Coelacanths are unexceptional products of evolution

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The coelacanth genome has been sequenced, which is good news all around…except that I found a few of the comments in the article announcing it disconcerting. They keep calling it a "living fossil" — and you know what I think of that term — and they keep referring to it as evolving slowly

The slowly evolving coelacanth

The morphological resemblance of the modern coelacanth to its fossil ancestors has resulted in it being nicknamed 'the living fossil'. This invites the question of whether the genome of the coelacanth is as slowly evolving as its outward appearance suggests. Earlier work showed that a few gene families, such as Hox and protocadherins, have comparatively slower protein-coding evolution in coelacanth than in other vertebrate lineages.

Honestly, that's just weird. How can you say its outward appearance suggests it is slowly evolving? The two modern species are remnants of a diverse group — it looks different than forms found in the fossil record.

And then for a real WTF? moment, there's this from Nature's News section.

It is impossible to say for sure, but the slow rate of coelacanth evolution could be due to a lack of natural-selection pressure, Lindblad-Toh says. Modern coelacanths, like their ancestors, "live far down in the ocean, where life is pretty stable", she says. "We can hypothesize that there has been very little reason to change." And it is possible that the slow genetic change explains why the fish show such a striking resemblance to their fossilized ancestors.

Snorble-garble-ptang-ptang-CLUNK. Reset. Does not compute. Must recalibrate brain.

None of that makes sense. The modern fish do not show a "striking resemblance" to their fossilize ancestors — they retain skeletal elements that link them to a clade thought to be extinct. This assumption that Actinistian infraclass has been unchanging undermines their conclusions — the modern species are different enough that they've been placed in a unique genus not shared with any fossil form.

Then the argument that they must live in a stable environment with a lack of natural-selection pressure is absurd. Selection is generally a conservative process: removing selection pressures from a population should lead to an increase in the accumulation of variability. Do they mean there has been increased selection in a very narrowly delimited but stable environment?

But even that makes no sense. We should still be seeing the accumulation of neutral alleles. Increased selection is only going to remove variability in functional elements, and most of the genome isn't. I suppose one alternative to explain slow molecular evolution would be extremely high fidelity replication, but even that would require specific selection constraints to evolve.

This article broke my poor brain. I couldn't see how any of this could work — it ignored the fossil evidence and also seemed to be in defiance of evolutionary theory. It left me so confused.

Fortunately, though, the journal BioEssays came to my rescue with an excellent review of this and past efforts to shoehorn coelacanths into the "living fossil" fantasy, and that also explained the molecular data. And it does it plainly and clearly! It's titled, "Why coelacanths are not 'living fossils'", and you can't get much plainer and clearer than that.

First, let's dismiss that myth of the unchanging Actinistian. Here's a phylogeny of the coelacanth-like fossils and their one surviving species.

coelacanth_fossils
Comparison of extant and selected extinct actinistians, commonly known as coelacanths. A phylogeny of Actinistia; schematic sketches of body outlines and approximate body length (given in metre) illustrate the morphological diversity of extinct coelacanths: some had a short, round body (Hadronector), some had a long, slender body (Rebellatrix), some were eel-like (Holopterygius) whereas others resembled trout (Rhabdoderma), or even piranha (Allenypterus). Note that the body shape of Latimeria chalumnae differs significantly from that of its closest relative, Macropoma lewesiensis.

Love it. I've been looking for a diagram like this for a long time; creationists often trot out this claim that coelacanths haven't changed in hundreds of millions of years, and there you can see — divergence and variation and evolution, for hundreds of millions of years.

In addition, we can look in more detail at the skull and limbs of these animals. This drawing is comparing modern Latimeria with its closest fossil relative, and even here there are dramatic differences in structure.

actinistian_bones
Comparison of the skeleton of extant and selected extinct coelacanths. A-D: Latimeria and its sister group Macropoma show numerous skeletal differences. A, B: Overall view of the skeletal organisation of the extant coelacanth and of its closest relative. A: Latimeria chalumnae. B: Macropoma lewesiensis. Relative to the body length, in L. chalumnae the vertebrae are smaller, the truncal region of the vertebral column is longer and the post anal region is shorter than in M. lewesiensis. In the latter region, the hemal arches (ventral spines) extend more ventrally in M. lewesiensis than in L. chalumnae. In addition, the swim bladder is ossified in Macropoma but not in Latimeria, and the basal bone of the first dorsal fin is characteristic of each genus. C, D: Comparison of the skulls of L. chalumnae and M. lewesiensis. C: In L. chalumnae, the mouth opens upward, the articular bone (yellow) is long and narrow, the parietonasal shield (red) is short, the premaxillary bone (orange) is devoid of denticle ornamentation, the dorsal part of the cleithum (light brown) is spiny, and the scapulocoracoid (green) is located on the ventral side. D: In contrast, in M. Lewesiensis, the mouth opens forward, the angular bone (yellow) is triangular, the parieto-nasal shield (red) is long, the premaxillary (orange) protrudes and forms a hemispherical snout which is ornamented with prominent denticles, the dorsal part of the cleithrum (light brown) is thick, and the scapulocoracoid, (green) is located more medially. Modified from [3]. E: Pectoral fin skeleton of L. chalumnae (above) and Shoshonia arctopteryx (below). The three first preaxial radials are numbered from proximal to distal. In L. chalumnae the fin appears nearly symmetrical because radial bones (orange) are arranged nearly symmetrically about the fin axis. The proximal preaxial radials 1-2 are extremely short and bear no fin ray, and the preaxial radial 3 is short and fractionated. In contrast, in S. arctopteryx the fin is strongly asymmetrical chiefly because proximal preaxial radials are long and all bear fin rays.

