Microevolution vs. Macroevolution

[Student Nurse]

Last semester I took Microbiology. Before then I was a Christian and believed in creation, but what I studied and what I saw undoubtedly proved evolution - hence the "switchover" or "atheistic conversion" or whatever you want to call it.

I hear a lot of Christians say "the microbiological world proves microevolution" (i.e. evolution on the small scale such as bacteria adapting to new hosts/environments and incorporating plasmids into their DNA in order to become resistant to antibiotics), "but that doesn't prove macroevolution" (ie human evolution)

If this isn't true, then what does it prove to you? How can something be true on the small scale and not on the large? (give examples please)

[micatala]

I am a Christian but also accept the fact of biological evolution (on the macro scale!). I don't personally view evolution, including human evolution, as incompatible with Christianity, so find it interesting that this particular issue led you to a change in belief, but that is perhaps not a relevant topic for the thread.


Having said that, I don't think that the documented instances of so-called micro-evolution (as defined by creationists) prove that macro-evolution occurred. It is the documented evidence that macro-evolution occurred that prove macro-evolution occurred. The only difference is we haven't been around long enough as a species to 'observe through history' an instance of macro-evolution occuring.

I would accept that the mechanisms of micro-evolution are essentially the same as those of macro-evolution, and so show by themselves that macro-evolution is entirely plausible. Creationists seek to deny this plausibility by postulating an artificial barrier between 'kinds' of organisms, but have never been able to adequately show that these barrieres exist, except in that they have not been 'crossed' over exceedingly short periods of time.

Together with the evidence we have for macro-evolution as documented by the fossil record among other things, the only explanation that makes any sense and squares with all the evidence including the evidence we have in 'real-time' of micro-evolution is that macro-evolution has occurred.

[otseng]

I would agree with micatala that believing in evolution (or even macro-evolution) doesn't mean that the Christian faith is wrong. There are many examples of Christians here that fully embrace evolutionary theory (though I'm not one of them).

But, to answer your question, The Steppingstone Problem page gives a good argument to your question.

Antibiotic resistance is indeed an example of evolution. A bacteria has a random mutation which allows it to survive under antibiotics, while the rest are killed off.

All antibiotics attack rather specific target sequences inside certain bacteria. Many times all the colony under attack has to do is alter the target sequence in just one bacterium by one or two genetic "characters" and resistance will be gained since the offspring of this resistant bacterium, being more fit than their peers, will take over the colony in short order.

But simple mutation/selection does not demonstrate that complex mutation/selection can occur.

The author gives the analogy of letters and sentences.

Random walk can get from any one-, two-, or three-letter words to any other via a path of meaningful words, as in the steppingstone sequence of cat - hat - bat - bad - bid - did - dig - dog. 'Evolution' (changing meaning or 'function') at this level is rather simple because the stepping-stones are so close together. But, with each additional minimum letter requirement, the growth of the meaningless sequences quickly outpaces the growth of the total number of meaningful sequences, and the ratio of meaningful to meaningless gets smaller and smaller at an exponential rate.

For example, there are around 30,000 meaningful seven-letter words and combinations of smaller words totaling seven letters, but there are 8,031,810,176 potential seven-letter sequences. This produces a situation in which an average meaningful seven-letter sequence is surrounded by over 250,000 meaningless sequences. Obviously then, compared to three-letter steppingstones, it is much harder to 'evolve' between meaningful seven-letter steppingstones without having to cross through a little ocean of meaningless sequences.

The problem is how can evolution randomly produce complex mutations? When we evolve 3 letters, it's easy. But, when it's even just 7 letters, it's much more difficult.

So, antibiotic resistance is a simple change, but as we go up in complexity, it's difficult, and even impossible, to find.

Many simple functions, such as de novo antibiotic resistance, are easy to evolve for any bacterial colony in short order. Moving up a level of complexity, there are far fewer examples of single protein enzymes evolving where a few hundred amino acids at minimum are required to work together at the same time (and many types of bacteria cannot evolve even at this level). However, there are absolutely no examples in the scientific literature of any function requiring more than a thousand or so amino acids working at the same time (as in the simplest bacterial motility system) ever evolving - period. (emphasis mine) The beneficial 'stepping-stones' are just too far apart due to all the junk that separates the few beneficial islands of function from every other island in the vast universe of junk sequences at such levels of informational complexity. The average time needed to randomly sort through enough junk sequences to find any other beneficial function at such a level of complexity quickly works its way into trillions upon trillions of years - even for an enormous population of bacteria with a high mutation rate.

