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Thursday, May 18, 2017

Jonathan Wells illustrates zombie science by revisiting junk DNA

Jonathan Wells has written a new book (2017) called Zombie Science: More Icons of Evolution. He revisits his famous Icons of Evolution from 2000 and tries to show that nothing has changed in 17 years.

I wrote a book in 2000 about ten images images, ten "icons of evolution," that did not fit the evidence and were empirically dead. They should have been buried, but they are still with us, haunting our science classrooms and stalking our children. They are part of what I call zombie science.
I won't bore you with the details. The icons fall into two categories: (1) those that were meaningless and/or trivial in 2000 and remain so today, and (2) those that Wells misunderstood in 2000 and are still misunderstood by creationists today.

Wednesday, May 03, 2017

Debating philosophers: The difference between genes and alleles

This is my third post on the Lu and Bourrat (2017) paper [Debating philosophers: The Lu and Bourrat paper]. Part of their argument is to establish that modern evolutionary theory is a gene-centric theory. They need to make this connection because they are about to re-define the word "gene" in order to accommodate epigenetics.

In my last post I referred to their defense of the Modern Synthesis and quoted them as saying that the major tenets of the Modern Synthesis (MS) are still the basis of modern evolutionary theory. They go on to say,

Tuesday, May 02, 2017

The selfish gene vs the lucky allele

The Selfish Gene was published forty-one years ago (1976) and last year there was a bit of a celebration. I think we can all appreciate the impact that the book had at the time but I'm not sure it's as profound and lasting as most people believe ["The Selfish Gene" turns 40] [The "selfish gene" is not a good metaphor to describe evolution] [Die, selfish gene, die!].

The main criticisms fall into two categories: (1) the primary unit of selection is the individual organism, not the gene, and (2) the book placed too much emphasis on adaptation (Darwinism). I think modern evolutionary theory is based on 21st century population genetics and that view puts a great deal of emphasis on the power of random genetic drift. The evolution of a population involves the survival of individuals within the population and that, in turn, depends on the variation that exists in the population. Thus, evolution is characterized by changes in the frequencies of alleles in a population.

Monday, March 20, 2017

Correcting the correction of a video about evolution

Charlie McDonnell is the author of a book called Fun Science: A Guide To Life, The Universe And Why Science Is So Awesome. He made a video on misconceptions about the theory of evolution (see below). Sally Le Page (below left) is an evolutionary biologist working on her Ph.D. at Oxford (UK). She noticed a few problems with the McDonnell video so she made one of her own to correct the misconception in the first video. Now it's my turn to correct the misconception in the video that corrects the first video!

Sally Le Page highlights six misconceptions in the McDonnell video. She points out that none of them are very important—they are "little niggles"—but she still thinks a comment is necessary. (I agree.)

Monday, January 02, 2017

The Edge question 2017

Every year John Brockman asks his stable of friends an interesting question. Brockman is a literary agent and most of the people who respond are clients of his. (I want to be one.) The question and responses are posted on his website Edge. This year's question is, "What scientific term or concept ought to be more widely known?"

This year, the introduction is more interesting than the responses. Here's part of what Brokman wrote,

Sunday, December 04, 2016

Kevin Laland's new view of evolution

The recent meeting at the Royal Society in London was organized by The Royal Society (UK) and The British Academy. The theme of the meeting was, "New trends in evolutionary biology: biological, philosophical and social science perspectives." The main organizers were Denis Noble, Nancy Cartwright, Patrick Bateson, John Dupré, and Kevin Laland. The point of the meeting was to discuss new evolutionary theory.

It's difficult to describe everything that went on at the meeting because so much of it was details about individual research results. These scientific talks were often presented as an alternative to modern ways of thinking about evolution. The general theme was that the Modern Synthesis was out-of-date and needed revision or, perhaps, replacement. There was very little discussion of evolutionary theory and how best to interpret those results. The data was supposed to speak for itself.

The only serious objections came from scientists who claimed the Modern Synthesis had already incorporated the ideas of niche construction, plasticity, epigenetics etc. This message was promoted mainly by Douglas Futuyma and Russell Lande. They weren't very successful.

Thursday, December 01, 2016

Learning about modern evolutionary theory: the drift-barrier hypothesis

Many evolutionary biologists are engaged in research that focuses on large organisms that are (presumably) adapting to a local environment. These "field biologists" are mostly concerned with rapid evolutionary changes. Those kind of changes are almost always due to natural selection. Many of these biologists are not interested in molecular evolution and not interested in any process other than natural selection.

Unfortunately, this promotes an adaptationist mentality where all of evolution is viewed through the filter of natural selection. This is the view criticized by Stephen Jay Gould and Richard Lewontin back in 1978 when they presented the Spandrels paper at a Royal Society meeting in London (UK).
Gould, S. J. and Lewontin, R.C. (1979) The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme. Proc. R. Soc. Lond. B 205:581-598. [doi: 10.1098/rspb.1979.0086
I believe there was a substantive change in our view of evolution back in the late 1960s and early 1970s. That's when the results of evolution at the molecular level were first being published. It lead to the development of Neutral Theory, Nearly-Neutral Theory and a growing appreciation of the importance of random genetic drift. Modern population genetics was able to cope easily with this new view of evolution.

Friday, April 22, 2016

Don't call it "The Theory of Evolution"

By now, we all know that a "theory" in science is much more than idle speculation, a point that has been made repeatedly over the past century. With respect to evolution, the most famous essay is by Stephen Jay Gould: "Evolution as Fact and Theory" and the latest explanation is an article in the New York Times by Carl Zimmer: In Science, It’s Never ‘Just a Theory’.

Unfortunately, it's not that simple and there are many scientists who use "theory" in the sense of hypothesis or speculation [see Facts and theories of evolution according to Dawkins and Coyne]. That's not what I want to talk about today.

What do scientists really mean when they refer to "The Theory of Evolution"? There is no single theory of evolution that covers all the mechanisms of evolution. There's the Theory of Natural Selection, and Neutral Theory, and the Theory of Random Genetic Drift, and a lot of theoretical population genetics. Sometimes you can lump them all together by referring to the Modern Synthesis or Neo-Darwinism. These terms are much more accurate than simply saying "The Theory of Evolution" as long as we all understand what those theories mean.

The problem with "The Theory of Evolution" is not only that it's ambiguous but it's misleading. It implies that there's only one theory to explain evolution. Another problem is that it sounds too much like we're talking about the history of life and saying that it's a "theory" that can be explained by evolution.

Instead of using the phrase "The Theory of Evolution," I think we should be referring to "evolutionary theory," which may come in different flavors. The term "evolutionary theory" encompasses a bunch of different ideas about the mechanisms of evolution and conveys a much more accurate description of the theoretical basis behind evolution. Douglas Futuyma prefers "evolutionary theory" in his textbook Evolution and I think he's right. It allows him to devote individual chapters to "The Theory of Random Genetic Drift" and "The Theory Natural Selection."

