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The argument from eyelid development

This is a new one for me. Earlier today I was summoned on Twitter to address an assertion by a creationist, @jarrydtrokis. I was slightly boggled.

He was baffled by eyelid development. It seems he thinks it requires…intelligent design!.

… Here’s one for you to ponder :) Eye lids in the womb… How are they formed? #IntelligentDesign?

Wait, what? What’s mystifying about eyelid formation?

The section of skin in the middle dies… How does it know to do that? And in a perfectly straight line???

Oh. It forms a straight line. Whoa. And he claims to have done research to get the answer.

The research I’ve done shows the scientists are at a loss for an explanation….

Gosh. I can do research, too. It’s easy to explain, with pictures even.

The eyelids separate in a straight seam because of how they got that way. The eyelids form by expansion of two epithelial sheets from above and below that meet in the middle. When you see how the eyelids develop, it’s easy to see how they separate in a straight line later. This is a series of images over the course of about a day in mouse development. In the first, you can see the eye sans eyelid, but ringed by epithelia. In the second, you can see that epithelium growing, expanding in a sheet over the eye. In the third, the sheet is beginning to close in a line over the middle, and in the fourth it has completely closed, but leaving a seam or scar in a straight line across it.

mouse_eyelid_sem

Wait, you say inquisitively, I’d like a closer look at that seam. Can you show me what is going on postnatally, as the eyelids separate? Sure can.

mouse_eyelid_tem

The first panel is 5 days postnatal in the mouse; the eyelids are still fused. But you can see a difference in the histology of the junctional region (J), and a depression at the arrowhead (you can also see the layers of keratin there). There’s something different in this area.

In the second panel, 10 days postnatally, the depression at the junctional region is deepening and you can see a stratum granulosum (SG) at the seam, while you can also see hair follicles (HF) forming in the adjacent portions of the lid.

The third and fourth panels are at 12 days, and now the keratin layers have extended into the depression from both the inside and outside, completing the separation of the two lids.

Now @jarrydtrokis might be tempted to say that Jesus did the separating, but that’s only true if Jesus is a polypeptide called epidermal growth factor, or EGF. EGF is a molecule that triggers growth and differentiation of keratinocytes, and it turns out that if you treat baby mice with EGF it accelerates the rate of eyelid separation.

I’m sorry, @jarrydtrokis, but your argument from ignorance wasn’t very persuasive, and your talents at ‘research’ are rather pathetic, since the paper describing all that was trivial to find. But then, isn’t this always the case with creationists? There are none so blind as those who will not see.



Findlater GS, McDougall RD, Kaufman MH (1993) Eyelid development, fusion and subsequent reopening in the mouse. J Anat. 183(1):121-9.

Comments

  1. Usernames are smart says

    Wait, wait. Okay.

    Now, the femur is straight. How did it know to do that? Checkmate!

    Okay, another one: there are four lumbar in the normal human spine. How did our body know to make four? Why not three or seven? Checkmate again!

    Last one, for now. How come the isles of langerham are not surrounded by water? You can’t explain it without Devine intervention! Checkmate, you lose!

    (Notice is given for humor-impaired)

  2. mathema says

    That’s a thorough “win” if I’ve ever seen one. That’s what happens when a creationist asks a biologist a “question”.

    And hey, if this is obviously God doing these things (in terms of ID), then you better tell those theologians that divine hiddenness is no longer an issue. It doesn’t exist anymore, as god isn’t hidden if we can blatantly see his design. But… oh no, that causes severe issues in the core theology. Contradictions, even.

    Contradictions lead to absurdities, and we know where that gets you. Just quit guys, you’re not getting anywhere.

  3. IslandBrewer says

    Ok, how about this:

    How come there are dwarfs AND midgets? Huh?

    Bet you never heard that one, before! CHECKMATE!

  4. agiftedhamster says

    Lovely, PZ. The only way to answer a stupid question is with the truth. Calm, objective truth.

