we would expect of stem onychophorans.

Building body plans, step by step

Taken together, we can summarize these findings as follows:

What we observe as the emergence of a new taxonomic unit (“phylum,” “family,” “genus,” and so on) is somewhat arbitrary (since it in actuality describes a continuum) and in fact is decided only in hindsight, based on the characteristics of monophyletic groups in the present day.

For better or for worse, taxonomy has been trying to shoehorn ancient species into modern categories. The fact that ancient species blur the distinctions between modern day taxonomic groups (such as arthropods and onychophorans) shows that what we recognize as large taxonomic groups (such as what we call “phyla”) are in fact best described as monophyletic groups in nested sets.

The fossil record supports the gradual acquisition of the characteristics we see in modern groups and subsequently use for classification.

The key defining features of arthropods (specialized segmentation, specialized appendages, hard exoskeletons, compound eyes, and a host of other characteristics) do not appear all at once in any one species in the fossil record. To say that “arthropods” arise and diversify in the Cambrian is not to say that fully-fledged (i.e. crown-group) arthropods appear suddenly out of nowhere. Rather, we see a range of species that demonstrate that the defining characteristics of crown-group arthropods were acquired over a long period of time. While stem-group species are not likely to be direct ancestors of crown-group species, their presence in the fossil record (and the nested hierarchy their characteristics produce) provides a means to determine the order in which the defining characteristics were assembled.

The Cambrian, though “explosive,” should not be misunderstood to be instantaneously producing crown-group species.

There is no doubt that the Cambrian “explosion”, was a spectacular diversification event – but it did not produce species with fully modern character sets instantaneously. Rather, we see a diversification of stem-group organisms, the sequential and serial addition of characteristics in some lineages over time (with the loss of other lineages), and the eventual production of character sets in successful monophyletic groups that we retrospectively recognize as taxonomic groupings.

In the next post in this series, we’ll examine the Cambrian origins of the lineage that eventually led to humans – the vertebrates.

For further reading

Budd, G.E. (2008). The earliest fossil record of the animals and its significance Phil. Trans. R. Soc. B  363, doi: 10.1098/rstb.2007.2232

Budd, G.E. and Telford, M.J. (2009). The origin and evolution of arthropods. Nature 457, 812-817 doi:10.1038/nature07890


Dennis Venema is professor of biology at Trinity Western University in Langley, British Columbia. He holds a B.Sc. (with Honors) from the University of British Columbia (1996), and received his Ph.D. from the University of British Columbia in 2003. His research is focused on the genetics of pattern formation and signaling using the common fruit fly Drosophila melanogaster as a model organism. Dennis is a gifted thinker and writer on matters of science and faith, but also an award-winning biology teacher—he won the 2008 College Biology Teaching Award from the National Association of Biology Teachers. He and his family enjoy numerous outdoor activities that the Canadian Pacific coast region has to offer. Dennis writes regularly for the BioLogos Forum about the biological evidence for evolution.

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Roger A. Sawtelle - #82602

September 13th 2013


If you want to understand a specific species, then you must look at the environment in which it lives.  Taxonomy does not take into account ecology.  It tells how life forms developed, not why they developed.  It is linear, one dimensional, and thus incomplete.

Arthropods developed in the Cambrian Age because the Cambrian environment was favorable to this form of life.  Cambrian arthropods were different from modern arthropods because the environment today is different.

When science leaves out the ecological dimension of evolution, we have an interesting “tree of life,” but not the context which makes it comprehensible.  That is the problem science has now.     

Please help me save science from itself.

Terrance - #82603

September 13th 2013

New paper in Cell, Rates of Phenotypic and Genomic Evolution during the Cambrian Explosion -  http://www.cell.com/current-biology/fulltext/S0960-9822(13)00916-0

Roger A. Sawtelle - #82608

September 13th 2013


Thank you for the heads up.  I had to dig some to find it, but it was there.

From my standpoint it does not say much according to the summary, just statistical models which say that evolution took place but not how or why.   

Maybe you have a different interpretation.


Paul Lucas - #82617

September 15th 2013

Roger, with respect, I think you overlook the problem the posts on the Cambrian Diversification (often called “Explosion”) is trying to address:  how the various phylum (higher taxa) all appear in the fossil record within a limited amount of time (geologically speaking).  Creationists often use this as evidence of direct creation.

Dennis here is making the argument that the traits associated with a particular “phylum” do not all appear at once.  It doesn’t matter what the ecology is for this argument. 

