Evolution of Hormone Signaling

Posted 11 January 2005 by PZ Myers

↗ The current version of this post is on the live site: https://pandasthumb.org/archives/2005/01/evolution-of-ho.html

Last week, I received some delusional e-mail from Phil Skell, who claims that modern biology has no use for evolutionary theory.

This will raise hysterical screeches from its true-believers. But, instead they should take a deep breath and tell us how the theory is relevant to the modern biology. For examples let them tell the relevance of the theory to learning…the discovery and function of hormones…[long list of scientific disciplines truncated]

Dr Skell is a sad case. He apparently repeats his mantra that biology has no need of evolution everywhere he goes, and has never bothered to actually crack a biology journal open to see if biologists actually do use the theory. In my reply to him, I did briefly list how evolution is used in every single one of his numerous examples, but today I'm going to focus on just the one I quoted above: hormones.

Now I'm not an endocrinologist, and I don't usually read much in the hormone literature, so it was just chance that I stumbled across a review article on this very topic in BioEssays. My point is that you don't have to be an expert in the discipline to find evidence that Skell is completely wrong; all it takes is a casual perusal of the general scientific literature and a prepared mind (alas, I fear that creationists don't do the first and lack the second. One of the reasons I am concerned about science education in grade schools is that one of the aims of the creationist movement is to make sure our kids lack prepared minds, too.)

The review paper by Heyland et al. (2004a) is well worth looking up. It has a long introduction that covers several important themes in modern evo-devo, that I'll just summarize briefly here.

Continue reading "Evolution of Hormone Signaling" (on Pharyngula)

16 Comments

DaveScot · 12 January 2005

ID or not ID is as important to practical applications in biology as whether the discovery of beer was accidental or happened by design is important to practical applications of brewing. Beer's the same either way and how it happened to be discovered is not relevant to the modern practice of brewing.

It's not a big deal. It's historic trivia. Hysteric trivia might be more apt though. If all the drama queens would disappear so would the brouhaha over ID.

Rilke's Grand-daughter · 12 January 2005

Dave, if I understand you correctly, your comments,

ID or not ID is as important to practical applications in biology as whether the discovery of beer was accidental or happened by design is important to practical applications of brewing. Beer's the same either way and how it happened to be discovered is not relevant to the modern practice of brewing.

imply that the question of ID is irrelevant to biology. I agree.

It's not a big deal. It's historic trivia. Hysteric trivia might be more apt though. If all the drama queens would disappear so would the brouhaha over ID.

You're leaving? I didn't know. Have a nice trip. %:->

charlie wagner · 12 January 2005

PZ wrote:

This is the kind of thing that leaves me scratching my head when a creationist announces that "the discovery and function of hormones" is not a subject that is enlightened by evolutionary theory. It really isn't at all difficult to find work that integrates evolution and endocrinology, and for which evolutionary explanations are indispensable.

I think you are confusing two different things. There is a difference between a subject "being enlightened" by evolutionary theory, where one would suspect that evolutionary theory contributes some important quality to the discovery that would not have been possible without the application of the theory, and explaining some observed phenomenon in terms of evolutionary theory, after the discovery has already been made. This paper you refer to does the latter. The observations were made without any benefit from evolutionary theory and would have been made, even if evolutionary theory did not exist. So evolutionary theory contributed not one single aspect to the discovery. Only after the discoveries were made, was the interpretation offered that fit in with prevailing evolutionary dogma. Phil Skell is absolutely correct. Biology has no need for evolutionary theory, and would do just as well without it. Can you give me even one example where the application of evolutionary theory to a research project has been an important component that preceeded and contributed to the outcome of that investigation? (Be careful that you don't confuse basic genetics, molecular biology, or molecular genetics with evolutionary theory.) Charlie Wagner http://enigma.charliewagner.com

Frank Schmidt · 12 January 2005

Charlie shows us once again that he really doesn't know Biology by offering the challenge:

Can you give me even one example where the application of evolutionary theory to a research project has been an important component that preceeded and contributed to the outcome of that investigation?