[Goat]

I would agree with micatala that believing in evolution (or even macro-evolution) doesn't mean that the Christian faith is wrong. There are many examples of Christians here that fully embrace evolutionary theory (though I'm not one of them).

But, to answer your question, The Steppingstone Problem page gives a good argument to your question.

Antibiotic resistance is indeed an example of evolution. A bacteria has a random mutation which allows it to survive under antibiotics, while the rest are killed off.

All antibiotics attack rather specific target sequences inside certain bacteria. Many times all the colony under attack has to do is alter the target sequence in just one bacterium by one or two genetic "characters" and resistance will be gained since the offspring of this resistant bacterium, being more fit than their peers, will take over the colony in short order.

But simple mutation/selection does not demonstrate that complex mutation/selection can occur.

The author gives the analogy of letters and sentences.

Random walk can get from any one-, two-, or three-letter words to any other via a path of meaningful words, as in the steppingstone sequence of cat - hat - bat - bad - bid - did - dig - dog. 'Evolution' (changing meaning or 'function') at this level is rather simple because the stepping-stones are so close together. But, with each additional minimum letter requirement, the growth of the meaningless sequences quickly outpaces the growth of the total number of meaningful sequences, and the ratio of meaningful to meaningless gets smaller and smaller at an exponential rate.

For example, there are around 30,000 meaningful seven-letter words and combinations of smaller words totaling seven letters, but there are 8,031,810,176 potential seven-letter sequences. This produces a situation in which an average meaningful seven-letter sequence is surrounded by over 250,000 meaningless sequences. Obviously then, compared to three-letter steppingstones, it is much harder to 'evolve' between meaningful seven-letter steppingstones without having to cross through a little ocean of meaningless sequences.

The problem is how can evolution randomly produce complex mutations? When we evolve 3 letters, it's easy. But, when it's even just 7 letters, it's much more difficult.

So, antibiotic resistance is a simple change, but as we go up in complexity, it's difficult, and even impossible, to find.

Many simple functions, such as de novo antibiotic resistance, are easy to evolve for any bacterial colony in short order. Moving up a level of complexity, there are far fewer examples of single protein enzymes evolving where a few hundred amino acids at minimum are required to work together at the same time (and many types of bacteria cannot evolve even at this level). However, there are absolutely no examples in the scientific literature of any function requiring more than a thousand or so amino acids working at the same time (as in the simplest bacterial motility system) ever evolving - period. (emphasis mine) The beneficial 'stepping-stones' are just too far apart due to all the junk that separates the few beneficial islands of function from every other island in the vast universe of junk sequences at such levels of informational complexity. The average time needed to randomly sort through enough junk sequences to find any other beneficial function at such a level of complexity quickly works its way into trillions upon trillions of years - even for an enormous population of bacteria with a high mutation rate.

ON the other hand, what you are not addressing is the fact the evolution is accumulative. That means that little mutations start adding up over time to bigger and bigger differences with the 'Parent' population. If there are two 'sister' branches that diverge, and do not interbreed, the differences become more and more pronounced. Eventually, the ability to interbreed disappears.

[Rob]

Last semester I took Microbiology. Before then I was a Christian and believed in creation, but what I studied and what I saw undoubtedly proved evolution - hence the "switchover" or "atheistic conversion" or whatever you want to call it.

I believe organic evolution is a fact. The evidence for the basic theory of descent with modification is overhwelming. So, as regards the fact of evolution there is no dispute. But there is a large differenence between the fact of organic evolution and the theories regarding its paths and mechanisms. You seem to be making a leap from one uncritical belief system to another in my view, if you don't take the time to distinguish between facts, paths, and mechanisms.

I hear a lot of Christians say "the microbiological world proves microevolution" (i.e. evolution on the small scale such as bacteria adapting to new hosts/environments and incorporating plasmids into their DNA in order to become resistant to antibiotics), "but that doesn't prove macroevolution" (ie human evolution)

I don't personally have much patience or desire to untangle the many misleading arguments made by creationists; it takes enough of my energy to untangle the complex arguments made by real scientists and biologists! But you appear to be just as naively assuming that this micro vs. macro question is only raised by creationists, when this could not be farther from the truth. In fact, the question of macro vs. micro is a question of mechanism(s), and has a long history of debate, including current debates within the scientific community. I could parade page after page of quotes showing conclusively this debate is alive and well within the scientific community, but will suffice to point you to a good summary of the issues: Macro vs. Micro debate from the perspective of modern genetics.