Here's how Futuyma explains the concept of theory in his book Evolution 2nd ed. p. 613.
So is evolution a fact or a theory? In light of these definitions, evolution is a scientific fact. That is, descent of all species, with modification, from common ancestors is a hypothesis that in the past 150 years or so has been supported by so much evidence, and so successfully resisted all challenges, that it has become a fact. But this history of evolutionary change is explained by evolutionary theory, the body of statements (about mutation, selection, genetic drift, developmental constraints, and so forth) that together account for the various changes that organisms have undergone. [my emphasis ... LAM]
He makes the same point in the opening pages of his book where he uses both terms when discussing the history of evolutionary theory. (Note that when Darwin used the word "theory" to describe natural selection he was not using it in the same sense as Gould and Zimmer to describe a modern scientific theory. That's why Futuyma uses "hypothesis" in the quote below.)
We now know that Darwin's hypothesis of natural selection on hereditary variation was correct, but we also know that there are more causes of evolution than Darwin realized, and that natural selection and hereditary variation themselves are more complex than he imagined. A body of ideas about the causes of evolution, including mutation, recombination, gene flow, isolation, random genetic drift, the many forms of natural selection, and other factors, constitute our current theory of evolution, or "evolutionary theory." Like all theories in science, it is a work in progress, for we do not yet know the causes of all of evolution, or all the biological phenomena that evolutionary biology will have to explain. Indeed, some details may turn out to be wrong. But the main tenets of the theory, as far as it goes, are so well supported that most biologists confidently accept evolutionary theory as the foundation of the science of life. p. 14 [my emphasis ... LAM]
When you're talking about the mechanisms of evolution, please use "evolutionary theory" instead of "the theory of evolution."

I wish the proponents of the Extended Evolutionary Synthesis would agree that the version of evolutionary theory they wish to extend is the one described by Douglas Futuyma. This would make it easier for them to explain what's wrong with that version and why their proposals are an improvement [see Templeton gives $8 million to prove that there's more to evolution than natural selection].


Thursday, January 28, 2016

"The Selfish Gene" turns 40

Richard Dawkins published The Selfish Gene 40 years ago and Matt Ridley notes the anniversary in a Nature article published today (Jan. 28, 2016): In retrospect: The selfish gene.

I don't remember when I first read it—probably the following year when the paperback version came out. I found it quite interesting but I was a bit put off by the emphasis on adaptation (taken from George Williams) and the idea of inclusive fitness (from W.D. Hamilton). I also didn't much like the distinction between vehicles and replicators and the idea that it was the gene, not the individual, that was the unit of selection ("selection" not "evolution").
It is finally time to return to the problem with which we started, to the tension between individual organism and gene as rival candidates for the central role in natural selection...One way of sorting this whole matter out is to use the terms ‘replicator’ and ‘vehicle’. The fundamental units of natural selection, the basic things that survive or fail to survive, that form lineages of identical copies with occasional random mutations, are called replicators. DNA molecules are replicators. They generally, for reasons that we shall come to, gang together into large communal survival machines or ‘vehicles’.

Richard Dawkins

Saturday, January 23, 2016

Richard Dawkins makes a mistake when describing why gene trees are evidence of evolution

Back in 2010, Richard Dawkins was answering questions on Reddit and one of the questions was "Out of all the evidence used to support the theory of evolution, what would you say is the strongest, most irrefutable single piece of evidence in support of the theory."

There are several ways to answer this question. Personally, I would take a minute to explain the difference between the "theory of evolution" and the history of life. I would point out that evolutionary theory includes things like Darwin's natural selection and there is overwhelming evidence proving that natural selection exists and operates today. The entire field of population genetics, which included other mechanisms of evolution such as random genetic drift, is massively supported by thousands of published papers in the scientific literature. There is absolutely no doubt at all that the current basic tenets of evolutionary theory are correct.

Thursday, December 03, 2015

Facts and theories of evolution according to Dawkins and Coyne

Sometime back in the pre-Cambrian (before blogs) there was a newsgroup called talk.origins—it still exists. In 1993 I wrote a little essay that tried to convince creationists1 of the difference between facts of evolution and evolutionary theory [Evolution is a Fact and a Theory]. I relied heavily on Stephen Jay Gould's essay on "Evolution as Fact and Theory" originally published in Discover magazine in 1981 and re-printed in Hen's Teeth and Horse's Toes.

I updated my thoughts on Gould's essay in 2007 [Evolution Is a Fact and a Theory] and added some more comment on the 30th anniversary [Evolution Is a Fact and a Theory].

Lot's of other people have presented their take on the facts and theories of evolution. Here's one from Richard Lenski and another from Ryan Gregory.

Thursday, November 26, 2015

Quotations

I'm creating a post where I can store quotations so I can link to them from other posts. Enjoy.
The great fear of many leading creationists and the misunderstanding of many creationist students is that accepting MN [methodological naturalism] rules for doing science will necesarily lead to a supernaturalless/Godless worldview.
Brian Alters (2005) p. 77

Persons in this faction [of theists] basically accept evolutionary theory with the proviso that the God of the Bible, not chance, decided the human outcome by directly guiding the process. Such theists are most commonly referred to as theistic evolutionists.
Brian Alters (2005) p. 62

Science reveals where religion conceals. Where religion purports to explain, it actually resorts to tautology. To assert that "God did it" is no more than an admission of ignorance dressed deceitfully as an explanation...
Peter Atkins

The defective design of organisms could be attributed to the gods of the ancient Greeks, Romans, and Egyptians, who fought with one another, made blunders, and were clumsy in their endeavors. But, in my view, it is not compatible with special action by the omniscient and omnipotent God of Judaism, Christianlity, and Islam.
Francisco J. Ayala (2004) p. 71

In conclusion, then, macroevolutionary processes are underlain by microevolutionary phenomena and are compatible with microevolutionary theories, but macroevolutionary studies require the formulation of autonomous hypotheses and models (which must be tested using macroevolutionary evidence). In this (epistemologically) very important sense, macroevolution is decoupled from microevolution: macroevolution is an autonomous field of evolutionary study.
Francisco J. Ayala (1983) p. 131

Science is not committed to the nonexistence of God, as it would be if it were based on metaphysical naturalism. Science is committed to naturalistic explanations. Science does not count any explanation that appeals to God or to supernatural phenomena as a scientific explanation (thus it is committed to methodological naturalism).
Lynn Rudder Baker (2000)

I once made the remark that two things disappeared in 1990: one was communism, the other was biochemistry and that only one of them should be allowed to come back.
Sydney Brenner (2000)

There will be no difficulty in computers being adapted to biology. There will be luddites. But they will be buried.
Sydney Brenner

One of the most frightening things in the Western world, and in this country in particular, is the number of people who believe in things that are scientifically false. If someone tells me that the earth is less than 10,000 years old, in my opinion he should see a psychiatrist.
Francis Crick

The Astonishing Hypothesis is that "You," your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cell and their associated molecules.
Francis Crick (1994)

My own view is that conclusions about the evolution of human behavior should be based on research at least as rigorous as that used in studying nonhuman animals. And if you read the animal behavior journals, you'll see that this requirement sets the bar pretty high, so that many assertions about evolutionary psychology sink without a trace.
Jerry Coyne (2009)

Although I am fully convinced of the truth of the views given in this volume, I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. It is so easy to hide our ignorance under such expressions as "plan of creation," "unity of design," etc., and to think that we give an explanation when we only restate a fact. Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject the theory.
Charles Darwin (1859)

The old argument of design in nature, as given by Paley, which formerly
seemed to me to be so conclusive, fails, now that the law of natural selection has been discovered. We can no longer argue that, for instance, the beautiful hinge of a bivalve shell must have been made by an intelligent being, like the hinge of a door by man. There seems to be no more design in the variability of organic beings and in the action of natural selection, than in the course which the wind blows.