Another way to look at this is what “higher taxa” really are.  They are simply groups of species.  The only biological reality is species.  Genus, family, order, class, and phylum are simply groups of species.  The Cambrian was the first (or perhaps second) of the major radiations following a mass extinction.  Because it happened so early, the result was new “phyla”.  Notice that the radiation in mammals after the KT extinction resulted in lots of new orders of mammals, but the class of mammals already existed, so no new phyla.

When you look at the number of species within many of the extinct phyla of the Cambrian, you find that they have 1-5 species each.  They are “phyla” because they left no descendents and therefore we can’t put them in today’s “lower” taxa of genus, family, etc.  It’s an artifact of the classification system.  Basically, the Cambrian is a radiation that produced many new species as populations evolved into new ecological niches.

Why were there new ecological niches?  There are many reasons:
1.Increased oxygen levels (which allowed for shells, which fossilize better).
2. The extinction of the Eidacaran animals.

That last is probably the most important.  The increased oxygen levels and the evolution of hard body parts means we have an artifact of a better preservation of the diversity of life at the Cambrian.  The Burgess Shales show a huge number of diverse species (all soft bodied) in the geological period prior to the Cambrian, but they are gone.  That’s a major extinction, which leaves open lots of ecological niches (just like the KT extinction left open a large number of ecological niches).  And therefore we see the Cambrian Diversification.

Yes, ecology plays a huge role in evolution.  Natural selection designs organisms to make a living.  Different ecologies require different designs, so you see evolution modifying populations to fit the ecologies.  Yes, there were ecologies that were favorable to arthropods in the Cambrian.  But here we get into the contingent nature of evolution.  For instance, to go from the multiple legs of centipedes and millipedes to the 6 legs of insects involves the change in a single basein a single gene: the Ubx gene.  Change that one base and you change a single amino acid from a serine to an alanine and you convert a millipede to a 6 legged animal.  And thus, the basic “body plan” of an insect depends on that particular mutation: 


Thus, although arthropods did well in the ecologies of the Cambrian, it is contingent variations that gave rise to the morphology.

Roger A. Sawtelle - #82625

September 15th 2013


Thank you for your comments.

This is the latest in a series of comments I have made concerning the role of ecology in evolution. 

“Yes, ecology plays a huge role in evolution.”  I am glad that we are in agreement.  This is the type of astatewment I was seeking from Dennis.    

 “Natural selection designs organisms to make a living.”  However here we are in disagreement.  I agree with Darwin that Variation creates new alleles, while Natural Selection determines which alleles will survives and prosper. 

Where I disagree with Darwin and certainly Darwinists is not in the fact of Natural Selection, but how it works.  I maintain with you that changes in the ecology, which are multifaceted, creates opportunites for new life forms, such as insects, as well as puts limits on older life forms, such as arthropods. 

Natural Selection selects those Variations which are better adapted to emerging ecologies.  Thus the Ecology through Natural Selection drives Evolutionary change more than genetic Variation, although both are necessary aspects of the process.  

You point to the continguent nature of evolution in that it is necessary to have the right gene in the right place at the right time and in the right circumstances.  That is correct. 

Now if you think that these specific events happen strictly by random chance, I have a beautiful bridge that I can sell you for a great price.  The fact that the change from many legs to six legs is created by one basic change suggests a plan, rather than random development that Darwin forsaw. 

To set up the false dichotomy of evolution or creationism distorts the discussion, which must be co0ncerning how does evolutionary change take place, not how to prove or disprove some ideology about evolution.          

Paul Lucas - #82632

September 16th 2013

Roger, what you are doing is trying to separate the parts of natural selection and then arguing about which is more important.  You can’t separate the parts.  Natural selection requires both.  If there are no variations, then there is nothing to select, is there?  OTOH, without the selection, then all the variations remain in the population and change is purely chance.  Genetic drift is variation without selection.

That combination of variation + selection = design.  Darwininian selection is an algorithm to get design.  In fact, I will submit to you that Darwinian selection is the only way to get design.  When human beings design, they do so by Darwinian selection.  It’s just that much of the variation and selection occurs in the mind before any of it is translated into material objects.

The environment (which is a more precise and accurate term than “ecology”) sets up the design problem.  Natural selection then produces the design to solve that problem.

