Pharyngeal Arches and 'Gill Slits'

Dawkins, Richard.  The Greatest Show on Earth: The Evidence for Evolution.  Free Press, New York.  2009.  Copyright.  Print-disabled archive.org copy read by full-text search; nothing stored.  Leaf = page + 44, from the archive.org page map and confirmed by the index entry "Cartesian Diver, 366-7" against the leaves where that passage falls.

1. 1a.

   Page 357:  “Fascinatingly, it is very obvious in human embryos, whose ‘pharyngeal arches’ are clearly derived from ancestral gills, as one can tell by looking at their detailed anatomy.  Of course they don’t function as gills, but five-week human embryos can be regarded as little pink fishes, with gills.” ↩ ↩ ↩ ↩

2. 1b.

   Pages 359–360:  “All that we need to know, to understand the history of our recurrent laryngeal nerves, is that in fish the vagus nerve has branches that supply the last three of the six gills, and it is natural for them, therefore, to pass behind the appropriate gill arteries.  There is nothing ‘recurrent’ about these branches: they seek out their end organs, the gills, by the most direct and logical route.” ↩

Langman, Jan.  Medical Embryology.  Williams & Wilkins, Baltimore.  4th edition.  1981.  Copyright.  Print-disabled archive.org copy read by full-text search; nothing stored.  Page from the archive.org page map, confirmed by the index entry "Pharyngeal arches, 268".  The 7th edition (T. W. Sadler, 1995, p. 312) keeps the same wording.

1. 2a.

   Page 268:  “The pouches gradually penetrate the surrounding mesenchyme, but do not establish an open communication with the external clefts (fig. 16-8).  Hence, although the development of pharyngeal arches, clefts, and pouches resembles the formation of gills in fishes and amphibia, in the human embryo real gills—branchia—are never formed.  Therefore, the term pharyngeal arches, clefts, and pouches has been adopted for the human embryo.” ↩ ↩ ↩

Moore, Keith L.  The Developing Human: Clinically Oriented Embryology.  W. B. Saunders, Philadelphia, 1982; reprinted with Islamic additions by Abdul-Majeed A. Azzindani, Dar Al-Qiblah, Jeddah.  3rd edition.  1983.  Moore's text is unchanged in the reprint; the Islamic additions are separate inserts.  Copyright.  Read from the copy in the source library; pages from the printed folios and running heads.  Chapter 10, The Branchial Apparatus and the Head and Neck, pp. 179–191; chapter 14 on the aortic arches, pp. 326–328.

1. 3a.

   Page 179:  “A branchial apparatus develops in human embryos, but no gills form.  Because gills do not form in the human embryo, some authors prefer to use the term pharyngeal arch instead of branchial arch, but the term chosen in the Nomina Embryologica is the one used in this book.” ↩

2. 3b.

   Page 179:  “By the end of the fourth week, four well-defined pairs of branchial arches are visible externally (Fig. 10-1D).  The fifth and sixth arches are small and cannot be seen on the surface of the embryo.” ↩ ↩

3. 3c.

   Page 183:  “A typical branchial arch contains an artery, a cartilaginous bar, a muscular component, and a nerve (Fig. 10-2).” ↩ ↩

4. 3d.

   Page 183:  “During the fifth week, the second branchial arch overgrows the third and fourth arches, forming an ectodermal depression known as the cervical sinus (Fig. 10-3A to D).  Gradually, the second to fourth branchial grooves and the cervical sinus are obliterated.  This occurs as the second branchial arch merges with the epicardial ridge, giving the neck a smooth contour (Fig. 10-3F and G).” ↩

5. 3e.

   Page 183:  “In fishes, the branchial arch arteries supply blood to the capillary network of the gills.  In the human embryo, the blood in these arteries passes right through the branchial arches and enters the dorsal aortae (Fig. 10-2B).” ↩ ↩ ↩

6. 3f.