Charles Darwin (c1880)

An atheist before Darwin could have said, following Hume: 'I have no explanation for complex biological design. All I know is that God isn't a good explanation, so we must wait and hope that somebody comes up with a better one.' I can't help feeling that such a position, though logically sound, would have left one feeling pretty unsatisfied, and that although atheism might have been logically tenable before Darwin, Darwin made it possible to be an intellectually fulfilled atheist.
Richard Dawkins

Theologians, if they want to remain honest, should make a choice. You can claim your own magisterium, separate from science's but still deserving of respect. But in that case you have to renounce miracles. Or, you can keep your Lourdes and your miracles ... But then you must kiss goodbye to separate magisteria and your high-minded aspiration to converge on science. The desire to have it both ways is not surprising in a good propagandist. What is surprising is the readiness of liberal agnostics to go along with it; and their readiness to write off, as simplistic, insensitive extremists, those of us with the temerity to blow the whistle.
Richard Dawkins (2003) p.150

It is absolutely safe to say that if you meet someone who claims not to believe in evolution, that person is ignorant, stupid or insane (or wicked, but I'd rather not consider that).
Richard Dawkins (1989)

... those evolutionists who see no conflict between evolution and their religious beliefs have been careful not to look as closely as we have been looking, or else hold a religious view that gives God what we might call a merely ceremonial role to play.
Daniel C. Dennett (1995) p.310

Operational science takes no position about the existence or non-existence of the supernatural; it only requires that this factor is not to be invoked in scientific explanations. Calling down special-purpose miracles as explanations constitutes a form of intellectual "cheating."
Richard E. Dickerson (1992) p.119

Seen in the light of evolution, biology is, perhaps, intellectually the most satisfying and inspiring science. Without that light it becomes a pile of sundry facts—some of them interesting or curious but making no meaningful picture as a whole.
Theodosius Dobbzhansky (Dobzhansky 1973)

It is wrong to hold creation and evolution as mutually exclusive alternatives. I am a creationist and an evolutionist. Evolution is God's, or Nature's method of creation. Creation is not an event that happened in 4004 BC; it is a process that began some 10 billion years ago and is still under way.
Theodosius Dobbzhansky (Dobzhansky 1973)

Under the conditions described [for Hardy-Weinberg equilibrium], there is a genetic inertia in mendelian populations. Unless mutation, selection, differential migration, certain changes in the mating pattern, or a drop in population size disturbs the equilibrium, there is no change in the genetic structure of the population. To a very large degree, overcoming this inertia (especially changing of the gene frequency) is what is described as "evolution."
Paul R. Ehrlich and Richard W. Holm (1963) p.95

Speciation is critical to conserving the results of both natural selection and genetic drift. Speciation is obviously central to the fate of genetic variation, and a major shaper of patterns of evolutionary change through evolutionary time. It is as if Darwinians—neo- and ulra- most certainly included—care only for the process generating change, and not about its ultimate fate in geological time.
Niles Eldredge (1995) p.106

Macroevolution is more than repeated rounds of microevolution.
Douglas H. Erwin (2000)

Just as mutation and drift introduce a strong random component into the process of adaptation, mass extinctions introduce chance into the process of diversification. This is because mass extinctions are a sampling process analogous to genetic drift. Instead of sampling allele frequenceis, mass extinctions samples species and lineages. ... The punchline? Chance plays a large role in the processes responsible for adaptation and diversity.
Freeman and Herron (1998) p.520

It is naïve to think that if a species' environment changes the species must adapt or else become extinct.... Just as a changed environment need not set in motion selection for new adaptations, new adaptations may evolve in an unchanging environment if new mutations arise that are superior to any pre-existing variations.
Douglas Futuyma

There is no justification for teaching creationism in the science classroom. But if it were taught, would it be subjected to the same critical analysis as the creationists insist should be brought to bear on evolution?
Douglas J. Futuyma (1982) p.217

I have championed contingency, and will continue to do so, because its large realm and legitimate claims have been so poorly attended by evolutionary scientists who cannot discern the beat of this different drummer while their brains and ears remain tuned to only the sounds of general theory.
Stephen Jay Gould (2002) p. 1339

The essence of Darwinism lies in its claim that natural selection creates the fit. Variation is ubiquitous and random in direction. It supplies raw material only. Natural selection directs the course of evolutionary change.
Stephen Jay Gould (1980)

Progress is a noxious, culturally embedded, untestable, nonoperational, intractable idea that must be replaced if we wish to understand the patterns of history.
Stephen Jay Gould (1988)

The shift of gene frequencies in local populations is an adequate model for all evolutionary processes—or so the current orthodoxy states.
Stephen Jay Gould (1980) p. 187

Rudyard Kipling asked how the leopard got its spots, the rhino its wrinkled skin. He called his answers "just-so stories." When evolutionists try to explain form and behavior, they also tell just-so stories—and the agent is natural selection. Virtuosity in invention replaces testability as the criterion for acceptance.
Stephen Jay Gould (1980)

Since 'change of gene frequencies in populations' is the 'official' definition of evolution, randomness has transgressed Darwin's border and asserted itself as an agent of evolutionary change.
Stephen Jay Gould (1983) p. 335

The first commandment for all versions of NOMA might be summarized by stating: "Thou shalt not mix the magisteria by claiming that God directly ordains important events in the history of nature by special interference knowable only through revelation and not accessible to science." In common parlance, we refer to such special interference as "miracle"—operationally defined as a unique and temporary suspension of natural law to reorder the facts of nature by divine fiat.
Stephen Jay Gould (1999) p. 84

[My diagram] accepts the Darwinian contention that microevolutionary modes and principles can build grand patterns by cumulation through geological immensity, but rejects the argument that such extrapolations can render the entire panoply of phenomena in life's history without adding explicitly macroevolutionary modes for distinctive expression of these processes at higher tiers of time ...
Stephen Jay Gould (2002) p. 21

The world is not inhabited exclusively by fools, and when a subject arouses intense interest, as this one has, something other than semantics is usually at stake.
Stephen Jay Gould (1982)

We wish to question a deeply engrained habit of thinking among students of evolution. We call it the adaptationist programme, or the Panglossian paradigm.
S.J. Gould & R.C. Lewontin (1979) p. 584

We welcome the richness that a pluralist approach, so akin to Darwin's spirit, can provide.
S.J. Gould & R.C. Lewontin (1979) p. 584