  5. chigau (違う) says

    michaelbusch #10
    Well. I never…
    Actually, I think I may have heard that before.
    I’m still concerned about [Usernames are smart]’s straight femurs.

  6. says

    What if I have 2 fused cervical vertebrae, is that 6 or 7 then? And also, 1 in around a million human babies are born without eyelids(I suggest googling for images only if you have a good stomach), is that Intelligent Design too?

  7. Ichthyic says

    OT… something appears to be wrong with the link system in FtB; I can click on links to personal posts in new threads, but things like thunderdome, the lounge, etc. can’t be clicked on.

    Also, the list of blogs on the front page of FtB seems broken.

    I’ve confirmed this with another person, anyone here having this problem?

  8. Ichthyic says

    ..detail:

    if you look a the recent comments, and try clicking on one that goes to thunderdome, the main part of it is not clickable at all, but for some weird reason the bracket part of it is?

    [Thunderdome]

    text not clickable, the but the brackets around it are.

    weird.

  9. Asher Kay says

    @Ichthyic

    It’s happening to me too, both in Firefox and Chromium. It seems to be something to do with the “now talk” thing. When I delete that from the DOM tree, I can click on the sidebar.

  10. Ichthyic says

    how do you get rid of it Asher? I see it on the lower right of my screen too, and it is totally nonfunctional.

    I recall it causing font problems a week or so ago on FtB as well.

    @Caine…

    so you have no problems at all with any of the links on the sidebar? I still can’t even get to the lounge.

  11. Asher Kay says

    I’m just doing an “inspect element” on the chat button and deleting the div with ID #nowtalk-root. It’s not a solution, though. It comes back when the page refreshes.

    I seem to recall that Caine is using script controls of some sort.

  12. Ichthyic says

    Disabling javascript gets rid of it.

    indeed it does, and also fixes the sidebar link problem.

    so, it’s not me, there IS something wrong with the scripting for that stupid nowtalk thing.

    grrr.

  13. bad Jim says

    The first time I held a newborn infant in my arms I was amazed to find it so perfectly formed, down to the last detail. It couldn’t be otherwise, of course – what, do we need to lick it into shape, like bears in a story by R.A. Lafferty? – but it was nevertheless wonderful, so tiny and pink, helpless and useless.

    We shrug off what P.Z. tells us, but this was unknown when I was growing up, pure hand-waving (“then a miracle occurs”). Now we’ve got movies. I can remember my uncle voicing annoyance at the idea that one might know the sex of a child before birth. Now he gets DVD’s of the ultrasound imagery.

  14. Lofty says

    Asher Kay

    Disabling javascript gets rid of it.

    Did that, everything now works again. Thanks for that!
    Firefox: Tools>Options>Content>Uncheck Enable JavaScript

  15. says

    Disabling javascript gets rid of it.

    Hm, my JS is on and Im not having any issues…(other than this annoying “chat live” button in the lower right hand corner, that seems to be ignoring my adblock, what is the purpose of that?)

  16. okeydoke says

    I’m waiting for a complete ID anatomical textbook. Imagine the debates. Try refuting the mother of all Gish gallops in the given timeframe. ^^

  17. says

    Ichthyic:

    so you have no problems at all with any of the links on the sidebar?

    No, but I about flipped the fuck out when I saw that chat thing – where in the fuck did it come from, and who the hell thought that was a good idea? Non-existent gods, someone get rid of that fucking thing.* Anyway, I killed it with no script.

    *I loathe crap like that, especially when you cannot close it or otherwise get rid of it. The site is bloated enough already.

  18. =8)-DX says

    For what it’s worth, he grudgingly admitted being “taught”:

    @AtheistWorld @mtbunyan @pzmyers By the way… My questions are not loaded. I actually want to hear the answer. #NotLikeOtherTheists

  19. paulburnett says

    “Usernames are smart” wrote “…the femur is straight.”

    You must not be familiar with a formerly common childhood disease, rickets – disturbing x-ray at http://en.wikipedia.org/wiki/Rickets disproves your hypothesis.

    Remember, rickets, like malaria, is brought to us by a Loving God(TM).