   Page 184, tables 10-1:  First arch: trigeminal nerve (V); muscles of mastication, mylohyoid and anterior belly of digastric, tensor tympani, tensor veli palatini; malleus, incus.  Second: facial nerve (VII); muscles of facial expression, stapedius, stylohyoid, posterior belly of digastric; stapes, styloid process, lesser cornu and upper part of the body of the hyoid.  Third: glossopharyngeal (IX); stylopharyngeus; greater cornu and lower part of the body of the hyoid.  Fourth and sixth: superior laryngeal and recurrent laryngeal branches of the vagus (X); cricothyroid, levator veli palatini, constrictors of the pharynx, intrinsic muscles of the larynx; thyroid, cricoid, arytenoid, corniculate and cuneiform cartilages.  “The fifth branchial arch is sometimes absent.  When present, it is rudimentary like the sixth arch and usually has no recognizable cartilage bar.” ↩ ↩

7. 3g.

   Page 185:  “The fourth and sixth arch cartilages fuse to form the laryngeal cartilages (Table 10-1), except for the epiglottis.” ↩

8. 3h.

   Page 187:  “The tubotympanic recess gives rise to the tympanic cavity and the mastoid antrum, which develop later as a dorsal expansion of the tympanic cavity.  The connection of the tubotympanic recess with the pharynx gradually elongates to form the auditory tube (pharyngotympanic tube, or Eustachian tube).”  “The pouch endoderm forms the surface epithelium and the lining of the crypts of the palatine tonsil.”  The second quotation concerns the second pouch. ↩ ↩

9. 3i.

   Page 187:  “Later, the parathyroid glands separate from the thymus and come to lie on the dorsal surface of the thyroid gland, which by this stage has descended from the foramen cecum of the tongue (Fig. 10-7C).” ↩

10. 3j.

    Page 188:  “By the sixth week, each dorsal portion develops into a superior parathyroid gland (often called parathyroid IV after its pouch of origin), which comes to lie on the dorsal surface of the thyroid gland.”  “The ultimobranchial body fuses with the thyroid gland and subsequently disseminates to give rise to the parafollicular cells, or C cells, of the thyroid gland.” ↩

11. 3k.

    Page 188:  “Only one pair of branchial grooves contributes to adult structures.  The first branchial groove persists as the epithelium of the external acoustic meatus (Fig. 10-7C).”  “The first branchial membrane, along with the intervening layer of mesoderm, gives rise to the tympanic membrane, or eardrum (Fig. 10-7C).” ↩

12. 3l.

    Page 188:  “They form where the epithelia of a branchial groove and a pharyngeal pouch approach each other, but they are temporary structures in the human embryo.  The endoderm of the pharyngeal pouches and the ectoderm of the branchial grooves are soon separated by mesoderm.” ↩ ↩

13. 3m.

    Page 191:  “Most of these abnormalities represent remnants of the branchial apparatus that normally disappear as these structures develop.  Most of these malformations are uncommon.”  “An abnormal tract (canal) opening both on the side of the neck and in the pharynx is called a branchial fistula”. ↩ ↩

14. 3n.

    Page 326:  “Although six pairs of aortic arches develop, they are not all present at the same time; e.g., by the time the sixth pair of aortic arches has formed, the first two pairs have involuted and disappeared (Fig. 14-31C).”  Page 327:  “The left fourth aortic arch forms part of the arch of the aorta.”  “The right fourth aortic arch becomes the proximal portion of the right subclavian artery.”  Page 327 also gives the first-arch remnant as the maxillary arteries, the second as the stems of the stapedial arteries, the third as the common carotid and first part of the internal carotid arteries, and the sixth as the pulmonary arteries and, on the left, the ductus arteriosus. ↩ ↩

15. 3o.

    Page 327:  “In about 50 per cent of embryos, the fifth pair of aortic arches are rudimentary vessels that soon degenerate, leaving no derivatives.  In about as many embryos, these arteries never develop.” ↩

16. 3p.

    Page 424:  “Early in the fourth week, a thickened plate of surface ectoderm, the otic placode, appears on each side of the developing hindbrain.” ↩

Coyne, Jerry A.  Why Evolution Is True.  Viking, New York.  2009.  Copyright.  The archive.org copy is print-disabled and was read by full-text search;  nothing was stored.  Leaf = page + 26, anchored by the book's index entries "branchial arches, 72, 74-75, 74, 83, 84" and "recurrent laryngeal nerve ... 82-84" against the leaves where those passages fall.

1. 4a.

   Page 74:  “Perhaps the most striking fishlike feature is a series of five to seven pouches, separated by grooves, that lie on each side of the embryo near its future head.  These pouches are called the branchial arches, but we'll call them "arches" for short (figure 16).” ↩

2. 4b.