One that comes to mind immediately is the recognition of the archaea by Carl Woese. Previously,they had been lumped with the prokaryotes. Woese's search for an evolutionarily valid scheme of classification led to the discovery that this group has unique biology. Woese's writings and seminars on the subject make it abundantly clear that this was an "important component." Indeed, it was a vital one. Others: catalytic RNA, posited by Francis Crick as an explanation for the prebiotic emergence of coding and catalysis; reverse transcription and oncogenes proposed by Howard Temin; the biochemical relationship of eukaryotic organelles to bacteria by Lynn Margulis and predecessors; combinatorial biochemistry which uses a Darwinian paradigm; essential parts of proteins (e.g., fibrinopeptides) by Russell Doolittle.... Need I go on? The argument from ignorance has a corollary: The deeper the ignorance, the louder the argument.

PZ Myers · 12 January 2005

Correct. Like Phil Skell, Charlie is just pulling things out of his own ignorant ass here.

This paper is doing both of the things he is saying: it is interpreting results in the light of evolutionary theory, and it is proposing further work founded in evolutionary theory. Look at the title. "Hormone signaling in evolution and development: a non-model system approach". Much of the paper is talking specifically about why a non-model system approach is necessary to test evolutionary hypotheses for the origin and modification of hormone signaling.

This paper is an excellent example of "application of evolutionary theory to a research project [that] has been an important component that preceeded and contributed to the outcome of that investigation".

charlie wagner · 12 January 2005

One that comes to mind immediately is the recognition of the archaea by Carl Woese. Previously,they had been lumped with the prokaryotes. Woese's search for an evolutionarily valid scheme of classification led to the discovery that this group has unique biology.
— Frank Schmidt

Woese says it best himself:

I am a molecular biologist turned evolutionist.

His work in molecular biology led directly to his evolutionary theories, not the other way around. The division of prokaryotes by Woese in 1977 was based on molecular studies of 16s rRNA's. It was also based on the fact that there are fundamental differences in transcription and translation, which more closely resembled eukaryotes than prokaryotes. There are also differences in the cell membrane and the flagella which set these organisms apart from other prokaryotes. It was these discoveries in the fields of microbiology and molecular biology that fueled Woese's evolutionary theories and led to the recognition of the Archaea as a unique group. It was not Woese's "search for an evolutionarily valid scheme of classification" that led to the discovery of the Archaea, it was good old, basic molecular biology, since before his 16s rRNA studies, he, along with most other microbiologists, had no idea that these might be anything other than run of the mill prokaryotes. Charlie Wagner http://enigma.charliewagner.com http://www.charliewagner.com

charlie wagner · 12 January 2005

...the biochemical relationship of eukaryotic organelles to bacteria by Lynn Margulis and predecessors...
— Frank Schmidt

First of all, Lynn Margulis is *not* a darwinian evolutionist. Her theory of endosymbiosis was not the product of evolutionary theory and at its inception was based upon some compelling data in the fields of ordinary cellular biology and genetics: From Wikipedia (accuracy verified) http://en.wikipedia.org/wiki/Endosymbiotic_theory#Evidence

