Science vs religion in the Princeton Guide to Evolution

The Princeton Guide to Evolution is a collection of 107 articles on various aspect of evolution. The editors felt they should address the obvious conflict between evolution/science and religion. There are at least five different approaches they could have taken.

1. An atheist perspective on the incompatibility of evolution/science and religion. Richard Dawkins or Jerry Coyne would be good choices.
2. An atheist perspective on the compatibility of science and religion (the accommodationist view). Michael Ruse or Nick Matzke are obvious choices.
3. A theist view of the incompatibility of evolution and religion. Phillip Johnson could have explained this view but so could a number of other creationists.
4. A theist explanation of the compatibility of evolution/science as long as they stick to their proper magisteria. Francis Collins, Ken Miller, and several other religious scientists could present their case.
5. The editors could have published four articles representing the main viewpoints or commissioned a single article that would have covered all the angles.

The big advantage of an atheist perspective is that it fairly represents the views of a majority of evolutionary biologists. Having a theist write the article would not be as fair. I think we can all agree that option #5 is by far the best choice.

Before reading any further, take a minute to decide what you would do if you were the editors of The Princeton Guide to Evolution.

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Arlin Stoltzfus explains evolutionary theory

A few days ago, I asked the following questions, Is the "Modern Synthesis" effectively dead?, and What do they mean when they say they want to extend the Modern Synthesis?. The point I was trying to make was that there are many different views on evolutionary theory and it's often difficult to figure out which version of evolutionary theory someone is defending.

For example, which version of evolutionary theory is compatible with the "selfish gene" as a metaphor for evolution? Or for adaptation? Which version of the "Modern Synthesis" is being attacked in the book edited by Massimo Pigliucci and Gerd Müller? Is it the version defended by Ernst Mayr? Does it incorporate Neutral Theory and random genetic drift?

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Is the "Modern Synthesis" effectively dead?

The "Modern Synthesis," or modern evolutionary synthesis, refers to a framework of evolutionary theory developed and promoted by prominent biologists in the 1940s. The term comes from the subtitle of a 1942 book by Julian Huxley. The central theme was the integration of "classic" evolution with population genetics.

Although the original version was fairly broad, the later versions of the "Modern Synthesis" were much less so. The so-called "hardening" of the Modern Synthesis has been documented by many historians; notably, Stephen Jay Gould. By the time of the Darwin Centennial (1959) most biologists thought of the "Modern Synthesis" as a form of Darwinism + population genetics where natural selection was pretty much the only game in town.

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Razib Khan doesn't like Gould and doesn't like new-fangled ideas like "neutralism" and "random genetic drift"

The article by David Dobbs [Die, selfish gene, die] has stirred up a lot of biologists. Some of them (Coyne, Dawkins) pointed out why David Dobbs is wrong about this particular attack on Darwinian ordodoxy while others (PZ Myers) have defended Dobbs.

Razib Khan has weighed in [Evolutionary orthodoxy may be boring, but it is probably true]. I strongly disagree with his post but it's important to be clear about the disagreement. If "evolution orthodoxy" means evolution by natural selection then, yes, it is definitely true. That's not being disputed. The question isn't whether evolution orthodoxy is correct, it's whether it is sufficient.

I'm also not defending the specifics of Dobbs' article. Many of the most recent attempts to extend evolutionary theory are misguided and Dobbs happens to focus on one of these misguided attempts. However, the main point of Dobbs' article was that the "selfish gene" metaphor is an inappropriate metaphor for evolution and I agree strongly with this conclusion even though Dobbs' argument was faulty.

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Steven Pinker defends "neo-Darwinism," whatever that is

Jerry Coyne posted a couple of tweets (see below) from Steven Pinker (photo) at Dawkins responds to Dobbs.

We shouldn't be surprised at the first one since Pinker is an evolutionary psychologist with a strong tendency to adaptationism. I don't know exactly what he means by "neo-Darwinism" (does he?) but I strongly suspect that it's very much like Darwinism. I'd love to know whether he thinks Neutral Theory and random genetic drift have been successful challenges to neo-Darwinism. If not, then it must mean that neo-Darwinism has incorporated those views. In that case, neo-Darwinism must have begun in the 1970s and somebody picked a very bad name for this view of evolutionary theory.