Roger: “You point to the continguent nature of evolution in that it is necessary to have the right gene in the right place at the right time and in the right circumstances.  That is correct. ”

Not exactly.  Instead, the contingent nature is that there are often several different designs that will work.  The contingent nature is that only one or a small subset of those designs are presented in the variations.  For instance, there are several ways for a bacterium to be resistant to penicillin:  an enzyme to degrade penicillin, a modified target so that penicillin does not bind to it, a membrane pump that pumps the penicillin outside the bacterium, etc.  The contingent nature is which one of those will arise.

“Now if you think that these specific events happen strictly by random chance, I have a beautiful bridge that I can sell you for a great price.   The fact that the change from many legs to six legs is created by one basic change suggests a plan, rather than random development that Darwin forsaw. ”

???  How does that suggest a plan?  There are several Serines and threonines in that area of the Ubx gene.  Any of them can be changed by mutation.  But only one of them causes the change from millipede to 6 legs.   Instead, it suggests many possible variations and it turns out this particular variation is useful, whereas the rest leave the animal the way it was.  There is no suggestion that God planned for 6 legged animals because there is no suggestion that God directly manufactured the Ubx gene in the first place.  There are many other forms of that gene that would still code for multilimbed creatures but not offer the chance to become 6 legged.

“To set up the false dichotomy of evolution or creationism distorts the discussion”

Creationism is a specific scientific theory.  It is a specific mechanism of how God creates.  Evolution is also a scientific theory and a different specific mechanism of how God creates.  So, yes, creationism and evolution are competing theories.  As it turns out, creationism is wrong.

Now, creation and evolution are not mutually exclusive.  To quote a prominent 19th century American theologian—Rev. James McCosh—“Christians should look on evolution simply as the method by which God works.” The Religious Aspects of Evolution, 2d ed. 1890, pg 68. (the book is back in print, you might want to get a copy)

Where you and I disagree is that we can look in evolution and find “proof” of God.  It appears to me that you are still looking at some type of “gap” within evolution so you can say “God has to work here”.  That seems to be what you tried to do with the Ubx gene and saying it indicates a “plan”.  I maintain that evolution, like the rest of science, is agnostic.  It permits God but doesn’t “prove” God.  Our evidence, as Christians, for the existence of God comes from outside science.  That evidence is supposed to be our personal relationship with God/Jesus.  Science is a poor and inadequate substitute for that evidence.

Roger A. Sawtelle - #82636

September 16th 2013


In my view evolution is not a theory, but a natural process, just as gravity is not a theory proposed by Isaac Newton.  Darwin suggested that his theory would some day be accepted as was Newton’s theory. 

What he did not forsee was that Nawton’s theory would be supplanted by Einstein’s theory.  In a sense he also did not anticipate the fact that natural physical sceinces are different from the biosciences. 

Science has become wedded to the idea that evolution = Darwinism that it confuses the theory with the naturaql process behind it.  Science tries to reduce evolution inot a simple physcial, process but living creatures are not non-living things, so it doesn’t really work.

I can agree that variation + selection = design.  However that does not mean that selection designs as you said.  If there is design, then human logic says there must be a designer because that is the way the world works. 

When human beings design, they do so by Darwinian selection. Please explain.  Does this mean that when God designs he uses Malthusian population theory?

You said before thaqt ecology plays a huge role in evolution, but here you do not even mention its role.

I am not making a gap for God, but to point out that this is very sophisicated system that cannot be reasonably thought to have occured by random chance.  God does not have to work in the gaps because God designed and works through the whole process just as Rev. McCosh said more than 100 years ago.!     

Creationists believe that God designed creatures individually.  ID says nature is too stupid to design the intricasies of life.  I think that God through the Logos can and did design nature to create even intelligent creatures like human beings.

Science does not permit or prove God.  It does not contradict the reality of God, while pointing to God’s existence.  In reality it assumes the fact of God, that is that the universe is a cosmos, not a chaos.

Ecology is a relatively new science which has displaced evolution.  [My dictionary ways the ecology and environment can be used interchangably.  Environment lacks the dynamic meaning of ecology.]  Religion is not only institution which is slow to change.                           

Paul Lucas - #82659

September 20th 2013

Roger, let’s start with that design and designer.  Before Darwin discovered Darwinian selection, the only way people knew to get design was by an intelligent agency: humans.  Thus “design” acquired an unspoken prepositional phrase: “by an intelligent agent”.  So when people said “design”, that phrase “by an intelligent agent” was always there.  But Darwinian selection is an unintelligent process that gives design.  So you can no longer use the word “designer” to mean “an intelligent agent”.  Yes, perhaps “ If there is design, then human logic says there must be a designer”, but that “designer” no longer has to be an intelligent being.  The “designer” can be Darwinian selection.