Through molecular phylogeny we are learning to adjust our theories of the paths of evolution, and through Evolutionary Developmental Biology, Devlopmental Genetics, and Comparative Genomics we are gaining new insights into the nature of variation and the possible mechanisms of evolution. From Horizontal Gene Transfer to Epigenetic Inheritance Systems and the Regulatory Genome System the field of evolutionary biology is currently undergoing a major conceptual revolutions.

Creationists and fundamentalist Christians/Muslims do not have a corner on uncritical acceptance of accepted dogma.

Chapter 12 Speciation and Developmental Evolution

The Genetic Basis of Species versus Larger Taxonomic Differences

It is the first issue -- the nature of the genetic differences that lead to speciation -- that has received the most attention and that has been the subject of the most controversy. The focus here is not on the genetic differences that lead to reproductive isolation, which may involve artifactual epistatic interactions, but on those genetic differences that lead to differential adaptation on the road to the formation of different species.

The starting point of most discussions is Fisher's argument that adaptive evolution is driven by mutations of individually minute effect (Fisher, 1930) -- "micromutations," to use the term from the older literature. To the extent that species formation is accompanied by or driven by such adaptive evolution, developmental evolution in species formation would also consist of changes of individually tiny effect. This view, however, has always seemed deeply implausible to numerous developmental biologists (e.g., Goldschmidt, 1940; Gilbert et al., 1996) and patently untrue to the majority of paleontologists, based on their study of the fossil record (Valentine and Erwin, 1987; Gould, 1994; Erwin, 1999). To many members of these groups, an important role for mutations of large, or at least visible, phenotypic effect -- so-called "macromutations" -- has seemed far more probable than not.

Nevertheless, the gulf between evolutionary geneticists on the one hand and developmental biologists and paleontologists on the other has narrowed in recent years, with a shift toward the position of the latter group. The new consensus is that some mutations of large phenotypic effect can and do play a part in speciation.

-- Wilkins, Adam S. The Evolution of Developmental Pathways. Massachusetts: Sinaur Associates; 2002; p. 462.

The science of biology enters the twenty-first century in turmoil, in a state of conceptual disarray, although at first glance this is far from apparent. When has biology ever been in a more powerful position to study living systems? The sequencing juggernaut has still to reach full steam, and it is constantly spewing forth all manner of powerful new approaches to biological systems, many of which were previously unimaginable: a revolutionized medicine that reaches beyond diagnosis and cure of disease into defining states of the organism in general; revolutionary agricultural technology built on genomic understanding and manipulation of animals and plants; the age-old foundation of biology, taxonomy, made rock solid, greatly extended, and become far more useful in its new genomic setting; a microbial ecology that is finally able to contribute to our understanding of the biosphere; and the list goes on. (Woese 2005: 99)

All this is an expression of the power inherent in the methodology of molecular biology, especially the sequencing of genomes. Methodology is one thing, however, and understanding and direction another. The fact is that the understanding of biology emerging from the mass of data that flows from the genome sequencing machines brings into question the classical concepts of organism, lineage, and evolution as the same time it gainsays the molecular perspective that spawned the enterprise. The fact is that the molecular perspective, which so successfully guided and shaped twentieth-century biology, has effectively run its course (as all paradigms do) and no longer provides a focus, a vision of the biology of the future, with the result that biology is wandering will-nilly into that future. This is a prescription for revolution--conceptual revolution. One can be confident that the new paradigm will soon emerge to guide biology in this new century…. Molecular biology has ceased to be a genuine paradigm, and it is now only a body of (very powerful) technique…. The time has come to shift biology’s focus from trying to understand organisms solely by dissecting them into their parts to trying to understand the fundamental nature of biological organization, of biological form. (Woese 2005: 99-100)