Evidence that mitochondria and chloroplasts arose via an ancient endosymbiosis of a bacteria is as follows: * Both mitochondria and chloroplasts contain DNA, which is fairly different from that of the cell nucleus, and that is in a quantity similar to that of bacteria. * Mitochondria utilize a different genetic code than the eukaryotic host cell; this code is very similar to bacteria and Archaea. * They are surrounded by two or more membranes, and the innermost of these shows differences in composition compared to the other membranes in the cell. The composition is like that of a prokaryotic cell membrane. * New mitochondria and chloroplasts are formed only through a process similar to binary fission. In some algae, such as Euglena, the chloroplasts can be destroyed by certain chemicals or prolonged absence of light without otherwise affecting the cell. In such a case, the chloroplasts will not regenerate. * Much of the internal structure and biochemistry of chloroplasts, for instance the presence of thylakoids and particular chlorophylls, is very similar to that of cyanobacteria. Phylogenies built with bacteria, chloroplasts, and eukaryotic genomes also suggest that chloroplasts are most closely related to cyanobacteria. * DNA sequence analysis and phylogeny suggests that nuclear DNA contains genes that probably came from the chloroplast. * Some genes encoded in the nucleus are transported to the organelle, and both mitochondria and chloroplasts have unusually small genomes compared to other organisms. This is consistent with an increased dependence on the eukaryotic host after forming an endosymbiosis. * Chloroplasts appear in very different groups of protists, which are in general more closely related to forms lacking them than to each other. This suggests that if chloroplasts originated as part of the cell, they did so multiple times, in which case their close similarity to each other is difficult to explain.

Not a word about any role played by evolutionary theory. Charlie Wagner

Wedgie World · 12 January 2005

Confusing evolutionary theory and darwinism Charlie? In fact Darwinism and symbiosis can live quite well symbiotically...

Frank Schmidt · 12 January 2005

Charlie, Charlie, Charlie... Your laziness causes you to deny the obvious. May I commend to your attention the following

Mibrobiology Reviews 58:1-9, 1994. There must be a prokaryote somewhere: Microbiology's search for itself. CR Woese Department of Microbiology, University of Illinois, Urbana 61801. While early microbiologists showed considerable interest in the problem of the natural (evolutionary) relationships among prokaryotes, by the middle of this century that problem had largely been discarded as being unsolvable. In other words, the science of microbiology developed without an evolutionary framework, the lack of which kept it a weak discipline, defined largely by external forces. Modern technology has allowed microbiology finally to develop the needed evolutionary framework, and with this comes a sense of coherence, a sense of identity. (emphasis added) Not only is this development radically changing microbiology itself, but also it will change microbiology's relationship to the other biological disciplines. Microbiology of the future will become the primary biological science, the base upon which our future understanding of the living world rests, and the font from which new understanding of it flows.

I heard Woese speak about this in 1977; he made very clear that his motivation was the necessity to involve evolution in the microbial world. Similarly, regarding Lynn Margulis, you state:

Not a word about any role played by evolutionary theory.

your own post lifted from Wikipedia contradicts your thesis:

* DNA sequence analysis and phylogeny suggests that nuclear DNA contains genes that probably came from the chloroplast.

Note: Sequence-based phylogeny is evolution these days. And it's really odd how this title came to be: Microcosmos: Four billion years of evolution from our microbial ancestors by Lynn Margulis and Dorian Sagan. ISBN 0520210646 Again, I heard Lynn Margulis speak about this in 1972. Her arguments were suffused with evolutionary theory.

charlie wagner · 12 January 2005

I heard Woese speak about this in 1977; he made very clear that his motivation was the necessity to involve evolution in the microbial world... Again, I heard Lynn Margulis speak about this in 1972. Her arguments were suffused with evolutionary theory.
— Frank Schmidt

I can't even remember what I had for breakfast this morning and you claim to remember what Carl Woese and Lynn Margulis said 28 and 33 years ago? The word "application" means "the act of putting something to a special use or purpose, such as using calculus to solve a problem or using a machine to perform work. Looking for presumptive phylogenetic (evolutionary) relationships is not the same as "applying the theory". What actually happened here was that molecular sequencing techniques were applied to the problem of establishing the phylogeny of prokaryotes. It was these newly developed techniques that were the driving force behind the research, not evolutionary theory, which had failed to solve the problem or contribute to it's solution for decades before. Then, when the problem was solved in 1977 by Woese and his asociates, using the techniques of molecular biology, it was that same "evolutionary theory" that impeded its acceptance for many years afterwards. The notion of polyphly among prokaryotes was unthinkable at the time and "adaptation" was called up to explain extreme niches such as are found in many Archaea. The flawed paradigm, that dismissed the search for microbial relationships and embraced the prokaryotic-eukaryotic dichotomy delayed the emergence of a phylogenetic framework for many years. Sadly, to this day many biologists still lump all prokaryotes into the same taxon. By the way, thanks for taking a look at my blog... Charlie Wagner