The authors make it clear that this idea of morphological conservation of the Actinistians is simply bogus.

In addition, an examination of the skeleton of the fossil genus Macropoma (approximately 70 Ma), the sister group of Latimeria and the only known fossil actinistian record from the Cretaceous to the present, shows some interesting differences. Not only are the extant coelacanths three times larger than their closest extinct relatives (about one and a half metres vs. half a metre), but there are also numerous structural differences. The swim bladder is ossified in Macropoma but filled with oil in Latimeria, indicating they were probably found in different types of environments. There are also noticeable differences in the vertebral column (the post anal region is shorter and ventral spines extend less ventrally in M. Lewesiensis compared with L. chalumnae), and in the attachment bones of the fins. In addition, Macropoma and Latimeria have distinctly dissimilar skull anatomies, resulting in noticeable differences in head morphology.

Finally, it should not be forgotten that external morphological resemblances can be based on a very different internal anatomical organisation. The most often emphasised resemblance between coelacanths is that they all have four fleshy-lobed-fins. Until recently, the anatomy of the lobed fins of coelacanths was only known in Latimeria, in which the pectoral fin endoskeleton is short and symmetrical. In 2007, Friedman et al. described the endoskeleton of the pectoral fin of Shoshonia arctopteryx, a coelacanth species from the mid Devonian, and therefore contemporary with Miguashaia. They showed that this earliest known coelacanth fin endoskeleton is highly asymmetrical, a characteristic that is probably ancestral since it resembles the condition found in early sarcopterygians such as Eusthenopteron, Rhizodopsis or Gogonasus. This result is additional support, if needed, that extant coelacanths have not remained morphologically static since the Devonian.

Well, so, you may be wondering, what about the molecular/genomic data? Doesn't that clearly show that they've had a reduced substitution rate? No, it turns out that that isn't the case. Some genes seem to be more conserved, but others show an expected amount of variation.

However, a closer look at the data challenges this interpretation [of slow evolution]: depending on the analysed sequence, the coelacanth branch is not systematically shorter than the branches leading to other species. In addition, most phylogenetic analyses - including analysis of Hox sequences - do not support the hypothesis that the Latimeria genome is slow evolving, i.e. they do not place coelacanth sequences on short branches nor do they detect low substitution rates. The clearest example, which involves the largest number of genes, is a phylogeny based study of forty-four nuclear genes that does not show a dramatic decrease, if any, in the rate of molecular evolution in the coelacanth lineage. What we know about the biology of coelacanths does not suggest any obvious reason why the coelacanth genome should be evolving particularly slowly.

So why is this claim persisting in the literature? The authors of the BioEssays article made an interesting, and troubling analysis: it depends on the authors' theoretical priors. They examined 12 relevant papers on coelacanth genes published since 2010, and discovered a correlation: if the paper uncritically assumed the "living fossil" hypothesis (which I've told you is bunk), the results in 4 out of 5 cases concluded that the genome was "slowly evolving"; in 7 out of 7 cases in which the work was critical of the "living fossil" hypothesis or did not even acknowledge it, they found that coelacanth genes were evolving at a perfectly ordinary rate.

Research does not occur in a theoretical vacuum. Still, it's disturbing that somehow authors with an ill-formed hypothetical framework were able to do their research without noting data that contradicted their ideas.

Maybe a start to correcting this particular instance of a problem is to throw out the bad ideas that are leading people astray. The authors strongly urge us to purge this garbage from our thinking.

Latimeria was first labelled as a 'living fossil' because the fossil genera were known before the extant species was discovered, and erroneous biological interpretations have grown and reports still show little morphological and molecular evolution. A closer look at the available molecular and morphological data has allowed us to show that most of the available studies do not show low substitution rates in the Latimeria genome, and furthermore, as pointed out by Forey [3] long before us, the supposed morphological stability of coelacanths from the Devonian until the present is not based on real data. As a consequence, the idea that the coelacanth is a biological 'living fossil' is a long held but false belief which should not bias the interpretation of molecular data in extant Latimeria populations. The same reasoning could be generalised to other extant species (such as hagfish, lamprey, shark, lungfish and tatuara, to cite few examples of vertebrates) that for various reasons are often presented as 'ancient', 'primitive', or 'ancestral' even if a lot of recent data has shown that they have many derived traits [58-64]. We hope that this review will contribute to dispelling the myth of the coelacanth as a 'living fossil' and help biologists keep in mind that actual fossils are dead.