   Page 75:  “Sometimes the embryonic gill slits fail to close in human embryos, producing a baby with a cyst on its neck.  This condition, an atavistic remnant of our fishy ancestors, can be corrected with surgery.” ↩ ↩

3. 4c.

   Page 75:  “Why do mammals form their heads and faces from the very same embryonic structures that become the gills of fish?” ↩

4. 4d.

   Page 76, figure 17:  “In the human embryo, the first, second, and fifth arches form briefly at the beginning of development, but disappear by four weeks of age, when the third, fourth, and sixth arches (distinguished by different shades of gray) form.” ↩

5. 4e.

   Page 78:  “The "adding new stuff onto old" principle is just a hypothesis— an explanation for the facts of embryology.” ↩

Wagner, Rudolph.  Elements of Physiology, for the Use of Students.  Sherwood, Gilbert & Piper, London.  Translated by Robert Willis.  1844.  Public domain.  Page from the printed folios 110 and 112 either side of the passage.  OCR slips corrected silently.

1. 5a.

   Page 111:  “The discovery and true interpretation of the branchial fissures in the embryo of the higher vertebrata, belongs to Rathke, Isis, 1825, vol. i.”  “Very recently Reichert has pursued the subject deeply ; he calls the branchial arches visceral arches — Muller’s Archiv fur 1837.  His assertion, that these are not branchial arches, is a mere dispute about a word ; it was never imagined that the parts in question were proper gills ; but they are vascular arches, Which are in every respect analogous to the vascular arches of the gills of fishes, only not branching like these.”  A footnote to the main text, which on the same page calls the openings "the branchial fissures — fissurae branchiales." ↩ ↩

Agassiz, Louis.  Twelve Lectures on Comparative Embryology, Delivered before the Lowell Institute, in Boston, December and January, 1848-9.  Henry Flanders & Co., Boston.  1849.  Phonographic report by James W. Stone.  Agassiz, Harvard zoologist, opposed Darwin to the end of his life.  Public domain.  Read from the archive.org text layer; page from the printed folios 96 and 97 either side of the passage.

1. 6a.

   Page 96:  “There is a period in the structure of the young Rabbit, (in which the investigations have been traced more extensively than in any other species,) when the young Rabbit resembles so closely the Fish, that it even has gills, living in a sac full of water breathing as Fishes do.” ↩ ↩ ↩

Graham, Anthony et al.  “A revised terminology for the pharyngeal arches and the arch arteries.”  Journal of Anatomy 243(4):564–569.  2023.  CC BY 4.0.  Based on three-dimensional reconstructions and high-resolution episcopic microscopy of human and mouse embryos.  Cited by section.  Mirror:  Europe PMC

1. 7a.

   Section 1. Introduction:  “They consist of epithelial layers, ectoderm externally and endoderm internally, which surround neural crest cells.  The neural crest cells, in turn, surround a mesodermal population.”  “The neural crest‐derived cells give rise to skeletal and connective tissues, the mesoderm to muscle and endothelium, the ectoderm to the skin and sensory neurons, and the endoderm to the lining of the pharynx and specialised organs”. ↩

2. 7b.

   Section 1. Introduction:  “The current description of the pharyngeal arches and their import, which is found in the standard, and widely read, textbooks of embryology and anatomy (e.g.—see [Schoenwolf, 2014, Standring, 2015]) and which is spread across the Internet, with numerous videos, is erroneous.  This situation has arisen from a mishmash of evolutionary, embryological and anatomical considerations, which have been in place since the early twentieth century, but which do not stand up to scrutiny.” ↩

3. 7c.

   Section 2. Evolutionary considerations:  “The basal condition for jawed vertebrates is to have seven pharyngeal arches.  These will give rise to the jaw, the hyoid and five gill arches.”  “The coelacanth Latimeria displays the ancestral state and has seven pharyngeal arches, while amphibia have six arches and amniotes five arches.” ↩

4. 7d.

   Section 4. The development of the pharyngeal arches:  “In amniotes, four pharyngeal pouches form and these can be identified both morphologically and molecularly (Graham et al., 2019).” ↩

5. 7e.

   Section 4. The development of the pharyngeal arches:  “Reconstructions of both human and murine embryos show unequivocally that there are but five arches formed during development (Figure 2).  There is no transient additional ‘fifth’ arch in normal development.” ↩ ↩

6. 7f.