(….) When one has worked one's entire career within the framework of a powerful paradigm, it is almost impossible to look at that paradigm as anything but the proper, if not the only possible, perspective one can have on (in this case) biology. Yet despite its great accomplishments, molecular biology is far from the "perfect paradigm" most biologists take it to be. This child of reductionist materialism has nearly driven the biology out of biology. Molecular biology’s reductionism is fundamentalist, unwavering, and procrustean. It strips the organism from its environment, shears it of its history (evolution), and shreds it into parts. A sense of the whole, of the whole cell, of the whole multicellular organism, of the biosphere, of the emergent quality of biological organization, all have been lost or sidelined. (p. 101)

Our thinking is fettered by classical evolutionary notions as well. The deepest and most subtle of these is the concept of variation and selection. How we view the evolution of cellular design or organization is heavily colored by how we view variation and selection. From Darwin’s day onward, evolutionists have debated the nature of the concept, and particularly whether evolutionary change is gradual, salutatory, or of some other nature. However, another aspect of the concept concerns us here more. In the terms I prefer, it is the nature of the phase (or propensity) space in which evolution operates. Looked at one way, variation and selection are all there is to evolution: The evolutionary phase space is wide open, and all manner of things are possible. From this “anything goes” perspective, a given biological form (pattern) has no meaning outside of itself, and the route by which it arises is one out of an enormous number of possible paths, which makes the evolution completely idiosyncratic and, thus, uninteresting (molecular biology holds this position: the molecular biologist sees evolution as merely a series of meaningless historical accidents). (p. 101)

The alternative viewpoint is that the evolutionary propensity space is highly constrained, being more like a mountainous terrain than a wide open prairie: Only certain paths are possible, and they lead to particular (a relatively small set of) outcomes. Generic biological form preexists in the same sense that form in the inanimate world does. It is not the case that “anything goes” in the world of biological evolution. In other words, biological form (pattern) is important: It has meaning beyond itself; a deeper, more general significance. Understanding of biology lies, then, in understanding the evolution and nature of biological form (pattern). Explaining biological form by variation and selection hand-waving argumentation is far from sufficient: The motor does not explain where the car goes. (pp. 101-102)

-- Woese, Carl R. (2005) Evolving Biological Organization. In Microbial Phylogeny and Evolution: Concepts and Controversies (Jan Sapp, ed.). Oxford: Oxford University Press, pp. 99-102.

It is often assumed that the only variation that is heritable is variation that is associated with genetic differences. However, ..., this position is empirically inadequate, as we now know of several different ways in which phenotypic variation can be reliably inherited through nongenetic pathways (see, e.g., Sollars et al. 2003; Oyama, Griffiths, and Gray 2001; Jablonka and Lamb 2005).

-- Pigliucci, Massimo and Kaplan Jonathan. Making Sense of Evolution: The Conceptual Foundations of Evolutionary Biology. Chicago: University of Chicago Press; 2006; pp. 15, cf. 1.

1. Sollars, V., X. Lu, X. Wang, M.D. Garfinkel, and D. M. Ruden. 2003. Evidence for epigenetic mechanism by which Hsp90 acts as a capacitor for morphological evolution. Nature Genetics 33: 70-74.
2. Oyama S., P. E. Griffiths, and R. D. Gray, ed. 2001. Cycles of Contingency. Cambridge, MA: MIT Press.
3. Jablonka, E., and M. J. Lamb. 2005. Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life. Cambridge, MA: MIT Press.
4. Jablonka, E. 2001. The systems of inheritance. In Cycles of Contingency, ed. S. Oyama, P. Griffith, and R. Gray, 99-116. Cambridge, MA: MIT Press.

There are multiple inheritance systems, with several modes of transmission for each system, that have different properties and that interact with each other. The include the genetic inheritance system (GIS), cellular or epigenetic inheritance systems (EISs), the systems underlying the transmission of behavior patterns in animal socieities through social leaning (BISs), and the communication system employing symbolical languages (SIS) (Jablonka, Lamb, Avital 1988). These systems all carry information, which I shall define here as the transmissible organization of an actual or potential state of a system. (Jablonka 2001: 100)

(....) Variations were assumed to be exclusively the consequence of the meiotic reshuffling of genes ... and of several classes of errors in DNA maintenance.... Errors that are not removed or repaired accurately b the DNA maintenance machinery were assumed to be the ultimate raw material for evolution by natural selection. Although there is no doubt that a lot of variation in DNA is indeed random in this sense, the view that all variation is random has been challenged. This challenge has come from several directions.