  20. says

    “There’s a little man in the sky that did it” is nowhere near as cool an explanation.

    Next up: my car stopped working! God did it!

  21. says

    bloated is right, and there’s something wrong with the mobile vs non-mobile detection. About half the time on my computer I get the mobile site (which isn’t readable because the lines of text go allllllllll the way across the screen and my eyes get bored, shutup it is a real problem) and about 99% of the time on my phone I get the full site which loads WAY too much crap through my data plan and is too small to read without zooming three times. (Plus whenever I click on a link I get some popup ad from zedo even though I have popups disabled in my phone browser.)

  22. kemist, Dark Lord of the Sith says

    Usernames are smart
    I have 5 lumbar.
    You have only 4???
    mutiemutiemutie!!!!

    That’s nuthin’.

    I’ve got one more pair of ribs than most people (cervical ribs, which god apparently gave me so I could experience the joys of bilateral thoracic outlet syndrome).

    Anatomy is weird.

    When you see the wild variations that can exist in anatomy, it rids you of the “perfectly formed” idea very quickly.

  23. says

    I’ve got one more pair of ribs than most people (cervical ribs, which god apparently gave me so I could experience the joys of bilateral thoracic outlet syndrome)

    Nonsense. God gave you cervical ribs so that medical students can experience extreme fatigue, agony and cramp by holding an arm for 12 hours while a surgeon removes said rib.

  24. lpetrich says

    That creationist’s argument reminds me of the arguments of latter-day vitalists like Rupert Sheldrake who claim that genes only encode proteins and the like, and not spatial information. Rupert Sheldrake claims that “morphogenetic fields” do it, sort of like Hans Driesch’s “entelechy” (a fancy term for a goal-seeking tendency).

    But it seem to me that such latter-day vitalists have conceded defeat on such things as metabolism and heredity, where the molecular mechanisms are *very* evident.

    To the extent that development is understood, it’s based on molecular mechanisms, so vitalists are going to lose there also.

  25. noastronomer says

    Quck question for clarification: Are the bottom four slides cross-sections?

    Mike.

  26. kantalope says

    per 33 – ya he is admitting that maybe there is an explanation for the eyelids (I’m not convinced – he read any of it) -but he’s still a committed ID’r. As in but sure eyelids can be explained, and eyeballs for that matter, and flagellum, and blood clotting, and multiple protein pathways but there’s other stuff that can’t be explained and that will have to chalked up to magic, err, goddidit. (While also admitting that the god of the gaps isn’t very convincing either.)

    Trouble is they all say that they believe in ID because of x. But when x is demonstrated be untrue, they don’t give up the belief in ID. So, I guess either the idea of x is just rationalization or something?

    I guess I just don’t understand them at all. If they say ID (or anything else really) is true because of some set of facts and then those facts turn out to be false, why doesn’t that change their opinion or understanding of ID? Are they just lying in the first instance that they believe because…? Are they such egotistical bastards that they cannot admit that maybe they were wrong about something? I just don’t know what’s going on in their seemingly confused little heads.

  27. alwayscurious says

    WWEGFD? (What would epithelial growth factor do?)

    @AtheistWorld @mtbunyan @pzmyers By the way… My questions are not loaded. I actually want to hear the answer. #NotLikeOtherTheists

    I missed this thread I think, the rest of his posts follow the “I’m politely listening to and rationally evaluating what you’re saying, but it is wrong because you didn’t say ‘Jesus says’ in your explanation”.

  28. kemist, Dark Lord of the Sith says

    Nonsense. God gave you cervical ribs so that medical students can experience extreme fatigue, agony and cramp by holding an arm for 12 hours while a surgeon removes said rib.

    Ah.

    I thought He just found it very funny to have someone occasionnally wake up with completely paralyzed arms. Which I guess it is, especially when said person wakes up with an urgent need to pee.

  29. Sastra says

    Here’s one for you to ponder :) Eye lids in the womb… How are they formed? #IntelligentDesign?