I think it's more likely that Pinker is just not thinking about Neutral Theory and random genetic drift when he says that challenges to neo-Darwinism have all failed to hold water.

The second tweet means that molecular biologists never knew about tRNA genes or ribosomal RNA genes or the genes for other RNAs that have won Nobel Prizes. I find this very surprising. It's true that some biochemists and molecular biologists are a bit behind in their field but I don't think it's fair to say that "molecular biologists" (i.e. the knowledgeable experts in the field) re-defined the word "gene" in that way.

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Die, selfish gene, die!

"Die, selfish gene, die!" is the provocative title of an article by science writer David Dobbs [Die, selfish gene die!].

Dobbs begins with ....

The selfish gene is one of the most successful science metaphors ever invented. Unfortunately, it’s wrong.

The article attracted the attention of Jerry Coyne who effectively dismantles the strange ideas promoted by Dobbs. Read all about it at: David Dobbs mucks up evolution, part I and David Dobbs mucks up evolution, part II.

As it turns out, this is just another example of a science writer who has been mesmerized by the latest effort to overthrow modern evolutionary theory by some scientist promoting their own work. In this case it's Mary Jane West-Eberhard.

But there's a more serious issue here and I'm not sure that Jerry Coyne recognizes it. The selfish gene metaphor can be interpreted in several different ways. Here's how Richard Dawkins describes it in the preface to the 1989 edition of The Selfish Gene.

The selfish gene theory is Darwin's theory, expressed in a way that Darwin did not choose but whose aptness, I should like to think, he would instantly have recognized and delighted in. It is in fact a logical outgrowth of orthodox neo-Darwinism, but expressed as a novel image. Rather than focus on the individual organism, it takes a gene's-eye view of nature.

Lot's of people misunderstand the selfish gene metaphor. They think it means that organisms behave selfishly but that's not what Dawkins meant at all.

Jerry Coyne explains this in his book Why Evolution Is True (p. 226) ....

As Dawkins shows clearly, the "selfish" gene is a metaphor for how natural selection works. Genes act as if they're selfish molecules: those that produce better adaptations act as if they're elbowing out other genes in the battle for future existence. And, to be sure, selfish genes can produce selfish behaviors. But there is also a huge scientific literature on how evolution can favor genes that lead to cooperation, altruism, and even morality.

There are two main criticisms of the selfish gene metaphor and both of them are quite valid. It's the reason why Dawkin's view hasn't caught on the the evolutionary biology textbooks. It usually merits nothing more than a footnote.

The most damning criticism comes from evolutionary biologists who point out that the primary unit of selection is the individual and not the gene. Stephen Jay Gould and Richard Lewontin are prominent opponents of what they see as an unnecessary reductionism in Dawkins' writing. Clearly, hierarchical theory (Gould) is inconsistent with the selfish gene metaphor because evolution can also operate at the level of groups and species (according to Gould and others). There are plenty of other evolutionary biologists who object to selfish genes for these reasons.

The second objection comes from the focus on natural selection and "Darwinism" (or neo-Darwinism). Many evolutionary biologists have a pluralistic view of modern evolutionary theory. That view includes random genetic drift where the appropriate metaphor might be "lucky gene" or "accidental gene." The problem with the Dawkins' metaphor, according to these critiques, is not that "selfish genes" don't exist, it's that the metaphor is not appropriate for evolution in general.

While I admire Jerry's take-down of Dobbs, I'm not sure that he (Jerry Coyne) fully appreciates these other criticisms of the selfish gene. Here's what Coyne wrote ...

Let me add one thing, though. I’m constantly puzzled these days by how often people argue that the neo-Darwinian synthesis is wrong, and that we need a new paradigm. Genetic assimilation, epigenetics, horizontal gene transfer—all of these buzzwords are evoked as reasons to jettison our “conventional” view of evolution. But always, when you look at the data, the evidence that these phenomena will overturn neo-Darwinism is nonexistent.

I’ve already written a lot on the epigenetics hype, and have shown that there’s no evidence that a single adaptation in nature involves the fixation in the DNA of an epigenetic alteration of the genome that isn’t initially inherited. Yet people keep banging on about epigenetics.