My practise as a scientist is atheistic. That is to say, when I set up an experiment I assume that no god, angel, or devil is going to interfere with its course; and this assumption has been justified by such success as I have achieved in my professional career. I should therefore be intellectually dishonest if I were not also atheistic in the affairs of the world. And I should be a coward if I did not state my theoretical views in public.
J.B.S. Haldane

Since religion ... stands or falls with the question of cosmic purpose, the Darwinian debunking of design—and with it the apparent undoing of cosmic teleology as well—strikes right at the heart of the most prized religious intuition of humans, now and always.
John F. Haught (2004) p. 230

Whatever the God implied by evolutionary theory may be like, He is not the Protestant God of waste not, want not. He is also not a loving God who cares about his productions. He is not even the awful God portrayed in the book of Job. The God of the Galapagos is careless, wasteful, indifferent, almost diabolical. He is certainly not the sort of God to whom anyone would be inclined to pray.
David I. Hull (1991) p. 486

Johnson finds the commitment of scientists to totally naturalistic explanations dogmatic and close-minded, but scientists have no choice. Once they allow reference to God or miraculous forces to explain the first origin of life or the evoluton of the human species, they have no way of limiting this sort of explanation.
David I. Hull (1991) p. 486

This evolutionary procedure —the formation of a dominant neocortex coupled with the persistence of a nervous and hormonal system partially, but not totally, under the rule of the neocortex—strongly resembles the tinkerer's procedure. It is somewhat like adding a jet engine to an old horse cart. It is not surprising ... that accidents, difficulties, and conflicts can occur.
François Jacob (1977) p.1166
Jacob, F. (1977) Evolution and Tinkering Sci. 196:1161-1166.

Natural selection has no analogy with any aspect of human behavior. However, if one wanted to play with a comparison, one would have to say that natural selection does not work as an engineer works. It works like a tinkerer—a tinkerer who does not know exactly what he is going to produce but uses whatever he finds around him whether it be pieces of string, fragments of wood, or old cardboards; in short it works like a tinkerer who uses everything at his disposal to produce some kind of workable object.
François Jacob (1977) p.1163

It is hard to realize that the living world as we know it is just one among many possibilities; that its actual structure results from the history of the earth. Yet living organisms are historical structures: literally creations of history. They represent, not a perfect product of engineering, but a patchwork of odd sets pieced together when and where opportunities arose. For the opportunism of natural selection is not simply a matter of indifference to the structure and operation of its products. It reflects the very nature of a historical process full of contingency.
François Jacob (1977) p.1166

Ecologists and microevolutionists are beginning to appreciate the importance of events over larger time scales than the decades or centuries that are their usual bounds, and a new effort is needed from both neontological and paleontological sides to get beyond a simple extrapolation of ecological phenomena into macroevolutionary time scales.
Jablonski, D. et al (1997)

Many biochemists find it easy to accept the concept that large portions of protein molecules serve mainly to bring the molecule up to suitable size and shape and have very little specific function as compared with small specialized active sites. Most of a protein molecule, according to this concept, can evolve freely by random drift
Thomas H. Jukes (1980) p.204

In conclusion, I would like to emphasize the importance of random genetic drift as a major cause of evolution. We must be liberated, so to speak, from the selective constraint posed by the neo-Darwinian (or the synthetic) theory of evolution.
Motoo Kimura (1991)

In contrast to the Darwinian theory of evolution by natural selection, the neutral theory emphasizes the great importance of random genetic drift (due to finite population size) and mutation pressure as the main causes of molecular evolution.
Motoo Kimura (1991)

According to the neutral mutation–random drift hypothesis of molecular evolution and polymorphism1,2, most mutant substitutions detected through comparative studies of homologous proteins (and the nucleotide sequences) are the results of random fixation of selectively neutral or nearly neutral mutations. This is in sharp contrast to the orthodox neo-Darwinian view that practically all mutant substitutions occurring within species in the course of evolution are caused by positive Darwinian selection.
Motoo Kimura (1977)

Calculating the rate of evolution in terms of nucleotide substitutions seems to give a value so
high that many of the mutations involved must be neutral ones

Motoo Kimura 1968

Selective elimination of definitely deleterious mutants and random fixation of selectively neutral or very slightly deleterious mutants occur far more frequently in evolution than positive Darwinian selection of definitely advantageous mutants.
Motoo Kimura and Tomoko Ohta (1974)

The main tenet of the neutral theory is that the great majority of evolutionary changes at the molecular level are caused not by Darwinian selection but by random fixation of selectively neutral (or very nearly neutral) alleles through random sampling drift under continued mutation pressure.
Motoo Kimura (1989)

There appears to be considerable latitude at the molecular level for random genetic changes that have no effect upon the fitness of the organism. Selectively neutral mutations, if they occur, become passively fixed as evolutionary changes through the action of random genetic drift.
J.L King and T.H. Jukes (1969) p.789

The idea of selectively neutral change at the molecular level has not been readily accepted by many classical evolutionists, perhaps because of the pervassiveness of Darwinian thought.
J.L King and T.H. Jukes (1969) p.788

The suggestion that macroevolution should be divorced from microevolution provides Creationists only with a debating point. It allows Creationists to say that there are some evolutonary theorists who distinguish the mechanisms studied in classical population genetics from those they take to be involved in large-scale evolutionary change ... But this is not to suppose that the distinction drawn by heterodox evolutionists is that favored by the Creationists.
Philip Kitcher (1982) p.150

Overheard at breakfast on the final day of a recent scientific meeting: "Do you believe in macroevolution?" Came the reply: "Well, it depends on how you define it.".
Roger Lewin (1980) p.884.

The central question of the Chicago conference was whether the mechanisms underlying microevolution can be extrapolated to explain the phenomena of macroevolution. At the risk of doing violence to the positions of some of the people at the meeting, the answer can be given as a clear, No.
Roger Lewin (1980) p.884.

The fact is that almost the entire theoretical apparatus of random genetic drift and directional selection can be derived from a haploid model of the genome and that the introduction of diploidy and sexual recombination makes no qualitative chane and only trivial quantitative changes in the predictions of evolution under these forces.
Richard C. Lewontin (1974) p.83

The [neoclassical] theory does not deny adaptive evolution but only that the vast quantity of molecular variation within populations and, consequently, much of the molecular evolution among species, has anything to do with that adaptive process
Richard C. Lewontin (1974) p.85

The false view of evolution as a process of global optimizing has been applied literally by engineers who, taken in by a mistaken metaphor, have attempted to find globally optimal solutions to design problems by writing programs that model evolution by natural selection.
Richard Lewontin

Evolution is a process of change in the genetic makeup of populations, with the most basic component being change in allele frequencies with time.
Wen-Hsiung Li (1997) p.35

... the independence of macroevolution is affirmed not only by species selection but also by other processes such as effect sorting among species.
Bruce S. Lieberman and Elisabeth S. Vrba (2005)

Macroevolution is given expanded meaning by punctuated equilibrium, which is a theory more about species and their reality and individuality (sensu Hull 1980) than about speciation.
Bruce S. Lieberman and Elisabeth S. Vrba (2005)