It has been shown that different nucleotiede sequences [modules, such as "introns" and "exons" and "hotspots" and "gene nurseries"] differ in the likelihood that they will be damaged, invaded by genomic parasites or replicated inaccurately. The rate and type of new variation may thus depend on how teh nucleotides in the sequence are organized, and this organization may be adaptive. (Jablonka 2001: 102)

(....) It seems that through natural selection [we don't really know how the origin of this hierarchical system] the mechanisms that allow selective control of gene expression have been coupled with mechanisms that determine teh fidelity of copying so that the inducible system that turns genes on and off [regulatory genome and epigenetic chromatin marking] also turns the production of mutations on and off. (Jablonka 2001: 102-103)

The "targeted" mutations cannot be said to be random in the classical sense, since adaptively advantageous mutations are preferentially (though not exclusively) induced under the appropriate conditions and in the relevant domains. Randomness has not been eliminated, but it has been restricted and channeled. However, the mutations are not goal-directed in any teleogical sense, and their targeted production is the consequence of natural selection that had acted on random variations. Variation has been targeted by selection to be preferentially generated in a subset of sites, under particular conditions. It is difficult to know how to define such variations. The term patterned variation, which has been suggested by the economist Ekkehart Schlicht with respect to cultural evolution, is the one I choose to use in this paper (Schlicht 1997). It is better than previously suggested terms such as directed, adaptive, induced, and guided variation because it does not carry the teleological connotation of premeditated design, yet does carry the connotation of some degree of preexisting structuring (by past natural selection). Once a system for generating patterned variation has evolved, it channels and guides evolution. (Jablonka 2001: 103)

(....) The ability to generate patterned variations forges direct links between heredity, development, and evolution. The generation of patterned variation is part of the developmental process no less than changes in transcriptional activation of genes, although the effect of changes in DNA may often last longer than changes in transcriptional activity. The process of generating patterned variation is part of both development and evolution. Although there is a certain (short-term) degree of autonomy of heredity and development if mutations are random, if they are patterned, heredity loses this partial independence. (Jablonka 2001: 103)

-- Jablonka, E. 2001. The systems of inheritance. In Cycles of Contingency: Developmental Systems and Evolution, ed. S. Oyama, P. Griffith, and R. Gray, 99-116. Cambridge, MA: MIT Press.

[QED]

Random walk can get from any one-, two-, or three-letter words to any other via a path of meaningful words, as in the steppingstone sequence of cat - hat - bat - bad - bid - did - dig - dog. 'Evolution' (changing meaning or 'function') at this level is rather simple because the stepping-stones are so close together. But, with each additional minimum letter requirement, the growth of the meaningless sequences quickly outpaces the growth of the total number of meaningful sequences, and the ratio of meaningful to meaningless gets smaller and smaller at an exponential rate.

For example, there are around 30,000 meaningful seven-letter words and combinations of smaller words totaling seven letters, but there are 8,031,810,176 potential seven-letter sequences. This produces a situation in which an average meaningful seven-letter sequence is surrounded by over 250,000 meaningless sequences. Obviously then, compared to three-letter steppingstones, it is much harder to 'evolve' between meaningful seven-letter steppingstones without having to cross through a little ocean of meaningless sequences.

The problem is how can evolution randomly produce complex mutations? When we evolve 3 letters, it's easy. But, when it's even just 7 letters, it's much more difficult.

otseng, where's the selection in that example? It isn't an analogy of natural selection without it. Sure it has a random element -- but as pointed out this soon fails to deliver anything non-trivial. The analogy being presented is missing the vital ingredient of selection that gives rise to an accumulation of non-trivial order.

Do the people who go to the trouble of publishing this sort of indefensible material really think it will be effective in persuading others that systems of natural ordering cannot possibly work? Can we really call it an honest approach?

[otseng]

otseng, where's the selection in that example? It isn't an analogy of natural selection without it. Sure it has a random element -- but as pointed out this soon fails to deliver anything non-trivial. The analogy being presented is missing the vital ingredient of selection that gives rise to an accumulation of non-trivial order.

If there's nothing to select from, then the selection step is moot.

First evolution would have to produce a mutation that is capable of being selected from. The article argues that selection would not apply to mutations that result in no meaning (junk DNA). This would be analagous to letters that do not make a meaningful word. Selection would only apply to functional DNA, letters that make meaningful words.