I’m not sure why the hype continues, but perhaps it has to do with the fact that the main paradigm of evolution—the neo-Darwinian synthesis—is largely consolidated, and is correct. Sure, there are surprises to come, and interesting new phenomena, but there’s no “quantum mechanics” of evolution on the horizon. Some theories don’t need to be overthrown because they’re generally right. Perhaps people don’t like working in a field where there’s no new “paradigm” to forge, and Kuhn has ruined us all!

The "neo-Darwinism is dead" trend may have to do with ambition, or perhaps with boredom. I don’t know. What I do know is that the many recent challenges to neo-Darwinism have all failed to hold water, but people keep pouring liquid into that sieve.

The problem here is that Jerry doesn't really say what he means by "neo-Darwinism." Most of his writing suggests that he's talking about natural selection, albeit updated by a knowledge of genetics. He does mention, from time to time, random genetic drift and other aspects of modern evolutionary theory but I'm not sure if he appreciates the fact that some legitimate evolutionary biologists really do think that neo-Darwinism is dead.

Here's the Wikipedia description of neo-Darwinism. It illustrates the problem.

Neo-Darwinism is the 'modern synthesis' of Darwinian evolution through natural selection with Mendelian genetics, the latter being a set of primary tenets specifying that evolution involves the transmission of characteristics from parent to child through the mechanism of genetic transfer, rather than the 'blending process' of pre-Mendelian evolutionary science. Neo-Darwinism can also designate Darwin's ideas of natural selection separated from his hypothesis of Pangenesis as a Lamarckian source of variation involving blending inheritance.

I think we should refer to modern evolutionary theory as "modern evolutionary theory" in order to make sure we're not talking about "Darwinism," "neo-Darwinism," or the hardened version of the "Modern Synthesis." Modern evolutionary theory includes an important role for random genetic drift, Neutral Theory, and population genetics.

We could clarify a lot of discussion if we stopped talking about extending "Darwinism" or extending the Modern Synthesis or proclaiming once again that the selfish gene has died. In fact, the selfish gene has died, it died almost thirty years ago but most people don't know that. RIP.

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Jason Rosenhouse defends Chris Mooney

Jason Rosenhouse read Chris Mooney's article on 7 Reasons Why It's Easier for Humans to Believe in God Than Evolution and liked it. Mooney was arguing that it's easier to believe in god(s) than in evolution because our evolutionary history selected for traits that predisposed us to think more like IDiots than like scientists.

I disagreed [Why don't people accept evolution? ]. Here's what I wrote last week ....
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How do creationists interpret Lenski's long-term evolution experiment?

Lenski's long-term evolution experiment has resulted in dozens of publications in high quality journals. It has led to significant insights into evolutionary processes [e.g. Lenski's long-term evolution experiment: the evolution of bacteria that can use citrate as a carbon source]. You may be wondering how Intelligent Design Creationists react to these results since most IDiots have a natural aversion to evidence.

Denyse O'Leary wasn't impressed [The Latest From Lenski’s Lab]. She doesn't know very much about science so she has to rely on the opinions of other IDiots. In this case, she relies on Ann Gauger who published a comment on the website of The Biologic Institute [Inovation or Rennovation].

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Lenski's long-term evolution experiment: the evolution of bacteria that can use citrate as a carbon source

Richard Lenski set up twelve flasks of E. coli B back in 1988. They were allowed to grow overnight in minimal medium containing 139μM glucose and 1,700 μM citrate. The glucose was the only carbon source that the parent strain could use and it limited growth of the cultures. The citrate was present as a standard chelating agent. The bacteria could not take up citrate and use it as an additional carbon source.

Every day the culture was diluted by transferring one ml to 99 ml of fresh medium (1/100). There were 6.64 generations per day or 2,423 generations per year (slightly more in a leap year).

These cultures were under strong selective pressure. Individual bacteria that could grow faster would out-compete other bacteria in the culture and take over. Lenski expected that each culture would show a variety of different solutions to the selective pressure with many common mutations and many that could be unusual.

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Ask a stupid question ... can anyone guess the answer?

I just love the IDiots. They never cease to amaze, and amuse, me. Here's the latest from David Klinghofer at: Intelligent Design as an Orange Flag.

The mention of ID seems to give many writers and commentators what they regard as a green light to blather on without taking a moment to grasp what they're writing about. Denouncing ID is one thing. Denouncing it without comprehending what the phrase refers to, which is amazingly common, is quite another.