Now, the reason I keep using “Darwinian selection” is because it is a two-step process.
1. Variation
2. Selection

You can’t separate the 2 and just say  ” that does not mean that selection designs as you said.”  You have to go back to when you said “I can agree that variation + selection = design”  Once you say that, then any statement that “human logic says there must be a designer” as in an intelligent being is null and void.  You can’t have it both ways.

When humans design we generate lots of variations in our mind.  We then select those variations against the environment that is what we want to achieve, whether that be this sentence I’m writing, cars, a new type of pliers, etc.  Most of the variations disappear.  We then manufacture those variations which pass selection.  We keep selecting, as we see engineers make modifications (variations) to car models each year, as I have been erasing and retyping parts of this post (spelling is part of the environment), etc. Now, a proof that Darwinian selection is the way to get design is that humans turn to it when the design problem is too tough for them.  What we can’t figure out how to design, Darwinian selection can.  Sometimes this is called “genetic algorithms”.  

1. MJ Plunkett and JA Ellman, Combinatorial chemistry and new drugs. Scientific American, 276: 68-73, April 1997. Summary of article: “By harnessing the creative power of Darwinian selection inside a test tube, chemists can now discover compounds they would not have known how to make. The key is combinatorial chemistry, a process that allows them to produce and screen millions of candidate molecules quickly and systematically.”
6. CW Petit, Touched by nature: putting evolution to work on the assembly line. US News and World Report, 125: 43-45, July 27, 1998. Use “genetic algorithms” (cumulative selection) to get design in industry. Boeing engineers had Darwinian selection design a wing for them for a jet to carry 600 passengers but have a wing the same size as a 747.

9. FS Santiago, HC Lowe, MM Kavurma, CN Chesterman, A Baker, DG Atkins,LM Khachigian, New DNA enzyme targeting Egr-1 mRNA inhibits vascular smooth muscle proliferation and regrowth after injury. Nature Medicine 5:1264-1269, 1999. Used Darwinian selection to design a DNA enzyme (not found in nature) that degrades mRNA for use in treating hyperplasia after balloon arthroplasty. Humans have no idea what the nucleotide sequence of the DNA enzyme because they didn’t make it—Darwinian selection did.

14. Jr Koza, MA Keane, MJ Streeter, Evolving inventions. Scientific American, 52-59, Feb 2003 check out http://www.genetic-programming.com/ 


 “In my view evolution is not a theory, but a natural process, just as gravity is not a theory proposed by Isaac Newton.”

I have no idea what you think “a theory” is in science, but both evolution and gravity are scientific theories.  Hypotheses/theories are statements about the natural world.  Those statements can be processes, such as the shared electron theory behind chemistry, or the theory of erosion.  Even the theories of electrical currents are about a process: the movement of electrons through a metal.

“Darwin suggested that his theory would some day be accepted as was Newton’s theory. What he did not forsee was that Nawton’s theory would be supplanted by Einstein’s theory. “

Doesn’t matter. Evolution is as accepted as was Newton’s theory in Darwin’s day, and as accepted as Einstein’s is now. Newton’s theory is still accepted today: it is a limiting case of Einstein’s theory.  At non-relativistic accelerations, Einstein’s equations reduce to Newton’s.

“I am not making a gap for God, but to point out that this is very sophisicated system that cannot be reasonably thought to have occured by random chance.  God does not have to work in the gaps because God designed and works through the whole process ... Creationists believe that God designed creatures individually.  ID says nature is too stupid to design the intricasies of life.  ”

You don’t seem to see the contradiction in these statements.  You say “God ... works through the whole process” but then you have God stepping in because the “whole process” is supposedly “too stupid”.  That’s a gap!  God has to directly manufacture things because there is a “gap” between members of the universe. BTW, evolution is not “random chance”.  Remember, selection is not chance; it is determinism.  So yes, you are making gaps to insert God into.  This is against Christian theology. By making gaps, you are saying that God did not create a complete universe.  Science got the idea of no gaps from Christianity.  

“Science does not permit or prove God.  It does not contradict the reality of God”

Again, you haven’t seen the internal contradiction here.   If science does not permit God, then it would certainly contradict the reality of God.  For instance, science does not permit an earth centered solar system, so science contradicts the reality of an earth centered solar system.  Science does permit the existence of God.

“ In reality it assumes the fact of God, that is that the universe is a cosmos, not a chaos.”

