Responding to a comment on my article: “Gill slits” by any other name…

I have decided to move this up from the comments section (cuz why not?) of my article “Gill slits by any other name…

Andy: Hi Troy, I read your post, and it is very well argued.

Thanks. [He said knowing that a “but” was coming.]

Andy: At the moment, I am a biology student at a local university, and one of my personal headaches is the promotion of either creation-ism or evolution-ism. To be honest with you and with all due respect, I really don’t care for either explanation.

Andy, with all due respect, you should know that for someone like me who has been in the “trenches” debating people pushing pseudoscience for years, the fact that you would refer to evolutionary theory as “evolutionism” is a large red flag that would strongly lead me to suspect that your understanding of evolutionary theory and science itself is likely wanting.

Unfortunately, your next sentence does little to disabuse me of my suspicion. Creationism is set of theological beliefs regarding a creation story written down in the 6th or 5th century B.C.E., accepted on faith and in the face of contravening facts by a tiny minority of people with any scientific background. Its mechanisms (God did it) are untestable and to the extent that it makes claims testable against the empirical world it has been falsified a thousand times over.

On the other hand evolutionary theory is a scientific explanation for a vast number of facts that is testable against further observations of the empirical world and used by the vast majority of the relevant scientific community as a guide to further research…whether you “care” for it or not.

That you would casually place them on the same level is yet another huge red flag.

Andy: As a student, the only thing that I am concerned about is true scientific facts that have been tested at a laboratory to the molecular level.

We are only three sentences in and we have three red flags. In my experience people who use terms such as “true scientific facts” (as opposed to what, “false scientific facts”?) tend to not to be particularly familiar with either the facts or what counts as scientific.

However, that is a nit compared to the philosophical problems with your above statement. Why on Earth would you limit yourself to what is testable in a laboratory at a molecular level? Better yet, why should anyone else take your narrow limits as to what to be concerned with seriously? Using your bizarre limitations, we would be throwing out vast swaths of empirical data, and not just in biology.

Molecules are great but they are not a perfect path to knowledge nor are they the only path.

Furthermore, the point of science is not simply collecting random facts, rather it is about explaining the facts that we observe [insert Darwin quote about collecting pebbles here]. In this case, we have detailed anatomical, physiological and genetic similarities between the pharyngeal structures of terrestrial vertebrate (hereafter “amniotes“) embryos and non-amniote vertebrates (amphibians and “fish”), set against a particular paleontological backdrop that needs a coherent explanation.

You do not like creationism, great. That should be a given and I am with you. However if you do not like evolutionary theory, then what is your better explanation for the gill-like appearance of the pharyngeal structures of amniote embryos (and everything else evolution explains)?

You cannot just sit back and say, “I don’t buy any of it” and expect to be taken seriously, especially in face of the apparent success of evolutionary theory.

Andy: My teacher presented this same example about the gill slits during a microbial genetics lecture.

I am not sure how the “gill slits” of vertebrate embryos are relevant to the genetics of microbes but OK…

AndyI was just exhausted of listening, so, I raised my hand and said that the information was outdated and more up-to-date data has been collected explaining that they are no longer gill slits, and they are pharyngeal pouches.

Huh, did you read my article to which you are supposedly responding? You are literally arguing semantics here. Regardless of what we call these structures in the embryos of amniotes, they exist, they resemble—in detail—the developing gills of non-terrestrial vertebrates, and we want to understand why this would be so.

AndyHe asked what was my source, and my reply was, with all due respect, professor, but your source is 150 years old and newer information was out that did not concentrate on a belief based teaching. He stopped and said he will do some more research and get back to us. He continued with the lecture as it was intended.

I am sorry but “your source is 150 years old”, even if true, is not an argument; old ≠ incorrect. FA = -FB (for every action there is an equal and opposite reaction) gets robotic probes to Mars despite the fact that Newton came up with the formula over three hundred years ago.

Furthermore, what is this “belief based teaching” to which you refer? Once again, if you read my article you would know that referring to these structures as “gill-slits” is not dependant on a belief in either creation or evolution as is evidenced by the fact that pre-Darwin creationists called them this.

Oh, and what is your source Andy?

AndyI agree; they look like gills until you dissect it, and then they look like pouches. I know in biology we name a lot of things base on morphological characteristics, and that is a great easy way to remember things.

No, no, no, again did you even read my article? Here, look at this diagram again:

Source, with modifications.

Source, with modifications.

There are clefts (or grooves) on the outside of the pharynx (red arrows) with corresponding pouches on the inside (blue arrows). These clefts and pouches are each separated by membranes that, in mammals, normally remain unperforated with the first (tympanic) membrane forming the so-called eardrum. Some of the post tympanic membranes do normally perforate and then reclose in some birds and reptiles embryos. They also temporarily perforate in the gill-bearing larvae of some amphibians and, of course, in fish they stay perforated and become gills.

Since I know some people are queasy about diagrams here are a few photographs of coronal sections done on various mammal embryos. First, an electron microscope picture of what I think is a stage 13 human embryo (Etchevers, 2008)(blue arrow points to the pharyngeal pouch and red to the corresponding cleft).