But of course we also shouldn't let that color our data. If analyses showed a significantly reduced substitution rate in the evolution of a species, it ought to get published. If nothing else, it would be an interesting problem for evolutionary theory. Coelacanths, though, don't represent that problem.


Amemiya CT, Alfldi J, Lee AP, Fan S, Philippe H, Maccallum I, Braasch I, Manousaki T, Schneider I, Rohner N, Organ C, Chalopin D, Smith JJ, Robinson M, Dorrington RA, Gerdol M, Aken B, Biscotti MA, Barucca M, Baurain D, Berlin AM, Blatch GL, Buonocore F, Burmester T, Campbell MS, Canapa A, Cannon JP, Christoffels A, De Moro G, Edkins AL, Fan L, Fausto AM, Feiner N, Forconi M, Gamieldien J, Gnerre S, Gnirke A, Goldstone JV, Haerty W, Hahn ME, Hesse U, Hoffmann S, Johnson J, Karchner SI, Kuraku S, Lara M, Levin JZ, Litman GW, Mauceli E, Miyake T, Mueller MG, Nelson DR, Nitsche A, Olmo E, Ota T, Pallavicini A, Panji S, Picone B, Ponting CP, Prohaska SJ, Przybylski D, Saha NR, Ravi V, Ribeiro FJ, Sauka-Spengler T, Scapigliati G, Searle SM, Sharpe T, Simakov O, Stadler PF, Stegeman JJ, Sumiyama K, Tabbaa D, Tafer H, Turner-Maier J, van Heusden P, White S, Williams L, Yandell M, Brinkmann H, Volff JN, Tabin CJ, Shubin N, Schartl M, Jaffe DB, Postlethwait JH, Venkatesh B, Di Palma F, Lander ES, Meyer A, Lindblad-Toh K. (2013) The African coelacanth genome provides insights into tetrapod evolution. Nature 496(7445):311-316.

Casane D, Laurenti P (2013) Why coelacanths are not 'living fossils': A review of molecular and morphological data. Bioessays 35: 332-338.


Larry Moran beat me to it!

103 Comments

Thanks PZ.

It is always important to remember that morphological and molecular evolution may be coupled or uncoupled. This is undoubtedly due to the complex relationship between genetics and morphology, given the complexity of developmental pathways.

Does anyone know if the complete genome sequence sheds any more light on the phylogenetic relationships between coelacanths, lungfish and tetrapods? Was this covered in the article? For many years the question proved hard to address. I had the impression that the consensus was that coelacanths are less closely related to tetrapods than lungfish. Does this relationship hold up given the new sequence data?

Well why are there still fossils, if coelecanths evolved from fossilized ancestral forms (or anyway, from relatives of those)?

See, there are always questions for evilutionists.

Glen Davidson

Posts like this one are the reason I keep on lurking at Pandas Thumb.

The issue discussed in this opening post has bothered me. It is indeed true that sometimes (or often) it has been indicated in public that a body shape that remains almost the same indicates either lack of evolution or slow evolution also at genetic level.

On the other hand, I do not remember anyone drawing a conclusion that the genetic makeup of ichthyosaur, dolphin and tuna fish should be highly similar.

According to the answer given here, there is no reason to assume that. Moreover, even the body shape is not quite as stable as sometimes indicated, at least not in the case of coelacanths.

Just wanted to tell that a layman might possibly have understood something about what you said.

I have not been able to find an answer to a question that I have been curious about for quite a few years now.

Have there ever been studies done on the rates of genetic change in creatures that have lived for thousands of years at low temperatures?

The reason I ask this is that there are some fundamental physic/chemistry notions behind the probabilities of mutations. The probability of a “jump” to another state is proportional to exp(-φ/kT), where φ is the height of a potential barrier between different configurations or states of a molecule.

If the general rule for rates of molecular evolution in living organisms is that they are pretty much “temperature independent,” then that would suggest that those barriers are large relative to kT. For example, room temperature kT is on the order of 1/40 of an electron volt.

I would expect that the barriers to molecular changes involved in genetic evolution would be at least 10 to 100 times larger; thus I would not expect any measurable differences in rates of molecular evolution given that the temperatures for life here on earth lie primarily within the range of liquid water.

Down at those geothermal vents, kT is greater because water is superheated under pressure; but one can also imagine that molecular configurations for extremophiles could be “more robust” – i.e., have slightly higher φ’s – also. They also live at considerably higher pressures.

I’m guessing that it is not likely that there will be measurable differences in molecular evolution rates across the entire spectrum of life. There is not much room for φ and T to vary without destroying the organism.

Technically speaking, shouldn’t the sentence be

Here’s a phylogeny of the coelacanth-like fossils and their one surviving genus.

?

https://me.yahoo.com/a/JxVN0eQFqtmg[…]X_Zhn8#57cad said:

Well why are there still fossils, if coelecanths evolved from fossilized ancestral forms (or anyway, from relatives of those)?

See, there are always questions for evilutionists.

Glen Davidson

Wait until, Byers hears that.

DS said:

Thanks PZ.