Frank Schmidt · 12 January 2005

Charlie, I do indeed remember the talks. Just like I remember when I met my wife and what the weather was like on the day my first child was born. It's my job. I think you are misrepresenting the way science works in your zeal to overthrow "orthodoxy."

Then, when the problem was solved in 1977 by Woese and his asociates, using the techniques of molecular biology, it was that same "evolutionary theory" that impeded its acceptance for many years afterwards.

Actually not. Look what really happened. First, the paper (Woese and Fox, 1977) was published in PNAS, not a bad rag. Secondly, the community got busy checking out the idea to see if it had merit. Because of the methodology, it was more easily accepted by the molecular crowd than the organismal group, but that's no big surprise. Then more and more people started taking it seriously as more Archeal characteristics became apparent. No big deal, really. Even at this late date, not everyone is totally convinced, and the nature of the LCA is still unclear even to those who are. That's science: it's a community effort and it involves work. Relativity didn't stop with E = mc² either. Your blog would be more valuable if it had a link to John Baez' crank science page.

charlie wagner · 13 January 2005

Frank wrote:

Look what really happened. First, the paper (Woese and Fox, 1977) was published in PNAS, not a bad rag. Secondly, the community got busy checking out the idea to see if it had merit. Because of the methodology, it was more easily accepted by the molecular crowd than the organismal group, but that's no big surprise. Then more and more people started taking it seriously as more Archeal characteristics became apparent. No big deal, really.

That's not quite the way Carl Woese remembers it:

"It was this same faith (that all prokaryotes were the same)...that accounted for the negative reaction to the discovery of the Archaea. Most of this reaction did not appear in print, which is regrettable, for it would make interesting and instructive reading today. However, this again is the way of paradigms: when facts or concepts arise that challenge them, these tend to be ignored. If that is not possible they are scoffed at and otherwise communally rejected- informally. (And the Archaea were greeted with reactions aplenty of this type.) Only as a last resort will the paradigm *formally* contest the novelty that threatens it (i.e. treat it scientifically).
— Carl Woese

Shades of Barbara McClintock, Lynn Margulis, Fred Hoyle, Alfred Wegener, Halton Arp, Hannes Alfven and the many others who endured this ridicule and rejection. The happiest moment in my life was when Barbara McClintock won the Nobel Prize for her work and everyone who mistreated her had to admit that she was right and they were wrong. I'm just glad that she lived long enough to experience complete vindication. My zeal is not to "overthrow orthodoxy", for the sake of overthrowing it. My zeal is to remove the impediments to scientific progress that result from the refusal to discard theories that have long ago been discredited by persons whose whole lives are invested in it. And while this may seem to some to be "the way science works", it sometimes has tragic results:

Can you understand why I have such distaste for the prokaryote-eukaryote dichotomy?This is not the unifying principle we all once believed it to be. Quite the opposite: it is a wall, not a bridge. Biology has been divided more than united, confused more than enlightened, by it. This...dogma has closed our minds, retarded microbiology's development, and hindered progress in general. Biological thinking, teaching, experimentation, and funding have all been structured in a false and counterproductive dichotomous way.
— Carl Woese

There are many similarities here to the evolutionary paradigm, which is doing the same kind of damage to scientific progress. Refusal to acknowledge the problems and zealously defending a worthless paradigm is not good science, although it has much historical precedent. As Gould says, "these hoops of steel are not easily unbound..." Charlie Wagner http://www.charliewagner.com