(Etchevers, 2008)

For comparison, here are some stained sections from a mouse (left, Zhang et al. 2005) and a pig (right, Shone & Graham 2014) at a similar point of development; once again blue arrows for pouches and red for clefts. Also, note in these photos that the aortic arches—the blood vessels—are visible within the pharyngeal arches (green arrows).

(Left, Zhang et al. 2005 – right, Shone & Graham 2014)

These are not just “pouches”! There are arteries (the blood vessels shown above), muscles, nerves and cartilaginous structures found on either side of the cleft/pouch pairs in the embryonic gills of “fish” and the corresponding pharyngeal arches of amniote embryos.

How do you get from this to, “they look like gills until you dissect it, and then they look like pouches” without ignoring all of these observable facts? These things exist and you need to explain them Andy.

AndyThe only thing that really gets to me is that either creationist or evolutionist keeps trying to push the subject in school.

The reason a competent science teacher (i.e. one who teaches evolutionary theory) would bring them up is because they are structures that have interested biologists since they were first discovered and whose existence is elegantly explained by descent from a common ancestor (evolution).

AndyHonestly, I paid for one of my books close to $300. I feel that my book should be filled with up-to-date information that has been tested, and that is going to help me in the future and not filled with propaganda of any kind.

The pharyngeal structures of amniote embryos are not propaganda. They exist and are observable by anyone with eyes to see. For example, please note that the photographs of the pharyngeal sections of mouse and pig embryos I reproduced above were both taken from papers published within the twenty-first century. Any modern textbook on vertebrate developmental biology is likely to have similar photos or diagrams of these structures.

AndyI guess it is easier to print the old stuff than to update the books to what they are intended to do, and that is to provide useful information that can help us treat diseases and give our patients a fighting chance.

Sorry Andy regardless of whether it comes from an older source or a current one, pharyngeal clefts, or “gill slits” exist in amniote embryos whether or not you want to accept the facts or the current best explanation for them, so please spare us the overwrought “won’t someone think of the ill people?!” shtick.

AndyTo this day, I haven’t seen a mermaid or an angel either in nature or in a lab, so, I will have to dismiss both claims as pending research and proper laboratory testing.


Yeah so at this point, I am starting to have doubts that you are for real Andy and not just a troll looking for attention. What the hell does a mermaid have to do with anything Andy? Please tell me you are not seriously suggesting that evolutionary theory somehow supports the existence of mermaids [Hint: the exact opposite is the case]. Because if you think it does, you may want to rethink your career path—perhaps something in the arts?

AndyPlease don’t take this the wrong way. I am a paying student who is discordant with the never-ending stories.

As I said, after the mermaid comment I am no longer sure how to take you Andy. Perhaps your response or lack thereof will clarify that question.

Regardless I want to thank you Andy. Formulating my response to you has made me consider adding a few things to my “gill-slit” article that I think could use some expansion or clarification. So anyway, Poe, troll or sincere, something positive has come from your comment, thanks.


Etchevers, Heather (2008) Development of the branchial arches (slide presentation downloaded on 10-29-16)

Shone, Victoria & Graham, Anthony (2014) Endodermal/ectodermal interfaces during pharyngeal segmentation in vertebrates, Journal of Anatomy, 225(5):479-91

Zhang, Zhen et al. (2005) Tbx1 expression in pharyngeal epithelia is necessary for pharyngeal arch artery development, Development, 132:5307-5315

Playing Chess with Pigeons on Facebook


While I have had a link to my personal Facebook page in the sidebar for some time, I don’t know if I have ever mentioned here that Playing Chess with Pigeons has its own Facebook page… Well, now I have.

I generally post cartoons and news stories directly related to CvE as well as links to science news stories that I think are interesting and/or obliquely related to the CvE debate.

Anyway, have a look, like, subscribe, share…

Secular Museum Blunder

To demonstrate once again that I am an equal opportunity critic, here is a nit I have to pick with a secular museum, namely the Riverside Metropolitan Museum located in downtown Riverside, CA. It is a small museum and most of its limited public floorspace is taken up by displays dealing with Native American culture and artifacts. However it also has a number of displays on natural history, primarily that of the mountains & deserts in Riverside County. It is near some of these displays I found the following stuck to a wall:


And here is the lone label seen in the bottom right-hand corner:


It reads, “Baron Cuvier’s Pterodactyl“, apparently a reference to the fact that it was the “father of paleontology” Georges Cuvier who dubbed one of the earliest discovered pterosaur fossils “Ptéro-Dactyle”.

Yeah, the problem is though the cast of the fossil accompanying the label is very clearly not of the genus Pterodactylus named by Cuvier. Rather it is a cast of a RhamphorhynchusHere for comparison is the holotype specimen of Pterodactylus:


The red arrow points to Pterodactylus’ rather diminutive tail, which stands in rather stark contrast to Rhamphorhynchus’ long kite-like tail which ends in a diamond shaped vane (see above). 