As we increase the number of letters, the chance of achieving a meaningful word dramatically decreases. Evolution would require for such a fortuitous mutation to occur. If it results in a junk word, then evolution would not apply, since it would confer neither an advantage nor disadvantage for the selection process.

And as the article states, "there are absolutely no examples in the scientific literature of any function requiring more than a thousand or so amino acids working at the same time (as in the simplest bacterial motility system) ever evolving - period." And if this mutation step is not achievable, then the selection step could not even take place.

What this all shows is that there are limits to evolution. Simple mutations can easily occur (micromutations). But as it gets more complex, it gets progressively more rarely, until at the thousand amino acid level where it gets impossible to find.

[QED]

If there's nothing to select from, then the selection step is moot.

Nothing? Then what's being added at random?

First evolution would have to produce a mutation that is capable of being selected from. The article argues that selection would not apply to mutations that result in no meaning (junk DNA). This would be analagous to letters that do not make a meaningful word. Selection would only apply to functional DNA, letters that make meaningful words.

As we increase the number of letters, the chance of achieving a meaningful word dramatically decreases. Evolution would require for such a fortuitous mutation to occur. If it results in a junk word, then evolution would not apply, since it would confer neither an advantage nor disadvantage for the selection process.

The idea that something can be neither an advantage nor disadvantage in the context of natural selection is often put forward to defeat natural selection but it fails miserably. Maybe you've never felt the need to optimise your php code. I've certainly spent many an hour trying to reduce the size of programs to fit into the limited architectures of embedded microprocessors. Everything has some cost; carrying around "dead weight" eats up precious resources that could be better used in other areas.

All biological systems are under similar constraints of finite resources so there's simply no such thing as a "neutral component" when it comes to natural selection.

And as the article states, "there are absolutely no examples in the scientific literature of any function requiring more than a thousand or so amino acids working at the same time (as in the simplest bacterial motility system) ever evolving - period."

I don't quite follow here, does this mean the article acknowledges the evolution of systems of up to a thousand or so amino acids?

What this all shows is that there are limits to evolution. Simple mutations can easily occur (micromutations). But as it gets more complex, it gets progressively more rarely, until at the thousand amino acid level where it gets impossible to find.

So the conclusion that Macroevolution can't happen is based on the failure to observe a system evolving beyond this known high-water mark? Sounds very dubious to me. With natural selection, a viable principle is offered which explains natural ordering. On the other hand Irreducible Complexity offers no principle by which we can understand the claimed limit to the ability of natural selection to achieve arbitrary levels of complexity. Until it does it can only be considered as pseudoscience.

[Rob]

The idea that something can be neither an advantage nor disadvantage in the context of natural selection is often put forward to defeat natural selection but it fails miserably.... Everything has some cost; carrying around "dead weight" eats up precious resources that could be better used in other areas.

All biological systems are under similar constraints of finite resources so there's simply no such thing as a "neutral component" when it comes to natural selection.

Sports on a Neutral Territory

Charles Darwin knew nothing about genes, gene pools, changes at the molecular level, or random drift, and his view of heredity was hopelessly antiquated. Although a reprint of Mendel's Veruche was readily available to him, he almost certainly did not read it (probably because it was written in German) and so was blissfully ignorant of the true nature of heredity. He was acquainted with mutations, but only in the form of sports, a term used by animal and plant breeders for rarities that appeared suddenly and deviated strikingly in their appearance from the norm. What he did not know, of course, he could not take into account in his formulation of an evolutionary theory, which he based exclusively on observations at the phenotypic level. He recognized only two types of modifications (today we would say mutation) -- deleterious and advantageous, and only one kind of evolutionary mechanism determining the fate of the modifications -- natural selection. In his view, natural selection weeded out the deleterious mutations and promoted the advantageous ones. Essentially, this was the same view adopted by virtually all knowledgeable evolutionary biologists whne genes, gene pools, and the rest, became known. If anybody considered the possibility of neutral mutations also existing the thought that they may participate in evolution was certainly inconceivable. Sewall Wright was well aware of the existence of random genetic drift, but he did not consider it as a mechanism on a par with natural selection. He believed that in small populations, genetic drift was responsible for rapidly creating new gene combinations from which natural selection then picked the fittest for fixation. But this was as far as he would go in challenging the orthodoxy. (Klein and Takahata 2002: 86-87)