I continue to find this amazing. What other subject, both controversial and somewhat recondite, seems to license apparently smart people to write and speak in such an uninformed way?

Gee, I wonder what other subject causes apparently smart people to behave like IDiots? What other subject gives people a green light to blather on when they don't have the slightest clue what they are talking about? Is there another subject that some people denounce without comprehending what it means? Hmmm .....

Can anyone think of such a subject?

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Was Louis Agassiz better in the concrete?

Back in the nineteenth century (i.e. more than one hundred years ago) there was a biologist named Louis Agassiz who didn't like Darwin's radical ideas about evolution. Agassiz, a very famous professor at Harvard, thought that there were major gaps n the fossil record and he lamented the apparent lack of transitional fossils. What he was looking for were fossils of direct ancestors of modern species and not their close cousins.

Stephen Meyer thinks this old debate is still relevant today so he writes it up in Darwin's Doubt as if nobody in the past one hundred years ever thought of an explanation. It fooled Denyse O'Leary (not hard) so she blogged about it today [Louis Agassiz: The selective incompleteness of the fossil record].

This reminds me of a famous photograph of the statue of Louis Agassiz embedded upside down in the courtyard in front of the zoology building at Stanford University. The statue tumbled from its place above the entrance during the San Francisco earthquake of 1906.

According to legend, a passing scientist remarked that,

Louis Agassiz was great in the abstract but not in the concrete.¹

Actually, it would be even better to say that Agassiz looks better in the concrete than in the abstract [see Agassiz in the Concrete and Persecution of Religious Scientists]. By the 1920s (earlier in Europe) Agassiz's reputation had been severely damaged by his willingness to let religious convictions dictate his science.²

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1. The story is apocryphal (a polite word for "false"). The quotation has been attributed to several men, including the President of Stanford, but all have denied it. Nevertheless, it's too good a story to abandon just because it happens to be untrue!

2. Stephen Jay Gould held the Alexander Agassiz Professor of Zoology Chair at Harvard from 1982 until his death in 2002. Alexander Agassiz was Louis Agassiz's son. Alexander served as President of the National Academy of Sciences.

Carnival of Evolution #66: The Day of the Doctor

This month's Carnival of Evolution is hosted by none other than John Wilkins. He's a philosopher but don't let that put you off. He blogs at Evolving Thoughts although from time to time he threatens to stop blogging. Encourage John by visiting The Day of the Doctor of Evolution: CoE #66.

The "Doctor" in the title is a reference to Dr. Who. Apparently John watched the first episodes in 1963!! "Who" knew that he was even born in 1963?

I was eight years old in late November 1963. I didn’t pay much attention to the TV news – some guy had been shot or something, and I wasn’t to know that C. S. Lewis had died until much later – but I was instantly taken by the eerie sound of the opening music of a new show. Yes, it was the very first episode of Dr Who, in glorious monochrome! I was a Whovian from the beginning, before it was cool. I’m so hip…

If you can't name the blue thingy on the right then you probably never win trivia games.

If you want to host a Carnival of Evolution please contact Bjørn Østman. Bjørn is always looking for someone to host the Carnival of Evolution. He would prefer someone who has not hosted before but repeat hosts are more than welcome right now! Bjørn is threatening to name YOU as host even if you don't volunteer! Contact him at the Carnival of Evolution blog. You can send articles directly to him or you can submit your articles at Carnival of Evolution although you now have to register to post a submission. Please alert Bjørn or the upcoming host if you see an article that should be included in next month's. You don't have to be the author to nominate a post.

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Elizabeth Pennisi writes about Richard Lenski's long-term evolution experiment

Elizabeth Pennisi has written about the long-term evolution experiment of Richard Lenski [The Man Who Bottled Evolution]. The experiment is in it's 25th year and it is entirely appropriate that Science magazine devotes several pages to describing the results. There have been some remarkable discoveries.

But I want to focus on a couple of things that Pennisi says in her article. There has also been a discussion on Panda's Thunb: Lenski’s experiment: 25 years and 58,000 generations. Pennisi writes ...