   Section 4. The development of the pharyngeal arches:  “The two most caudal arches do not generate any defined muscular and skeletal elements during the period of their existence.  In current tables, these arches are generally assumed to form components of the larynx.  Such derivatives, however, do not appear until long after the last two arches have been remodelled (de Bakker et al., 2017; Poopalasundaram et al., 2019).” ↩

7. 7g.

   Section 4. The development of the pharyngeal arches:  “The first pouch and its groove/cleft will form the Eustachian tube and external auditory meatus.  From the second pouch will be formed the palatine tonsils.  The third pouch will give rise to the thymus and two of the parathyroid glands.  The fourth pouch will form the remaining two parathyroid glands as well as the ultimobranchial body.” ↩ ↩

8. 7h.

   Section Abstract:  “In this revised scheme, the pharyngeal arches are to be labelled as follows—the first, most cranial, the mandibular (M), the second, the hyoid (H), the third, the carotid (C), the fourth, the aortic (A) and the last, most caudal, the pulmonary (P).” ↩

Gillis, J. Andrew, and Olivia R. A. Tidswell.  “The Origin of Vertebrate Gills.”  Current Biology 27(5):729–732.  2017.  CC BY 4.0.  Read from Europe PMC; cited by section.  Mirror:  Europe PMC

1. 8a.

   Section Results and Discussion:  “Pharyngeal arch development begins with the iterative outpocketing of foregut endoderm in a rostral-to-caudal sequence, giving rise to a series of endodermal pouches [16].  These pouches subsequently contact and fuse with overlying surface ectoderm, resulting in the perforation of gill slits and the delineation of arches (Figure 2A).” ↩ ↩ ↩

2. 8b.

   Section Results and Discussion:  “In labeled embryos reared to S27/28 (∼40–50 dpi; n = 7), CM-DiI-positive external gill filaments were readily apparent (Figure 3E), while histological analyses revealed CM-DiI-positive epithelium on both the external (Figure 3F) and internal gill filaments (Figures 3G and 3H).” ↩

3. 8c.

   Section Summary:  “However, the evolutionary history of vertebrate gills has been the subject of a long-standing controversy [2, 3, 4, 5, 6, 7, 8].” ↩

Gillis, J. Andrew et al.  “Developmental evidence for serial homology of the vertebrate jaw and gill arch skeleton.”  Nature Communications 4:1436.  2013.  Author manuscript read from Europe PMC; cited by section.  Mirror:  Europe PMC

1. 9a.

   Section Introduction:  “For example, mice lacking Dlx1 and/or Dlx2 exhibit striking upper jaw malformations but effectively normal lower jaws8,9 while mice lacking both Dlx5 and Dlx6 exhibit a homeotic transformation of their lower jaw into an upper jaw10,11.”  Section Nested Dlx expression in elasmobranch pharyngeal arches:  “These expression patterns produce a combinatorial ‘Dlx code’ in all pharyngeal arches (Fig. 2g,n), essentially indistinguishable from that characterized in the mammalian mandibular arch”.  The numbers 8,9 and 10,11 are reference marks. ↩ ↩

2. 9b.

   Section Abstract:  “Gegenbaur’s classical hypothesis of jaw-gill arch serial homology is widely cited, but remains unsupported by either paleontological evidence (e.g. a series of fossils reflecting the stepwise transformation of a gill arch into a jaw) or developmental genetic data (e.g. shared molecular mechanisms underlying segment identity in the mandibular, hyoid and gill arch endoskeletons).” ↩

Minoux, Maryline et al.  “Rostral and caudal pharyngeal arches share a common neural crest ground pattern.”  Development 136(4):637–645.  2009.  Author manuscript read from PMC; cited by section.  Mirror:  PMC

1. 10a.

   Section Abstract:  “Colinear Hox gene expression patterns underlie arch specific morphologies, with the exception of the first (mandibular) arch, which is devoid of any Hox gene activity.”  “Here, we show that the simultaneous inactivation of all Hoxa cluster genes in NCCs leads to multiple jaw and first arch-like structures, partially replacing second, third and fourth arch derivatives, suggesting that rostral and caudal arches share the same mandibular arch-like ground patterning program.” ↩ ↩

2. 10b.