In 1968, however, Motoo Kimura published a short article in Nature, innocently entitling it "Evolutionary rate at molecular level". With its seeming innocuousness, however, came a blow under which the monolith of evolutionary theory began to crack. Prompted by certain inconsistencies between predictions based on the theory of natural selection and the degree of genetic variability observed in natural populations at the molecular level, Kimura put forward two revolutionary theses. First, at the molecular level, neutral mutations are far more common than advantageous mutations; and second, neutral mutations are fixed by random genetic drift, fixation being the prevailing mechanism of evolution at the molecular level. The implication of both theses was that in addition to natural selection, there is a second principle mechanism of evolution -- fixation of neutral mutations by random genetic drift. The Americans Jack Lester King and Thomas H. Jukes, who reached a similar conclusion at about the same time and published their deductions in Science one year after Kimura, expressed their challenge to orthodoxy more bluntly by entitling their article "Non-Darwinian evolution". The soft-spoken, shy, and modest Kimura thus became the third in our gallery of unlikely revolutionaries. The publication of his two theses in Nature had an impact on the biological community comparable to Martin Luther posting his 95 Theses on the door of the Wittenberg Castle Church. (Klein and Takahata 2002: 87)

The reaction to the Kimura-King-Jukes neutral theory of molecular evolution, as it came to be known, was swift and savage. It cannot be true, proclaimed one eminent evolutionary biologist, without offering specific reasons for the rejection. Random drift does occur, but has nothing to do with evolution, said others. Later, as so often happens with revolutionary ideas, there were those who claimed that the neutral theory idea was meritorious but not truly novel. The choice of the expression "non-Darwinian" in the title of the article by King and Jukes in particular was equivalent to poking a stick into a hornets' nest -- and the hornets were not amused! Much of the initial critique revealed a lack of understanding on the part of the respondents. Some opponents thought, for example, that the neutral theory denied the existence of natural selection, which of couse it did not. Kimura made it clear from the very beginning that his theory applied to the major part, but not to all of the mutations occurring in a population. Specifically, he excluded all mutations responsible for the emergence of adaptive characters from his considerations. (Adaptive, in this context, refers to any inherited character that makes an organism more adjusted to the conditions of its environment.) These mutations are very rare, but when they do occur, they are rapidly driven toward fixation by Darwinian natural selection. Because of their rare occurrence and rapid fixation, such mutations contribute very little to variability in populations, which Kimura was trying to account for. Kimura also had to explain that he did not deny the existence of disadvantageous mutations and that he was not claiming that all mutations were neutral. (Beyond their initial salvo, King and Jukes did not actively participate in the controversey surrounding the neutral theory, the defense of which was left largely to Kimura and his followers. Kimura later brilliantly summarized his position in his book entitled -- how else? -- The Neutral Theory of Molecular Evolution, a masterpiece of scientific writing.) Kimura chose to ignore the deleterious mutations because they contributed neither to the observable variability, not to molecular evolution. (Klein and Takahata 2002: 87)

(....) The dust has not yet settled after the battle, but it has cleared to the extent that the positions of the entrenched armies are now visible. The mode of fighting has changed, too. God are the days of inflamatory rhetoric; attention is finally focused on designing tests that can pit explanations based on the neutral theory against those based on the selection theory. The two theories differ in their predictions, some of which can be subjected to experimental verification. (Klein and Takahata 2002: 88)

(....) Although the controversey continues, it has become clear that if natural selection influences the fixation of mutations, most of the time its effects are very difficult to demonstrate. The debate has also led to the realization that drift is a factor that cannot be ignored in any explanation of evolutionary changes at the molecular level. Finally, the neutral theory, backed by elegant mathematical constructions, provides the foundations on which more complex explanations of molecular evolution can be built. (Klein and Takahata 2002: 88-89)

-- Klein, Jan, and Takahata, Naoyuki (2002) Where Do We Come From? The Molecular Evidence for Human Descent. Berlin: Springer-Verlag.

It appears you are "blissfully ignorant of the true nature of heredity" as well as the history of biology QED. It also appears your critique reveals a serious "lack of understanding" of biology. But this does not surprise me as you have repeatedly made statements that show an almost complete lack of understanding of biology and a proclivity, almost a talent, in your ability to fail to distinguish between metaphor and empirical reality, or between models and living organisms, and between imitations inspired by living biological organisms and the actual living biological organisms themselves, thereby conflating the trivial with the truly non-trivial.