Colin · 13 January 2005

I'm not a scientist, so I may be way off-base, but isn't the lesson here that Woese challenged the prevailing "dogma" with /science/? That is to say, rather than making rhetorical and political arguments about how scientists are chasing a "worthless paradigm," he actually /discovered something new/ that had a significant impact on the system. That's the largest failing of the anti-science crank crowd; none of the ideological complaints about evolution diminish its contributions to human knowledge, or credit a single discovery to the ID/Creation Science/YEC crowd.

charlie wagner · 13 January 2005

Colin,
You're correct, there are two completely different things going on here and they are almost mutually exclusive of each other. First there is the political/ideological debate that rages here and elswhere, sometimes referred to as "the evolution-creationism debate", that has very little to do with science, and then there is the actual scientific work that goes on daily in laboratories, the research into molecular biology, molecular genetics and other scientific disciplines.
Those folks who actually work in the science field and do the actual research almost never get involved in public discussions of evolution, and very few of the public debaters (myself included) are involved in actually doing the science.
However, the science is what it's all about, and I involve myself in the public debate to draw attention to the actual research which is being done, and may help people to make up their own minds about the problem, research that might be overlooked by those who don't read the scientific journals.
The same thing happened in the 70's when new discoveries were being made in the role heredity plays in intelligence and the psychometrics involved. As soon as legitimate researchers discovered that the public was largely opposed to their findings, they withdrew from the debate almost entirely and retreated to their safe havens, where they continued their research, published it in little-read journals and discussed it among themselves while the public debate over IQ and the inheritance of intelligence, the so-called "nature vs nurture debate" raged on in the popular media.
This is what is happening right now in evolutionary research. The real investigators, those who do the real science have largely withdrawn from the debate, retreated to their laboratories and continue to study their disciplines while the "evolution-creationism" debate rages on in another room. I know this is true because I've written to many researchers about the significance of their work or their interpretation of it and I've encountered either no response, or something along the line of "I have no problem with evolution...goodbye!"
The additional factor here is that the spectre of creationism strikes fear into the heart of most scientists. Most legitimate researchers are very reluctant to say anything that creationists might seize upon and use against science and evolutionary theory. And who can blame them?

Frank Schmidt · 13 January 2005

Charlie again imitates Lucy from Peanuts "If you can't be right, be wrong at the top of your voice":

The real investigators, those who do the real science have largely withdrawn from the debate, retreated to their laboratories and continue to study their disciplines while the "evolution-creationism" debate rages on in another room.

The "other room" you speak of is in the religio-political arena only. The fact that real work is being done doesn't mean that we cede the field to the ID cranks. Note the Pandas thumb page about the number of scientists who have taken on the issue. Or the many NCSE supporters who are distinguished, active, scientists. Scientists do speak out on issues that inhibit their ability to do science, as IDC does. Or do you really delude yourself into thinking that there is some young Einstein toiling away in his/her lab, ready to blow the rest of us out of the water? Don't hold your breath.

Colin · 13 January 2005

I don't think anyone here would be surprised to learn that most scientists are disengaged from the political, legal, and rhetorical polemic. I was already aware of that; I dated an evolutionary biology PhD student when I was in law school, and when I was writing about the constitutional barriers to creationist education I had a very difficult time engaging her in the discussion. ID/creationist arguments were so fatuous to her that the discussion simply wasn't worth her time or energy.

But that's exactly the reason why the constant political, legal, and rhetorical complaints are so facile. There are no ID researchers out trying to discover new things, or even forthrightly engaging actual science in an attempt to discover truth. The schism you describe is between actual scientists, researching and learning about evolution and its processes, and creationists pursuing an antiscientific agenda predicated on religious and cultural grounds. The evolutionary discussion is happening in laboratories, journals, and classrooms at all levels, while the creationist discussion is happening on the political and rhetorical level. Which one of these is more powerful depends on the context, but only one of them is designed to actually /learn./ The other is an exercise in power, without any benefit to society beyond reinforcing the beliefs of the true believers.