   Section Results, Homeosis of second, third and fourth arch derivatives:  “In particular, the stapes, styloid process and lesser horns of the hyoid bone were absent and were replaced by mirror-image duplications of first arch-like structures, including partially duplicated Meckel’s cartilage (MC2), incus (I2), malleus (M2), tympanic (T2) and pterygoid (P2) bones, as well as transformed gonial (G*) and ectopic squamosal (SQ2) bones.” ↩

Graham, Anthony, and Jo Richardson.  “Developmental and evolutionary origins of the pharyngeal apparatus.”  EvoDevo 3:24.  2012.  Review, King's College London.  CC BY 2.0.  Cited by section.  Mirror:  Europe PMC

1. 11a.

   Section The pharyngeal arches:  “These structures are first evident at about three to four weeks of human development, and it is within these that the nerves, muscles, skeletal tissues and epithelial specializations of the pharynx are subsequently laid down and fashioned.” ↩

2. 11b.

   Section The development of the pharyngeal arches - a key role for endoderm:  “The first indication of pharyngeal arch formation is not the migration of neural crest cells from the brain but rather the outpocketing of the endoderm to form the pharyngeal pouches [7,8].  Ablation studies in chicks also demonstrated that the pharyngeal pouches will form and contact the ectoderm in the absence of neural crest cells, and that these crestless pharyngeal segments are regionalized and have a sense of identity [7].” ↩ ↩ ↩

3. 11c.

   Section Deuterostome origins of endodermal outpocketing:  “In cephalochordates, such as amphioxus, there are no neural crest cells to fill the pharyngeal region and the pharyngeal slits are relatively simple”.  “Significantly, as is seen in vertebrates, the amphioxus Pax1/9, Eya, Six1/2 and Six4/5 genes are all coexpressed in the pharyngeal endoderm [17,18].”  “Thus, the expression domains of these orthologues of key pharyngeal genes provide strong evidence for homology between pharyngeal development in vertebrates and amphioxus.”  The same section reports amphioxus Tbx1/10 expressed in the pharyngeal segments. ↩ ↩

4. 11d.

   Section Deuterostome origins of endodermal outpocketing:  “In this species, it was similarly observed that Pax1/9, Eya and Six expression is associated with the formation of the gill pores by the endoderm.  Tbx1 expression, however, was not found to be associated with the pharyngeal endodermal.”  The species is the acorn worm Saccoglossus kowalevskii. ↩

5. 11e.

   Section The development of the pharyngeal arches - a key role for endoderm:  “In all vertebrates, there is a single post-otic stream of neural crest cells that fills a variable number of posterior arches - seven in lampreys, five in teleosts, three in amniotes”.  Section From jawless to jawed vertebrates:  “They display dorsoventrally restricted expression of Dlx genes, and other key transcription factors, and, as in gnathostomes, endothelin signalling is important for the ventral pharyngeal skeleton in lampreys, as it is in gnathostomes [28,29].” ↩

6. 11f.

   Section Pharyngeal metamerism - beyond the phylotypic stage:  “During development, the opercular bones form within the second arch and expand posteriorly to overlie the gill-bearing arches [32].”  Section Tetrapod evolution - remodelling of the posterior pharyngeal segments:  “In particular, the caudal edge expresses Shh, which is a proliferative driver in many epithelia, and Shh signalling is required for posterior expansion of the second arch in both species [3].”  “These events mirror what is observed during amphibian metamorphosis and it has recently been shown that the fusion of the caudal edge of the second arch and the loss of the sinus also requires thyroid hormone signalling [3].”  Both species means chick and zebrafish. ↩ ↩

Okabe, Masataka, and Anthony Graham.  “The origin of the parathyroid gland.”  Proceedings of the National Academy of Sciences 101(51):17716–17719.  2004.  Copyright.  Read from PMC; cited by section.  Mirror:  PMC

1. 12a.

   Section Abstract:  “We find that Gcm-2 is present not only in tetrapods but also in teleosts and chondrichthyans, and that in these species, Gcm-2 is expressed within the pharyngeal pouches and internal gill buds that derive from them in zebrafish (Danio rerio), a teleost, and dogfish (Scyliorhinus canicula), a chondrichthyan.”  “We further show that the gills express the calcium-sensing receptor, which is used in tetrapods to monitor serum calcium levels.  These results indicate that the tetrapod parathyroid gland and the gills of fish are evolutionarily related structures, and that the parathyroid likely came into being as a result of the transformation of the gills during tetrapod evolution.” ↩ ↩

2. 12b.