The universe doesn't seem to me to be like the kind of entity that could have a higher purpose. I literally don't know what it would mean to say that the universe has a higher purpose. But I also have to say just simply as far as my own personal experience is concerned I have not found it a depressing doctrine. I do not find myself in the least depressed by feeling that if there is a purpose it's a purpose in my friends in my people I love and myself and human beings. It's a product of human beings it's not something that's sort of you know comes out the physical universe because the universe was created.
John Maynard Smith (1998)

Molecular genetics has found that mutations frequently occur in which the new allele produces no change in the fitness of the phenotype. Kimura (1983) has called the occurrence of such mutations neutral evolution, and others have referred to it as non-Darwinian evolution. Both terms are misleading. Evolution involves the fitness of individuals and populations, not of genes. When a genotype, favored by selection, carries along as hitchhikers a few newly arisen and strictly neutral alleles, it has no influence on evolution. This may be called evolutionary 'noise' but it is not evolution. However, Kimura is correct in pointing out that much of the molecular variation of the genotype is due to neutral mutations. Having no effect on the phenotype, they are immune to selection.
Ernst Mayr (2001) p.199

... I pointed out more than a decade ago (1977) that 'the reductionist explanation, so widely adopted in recent decades— Evolution is a change in gene frequencies in populations—is not only not explanatory, but is in fact misleading. Far more revealing is the definition: 'Evolution is change in the adaptation *and* in the diversity of populations of organisms.'
Ernst Mayr (2001) p.162

Neither the discovery of numerous new facts relating to evolution nor the development of new concepts of speciation and genetic variation have required any essential revision of the picture of evolution as developed during the evolutionary synthesis. I emphatically deny the claims of various authors that these recent developments have led to an end of Darwinism, or of neo-Darwinism, or of the evolutionary synthesis.
Ernst Mayr (1988) p.191

The attack directed by Gould and Lewontin against unsupported adaptationist explanations in the literature is fully justified. But the most absurd among these claims were made several generations ago, not by modern evolutionists.
Ernst Mayr (1988) p.152

[referring to Tielhard de Chardin] ... it's author can be accused of dishonesty only on the grounds that before deceiving others he has taken great pains to deceive himself.
Peter Medawar (1961) p.1

Although not completely random, chance does affect which mutations, which mistakes, appear in which individuals. ... this inherent unpredictability is not a matter of inadequate scientific knowledge. Rather, it is a reflection that the behavior of matter itself is indeterminate, and therefore unpredictable. It is one of the reasons why we cannot predict, with any detailed certainty, the future path of evolution.
Kenneth R. Miller (1999) p. 233

... evolution is as much a fact as anything we know in science. It is a fact that we humans did not appear suddenly on this planet, de novo creations without ancestors, and it is a fact that the threads of ancestry are clear for us and for hundreds of other species and groups.
Kenneth R. Miller (1999) p. 233

No question about it. Rewind that tape, let it run again, and events might come out differently at every turn. Surely this means that mankind's appearance on this planet was not preordained, that we are here not as the products of an inevitable procession of evolutionary success, but as an afterthought, a minor detail, a happenstance in a history that might just as well have left us out. I agree.
Kenneth R. Miller (1999) p. 233

In any discussion of the question of "Intelligent Design," it is absolutely essential to determine what is meant by the term itself. If, for example, the advocates of design wish to suggest that the intricacies of nature, life, and the universe reveal a world of meaning and purpose consistent with an overarching, possibly Divine, intelligence, then their point is philosophical, not scientific. It is a philosophical point of view, incidentally, that I share, along with many scientists.
Kenneth R. Miller (2004) p. 94

The thesis I shall present in this book is that the biosphere does not contain a predictable class of objects or of events but constitutes a particular occurrence, compatible indeed with first principles, but not deducible from those principles and therefore essentially unpredictable.
Jacques Monod (1971) p.43

All religions, nearly all philosophies, and even a part of science testify to the unwearying, heroic effort of mankind desperately denying its own contingency."
Jacques Monod (1971) p.44

Another curious aspect of the theory of evolution is that everybody thinks he understands it. I mean philosophers, social scientists, and so on. While in fact very few people understand it, actually, as it stands, even as it stood when Darwin expressed it, and even less as we now may be able to understand it in biology.
Jacques Monod (1974)

... I must correct a wrong idea that has been spreading for the past three or four years. It was discovered some years ago that in some cases, the transcription of step from DNA to RNA works in the reverse direction. That is nothing surprising. ... it could be predicted that such events could occur. They do occur, indeed, but this must not be taken to mean that information from protein could possibly go back to the genome. ... I am ready to take any bet you like that this is never going to turn out to be the case.
Jacques Monod (1974) p.394

The privilege of living beings is the possession of a structure and of a mechanism which ensures two things: (i) reproduction true to type of the structure itself, and (ii) reproduction equally true to type, of any accident that occurs in the structure. Once you have that, you have evolution, because you have conservation of accidents. Accidents can then be recombined and offered to natural selection to find out if they are of any meaning or not.
Jacques Monod (1974) p.394

The aspect of evolutionary theory that is unacceptable to many enlightened people, either scientists or philosophers, or idelogists of one kind or another, is the completely contingent aspect which the existence of man, societies, and so on, must take if we accept this theory.
Jacques Monod (1974) p.394

We must conclude that the existence of any particular species is a singular event, an event that occurred only once in the whole of the universe and therefore one that is also basically and completely unpredictable, including that one species which we are, namely man.
Jacques Monod (1974) p.395

While de Vries' and Goldschmidt's views on the origin of species were extreme and unrealistic, from our current knowledge of genetics, de Vries' ideas led Morgan (1925, 1932) to propose a more resonable theory of evolution. ... In his view, selection plays a less important role than mutation, its chief role being to preserve useful mutations and eliminate unfit genotypes. That is, natural selection is regarded merely as a sieve to choose beneficial mutations. For this reason, his theory is often called mutationism, but a better terminology would be mutation-selection theory or classical theory in Dobzansky's sense, since he did not neglect natural selection.
Masatoshi Nei (1987) p.406

At the DNA level, most new genes seem to have been produced by gene duplication and subsequent nucleotide changes .... In these cases, the mutational change of DNA (duplication and nucleotide substitution) is clearly responsible for creating a new gene of character. Natural selection plays no such role. The role of natural selection is to eliminate less fit genotypes and save a beneficial one when there are many different genotypes in the same environment. Therefore, it seems clear that at the molecular level evolution occurs primarily by mutation pressure, though positive selection certainly speeds up gene substitution in populations.
Masatoshi Nei (1987) p.415

... are all individual differences in morphological and physiological characters adaptive as claimed by extreme neo-Darwinians? More than 4 billion people live on this planet, and all of them except identical twins are different with respect to morphological and physiological characters. Are all these differences adaptive? Is random genetic drift unimportant for generating morphological and physiological diversity among organisms? It seems to me that in some morphological characters a substantial part of genetic variation is nonadaptive.
Masatoshi Nei (1987) p.422