    My first thought was that this guy wasn’t really asking the question it looks like he’s asking — “what’s the step-by-step mechanism of eyelid formation?” Instead he was asking how the body of a baby which had never been outside the womb would have “known” that it would need eyelids to cover those eyes. How would it have ‘known’ it needs eyes in the first place even, given that you need neither eyes nor eyelids in the womb? This is mysteriously prescient. It can’t be accounted for.

    Maybe that is not at all what he meant and PZ’s detailed answer sufficiently responded to the question in his mind. If he’s backing down, that’s good indication that this is the case. But I am pessimistic. The ignorance of many ordinary people who reject evolution seems to go back very, very far and entail very, very simplistic models of how things work. They still see intuitive “problems” in areas we think we’ve already established as solved. He may be giving up the question only because he lacks the technical ability to explain why this doesn’t actually address his concern. I don’t know. Hate to think this elegant description and explanation might have been wasted because it’s too advanced and he can’t understand how evolution can “design” for the individual through a selection process of ancestors and environment.

  30. Richard Smith says

    This piece was a real eye-opener!

    As for personal mutations, all I know of for sure is an extra upper left lateral incisor. I suspect, having been born with ankyloglossia and a small pituitary gland, that there might be a few other little quirks along the mid-line.

  31. seston says

    Creationists keep doing the same thing over and over again. They keep rooting around for something where “scientists are at a loss for an explanation”. Really? So that means god? Really? You want to play that game? You really want to play THAT game again? Well Neil deGrasse Tyson has this to say

    “Does it mean, if you don’t understand something, and the community of physicists don’t understand it, that means God did it? Is that how you want to play this game? Because if it is, … If that’s how you want to invoke your evidence for God, then God is an ever-receding pocket of scientific ignorance that’s getting smaller and smaller and smaller as time moves on – so just be ready for that to happen, if that’s how you want to come at the problem.”

    Sorry creationists you fail yet again.

  32. Amphiox says

    Just for the common interest:

    The most common number of lumbar vertebrae is 5, the second is 6, which is most often a lumbarized S1 (sacral) segment.

    In mammals the number of cervical vertebrae is typically 7 (even a giraffe has only 7 vertebrae, just really big ones), while in many other vertebrate lineages, the cervical vertebrae can vary significantly, both within and among species. The reason for this is AFAIK unknown, but the fact that when cervical ribs do exist in mammals, they rather frequently cause at least minor problems that can affect fitness in the wild is suggestive.

    When two or more levels are fused congenitally, they are usually still counted as separate levels if the segmentation between them remains recognizable.

    Vertebral levels, of course, arise through the embryonic process of segmentation, which is fundamental in development.

  33. says

    Paul Burnett says: “Remember, rickets, like malaria, is brought to us by a Loving God(TM).”

    Noooope…. they are brought to you by humans ….with brains given by a loving God….but decided the gift was useless so threw it away and told God to piss off. That’s why you’ve got rickets and Malaria!

    evidence, please..you plead?

    Humans don’t know how to feed their kids and they insist in living in swamps. Go figure.

    Oh, as for eyelids….they’re a gimmie. Buy eyes, get lids free. Now, that’s a loving God.

    Evolution is not interested in twofers. It can’t handle generosity or coordination for that matter.

    Physics and chemistry don’t think for a living.

  34. kemist, Dark Lord of the Sith says

    Noooope…. they are brought to you by humans ….with brains given by a loving God….but decided the gift was useless so threw it away and told God to piss off. That’s why you’ve got rickets and Malaria!

    Humans don’t know how to feed their kids and they insist in living in swamps. Go figure.

    Ah yes, the poor choose not to eat properly and to live in those places. The only reason their kids get malnourished is ’cause they don’t know what to eat. How very stupid of them. They should have been born with paler skins and more money.

    But those are not the only love your god has bestowed on us.

    There is a worm that likes to eat human eyes. Exclusively. Childhood cancers. Huntington’s and other genetic diseases. Congenital defects like Arnold-Chiari malformation and cervical ribs.