   Section Results:  “In all embryos injected with the control MO (n = 49), gill buds formed”.  “Contrastingly, in 85% of the embryos that received an injection of the Gcm-2 antisense MO (n = 34), gills buds did not form.”  MO is a morpholino, an antisense reagent that blocks the gene's product. ↩

3. 12c.

   Section Discussion:  “This interpretation also would explain the positioning of the parathyroid gland within the pharynx in the tetrapod body.  Were the parathyroid gland to have emerged de novo with the evolution of the tetrapods, it could, as an endocrine organ, have been placed anywhere in the body and still exert its effect.” ↩

Menton, David N.  Human Embryo "Gill Slits" During Development.  1991.  Copyright 1991 Missouri Association for Creation.  Menton, a PhD cell biologist, taught anatomy at Washington University School of Medicine and later worked for Answers in Genesis.  Read from the Wayback Machine copy.  Mirror:  Archive.org

1. 13a.

   “In fact, neither gills nor their slits are found at any stage in the embryological development of any mammal including man.  The folds in the neck region of the mammalian embryo, that are erroneously called "gills", are not gills in any sense of the word and never have anything to do with breathing.  They are merely flexion folds, or wrinkles, in the neck region resulting from the sharply down turned head and protruding heart of the developing embryo.  These folds eventually develop into a portion of the face, inner ear, tonsils, parathyroid and thymus.” ↩ ↩ ↩ ↩

Guliuzza, Randy J.  “Major Evolutionary Blunders: Haeckel's Embryos Born of Evolutionary Imagination.”  Acts & Facts, Institute for Creation Research.  Oct 31, 2016.  Guliuzza, an engineer and physician, was ICR's National Representative.  Copyright.

1. 14a.

   Section Imaginary Gill Slits, Tails, and Biogenic Laws:  “The truth is that these are only folds of tissue in the pharynx region of vertebrates during the pharyngula stage of development.  For mammals, birds, and reptiles, they never develop into a structure that is in any way like fish gills.  In humans, for instance, this fold tissue develops into cartilage or bone for the jaw, inner ear, hyoid, and voice box.  Muscles for the face, temple, and neck form out of them, as well as the thyroid, parathyroid, and thymus glands.” ↩ ↩

Engler, Patricia.  “Heart Rhythm Established: Day 28 in the Life of an Unborn Baby.”  Answers in Genesis.  Dec 28, 2021.  Modified 9 September 2022.  Copyright.

1. 15a.

   Section Evidence for Evolution?:  “But human pharyngeal arches are neither gills nor slits, and they don’t have anything to do with supplying oxygen to the embryo.  Labeling these tissue folds “gill slits” anyway is a propaganda technique called association, meant to make humans seem closer to fish than we really are.4 A biblical interpretation of pharyngeal arches is that they’re a good design our Creator could apply to multiple creatures.”  The 4 is an endnote number. ↩ ↩ ↩

Agassiz, Louis.  “Evolution and Permanence of Type.”  The Atlantic Monthly 33:92–101.  Jan 1874.  Agassiz's last essay, written against evolution.  Public domain.  Page from the running heads of the bound volume.

1. 16a.

   Page 98:  “The higher Vertebrates, including man himself, breathe through gill-like organs in the early part of their life.  These gills disappear and give place to lungs only in a later phase of their existence.” ↩

Wells, Jonathan.  Icons of Evolution: Science or Myth?  Regnery, Washington DC.  2000.  Chapter 5, section "Gill slits" are not gill slits.  Copyright.  Print-disabled archive.org copy read by full-text search; nothing stored.  Printed page = leaf − 18, anchored by the index entries "gill-like structures in, 106" and "Rager, Gunter, 106" against the leaf where those passages fall.

1. 17a.

   Page 105:  “Raven and Johnson’s Biology claims that “early in their development, human embryos possess gill slits, like a fish.”  And Futuyma’s Evolutionary Biology likewise states: “Early in development, human embryos are almost indistinguishable from those of fishes, and briefly display gill slits.”” ↩

2. 17b.

   Page 105:  “Midway through development, all vertebrate embryos possess a series of folds in the neck region, or pharynx.” ↩

3. 17c.