Does anyone know if the complete genome sequence sheds any more light on the phylogenetic relationships between coelacanths, lungfish and tetrapods? Was this covered in the article? For many years the question proved hard to address. I had the impression that the consensus was that coelacanths are less closely related to tetrapods than lungfish. Does this relationship hold up given the new sequence data?

I recall, someone saying that the paper did shed light on the phylogenetic relationship between coelacanths, lungfish, tetrapods. Lungfish are more closely related to tetrapods.

Are there examples of living animals (birds,insects,sharks etc) that DO resemble their respective fossil ancestors extremely closely? So closely in fact that selection seems to have been made redundant by the stability of the environment. Really, just asking!

Wait a minute. Lets think about this. If My Myers is saying past and present, very present, scholarship on these things is so poor then creationists are right to lack and teach lack of confidence in anything from evolutionary biology. Its not just this fish!

If its a Coel and has relatives in fossils said to be so long ago then the differences are so small to in effect say its unchanged. They even invoked here about size. What does that matter? Irrelevant.

Mr Myers is stressing small differences to press the point this fish type has been evolving with the best of them. Its very little different from what i read here. There is indeed no living fossils because this presumes the fossils indicates ancient ages. Its just a more common type that survived from a greater diversity living a few thousand years ago as the great flood took place. there are many types of creatures unchanged from fiossil relatives in strata below the k-pg line.

My Myers is right however about modern literature in science fails to do a good job in origin issues. We know that fossil is still unmorphed.

robert van bakel said:

Are there examples of living animals (birds,insects,sharks etc) that DO resemble their respective fossil ancestors extremely closely? So closely in fact that selection seems to have been made redundant by the stability of the environment. Really, just asking!

I’m no biologist, but IIRC, aren’t sharks pretty well adapted to their environment, and also a very old lineage? I realize that there’s a wide variety of extant shark species, but aren’t the shark fossils pretty closely matched to some of them? I do seem to recall that fossil shark teeth are pretty similar to modern shark teeth.

Well, Robert, you did get a few things right from the OP:

Robert Byers said: Mr Myers is stressing small differences to press the point this fish type has been evolving with the best of them.

Yes. Now you’re getting it. Small differences added up over time equals evolution.

There is indeed no living fossils…

Correct. That is what Professor Myers is saying. You read that part correctly …

…because this presumes the fossils indicates ancient ages.

and then you went off the rails. Professor Myers did not say that at all.

Wait a minute. Lets think about this.

Yes. Let’s. That’s what we’ve been asking you to do for some time, and you can never bother to think outside the bible-shaped box that you have trapped yourself in.

Mike Elzinga said:

I have not been able to find an answer to a question that I have been curious about for quite a few years now.

Have there ever been studies done on the rates of genetic change in creatures that have lived for thousands of years at low temperatures?

The reason I ask this is that there are some fundamental physic/chemistry notions behind the probabilities of mutations. The probability of a “jump” to another state is proportional to exp(-φ/kT), where φ is the height of a potential barrier between different configurations or states of a molecule.

If the general rule for rates of molecular evolution in living organisms is that they are pretty much “temperature independent,” then that would suggest that those barriers are large relative to kT. For example, room temperature kT is on the order of 1/40 of an electron volt.

I would expect that the barriers to molecular changes involved in genetic evolution would be at least 10 to 100 times larger; thus I would not expect any measurable differences in rates of molecular evolution given that the temperatures for life here on earth lie primarily within the range of liquid water.

Down at those geothermal vents, kT is greater because water is superheated under pressure; but one can also imagine that molecular configurations for extremophiles could be “more robust” – i.e., have slightly higher φ’s – also. They also live at considerably higher pressures.

I’m guessing that it is not likely that there will be measurable differences in molecular evolution rates across the entire spectrum of life. There is not much room for φ and T to vary without destroying the organism.

That’s an excellent point and you’re almost certainly right.

Because of my human-centric education, I’ve usually studied things that happen at about 37 degrees centigrade.

However, most of the biosphere is not homothermic, and much of it lives at substantially lower temperature than that.

I don’t know off the top of my head, and the detailed kinetics of the chemistry behind common mutations isn’t at my fingertips, but your intuition is likely to be correct here. Within the range of temperatures that permit actively reproducing terrestrial life, temperature probably doesn’t impact on overall mutation rate in a way that is strongly significant for evolution.

Remember that even hot springs bacteria can be killed by raising the temperature a little bit higher, and bacteria effectively stop dividing at temperatures that often exist naturally on some parts of the planet. Actively reproducing life requires a narrow temperature range.

Robert Byers said:

Wait a minute. Lets think about this. If My Myers is saying past and present, very present, scholarship on these things is so poor then creationists are right to lack and teach lack of confidence in anything from evolutionary biology. Its not just this fish!

If its a Coel and has relatives in fossils said to be so long ago then the differences are so small to in effect say its unchanged. They even invoked here about size. What does that matter? Irrelevant.

Mr Myers is stressing small differences to press the point this fish type has been evolving with the best of them. Its very little different from what i read here. There is indeed no living fossils because this presumes the fossils indicates ancient ages. Its just a more common type that survived from a greater diversity living a few thousand years ago as the great flood took place. there are many types of creatures unchanged from fiossil relatives in strata below the k-pg line.