Sorry, but having an ordered universe is an assumption, but it does not assume God.  It just means the universe is ordered, not why the universe is ordered.  Historically, yes, science did get that assumption about the physical universe (as well as the other 4 assumptions about the universe necessary to do science) from Judeo-Christianity.  That historical fact is one major piece of evidence against the “warfare” view of science and religion.  However, science didn’t have to get the assumptions from religion, scientists could have reached them on their own without religion.  Judeo-Christianity gave them a shortcut.  I suggest the book The Fire in the Equations by Kitty Ferguson

“Ecology is a relatively new science which has displaced evolution”

Ecology is relatively new, but it cannot “displace” evolution.  Ecology and evolution work on separate problems.  That is why you see departments of “Ecology and Evolution”.   Even Wikipedia recognizes that, and discusses a new field at the intersection of ecology and evolution: evolutionary ecology:  http://en.wikipedia.org/wiki/Evolutionary_ecology

Ecology deals with the interactions of species within a geographical area and the changes of those interactions over a relatively short period of time.  Ecology does not deal with the “origin of species”.  It may discuss the displacement of species within a biome as the biome changes, but it does so through existing species, not new species.  Evolution deals with the origins of new taxa over generations.  I don’t know what dictionary you are using, but it is clear that “ecology” and “environment” cannot have the same definition.  Wikipedia has ecology described as: “Ecology (from Greekοἶκος, “house”; -λογία, “study of”[A]) is the scientific study of interactions among organisms and their environment, such as the interactions organisms have with each other and with their abiotic environment

Obviously, if ecology = environment, then you can’t define ecology in terms of itself.  Usually, ecology focusses on the interactions of organisms with other populations.  In evolution, part of the “environment” is the organism’s siblings, parents, etc.  

Roger A. Sawtelle - #82661

September 20th 2013

However, science didn’t have to get the assumptions from religion, scientists could have reached them on their own without religion.

You make this statement, but you fail to indicate how, on what basis.  In any case it is too late.  If one knows something from one source, especially something which is not obvious, it is too late to say that one could have learned it from another source. 

The fact is from my perspective and I have not found any other rational view, if the universe does have a rational structure, that is governed by rational natural laws, then a rational all- powerful God is the only reasonable Candidate Who could have possibly done this task almost by definition. 

Whether this God is the God of the Bible is another discussion.  Obviously I think so and so do many people.     

In fact science is not about assumptions.  Science is not about worldviews.  It isw about factsPhilosophy and theology are about worldviews. 

Dawkins and Dennett claim that science supports their worldview, which it does not, unless they start with a materialistic worldview and think in a circular manner.  That is exactly, of course, what they do.   

Dawkins and Dennett claim that Life has not meaning and purpose.  That is based on their assumption that there is no design of nature, there is apparent design and purpose, but no real design and purpose.  Thus birds in the northern hemisphere do not fly south to avoid cold weather, but for some vague evolutionary advantage.

Ecology gives rational explanation for natural selection that Darwin, Dawkins, and Dennett do not give.  Ecology is the rational scientific means God uses to govern God creation and create humans and all living creatures.      


Roger A. Sawtelle - #82663

September 20th 2013


Forgive me for acknowledging you above and not responding to the first part of your statement.

Thank you for your response.

But Darwinian selection is an unintelligent process that gives design.

To say that Darwinian selection is unintelligent means that it is irrational and has no purpose.  Is gravity unintelligent process that has no meaning and purpose?  If so, why E = mc2?

You want me to think that intelligent people are the product of an irrational process of a irrational universe.  If nature is irrational, then why do rational homo sapiens have an evolutionary advantage?

Yes, you can take God out of the universe if you are willing to think that the universe is chaos, is irrational.  I hope that people will not go that far, however, reading books like the well received The Atheist’s Guide to Reality by Alex Rosenburg reveals that intelligent people are willing to follow bad ideas to their bad conclusions.

At times I reduce bad ideas to there basic consequences, argument ad absurdia, but here atheists are doing my work for me and taking it seriously.   

Ecology does provide evolution with design and it does so because because God created the universe as an cosmos.  Darwinism by itself is not cosmos, because it does not understand natural selection properly.     

Paul Lucas - #82665

September 20th 2013

Roger: “Science has become wedded to the idea that evolution = Darwinism that it confuses the theory with the naturaql process behind it.  Science tries to reduce evolution inot a simple physcial, process but living creatures are not non-living things, so it doesn’t really work.”