   Page 105:  “But pharyngeal folds are not gills.  They’re not even gills in pharyngula-stage fish embryos.”  Page 106:  “In a fish, pharyngeal folds later develop into gills, but in a reptile, mammal, or bird they develop into other structures entirely (such as the inner ear and parathyroid gland).  In reptiles, mammals, and birds, pharyngeal folds are never even rudimentary gills”. ↩ ↩

4. 17d.

   Page 106:  “In other words, there is no embryological reason to call pharyngeal pouches “gill-like.”  The only justification for that term is the theoretical claim that mammals evolved from fish-like ancestors.”  “But once this is done, development cannot be used as evidence for evolution without plunging into circular reasoning”. ↩ ↩

Darwin, Charles.  On the Origin of Species by Means of Natural Selection.  John Murray, London.  1st edition.  1859.  Public domain.  Darwin Online transcription with page markers, in the source library.

1. 18a.

   Page 479:  “We may cease marvelling at the embryo of an air-breathing mammal or bird having branchial slits and arteries running in loops, like those in a fish which has to breathe the air dissolved in water, by the aid of well-developed branchiæ.” ↩

Haeckel, Ernst.  The Evolution of Man: A Popular Exposition of the Principal Points of Human Ontogeny and Phylogeny.  Volume 1.  D. Appleton and Company, New York.  1879.  English translation of Anthropogenie, 3rd German edition.  Public domain.  Pages from the running heads.  Obvious OCR slips are corrected silently.

1. 19a.

   Page 263:  “These very characteristic gill-openings and gill-arches are found in the human embryo, and in the embryos of all higher Vertebrates, at an early period of their development, in that form in which they are retained throughout life by the lower Vertebrates.”  “The fact that they originally actually exist in the same form as in Fishes, is, however, one of the most interesting proofs of the descent of these three higher classes of Vertebrates from the Fishes.”  Page 355:  “On the right and left walls of the intestinal head-cavity, in the anterior portion, first one, and then several pairs of sac-like protuberances are formed, which break through the entire thickness of the side wall of the head.  They thus become slits through which there is a free passage from without into the throat-cavity”. ↩

2. 19b.

   Page 263:  “In Mammals, Birds, and Reptiles they never act as true organs of respiration, but gradually develop into very different organs.” ↩

Langman, Jan.  Medical Embryology: Human Development—Normal and Abnormal.  Williams & Wilkins, Baltimore.  1st edition.  1963.  Copyright.  Print-disabled archive.org copy read by full-text search; nothing stored.  Page from the archive.org page map, confirmed by the index entry "Pharyngeal arches, 50, 198".

1. 20a.

   Page 198:  “The level of these grooves, known as the pharyngeal clefts, corresponds to that of the pharyngeal pouches, but although the clefts and pouches come in close contact, they rarely communicate with each other in the form of open gills.” ↩

Wolpert, Lewis.  The Triumph of the Embryo.  Oxford University Press.  1991.  Copyright.  Print-disabled archive.org copy read by full-text search; nothing stored.  Page from the archive.org page map, and it is the page Wells 2000 cites.  Wells quotes only the last two sentences, with small changes.

1. 21a.

   Page 185:  “An example is the arches and clefts in the head region of the embryos of all vertebrates.  These arches and clefts gave rise to the gills in primitive jawless fish.  In later vertebrates they became modified to form jaws and other structures.  A higher animal, like a mammal, passes through an embryonic stage when there are structures that resemble the gill clefts of fish.  But this resemblance is illusory and the structures in the mammalian embryo only resemble the structures in the embryonic fish that will give rise to gills.” ↩ ↩

Isaak, Mark.  “CB704: Gill slits.”  Index to Creationist Claims, TalkOrigins Archive.  May 22, 2003.  Created 17 February 2001, modified 22 May 2003.  The claim it answers is taken from Wells 2000, pp. 105–107.

1. 22a.

   Section Response:  “The pharyngeal pouches that appear in embryos technically are not gill slits, but that is irrelevant.  The reason they are evidence for evolution is that the same structure, whatever you call it, appears in all vertebrate embryos.” ↩

Shono, Takanori et al.  “Two Paralogues as They Like It: Conserved and Divergent Evolution of Vertebrate Gcm Genes.”  Evolution & Development 28(3).  2026.  CC BY 4.0.  Okabe, the last author, led the 2004 study, so this is not an independent check.  Mirror:  PMC

1. 23a.