In this book, I have examined various aspects of molecular evolution and concluded that mutation is the driving force of evolution at the molecualr level. I have also extended this view to the level of phenotypic evolution and speciation, though I do not deny the importance of natural selection in evolution. I have challenged the prevailing view that a population of organisms contains virtually all sorts of variation and that the only force necessary for a particular character to evolve is natural selection. I have also emphasized the unpredictability of the evolutionary fate of organisms caused by uncontrolable external factors such as rapid climatic changes, geological catastrophes, or even asteroid impacts.
Masatoshi Nei (1987) p.431

The primary cause of evolution is the mutational change of genes. A mutant gene or DNA sequence caused by nucleotide substitution, insertions/delections, recombination, gene conversion, and so forth may spread through the population by genetic drift and/or natural selection and eventually be fixed in the species.
Masatoshi Nei and Sudhir Kumar (2000) p.4

Most new mutations are deleterious, and most mutations with very small effects are likely to be very slightly deleterious. Such mutations are selected against in large populations, but behave as if neutral in small populations.
Tomoko Ohta (1996) p.96

Mutation is a fundamental process for evolution. Under the orthodox view, mutations are raw materials on which natural selection works and organismal evolution is mainly governed by selection. With the accumulation of molecular data, the importance of random drift is being reevaluated. If the effect of a mutant is very small, random drift rather than selection determines its fate.
Tomoko Ohta (1998) p.83

Are we here because of a natural superiority (opposable thumbs, big brains and so on), or are we just plain lucky? In other words, is the evolution of life a fair game, as the survival-of-the-fittest doctrine so strongly implies?
David Raup (1991) p.xi

Is extinction through bad luck a challenge to Darwin's natural selection? No. Natural selection remains the only viable, naturalistic explanation we have for sophisticated adaptations like eyes and wings. We would not be here without natural selection. Extinction by bad luck merely adds another element to the evolutionary process, operating at the level of species, families, and classes, rather than the level of local breeding populations of single species. Thus, Darwinism is alive and well, but, I submit, it cannot have operated by itself to produce the diversity of life today.
David Raup (1991) p.192

Evolution at the molecular level appeared to have properties that would not have been predicted if it were driven by natural selection; and much of molecular evolution is now widely (if not universally) thought to be non-adaptive.
Mark Ridley (1997) p.4

A habit has grown up among some molecular biologists of using homology to mean similarity, regardless of whether the similarity is due to descent from a common ancestor. They thus talk about the "% homology" between two molecules, meaning the percentage of amino acid, or nucleotide sites that are the same in the two molecules. They are often criticized for their unorthodox usage .
M. Ridley (1997) p.208

The working biologist's reaction on learning that evolutionary theory does not fit some philosophical criterion for what a scientific theory should be like is—so much the worse for philosophy.
M. Ridley (1997) p.368

... Kimura's original radical claim, that most molecular evolution proceeds by drift, not selection, remains intact in the nearly neutral theory. It still contrasts strongly with the view that molecular evolution is powered by Darwinian natural selection.
M. Ridley (1997) p.78

Many universes can exist, with all possible combinations of physical laws and constants. In that sense, we just happen to be in the particular one that was suited for the the evolution of our form of life. When cosmologists refer to the anthropic principle, this is all they usually mean. Since we live in this universe, we can assume it possesses qualities suitable for our existence.
Eugenie C. Scott (2004)

... the thesis that evolution is primarily driven by natural selection is sometimes called Darwinism. Unfortunately, many people misapply the term to refer to the concept of descent with modification itself, which is erroneous. Natural selection is not the same as evolution.
Eugenie C. Scott (2004) p.34

Scientists sometimes colloquially refer to macroevolution as "evolution above the species level," but this term does not do justice to the complexity of topics included within the concept.
Eugenie C. Scott (2004) p.183

Micro- and macroevolution are thus different levels of analysis of the same phenomenon: evolution. Macroevolution cannot solely be reduced to microevolution because it encompasses so many other phenomena: adaptive radiation, for example, cannot be reduced only to natural selection, though natural selection helps bring it about.
Eugenie C. Scott (2004) p.183

If God is intervening into our world, he must be doing so in some measurable way. That's what we do with science. We measure.
Michael Shermer (2006)

If a sect does officially insist that its structure of belief demands that evolution be false, then no compromise is possible. An honest and competent biology teacher can only conclude that the sect's beliefs are wrong and that its religion is a false one.
George Gaylord Simpson (1964)

I do not think that evolution is supremely important because it is my speciality. On the contrary, it is my speciality because it is supremely important.
George Gaylord Simpson (1961)

The extreme view that evolution is basically or over all an orthogenetic process is evidence that some scientists' minds tend to move in straight lines, not that evolution does.
George Gaylord Simpson (1949)

Macroevolution is decoupled from microevolution, and we must envision the process governing its course as being analogous to natural selection but operating at a higher level of organization.
Steven M. Stanley (1975) p.648

The microevolutionary process that adequately describes evolution in a population is an utterly inadaquate account of the evolution of the earth's biota. It is inadequate because the evolution of the biota is more than the mutational origin and subsequent survival or extinction of genes in gene pools. Biotic evolution is also the cladogenetic origin and subsequent survival and extinction of gene pools in the biota.
George C. Williams (1992) p.31

I'm not going to be one of these scientists who keep wafling and saying "oh well, science has it's role, religion has it's role... science has it's own kind of truth and religion has it's own kind of truth... somehow, as we work more and more they will somehow come together." I don't believe that for a minute. I don't think that Darwin would have believed it.
Edward O. Wilson

The fundamantal evolutionary event is a change in the frequency of genes and chromosome configurations in a population. If a population of butterflies shifts through time from 40 percent blue individuals to 60 percent individuals, and if the color blue is hereditary, evolution of a simple kind has occurred.
Edward O. Wilson (1992) p.75

That evolution involves nonadaptive differentiation to a large extent at the subspecies level is indicated by the kinds of differences by which such groups are actually distinguished by systematicists. It is only at the subfamily and family levels that clear-cut adaptive differences become the rule. The principal evolutionary mechanisms in the origin of species must thus be an essentially nonadaptive one.
Sewell Wright (1932) p.38

(concerning more evidence for evolution) Some beating of dead horses may be ethical, where here and there they display unexpected twitches that look like life.
Emile Zuckerkandl and Linus Pauling (1965) p.101


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Wednesday, November 25, 2015

Selfish genes and transposons

Back in 1980, the idea that large fractions of animal and plant genomes could be junk was quite controversial. Although the idea was consistent with the latest developments in population genetics, most scientists were unaware of these developments. They were looking for adaptive ways of explaining all the excess DNA in these genomes.

Some scientists were experts in modern evolutionary theory but still wanted to explain "junk DNA." Doolittle & Sapienza, and Orgel & Crick, published back-to-back papers in the April 17, 1980 issue of Nature. They explained junk DNA by claiming that most of it was due to the presence of "selfish" transposons that were being selected and preserved because they benefited their own replication and transmission to future generations. They have no effect on the fitness of the organism they inhabit. This is natural selection at a different level.