What does “Darwinism” mean to you?  To evolutionary biologists, Darwinism is used 1 of 2 ways:
1. The original 5 theories proposed by Darwin that are lumped together under the term “evolution”.
2.  The Modern Synthesis, sometimes called “Neo-Darwinism”.  The Modern Sythesis was a realization that Mendelian genetics, population genetics, and the fossil record all made a seamless whole.  Oftentimes the Modern Synthesis is made into a strawman—by some evolutionary biologists—so they can try to gain fame by making a “new” theory.  The evo-devo people did this.

It looks to me that you are trying to equate evolution = Darwism = atheism.  That would fit your statement that I was “pushing an ideology” when I was simply explaining evolution.  There is a subset of atheists out there (Shermer calls them “militant atheists”) who do try to equate evolution and atheism.  Nearly every creationist/IDer also makes the equation that evolution = atheism or Darwinism = atheism.  All of them are wrong.  Evolution is not atheism.  Never has been.  Isn’t now.

When you say “Science tries to reduce evolution inot a simple physcial, process but living creatures are not non-living things, so it doesn’t really work” it sounds like you think the physical processes cannot account for evolution.  But later you say:
” I think that God through the Logos can and did design nature to create even intelligent creatures like human beings.”

In this statement you say that the physical processes do account for evolution!  You have God (as Creator not Logos) create the natural processes so that they can create all the species, even us.  

If you really think the second, you are following in Darwin’s thoughts.  How about that?

“To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual.” C. Darwin, On the Origin of Species,pg. 449.

Notice that phrase that I emphasized—secondary causes.  That is a Christian term, not a scientific one.  It is very similar to your “did design nature to create”.  Look up the term.

I said creationists/IDers nearly universally try to equate evolution and atheism.  Phillip Johnson, one of the founders of ID, does this in his book The Wedge of Truth. In that book Johnson wants to use ID primarily to fight atheism.  However, in other writings Johnson does admit that evolution and atheism are not one and the same:

“The blind watchmaker thesis makes it possible to be an intellectually fulfilled atheist by supplying the necessary creation story. It does not make it obligatory to be an atheist, because one can imagine a creator who works through natural selection.” Phillip Johnson Reason in the Balance, pg. 73

In order to be an “intellectually fulfilled atheist” the atheist must first make the statement of faith “natural = without God”.  There is nothing in science or Judeo-Christianity to justify that belief; it is truly a blind faith. Ironically, creationists/IDers have the same statement of faith.  You echo it throughout your post: you have God acting only when “natural” is not sufficient.   It’s really, really bad Christian theology and contrary to several texts in scripture.  

Roger A. Sawtelle - #82670

September 21st 2013


Please, somehow you think that I am ID.  I am not.  I think that God made nature perfectly capable of governing itself using God’s created laws.  The biggest problem God has and we have is humanity, not nature.

All this time and energy spent on evolution could and should be spent on working together to solve human problems such as climate change and world peace.  One of the biggest lies of scientism is that once humans understand nature, all of our real problems will be solved.

This does not mean that there are no serious scientific and philosophical problems with Darwinian thought especially the way that Dawkins and Dennett practice and preach it.  I understand that there are other strands of evolutionary thinking, but this one seems to be the most influential right now and also the most toxic. 

If you really want to understand what I am saying and why, instead of trying to fit me into some ID stereotype, you need to read my book DARWIN’S MYTH: Malthus, Ecology, and the Meaning of Life.   

This is a complex problem with no easy answers.  As with other difficult problems each side has part of the answer and is part of the problem.  The answer is reconciling all sides with an answer that satisfies their real needs.

You have some good ideas and have done some homework, but you still need to understand how natural selection works, rather than accept Malthusian dogma.  I commend my book as a good place to start.   



Lou Jost - #82690

September 25th 2013

Roger, you haven’t learned anything from our earlier discussions. “Maltusian dogma”?  I showed you in previous posts that natural selection is a simple mathematical consequence of differential rates of reproduction, and it even happens if growth is unlimited (ie without Malthus). Of course, we know that every species’ growth IS limited by physical and ecological constraints, so Malthus is clearly right about that.

Roger A. Sawtelle - #82742

September 30th 2013


Life is not about math.  Life is about living.

The books on population models that you refered me to are quite clear that math models are not life.

Yes, organisms are mortal and subject to change as Malthus said.  However Darwin and Dawkins clearly say that natural selection is not random, but determinate.

The problem is that Darwin, Dawkins, et al. never explain the reason behind this determinate system.  If there is no reason, then we are talking about magic, not science, which is what much evolution has become.     

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