   Section Introduction:  “In teleostean and chondrichthyan fishes such as zebrafish and small‐spotted catshark (also known as lesser‐spotted dogfish), the Gcm2 orthologues are primarily expressed in the gills, supporting the view that gills represent the evolutionary origin of the parathyroid glands (Hanaoka et al. 2004; Hogan et al. 2004; Okabe and Graham 2004).  In addition to its role in the gills, the Gcm2 orthologues in the teleost are also expressed in the skin, where it is required for the differentiation of ionocytes (Esaki et al. 2009; Shono et al. 2011).” ↩

Thomas, Brian.  “Do People Have 'Gill Slits' in the Womb?”  Creation Science Update, Institute for Creation Research.  Jul 20, 2012.  Copyright.

1. 24a.

   “Since the pouches are tissues organized into folds and have known functions, then there is no scientific reason to even suspect that they reflect any evolutionary past.”  “Now, not only is his sketch work on embryos "one of the most famous fakes in biology," but every pouch and fold of the human embryo itself is now known to be fully functional, precisely timed, and intricately arranged.” ↩ ↩

The test used across this series is set out in Arguments from Bad Design, Part 1, "Vestigial does not have to mean useless," and applied in Vestigial Structures.  A present function answers the claim that a structure is useless.  It does not answer the separate claim that the structure is a modified copy of something in an ancestor, which needs homology, reduction or modification, and a distribution across a tree built from other characters.  The pharyngeal arches pass the first step easily.  The argument is about the second and third. ↩ ↩ ↩

Mitchell, Tommy, and Elizabeth Mitchell.  “Something Fishy About Gill Slits!”  Answers in Genesis.  Mar 14, 2007.  Modified 13 March 2025.  Elizabeth Mitchell is a physician trained in obstetrics and gynecology.  Copyright.  Cited by paragraph.

1. 26a.

   Paragraph So what are these misnamed structures?:  “Actually, they are nothing more than folds in the region of the tiny embryo’s throat.”  “Just as many people develop a double chin when bending the neck forward, so the embryo has folds in its neck area due to this flexing.” ↩

2. 26b.

   Paragraph We scientists especially like to name things:  “Gill slits is a misleading name, since these folds are neither gills nor slits.” ↩

3. 26c.

   Paragraph The outer and middle ear:  “The outer and middle ear as well as the bones, muscles, nerves, and glands of the neck develop from these folds.  Only superficially do these important folds ever resemble gills; the pharyngeal arches are no more related to gills than stars are to streetlights.” ↩

Batten, Don et al.  “What about similarities and other such arguments for evolution?”  The Creation Answers Book, 109–125.  Creation Book Publishers.  8th edition.  Edited by Don Batten.  2019.  Chapter 7, chapter PDF served by Creation Ministries International, file dated December 2019.  Copyright.

1. 27a.

   Page 115:  “These ‘pharyngeal clefts’, as they are properly called, which delineate ‘throat pouches’, never have any breathing function, and are never ‘slits’ or openings.”  “Specialist embryology textbooks acknowledge that human embryos do not have gill slits.”  The chapter then quotes Langman, Medical Embryology, 3rd ed., 1975, p. 262, a wording that could not be checked. ↩

2. 27b.

   Pages 117–118:  “ReMine21 argues that it points to an intelligent designer who designed living things.  God made things similar to show that there is one Creator (similarity at the pharyngula stage), but with a pattern of similarity that could not result from common ancestry (the earlier stages of embryo development differ).”  The 21 is the endnote number, citing ReMine, The Biotic Message, 1993, p. 370.  The page break falls after "but with". ↩

Britain, Troy.  ““Gill slits” by any other name….”  Playing Chess with Pigeons.  May 31, 2012.  Blog of a critic of creationism.  The link in Eric's research notes.  Used as a finding aid; each primary it quotes and this article uses was re-read from its own source.

1. 28a.

   “This is essentially a semantic argument about what we call these structures in vertebrate embryos combined with a straw man argument; and this combination is far from being new.”  “In fact Agassiz, a creationist, is the only scientist I have ever read that actually claimed that the embryos of amniotes have functional gills!” ↩