This prompted some responses in later editions of the journal and then responses to the responses.

Here's the complete series ...

Sunday, November 22, 2015

What do pseudogenes teach us about intelligent design?

The human genome has about 14,000 pseudogenes that are derived from protein-coding genes and an unknown number derived from genes that specify functional noncoding RNAs. There is abundant evidence that the vast majority of these pseudogenes are nonfunctional by all measurable criteria.
It would be perverse to deny the existence of pseudogenes. Almost all of them are junk DNA with no known function. Anyone who claims otherwise can be dismissed as a kook and it's not worth debating those people.

The presence of a single well-characterized pseudogene at the same locus in the genomes of different species is powerful evidence of common descent. For example, Ken Miller has long argued that the existence of common pseudogenes in chimpanzees and humans is solid evidence that the two species share a common ancestor. He uses the β-globin pseudogene and the gene for making vitamin C as examples in Only a Theory: Evolution and the Battle for America's Soul.

Wednesday, July 29, 2015

Michael Lynch on modern evolutionary theory

Of the Five Things You Should Know if You Want to Participate in the Junk DNA Debate, the most difficult to explain is "Modern Evolutionary Theory." Most scientists think they understand evolution well enough to engage in the debate about junk DNA. However, sooner or later they will mention that junk DNA should have been deleted by selection if it ever existed. You can see that their worldview leads them to believe that everything in biology has an adaptive function.

It's been a few years since I posted Michael Lynch's scathing comments on panadaptationism and how it applies to understanding genomes [Michael Lynch on Adaptationism and A New View of Evolution]. You're in for a treat today.

Here's what you need to know about evolution in order to discuss junk DNA. The first quotation is from the preface to The Origins of Genome Architecture (pages xiii-xiv). The second quotations are from the last chapter (page 366 and pages 368-369.
Contrary to popular belief, evolution is not driven by natural selection alone. Many aspects of evolutionary change are indeed facilitated by natural selection, but all populations are influenced by nonadaptive forces of mutation, recombination, and random genetic drift. These additional forces are not simple embellishments around a primary axis of selection, but are quite the opposite—they dictate what natural selection can and cannot do. Although this basic principle has been known for a long time, it is quite remarkable that most biologists continue to interpret nearly aspect of biodiversity as an outcome of adaptive processes. This blind acceptance of natural selection as the only force relevant to evolution has led to a lot of sloppy thinking, and is probably the primary reason why evolution is viewed as a soft science by much of society.

A central point to be explained in this book is that most aspects of evolution at the genome level cannot be fully explained in adaptive terms, and moreover, that many features could not have emerged without a near-complete disengagement of the power of natural selection. This contention is supported by a wide array of comparative data, as well as by well-established principles of population genetics. However, even if such support did not exist, there is an important reason for pursuing nonadaptive (neutral) models of evolution. If one wants to confidently invoke a specific adaptive scenario to explain an observed pattern of comparative data, then an ability to reject a hypothesis based entirely on the nonadaptive forces of evolution is critical.

The blind worship of natural selection is not evolutionary biology. It is arguably not even science.

Michael Lynch
Despite the tremendous theoretical and physical resources now available, the field of evolutionary biology continues to be widely perceived as a soft science. Here I am referring not to the problems associated with those pushing the view that life was created by an intelligent designer, but to a more significant internal issue: a subset of academics who consider themselves strong advocates of evolution but who see no compelling reason to probe the substantial knowledge base of the field. Although this is a heavy charge, it is easy to document. For example, in his 2001 presidential address to the Society for the Study of Evolution, Nick Barton presented a survey that demonstrated that about half of the recent literature devoted to evolutionary issues is far removed from mainstream evolutionary biology.

With the possible exception of behavior, evolutionary biology is treated unlike any other science. Philosophers, sociologists, and ethicists expound on the central role of evolutionary theory in understanding our place in the world. Physicists excited about biocomplexity and computer scientists enamored with genetic algorithms promise a bold new understanding of evolution, and similar claims are made in the emerging field of evolutionary psychology (and its derivatives in political science, economics, and even the humanities). Numerous popularizers of evolution, some with careers focused on defending the teaching of evolution in public schools, are entirely satisfied that a blind adherence to the Darwinian concept of natural selection is a license for such activities. A commonality among all these groups is the near-absence of an appreciation of the most fundamental principles of evolution. Unfortunately, this list extends deep within the life sciences.

....

... the uncritical acceptance of natural selection as an explanatory force for all aspects of biodiversity (without any direct evidence) is not much different than invoking an intelligent designer (without any direct evidence). True, we have actually seen natural selection in action in a number of well-documented cases of phenotypic evolution (Endler 1986; Kingsolver et al. 2001), but it is a leap to assume that selection accounts for all evolutionary change, particularly at the molecular and cellular levels. The blind worship of natural selection is not evolutionary biology. It is arguably not even science. Natural selection is just one of several evolutionary mechanisms, and the failure to realize this is probably the most significant impediment to a fruitful integration of evolutionary theory with molecular, cellular, and developmental biology.

Natural selection is just one of several evolutionary mechanisms, and the failure to realize this is probably the most significant impediment to a fruitful integration of evolutionary theory with molecular, cellular, and developmental biology.It should be emphasized here that the sins of panselectionism are by no means restricted to developmental biology, but simply follow the tradition embraced by many areas of evolutionary biology itself, including paleontology and evolutionary ecology (as cogently articulated by Gould and Lewontin in 1979). The vast majority of evolutionary biologists studying morphological, physiological, and or behavioral traits almost always interpret the results in terms of adaptive mechanisms, and they are so convinced of the validity of this approach that virtually no attention is given to the null hypothesis of neutral evolution, despite the availability of methods to do so (Lande 1976; Lynch and Hill 1986; Lynch 1994). For example, in a substantial series of books addressed to the general public, Dawkins (e,g., 1976, 1986, 1996, 2004) has deftly explained a bewildering array of observations in terms of hypothetical selection scenarios. Dawkins's effort to spread the gospel of the awesome power of natural selection has been quite successful, but it has come at the expense of reference to any other mechanisms, and because more people have probably read Dawkins than Darwin, his words have in some ways been profoundly misleading. To his credit, Gould, who is also widely read by the general public, frequently railed against adaptive storytelling, but it can be difficult to understand what alternative mechanisms of evolution Gould had in mind.


Friday, July 24, 2015

John Parrington discusses pseudogenes and broken genes

We are discussing Five Things You Should Know if You Want to Participate in the Junk DNA Debate and how they are described in John Parrington's book The Deeper Genome: Why there is more to the human genome than meets the eye. This is the fourth of five posts.