My Myers is right however about modern literature in science fails to do a good job in origin issues. We know that fossil is still unmorphed.

He did it again. After arguing for months that fossils are “nonbiological” and therefore cannot be used to study the past history of life, Robert once again barfs out some verbal diarrhea claiming that the fossils are evidence for the magic flood! After going on and on about how the different fields of science are separate and paleontology cannot tell us anything about biology, he barfs out this little gem. So I guess you can use fossils to learn about the past history of life after all. And since, by his own logic, fossils that have changed little in millions of years are evidence of little evolution, then I guess all of the fossils that have changed dramatically are really good evidence for evolution.

Time to dump the twit to the bathroom wall again. His mindless mumbling verges on the incomprehensible anyway. It is obvious that he literally doesn’t think before he posts, but that may just be because he is incapable of rational thought. This is your mind on creationism.

robert van bakel said:

Are there examples of living animals (birds,insects,sharks etc) that DO resemble their respective fossil ancestors extremely closely? So closely in fact that selection seems to have been made redundant by the stability of the environment. Really, just asking!

Yes. In these cases, the living organisms would be classified as being in the same genus. Like, fossil species in Cyprinus, Carassius, Canis, Panthera, Helix, Acer, Ginkgo, Celtis, Eucommia, for example. In some cases, researchers determine that a fossil specimen is so similar to the living counterpart, they determine that both belong to the same species.

I have been following the recent spate of postings about the Coelacanth genome. This is the most useful one of ‘em all. So I am ready to expunge the idea of ‘living fossil’ for the coelacanth in my mind. What about horseshoe crabs? Any thoughts?

There is also the idea that some mutations are caused by radiation - nuclear and ultraviolet. Coelacanths live in deep water, below 100 meters, down to at least 500. There must be less EMR down there to cause mutations.

Or is this pure nonsense?

robert van bakel said:

Are there examples of living animals (birds,insects,sharks etc) that DO resemble their respective fossil ancestors extremely closely? So closely in fact that selection seems to have been made redundant by the stability of the environment. Really, just asking!

Please also consider the incredible example of the Crinoid http://en.wikipedia.org/wiki/Crinoid I think they are a showstopper if not an evolution stopper the Crinoid looks exactly like it’s fossil. The Coelacanths remind me of Darwin’s finches either born to be what they are or each adapted to the environment. It seams inhabitants of the Earth were subjected to http://en.wikipedia.org/wiki/Adaptive_radiation This suggests to me that the creatures molicules were perhaps changed due to been trigerd by external influences rather than an independant internal biological prosseses of DNA RNA proceedure.

Marilyn said:

robert van bakel said:

Are there examples of living animals (birds,insects,sharks etc) that DO resemble their respective fossil ancestors extremely closely? So closely in fact that selection seems to have been made redundant by the stability of the environment. Really, just asking!

Please also consider the incredible example of the Crinoid http://en.wikipedia.org/wiki/Crinoid I think they are a showstopper if not an evolution stopper the Crinoid looks exactly like it’s fossil. The Coelacanths remind me of Darwin’s finches either born to be what they are or each adapted to the environment. It seams inhabitants of the Earth were subjected to http://en.wikipedia.org/wiki/Adaptive_radiation This suggests to me that the creatures molicules were perhaps changed due to been trigerd by external influences rather than an independant internal biological prosseses of DNA RNA proceedure.

Are you a crackpot?

Marilyn said:

robert van bakel said:

Are there examples of living animals (birds,insects,sharks etc) that DO resemble their respective fossil ancestors extremely closely? So closely in fact that selection seems to have been made redundant by the stability of the environment. Really, just asking!

Please also consider the incredible example of the Crinoid http://en.wikipedia.org/wiki/Crinoid I think they are a showstopper if not an evolution stopper the Crinoid looks exactly like it’s fossil. The Coelacanths remind me of Darwin’s finches either born to be what they are or each adapted to the environment. It seams inhabitants of the Earth were subjected to http://en.wikipedia.org/wiki/Adaptive_radiation This suggests to me that the creatures molicules were perhaps changed due to been trigerd by external influences rather than an independant internal biological prosseses of DNA RNA proceedure.

I have been wondering if the whole ‘living fossil’ notion is just an illusion that needs to be abandoned because we would have to refer to thousands of species as living fossils, once we thought of it. Consider the number of bacteria like cyanobacteria and methanogens, and other bacteria that should be referred to as living fossils because they look like, and have metabolisms attributed to fossil bacteria. Then come the various invertebrates – jellyfish and squid and molluscs and arthropods that have more than a passing resemblance to fossils. Next are the various lizards that look like fossil lizards, fossil turtles that are pretty similar to turtles we see today, and so on. So living fossils are the many lineages that happened to not go extinct AND did not go through an arbitrary amount of divergent evolution. We must be up to our necks in living fossils. OR the whole idea of living fossils is just not useful. I am wondering if we should favor the latter.

Marilynn is a transitional form; like other creationists she can never be convinced, but like science supporters, she seems to have some interest in the real world and is not given to unjustified raging.