Lenski's humble E. coli have shown, among other things, how multiple small mutations can prepare the ground for a major change; how new species can arise and diverge; and that Gould was mistaken when he claimed that, given a second chance, evolution would likely take a completely different course. Most recently, the colonies have demonstrated that, contrary to what many biologists thought, evolution never comes to a stop, even in an unchanging environment.

Let's talk about two issues in that paragraph.

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Why don't people accept evolution?

Chris Mooney (remember spin framing?) is at it again. This time he writes for Mother Jones: 7 Reasons Why It's Easier for Humans to Believe in God Than Evolution.

Before we look at the seven reasons let's remember the poll from 2005 that surveyed acceptance of evolution in 34 countries. Note that the percentage of the population who reject evolution ("false") is somewhere between 10% and 20% in the countries at the top of the list. About 75% of the people in those countries think that evolution is true.

In the USA the percentage who reject evolution is closer to 40% and only about 40% think that evolution is true. Clearly if we're going to ask why it's easier for humans to believe in god(s) than in evolution then we have to take these differences into account. It seems reasonable, doesn't it, to look for something that the USA, Turkey, and Cyprus have in common that makes people not accept evolution?

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Answering ten questions from the IDiots

On this American Thanksgiving Day, David Klinghoffer gives thanks for Richard Dawkins and Jerry Coyne [Thank Goodness for Richard Dawkins]. He says ...

... we're also grateful for guys like Richard Dawkins and Jerry Coyne who provide a rich source of unintended comedy. See, for example, our colleague Dr. Michael Egnor's always entertaining mining of Coyne's writings.*

* Admittedly we'd be even more pleased to have a worthy opponent on the Darwin side of the debate who did not run from a fight every time but answered our best arguments and evidence in a lucid, trenchant and informative style.

Well, I gotta tell you, David, that I'll be eternally grateful to the Discovery Institute for sending us Dr. Michael Egnor. It's the gift that just keeps on giving, and giving, and giving ....

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Natural selection may not lead to evolution?

I recently discovered a new book called The Princeton Guide to Evolution. It looks pretty authoritative so I ordered a copy.

There are excerpts online. The first chapter is "What Is Evolution?" by Jonathan Losos. I'm not very impressed with his answer but I was shocked to read the following passage.

The logic behind natural selection is unassailable. If some trait variant is causally related to greater reproductive success, then more members of the population will have that variant in the next generation; continued over many generations, such selection can greatly change the constitution of a population.

But there is a catch. Natural selection can occur without leading to evolution if differences among individuals are not genetically based. For natural selection to cause evolutionary change, trait variants must be transmitted from parent to offspring; if that is the case, then offspring will resemble their parents and the trait variants possessed by the parents that produce the most offspring will increase in frequency in the next generation.

However, offspring do not always resemble their parents. In some cases, individuals vary phenotypically not because they are different genetically, but because they experienced different environments during growth (this is the “nurture” part of the nature versus nurture debate; see chapters III.10 and VII.1). If, in fact, variation in a population is not genetically based, then selection will have no evolutionary consequence; individuals surviving and producing many offspring will not differ genetically from those that fail to prosper, and as a result, the gene pool of the population will not change. Nonetheless, much of the phenotypic variation within a population is, in fact, genetically based; consequently, natural selection often does lead to evolutionary change.

I never heard to this idea before (that natural selection may not lead to evolution). I thought that natural selection was DEFINED as a change in the frequency of alleles in a population due to selection. Doesn't it have to have a genetic component?

Does this mean that natural selection may not lead to adaptation? Or, does it mean that adaptation isn't necessarily evolution?

The chapters are written by an impressive group of authors (Jonathan Losos is the editor-in-chief). It must represent the current consensus among evolutionary biologists. I'm surprised that I never heard of this definition of natural selection.

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Little Richie Dawkins

One thing that draws me to the ID movement is that it has the polite and understated ethic that science is supposed to have -- but does not have when the subject is evolution.

Stephen A. BatzerHere's a video that was posted today on Uncommon Descent by Salvador Cordova. Before watching it, read my post on: Why are Darwinists do uncivil?. It links to an IDiot post by Stephen A. Batzer where he complains about "Darwinists" being uncivil.

Here's one of the points that Batzer makes ...

Thought leaders in the Darwinian movement, such as Dawkins, Prothero, Shermer and so on, inculcate and advocate incivility by their own example. Look at the way biologist James Shapiro and philosopher Jerry Fodor have been treated. It's ugly.