Amusingly this is not the first time that these two genera have been confused. Apparently Rhamphorhynchus was originally misidentified as a species of Pterodactylus but after a few rounds of reclassification finally ended up as its own genus by the hand of Richard Owen 1861.

So a wag of my finger to the Riverside Metropolitan Museum; you need to fact check your displays.

Consilience and whale evolution

Way, waaay back in December of 2005 (ye gods has been ten years already?!) I wrote a Feedback response on the Talk Origins Archive to a question about the vestigial pelvic bones found in modern whales. In this case the questioner did not believe them to be truly vestigial, no doubt due to holding erroneous beliefs regarding the subject. In my response I of course took the time to correct their faulty views, however I also used the opportunity to talk about the concept of consilience wherein multiple independent lines of evidence converge on a single explanation, giving us greatly increased confidence that those explanations (hypothesis/theories) are likely to be accurate reflections of reality, i.e. “true”. 

I have now and again thought of going back and using that post as a spring-board for a more detailed examination of this subject and who knows, I may still do so someday. In the meantime however, here is a great video from Stated Clearly that I ran across on Facebook recently that uses the same topic—whales—to essentially do the same thing I did all those years ago; make a point about the consilience of evidence pointing to a pretty definite conclusion with regards to not just the ancestry of cetaceans but the evolution of life in general. Better they include more details than I did and it has animations.

Check it out:

I miss answering the feedback question on Talk Origins…

Beware the Coursera bait and switch!


On July 30 I signed up on Coursera to take their “verified certificate” version of the course Evolution: A Course for Educators, taught by Joel Cracraft and David Randle of the American Museum of Natural History. I figured it would be fairly easy given my background and the certificate would add a little something to my resume. So, as I said, I signed up, paid the $29 fee for the certificate got an email receipt back from Coursera and waited for the class to start on Aug. 3rd.

Aug. 3rd quickly rolls around and I get another email, ostensibly from Cracraft & Randle, welcoming me to the course.


Then I tried to log in and start the course only to get a 404 error message telling me that the page for the course isn’t there.

I contact Coursera and they send back the usual “use X browser & clear your cache” troubleshooting message. I was already using browser X and I cleared my cache but this has no effect and I inform Coursera of this.

Next I get an email telling me that the course I signed up for has “changed format” (apparently in a matter of days) and that I needed to “un-enroll” from the old course, get my money back and then re-enroll in the new version.

One problem though, the new “format” is $20 more than the old one!

I suggest to them that since I already paid the price they had asked for (and got a receipt & welcoming email etc.) that they should allow me access to the course.

They responded by refunding my money and telling me (in corporate happy talk) that it was too damn bad and that if I wanted to take the course I would have to cough up $49 dollars, going so far as to suggest that I look into their financial aide services if I thought that would help.

Well, instead of paying more money I am telling everyone I know about their bait and switch and asking that you pass this on on Facebook and Twitter and the like. Thanks!

By the way, does anyone out there know Cracraft or Randle? I wonder what they would think of how Coursera treats their would-be students. 

[And I was so looking forward to the Dinosaur Paleobiology course they offer as well…]

Marriage Equality at last!

I cannot let this wonderful historic day go unremarked upon here on PCwP. The Supreme Court of the United States has ruled in favor of marriage equality for all Americans straight or gay! Good on the SCOTUS majority! Well done! Here is a link to their official decision in the Obergefell v. Hodges case.

As for the SCOTUS minority, congratulations, you will go down in history as those on the wrong side of the fight for freedom, equality, and humanity.

And now a little poorly concealed bragging



Last weekend while I was awaiting delivery of my copy of Cambridge University historian of science Nick Hopwood‘s new book Haeckel’s Embryos: Images, Evolution, and Fraud (2015) on 19th century biologist Ernst Haeckel and his (in)famous embryo illustrations, (which I have written about a few times here an PCWP and elsewhere), I got a Facebook notification that I had been “tagged” in a post by my friend (in real life, not just Facebook) and colleague Dr. Nick Matzke. The somewhat cryptic post said the following:

Hey look who’s in the acknowledgements – Troy Britain

Attached to this comment was the following picture:


Thereafter the comments conversation between Nick M. and I went like this:

Me: Wait, wait, wait, this isn’t Hopwood’s new book is it (my copy is in route)?!

NickYep it is!!

Me: Holy crap!

Nick: Immortality!

Apparently Professor Hopwood was kind enough to mention me (and Nick Matzke as well) in the acknowledgements section of his new book (page 304).

 The relevant section reads as follows:

For crucial pieces of advice, I thank Thomas Brandstetter, Troy Britain, Solveig Jülich, Ron Ladouceur, Nick Matzke, Signe Nipper Nielsen, Ron Numbers, Jesse Olszynko-Gryn, and Constance Sommerey…

Quite an honor! All the more given the company of people like Nick Matzke, Ron Numbers and the rest.

Thank you Prof. Hopwood, you are too kind! And thank you for writing this book! It needed to be done and I look forward to reading it (or rather the rest of it, I’m up to chap. 3 already)!