Therefore I will reply to the comment.

Please also consider the incredible example of the Crinoid http://en.wikipedia.org/wiki/Crinoid I think they are a showstopper if not an evolution stopper the Crinoid looks exactly like it’s fossil.

The whole point of this thread is that some (many, actually) basic anatomic plans are conserved for enormous amounts of time. However, this doesn’t mean that those lineages didn’t and don’t evolve.

If you want a really obvious example of a long-conserved morphology, go find an ordinary cockroach.

The reason Coelacanths are famous is because that particular morphology is common in fossils, but was considered extinct, and then in the sixties someone caught a modern Coelacanth. There are innumerable lineages that are more ancient and more anatomically conservative than Coelacanths.

The Coelacanths remind me of Darwin’s finches either born to be what they are or each adapted to the environment. It seams inhabitants of the Earth were subjected to http://en.wikipedia.org/wiki/Adaptive_radiation

That is basically correct.

This suggests to me that the creatures molicules were perhaps changed due to been trigerd by external influences rather than an independant internal biological prosseses of DNA RNA proceedure.

This is called Lamarckism. It is a perfectly good idea, named after a brilliant man. However, it is one of the many perfectly good ideas brilliant people have had, which turn out in the long run to be wrong.

What happens is that each replication of DNA produces offspring DNA that is slightly different from parent DNA. The differences are independent of the “needs” or “wishes” of organisms; they occur at random. “Random” refers to something that humans can measure or deduce the frequency or probability of, but can’t predict exactly.

If the changes in the DNA (RNA in the case of a some viruses) impact on the phenotype - they usually don’t, but if they do - the phenotypic variation may give the individual who carries it some advantage or disadvantage in reproduction - note that this advantage or disadvantage may be so small as to be imperceivable in the short term.

Also, an allele may change in frequency due to random chance, because it is linked to another allele that is more strongly selected one way or the other, or because it is recessive.

There’s plenty more to learn but those are the basics of how it works.

Lamarckism isn’t religious (or anti-religious), it’s a hypothesis of how elvolution might work, but overall, it’s not supported. There are lineages in which DNA repair mechanisms can be suppressed in high stress environments (thus leading to a higher net mutation rate); this is called by some “neo-Lamarckism”, for better or for worse.

PZ Myers: “Coelacanths, though, don’t represent that problem.”

Was Atheist PZ Myers conclusion ever in doubt?

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

Jeezy C you’re stupid, Ray.

Ray Martinez said:

PZ Myers: “Coelacanths, though, don’t represent that problem.”

Was Atheist PZ Myers conclusion ever in doubt?

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

Ray Martinez said:

PZ Myers: “Coelacanths, though, don’t represent that problem.”

Was Atheist PZ Myers conclusion ever in doubt?

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

SInce Ray needs for gods to exist, his conclusion against evolution was never in doubt and never will be regardless of the evidence.

Ray Martinez said:

PZ Myers: “Coelacanths, though, don’t represent that problem.”

Was Atheist PZ Myers conclusion ever in doubt?

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

The problem, Ray, is that us Evil Atheists™, Meyers included, are more than happy to posit scenarios that are a problem for Darwinian evolution.

A truly de nevo structure for which there is no antecedent. The infamous rabbit in Precambrian strata. The list goes on and on and we have discussed many, many scenarios here that would go a long way to disproving Darwinian evolution.

Darwin himself was troubled by what he thought were fatal flaws in his theory (mostly, that the Earth just wasn’t old enough).

Organisms living in places like the Great Rift valley, where the environment swings between dense forest and open savannah every 300,000 years feel an enormous amount of selections pressure, and species come and go with regularity.

Organisms like the celocanth, cockroach and crionid, organisms that are well suited to their lives in a small environmental niche that’s stable in the very long-term just don’t face the same amount of selection pressure as creatures in more dynamic niches, and therefore don’t change very fast.

As Meyers sums up “It’s just not a problem”. If you feel it is a problem for evolution, why don’t you please tell us exactly why.

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

1) Atheists existed before the theory of evolution.

2) Atheists exist who don’t know about, or improperly understand, the theory of evolution.

3) Many religious people accept and understand biological evolution.

So why is Ray trying to say that the theory of evolution is about atheism?

Remember, people, it’s really mainly about society and politics. Science is popular and credible. But science annoys people who make money off things like tobacco or fossil fuels, by raising neutral, objective concerns about the use of those products. Therefore you have to make science shut up, but people like science. But you figure that maybe people like Jesus even better, so you try to tell them that they can’t have both science and Jesus. Then, you figure, science will shut up and you won’t have to put warning labels on your cigarette packs any more. Also, you can claim that some people are less human than others without some propeller beanie wearing scientist contradicting you with talk about “genetics” (naturally, some people who talk about Jesus are a problem here, too, but it’s a lot easier to say “My arbitrary interpretation of the Bible is better than your arbitrary interpretation of the Bible” than to argue with science).

DS said:

Ray Martinez said:

PZ Myers: “Coelacanths, though, don’t represent that problem.”