True complexity and the nature of existence

My concern … is true complexity and its relation to physics. This is to be distinguished from what is covered by statistical physics, catastrophe theory, study of sand piles, the reaction diffusion equation, cellular automata such as “The Game of Life,” and chaos theory. Examples of truly complex systems are molecular biology, animal and human brains, language and symbolic systems, individual human behavior, social and economic systems, digital computer systems, and the biosphere. This complexity is made possible by the existence of molecular structures that allow complex biomolecules such as RNA, DNA, and proteins with their folding properties and lock-and-key recognition mechanisms, in turn underlying membranes, cells (including neurons), and indeed the entire bodily fabric and nervous system. (Ellis 2004: 607)

True complexity involves vast quantities of stored information and hierarchically organized structures that process information in a purposeful manner, particularly through implementation of goal-seeking feedback loops. Through this structure they appear purposeful in their behavior (“teleonomic”). This is what we must look at when we start to extend physical thought to the boundaries, and particularly when we try to draw philosophical conclusions -- for example, as regards the nature of existence -- from our understanding of the way physics underlies reality. Given this complex structuring, one can ask, “What is real?”, that is, “What actually exists?”, and “What kinds of causality can occur in these structures?” (Ellis 2004: 607)

(….)

Not only are complex systems hierarchic, but the levels of this hierarchy represent different levels of abstraction, each built upon the other, and each understandable by itself (and each characterized by a different phenomenology). This is the phenomenon of emergent order. All parts at the same level of abstraction interact in a well-defined way (which is why they have a reality at their own level, each represented in a different language describing and characterizing the causal patterns at work at that level). (Ellis 2004: 612)

We find separate parts that act as independent agents, each of which exhibit some fairly complex behavior, and each of which contributes to many higher level functions. Only through the mutual co-operation of meaningful collections of these agents do we see the higher-level functionality of an organism. This emergent behavior -- the behavior of the whole is greater than the sum of its parts, and cannot even be described in terms of inter-component linkages. This fact has the effect of separating the high-frequency dynamics of the components -- involving their internal structure -- from the low-frequency dynamics -- involving interactions amongst components. (Simon 1982.)

(....) In a hierarchy, through encapsulation, objects at one level of abstraction are shielded from implementation details of lower levels of abstraction.

-- Ellis, George F. R. True complexity and its associated ontology. In Science and Ultimate Reality: Quantum Theory, Cosmology and Complexity (John D. Barrow, Paul W. Davies, and Charles L. Harper, Jr., ed.). Cambridge: Cambridge University Press; 2004; p. 612.

The critique of pseudoscience cuts both ways. To ignore the factual evidence which proves the fact of organic evolution by critiquing the tentative nature of the theories about paths and mechanisms is to fail to understand the nature of science and to espouse pseudoscience. Similarly, to ignore the fact of the limitations imposed by the statistical methods of correlation and to confuse correlation with causation it to make pseudoscientific dogmas out of tentative theories of paths and mechanisms. Both are a form of pseudoscience; one creationism, the other scientism.

[QED]

Thank you Rob for pointing out once again my considerable shortcomings. I usually preface my declarations about matters biological by admitting that I am not a biologist. I see I failed to make that step when answering otseng -- but I know he's a programmer and I think he knows the same of me.

Now let's not lose sight of my supposed gaff here. In order to defeat natural selection as a viable mechanism for the creation of apparent design otseng has suggested that selection "stalls" when confronted with a "neutral" mutation. Looking at this from a general "physics" point of view it struck me that only a naive view of physics would permit such an idea. Only in idealised conditions far removed from the metabolic world could we suppose such a thing as "zero cost". Is this not the case Rob?

Perhaps you are looking at this over a particular scale? My argument is presented as a general principle (one which I suspected was being missed). How immediate the effects would be over all scales of natural selection would be something variable. I would hazard a guess that the sensitivity to "cost" would be higher at the molecular level. But what you and Motoo Kimura seem to be suggesting is that some mutations come at precisely zero cost. You will have to explain to me how these "mass-less" entities come about before I can accept your slamming verdict on my reply to otseng.