The video was produced by Mike Booth. Decide for yourself if the evolution side of the debate behaves like the IDiots. (Apologies to Richard Dawkins for propagating this nonsense but people need to see the depths to which the Intelligent Design Community can sink.)


UPDATE: Denyse O'Leary has responded to this post [Huh? Actually, we thought Little Richie (Dawkins) was a special creation, just for us…]. She says, "Moran thinks it originated in the ID community. Unclear why because it’s really not about our usual questions and concerns." Actually I don't know anything about Mike Booth or whether he is a support of Intelligent Design Creationism. I looked, but I couldn't find anything. What I do know is that IDiots like Denyse O'Leary post the obnoxious video on their websites. O'Learly also says this about the video, "It’s also not a lot nastier than the old showman himself." I think I'll let intelligent people decide for themselves who is nastier. I'm glad that Denyse O'Leary at least acknowledges that the video she posted was nasty.

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Claudiu Bandea Shows Why Attacking Dan Graur Is a Very Bad Idea

Claudiu Bandea is a frequent commenter on this blog. Whenever the subject of junk DNA comes up he reminds us that he had a theory over twenty years ago. Now he has published(?) an advertisement at: On the concept of biological function, junk DNA and the gospels of ENCODE and Graur et al.. Here's the abstract ...

In a recent article entitled “On the immortality of television sets: "function" in the human genome according to the evolution-free gospel of ENCODE”, Graur et al. dismantle ENCODE’s evidence and conclusion that 80% of the human genome is functional. However, the article by Graur et al. contains assumptions and statements that are questionable. Primarily, the authors limit their evaluation of DNA’s biological functions to informational roles, sidestepping putative non-informational functions. Here, I bring forward an old hypothesis on the evolution of genome size and on the role of so called ‘junk DNA’ (jDNA), which might explain C-value enigma. According to this hypothesis, the jDNA functions as a defense mechanism against insertion mutagenesis by endogenous and exogenous inserting elements such as retroviruses, thereby protecting informational DNA sequences from inactivation or alteration of their expression. Notably, this model couples the mechanisms and the selective forces responsible for the origin of jDNA with its putative protective biological function, which represents a classic case of ‘fighting fire with fire.’ One of the key tenets of this theory is that in humans and many other species, jDNAs serves as a protective mechanism against insertional oncogenic transformation. As an adaptive defense mechanism, the amount of protective DNA varies from one species to another based on the rate of its origin, insertional mutagenesis activity, and evolutionary constraints on genome size.

It's not a good idea to attack someone who; (a) is an expert in the field, (b) is intelligent and outspoken, and (c) has a blog. But that never stopped Claudiu Bandea before so why should it now?

Here's part of how Dan Graur responds at: A Pre-Refuted Hypothesis on the Subject of “Junk DNA”. There's more, read it all.

The first problem with this hypothesis is that big eukaryotic genomes consist mostly of very few active transposable elements and numerous dead transposable elements. So, big genomes seem to need little protection. Moreover, a positive correlation exists between genome size and number of transposable elements. In 2002, Margaret Kidwell published a paper entitled “Transposable elements and the evolution of genome size in eukaryotes.” In it, she showed that an approximately linear relationship exists between total transposable element DNA and genome size. Copy numbers per family of transposable elements were found to be low and globally constrained in small genomes, but to vary widely in large genomes. Thus, the major characteristic of large genomes is the absence of selective constraint on transposable element copy number.

Given that the vast majority of transposable elements are dead, the most parsimonious explanation is that the continuous accumulation of dead transposable elements is the reason for genomes becoming large. Let me spell it out: the “large” part in “large genomes” is made of transposable elements. Genome do not become large first and then protect genetic information by becoming sinks of transposable elements.

The other problem with the protection-from-mutation hypothesis is that it assumes selection on mutation to be effective. Selection on mutation is referred to in population genetics as second-order selection. The reason is that this type of selection is anticipatory. It protects against a possibility, not an actuality. Second-order selection on mutation (mutability) requires huge effective population sizes, so huge in fact that they are only found in a few bacteria and viruses. Unfortunately for the protection-from-mutation hypothesis, genome size is known to be inversely correlated with effective population size. In other words, huge genomes are found in species that have very small effective population sizes. So small, in fact, that even regular selection (first-order selection) is not very effective.