    But those are not even the worst of it.

    The universe is a mind-numbingly big place the majority of which is utterly hostile to life. Life’s existence on our puny little planet could be wiped anytime by one of the numerous rocks that hurtle through space, showing all your prayers, saviors and holy texts for the arrogantly inane and pointless things they are.

    So much “love”.

  35. devnll says

    It cracks me up that people still argue from Inconceivable Complexity in the same world where engineers use genetic algorithms to streamline design.

  36. Compuholic says

    @devnll:

    Not only that: In computer science we usually prefer mathematical optimization because

    a) it is way more efficient than evolutionary algorithms
    b) with evolutionary algorithms you usually cannot tell of you have reached the global optimum

    Evolutionary algorithms are usually used when the problem is not understood very well and/or the problem is … wait for it … too complex to solve mathematically.

  37. DLC says

    But if these eyelids “evolved” as you claim, which of the two evolved first ? ! !11!

    #DumbShitCreationistsSay

  38. says

    But…but…the top eyelid would have nothing to meet up with, having to wait around for thousands of years for the bottom of the eyelid to evolve. Therefore God!
    Dur.

  39. David Marjanović says

    1 in around a million human babies are born without eyelids

    In amphibians, eyelids grow as part of metamorphosis. No complete metamorphosis, no eyelids.

    The point of eyelids is to protect the eyes from drying out.

    The site is bloated enough already.

    Oh yes! Trying to load the main page (in particular) takes quite long on this 6-year-old laptop: waiting for facebook.com, waiting for twitter.com, waiting for buttons.fucking.reddit.com… *Picard & Riker double facepalm*

    I can’t see a chat, though. Firefox 19.0.2 (with Adblock Plus).

    latter-day vitalists like Rupert Sheldrake who claim that genes only encode proteins and the like, and not spatial information. Rupert Sheldrake claims that “morphogenetic fields” do it

    In the real world most of us live in, morphogenetic fields are protein gradients, and the proteins are encoded by genes. Spatial information boils down to gene regulation.

    Sheldrake simply hasn’t opened a fucking textbook in the last 20 years.

    To the extent that development is understood, it’s based on molecular mechanisms, so vitalists are going to lose there also.

    They did, long ago. Sheldrake just hasn’t noticed, because he hasn’t bothered to learn.

    Are the bottom four slides cross-sections?

    Yes.

    This piece was a real eye-opener!

    *cringe*

    In mammals the number of cervical vertebrae is typically 7 (even a giraffe has only 7 vertebrae, just really big ones), while in many other vertebrate lineages, the cervical vertebrae can vary significantly, both within and among species. The reason for this is AFAIK unknown

    Huge study on dead fetuses by Frietson Galis: deviations in the position of the cervicothoracic boundary in humans are highly significantly associated with embryonic-onset cancer*.

    The proximate trigger for carcinogenic mutations are often oxygen radicals. You produce the more of those the faster your metabolism is. It is thus not surprising that, among placental mammals, the only stable deviations from the usual number of 7 are found in those placentals with the slowest metabolisms: sloths and sea cows. The former, at least, also have a lot of individual variation. Similarly, it is not surprising that there’s a lot of variation in lizards, while there’s less (if any) in turtles.

    Birds have very fast metabolisms, but also wild swings in the number of cervical vertebrae. For unknown reasons, however, birds hardly ever get cancer (except from carcinogenic viruses). *shrug*

    * …the very existence of which proves sc_number wrong. Be ashamed, sc_number: you formed an opinion before you knew enough about the topic.

  40. David Marjanović says

    apis.google.com, plusone.google.com, pixel.quantserve.com (IIRC), clk.about.com…

    Seriously, why? Especially about.com: who needs that???

  41. Lofty says

    David Marjanović, tracking is probably all about tracking ad revenue, you know, what pays for free access.

  42. tonyatkinson says

    This is now my favourate piece creationist bashing ever.
    A fascinating and beautiful research paper, clearly explained- each sentence like a punch to the jaw.