1. Genetic load
John Parrington and the genetic load argument
2. C-Value paradox
John Parrington and the c-value paradox
3. Modern evolutionary theory
John Parrington and modern evolutionary theory
4. Pseudogenes and broken genes are junk (this post)
John Parrington discusses pseudogenes and broken genes
5. Most of the genome is not conserved
John Parrington discusses genome sequence conservation

4. Pseudogenes and broken genes are junk

Parrington discusses pseudogenes at several places in the book. For example, he mentions on page 72 that both Richard Dawkins and Ken Miller have used the existence of pseudogenes as an argument against intelligent design. But, as usual, he immediately alerts his readers to other possible explanations ...
However, using the uselessness of so much of the genome for such a purpose is also risky, for what if the so-called junk DNA turns out to have an important function, but one that hasn't yet been identified.
This is a really silly argument. We know what genes look like and we know what broken genes look like. There are about 20,000 former protein-coding pseudogenes in the human genome. Some of them arose recently following a gene duplication or insertion of a cDNA copy. Some of them are ancient and similar pseudogenes are found at the same locations in other species. They accumulate mutations at a rate consistent with neutral theory and random genetic drift. (This is a demonstrated fact.)

It's ridiculous to suggest that a significant proportion of those pseudogenes might have an unknown important function. That doesn't rule out a few exceptions but, as a general rule, if it looks like a broken gene and acts like a broken gene, then chances are pretty high that it's a broken gene.

As usual, Parrington doesn't address the big picture. Instead he resorts to the standard ploy of junk DNA proponents by emphasizing the exceptions. He devotes more that two full pages (pages 143-144) to evidence that some pseudogenes have acquired a secondary function.
The potential pitfalls of writing off elements in the genome as useless or parasitical has been demonstrated by a recent consideration of the role of pseudgogenes. ... recent studies are forcing a reappraisal of the functional role of these 'duds."
Do you think his readers understand that even if every single broken gene acquired a new function that would still only account for less than 2% of the genome?

There's a whole chapter dedicated to "The Jumping Genes" (Chapter 8). Parrington notes that 45% of our genome is composed of transposons (page 119). What are they doing in our genome? They could just be parasites (selfish DNA), which he equates with junk. However, Parrrington prefers the idea that they serve as sources of new regulatory elements and they are important in controlling responses to environmental pressures. They are also important in evolution.

As usual, there's no discussion about what fraction of the genome is functional in this way but the reader is left with the impression that most of that 45% may not be junk or parasites.

Most Sandwalk readers know that almost all of the transposon-related sequences are bits and pieces of transposons that haven't bee active for millions of years. They are pseudogenes. They look like broken transposon genes, they act like broken genes, and they evolve like broken transposons. It's safe to assume that's what they are. This is junk DNA and it makes up almost half of our genome.

John Parrington never mentions this nasty little fact. He leaves his readers with the impression that 45% of our genome consists of active transposons jumping around in our genome. I assume that this is what he believes to be true. He has not read the literature.

Chapter 9 is about epigenetics. (You knew it was coming, didn't you?) Apparently, epigentic changes can make the genome more amenable to transposition. This opens up possible functional roles for transposons.
As we've seen, stress may enhance transposition and, intriguingly, this seems to be linked to changes in the chromatin state of the genome, which permits repressed transposons to become active. It would be very interesting if such a mechanism constituted a way for the environment to make a lasting, genetic mark. This would be in line with recent suggestions that an important mechanism of evolution is 'genome resetting'—the periodic reorganization of the genome by newly mobile DNA elements, which establishes new genetic programs in embryo development. New evidence suggests that such a mechanism may be a key route whereby new species arise, and may have played an important role in the evolution of humans from apes. This is very different from the traditional view of evolution being driven by the gradual accumulation of mutations.
It was at this point, on page 139, that I realized I was dealing with a scientist who was in way over his head.

Parrington returns to this argument several times in his book. For example, in Chapter 10 ("Code, Non-code, Garbage, and Junk") he says ....
These sequences [transpsons] are assumed to be useless, and therefore their rate of mutation is taken to taken to represent a 'neutral' reference; however, as John Mattick and his colleague Marcel Dinger of the Garvan Institute have pointed out, a flaw in such reasoning is 'the questionable proposition that transposable elements, which provide the major source of evolutionary plasticity and novelty, are largely non-functional. In fact, as we saw in Chapter 8, there is increasing evidence that while transposons may start off as molecular parasites, they can also play a role in the creation of new regulatory elements, non-coding RNAs, and other such important functional components of the genome. It is this that has led John Stamatoyannopoulos to conclude that 'far from being an evolutionary dustbin, transposable elements appear to be active and lively members of the genomic regulatory community, deserving of the same level of scrutiny applied to other genic or regulatory features. In fact, the emerging role for transposition in creating new regulatory mechanisms in the genome challenges the very idea that we can divide the genome into 'useful' and 'junk' coomponents.
Keep in mind that active transposons represent only a tiny percentage of the human genome. About 50% of the genome consists of transposon flotsam and jetsam—bits and pieces of broken transposons. It looks like junk to me.

Why do all opponents of junk DNA argue this way without putting their cards on the table? Why don't they give us numbers? How much of the genome consists of transposon sequences that have a biological function? Is it 50%, 20%, 5%?


John Parrington and modern evolutionary theory

We are continuing our discussion of John Parrington's book The Deeper Genome: Why there is more to the human genome than meets the eye. This is the third of five posts on: Five Things You Should Know if You Want to Participate in the Junk DNA Debate

1. Genetic load
John Parrington and the genetic load argument
2. C-Value paradox
John Parrington and the c-value paradox
3. Modern evolutionary theory (this post)
John Parrington and modern evolutionary theory
4. Pseudogenes and broken genes are junk
John Parrington discusses pseudogenes and broken genes
5. Most of the genome is not conserved
John Parrington discusses genome sequence conservation

3. Modern evolutionary theory

You can't understand the junk DNA debate unless you've read Michael Lynch's book The Origins of Genome Architecture. That means you have to understand modern population genetics and the role of random genetic drift in the evolution of genomes. There's no evidence in Parrington's book that he has read The Origins of Genome Architecture and no evidence that he understands modern evolutionary theory. The only evolution he talks about is natural selection (Chapter 1).

Here's an example where he demonstrates adaptationist thinking and the fact that he hasn't read Lynch's book ...
At first glance, the existence of junk DNA seems to pose another problem for Crick's central dogma. If information flows in a one-way direction from DNA to RNA to protein, then there would appear to be no function for such noncoding DNA. But if 'junk DNA' really is useless, then isn't it incredibly wasteful to carry it around in our genome? After all, the reproduction of the genome that takes place during each cell division uses valuable cellular energy. And there is also the issue of packaging the approximately 3 billion base pairs of the human genome into the tiny cell nucleus. So surely natural selection would favor a situation where both genomic energy requirements and packaging needs are reduced fiftyfold?1
Nobody who understands modern evolutionary theory would ask such a question. They would have read all the published work on the issue and they would know about the limits of natural selection and why species can't necessarily get rid of junk DNA even if it seems harmful.

People like that would also understand the central dogma of molecular biology.


1. He goes on to propose a solution to this adaptationist paradox. Apparently, most of our genome consists of parasites (transposons), an idea he mistakenly attributes to Richard Dawkins' concept of The Selfish Gene. Parrington seems to have forgotten that most of the sequence of active transposons consists of protein-coding genes so it doesn't work very well as an explanation for excess noncoding DNA.