Thomas Huxley was proven right again: "The great tragedy of Science is the slaying of a beautiful hypothesis by an ugly fact." Several ugly facts in this case.

I can't count the number of people who have tried to explain to Claudiu Bandea that his idea is ridiculous. Hopefully, this last embarrassment will silence him.

Naturally, the Intelligent Design Creationists are all over it [Another response to Darwin’s followers’ attack on the “not-much-junk-DNA” ENCODE findings].

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Which Way Did Darwin Walk?

For some reason the title reminds me of "What Does the Fox Say." Oh well, PZ Myers is desperately interested in knowing which way Darwin walked when he took a stroll on the Sandwalk [An important historical question!].

I know which way PZ walked 'cause I led him!

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Is Baker's Yeast a Good Model for the Evolution of Multicellularity?

R. Ford Denison has an excellent blog called This Week in Evolution. He recently posted an article about the evolution of multicellularity [Evolving-multicellularity lab exercises]. That post contains a link to a paper he recently published with a former student (Ratcliff et al., 2013). Here's the abstract.

Multicellularity was one of the most significant innovations in the history of life, but its initial evolution remains poorly understood. Using experimental evolution, we show that key steps in this transition could have occurred quickly. We subjected the unicellular yeast Saccharomyces cerevisiae to an environment in which we expected multicellularity to be adaptive. We observed the rapid evolution of clustering genotypes that display a novel multicellular life history characterized by reproduction via multicellular propagules, a juvenile phase, and determinate growth. The multicellular clusters are uniclonal, minimizing within-cluster genetic conflicts of interest. Simple among-cell division of labor rapidly evolved. Early multicellular strains were composed of physiologically similar cells, but these subsequently evolved higher rates of programmed cell death (apoptosis), an adaptation that increases propagule production. These results show that key aspects of multicellular complexity, a subject of central importance to biology, can readily evolve from unicellular eukaryotes.

Here's the problem. Most fungi are multicellular and Saccharomyces cerevisiae (budding yeast) almost certainly evolved from an ancestor that could form hyphae. In fact, wild-type diploid strains or Saccharomyces cerevisiae will form multicellular filaments (pseudohypha) in response to starvation for nitrogen (Liu et al., 1996).

Many of the common lab strains have lost the ability to form multicellular pseudohyphae because they carry a nonsense mutation in the FLO8 gene (Liu et al., 1996). Presumably, those strains have been selected by bakers and brewers over the past several thousand years.

In their discussion, Ratcliff et al. (2012) say ...

Although known transitions to complex multicellularity, with clearly differentiated cell types, occurred over millions of years, we have shown that the first crucial steps in the transition from unicellularity to multicellularity can evolve remarkably quickly under appropriate selective conditions.

I don't this this is quite fair since the yeast strain is just reverting to a primitive condition. This might only have required one or a few mutations. It's not a very good model for de novo evolution of multicellarity.

The work from Gerry Fink's lab (e.g. Liu et al. 1996) is a good example of why we should be cautious using yeast as a model for anything. The yeast strains used in the lab have been selected for specific characteristics since bread-making and beer-making were first invented over 4000 years ago. We need to be cautious about drawing general conclusions based on work with lab yeast strains.

The lab exercise based on the Ratcliff et al. (2012) paper [Experimental Evolution of Multicellularity] may be interesting but it's also misleading. The description of that experiment implies that students are reproducing the ancient evolution of multicellularity from single-cell organisms. Instead, what students are actually looking at is the reversion of a derived, exclusively single-cell strain, to the more primitive multicellular state. That's not the same thing.

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[Photo Credit: That's Ford at a rally in Ottawa where we were protesting the Conservative government's clamp-down on science in Canada. He took advantage of the audience to advertise his book.

Liu, H., Styles, C.A. and Fink, G.R. (1996) Saccharomyces cerevisiae S288C has a mutation in FL08, a gene required for filamentous growth. Genetics 144:967-978. [PDF]

Ratcliff, W.C., Denison, R.F., Borrello, M. and Travisanoa, M. (2012) Experimental evolution of multicellularity. Proc. Natl. Acad. Sci. (USA) 109:1595-1600. [doi: 10.1073/pnas.1115323109]