Was Atheist PZ Myers conclusion ever in doubt?

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

Since Ray needs for gods to exist, his conclusion against evolution was never in doubt and never will be regardless of the evidence.

The response, in essence, simply reverses the point, giving me a taste of my own medicine.

Since I am a Christian and Paleyan Creationist my conclusion against evolution is never in doubt. This is completely true.

Christians have no choice, neither do Atheists. This is one of only two points I really wish to make. The other point is: When “Christians” accept the Atheist explanation of evidence (evolution) instead of the Biblical explanation, and Paley’s explanation, they are without excuse, traitors and buffoons. Again, since the only issue is which assumption or interpretive philosophy best explains the evidence, Theism/Supernaturalism or Atheism/Naturalism-Materialism, the fact that “Christian” Evolutionists side with the latter, and not the former, exposes them, as I observed, to be traitors and buffoons (quote marks justified).

Ray Martinez said:

buffoons…

Look in the mirror, Ray.

stevaroni said:

Ray Martinez said:

PZ Myers: “Coelacanths, though, don’t represent that problem.”

Was Atheist PZ Myers conclusion ever in doubt?

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

The problem, Ray, is that us Evil Atheists™, Meyers included, are more than happy to posit scenarios that are a problem for Darwinian evolution.

A truly de nevo structure for which there is no antecedent. The infamous rabbit in Precambrian strata. The list goes on and on and we have discussed many, many scenarios here that would go a long way to disproving Darwinian evolution.

Darwin himself was troubled by what he thought were fatal flaws in his theory (mostly, that the Earth just wasn’t old enough).

Organisms living in places like the Great Rift valley, where the environment swings between dense forest and open savannah every 300,000 years feel an enormous amount of selections pressure, and species come and go with regularity.

Organisms like the celocanth, cockroach and crionid, organisms that are well suited to their lives in a small environmental niche that’s stable in the very long-term just don’t face the same amount of selection pressure as creatures in more dynamic niches, and therefore don’t change very fast.

As Meyers sums up “It’s just not a problem”. If you feel it is a problem for evolution, why don’t you please tell us exactly why.

That was the spirit of my point: “It’s just not a problem” (Myers) because Atheists, since no God exists, have no choice but to conclude that evolution-did-it.

And Evolutionists have made it perfectly clear: problems do not constitute real problems (potential genuine falsification) for a theory held true since circa 1872. Evolution, contrary to what Myers says, is NOT subject to falsification. Once the concept is accepted to explain diversity it is never eligible to be falsified. What is eligible for falsification or modification is how evolution occurs, not if evolution occurs.

So if your main or concluding points have not been answered satisfactorily, please let me know.

Ray Martinez said:

DS said:

Ray Martinez said:

PZ Myers: “Coelacanths, though, don’t represent that problem.”

Was Atheist PZ Myers conclusion ever in doubt?

Since no God exists Atheists must conclude for evolution; so the answer is no: the conclusion for “evolution-did-it” was never in doubt.

Since Ray needs for gods to exist, his conclusion against evolution was never in doubt and never will be regardless of the evidence.

The response, in essence, simply reverses the point, giving me a taste of my own medicine.

Since I am a Christian and Paleyan Creationist my conclusion against evolution is never in doubt. This is completely true.

Christians have no choice, neither do Atheists. This is one of only two points I really wish to make. The other point is: When “Christians” accept the Atheist explanation of evidence (evolution) instead of the Biblical explanation, and Paley’s explanation, they are without excuse, traitors and buffoons. Again, since the only issue is which assumption or interpretive philosophy best explains the evidence, Theism/Supernaturalism or Atheism/Naturalism-Materialism, the fact that “Christian” Evolutionists side with the latter, and not the former, exposes them, as I observed, to be traitors and buffoons (quote marks justified).

No Ray You are wrong again. Rational people don’t decide what to believe based on their preconceptions or prejudices or religious convictions. You are the only one doing that, all the rest is simply projection on your part. One last time for the thinking impaired, the only valid justification for any belief is the evidence. You don’t have any Ray and you ignore all of the evidence for evolution. You refuse to even consider it because you are the one who has no choice. Thanks for admitting once again what everyone already knows. You do not honor the evidence, you cannot. Your opinion is completely worthless.

I am familiar with the evidence and I have a choice. I choose to honor the evidence no matter the cost. You don’t even have the intellectual honesty to look at the evidence.

Time to dump the religious fanatic to the bathroom wall and get back to discussing biology.

If Ray wants to discuss science he can get to it. IF not he can piss off. No one is interested in his religious delusions.

So mister immutabalist, how do you explain the numerous skeletal differences observed between the fossil and modern coelacanths. Sure don’t look immutable to me.

1. Darwin:

the periods during which species have been undergoing modification, though very long as measured by years, have probably been short in comparison with the periods during which these same species remained without undergoing any change.

2. 19th vs. 21st century. It is not very smart to ignore the fact that some research has been done in the interim.

Wrote this article on ceolocanths and lungfish yesterday:

http://www.policymic.com/articles/3[…]ng-ourselves

Jon said:

Wrote this article on ceolocanths and lungfish yesterday:

http://www.policymic.com/articles/3[…]ng-ourselves

Jon,

NIce article, You explained the phylogenetic analysis and its significance very well. I really liked the picture of the lungfish. Also, thanks for the link to the original article, that’s something I wish all science reporters would include in summaries of original literature.

The original article includes a phylogenetic analysis for 251 genes demonstrating the slow rate of molecular evolution in coelacanths relative to lungfish. It also includes a detailed analysis of hox gene evolution, complete with an analysis of cis regulatory regions and transgenic experiments. Perhaps PZ could start another thread concentrating on these issues.

Rolf said:

1. Darwin:

the periods during which species have been undergoing modification, though very long as measured by years, have probably been short in comparison with the periods during which these same species remained without undergoing any change.

2. 19th vs. 21st century. It is not very smart to ignore the fact that some research has been done in the interim.

Such is the peril of believing in and repeating verbatim the false prophecy that “Darwinism (sic)” will fail any day now for the last 150+ years.

Hey Steve, how about this, why don’t you look up “punctuated equilibrium” and see what you find? If after that you still think that the fact that evolution can occur slowly or quickly is a problem you can explain why. If after that you still think that this somehow disproves Darwin you can explain why. If you then think that Gould should be venerated as a saint instead of Darwin you can explain why. Until you educate yourself, your ignorant opinions are worthless, as usual.

The last straw has slipped through your fingers and your you are grasping at air.

Wikipedia has an article which discusses this: Italian wall lizard.

SteveP’s comments re fast or slow evolution reminds me of AGW deniers who represent the scientific case as “wanting it both ways”, thus “warming proves AGW and cooling proves AGW”. It’s as if there is something inherent in the science-denying mind that demands reality be simple and conducive to one-sentence rules.

Or like they don’t know what “average” means?

Henry J said:

Or like they don’t know what “average” means?

Nor do they know what “evolution” means, or what “evidence” means.

Just noticed today at the American Museum of Natural History that the coelacanth is referred to as a living fossil. They also say that it has changed little. Old habits die hard!

PA Poland said:

[.…]

And gradual step-wise change is all that is needed to explain the diversity of life OBSERVED in the real world. And there are many mechanisms KNOWN to produce morphological changes of various scales. The fact you are ignorant of them will not make them go away.

There are findings that would falsify evolution - you have not presented any of them.

‘Lightning speed’ ?!?! Seriously ?

Forty years is about 40 generations for those lizards, and observations of REALITY show that changes can fix very quickly under some conditions.

Selection can work very quickly, changing the make up of a population within a short time (it scales to population size - small populations can change faster than larger ones).…

What would be a rate of mutation that falsifies selection?

And how do you explain the decibel ordnance seen in pistol shrimp? Aren’t we told that single-step macromutations don’t happen?

Ray Martinez said:

PA Poland said:

[.…]

And gradual step-wise change is all that is needed to explain the diversity of life OBSERVED in the real world. And there are many mechanisms KNOWN to produce morphological changes of various scales. The fact you are ignorant of them will not make them go away.

There are findings that would falsify evolution - you have not presented any of them.

‘Lightning speed’ ?!?! Seriously ?

Forty years is about 40 generations for those lizards, and observations of REALITY show that changes can fix very quickly under some conditions.

Selection can work very quickly, changing the make up of a population within a short time (it scales to population size - small populations can change faster than larger ones).…

What would be a rate of mutation that falsifies selection?

Selection works because some variants have an easier time living long enough to reproduce than others; in order to falsify selection, you’d have to show that a mutation that should be lethal is spreading through a population.

As to mutational rate, the maximum rate is around 1/L per replication, where L is the number of nucleotides vital for survival; beyond that, you’re looking at ‘mutational meltdown’, where a viable state cannot be maintained.

There are a few conditions where the rate can go higher (such as the fitness peak is so wide that just about any sequence would do), but nearly all organisms examined so far have rates well below ‘meltdown’ levels.

The highest rate, IIRC, is for a viroid. This parasitic strand of RNA is 399 bases long, and has an error rate of 1 per 400 nucleotides/replication.

And how do you explain the decibel ordnance seen in pistol shrimp? Aren’t we told that single-step macromutations don’t happen?

What makes you think that it was a single-step macromutation (other than a pathological need to find somewhere to shoehorn your Magical Sky Pixie into the picture) ?

What next - blubbering about how the bombadier beetle couldn’t have evolved without blowing itself up, therefore “XTIAN MAGICAL SKY PIXIE DIDIT !!!1!!1!!!” ?

All of the pistol shrimp’s abilities are explainable as alterations of basic abilities all shrimp have - its decibel ordnance is just due to extremely fast muscle contraction and elastic tissues to store up effort until needed.

And your ‘explanation’ of the pistol shrimp’s abilities is what again ?

Oh, right : “*** MY *** Magical Sky Pixie willed it thus !!!!!1!!!!!1!!!!1!!!”

About this Entry

This page contains a single entry by PZ Myers published on April 20, 2013 2:10 PM.

Do “Darwinists” Really Lack Compassion? was the previous entry in this blog.

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