The Eternal Question

July 11, 2013 • 6:55 am

I received a query from a science reporter at the Chicago paper The Daily Herald, who occasionally asks me to help answer kids’ science questions.

Here’s her query:

Dr. Coyne:
Would you have time to respond to a reader question, “Which came first, the chicken or the egg?” This came from a fifth or sixth grader. I would need a response by end-of-day today. Sorry for the late notice.
There are two ways to answer this evolutionary question, depending on how you interpret it. (I’ve sent my response in already.)
 I’ll leave the readers to ponder this, but you should all know the scientifically correct answer(s).
Get on it!
Oh, and you might look at the images illustrating this question, for the salacious ones are funny.

157 thoughts on “The Eternal Question

  1. The egg came first, in that there were reptile eggs (assuming we’re only talking about hard-shell eggs) millions of years before there were chickens. Over time, what hatched from the eggs of a particular family of animals came to be what we recognise as a chicken. So the egg system was already in place, the chicken evolved along the way.

  2. I’m gonna go ahead and call that a victory for the egg.

    I’m sure the dinosaurs agree.

    1. I think the word “chicken” stands in for both the species and a gender. I’m obviously being frivolous here. Fortunately, other posters have made salient points. I like the first post: I’m with the egg in terms of evolutionary history. (No misandry here!:)

      1. Is “chicken” sometimes used to refer to gender? I thought “chicken” was the animal, and depending on whether that chicken was male or female, it would be a rooster or a hen.

        1. It is common for someone to say, “I have eight chickens and two roosters”. It is also common for someone to say,”Will you loan me some money?”, and even though common usage is really what matters, ‘loan’ as a verb makes me grit my teeth.

        2. Thanks for pointing that out. I was thinking of a common and perhaps incorrect use of “chicken”.

          1. The hen will lay an egg whether it is fertilized or not. No chicken inside, of course, but an egg just the same.

      1. Isaiah 11:8
        And the sucking child shall play on the hole of the asp, and the weaned child shall put his hand on the cockatrice’ den. *snicker, snicker… giggle*

        Isaiah 59:5
        They hatch cockatrice’ eggs, and weave the spider’s web: he that eateth of their eggs dieth, and that which is crushed breaketh out into a viper. *giggity-giggity*

        Looks like the cock came first. At least in Isaiah.

        1. But a cockatrice is not a cock.

          cockatrice /”kQktrVIs, -trIs/ n.LME. [OFr. cocatris f. med.L calcatrix, cauc- fem. agent-n. f. L calcare to tread, track, f. calx heel, rendering Gk ikhneumon tracker (see ICHNEUMON).]
          1 A fabulous reptile, whose gaze or breath is fatal, hatched by a serpent from a cock’s egg; a basilisk. LME.
          b Chiefly Her. A monster represented as a two-legged dragon (or wyvern) with a cock’s head and a barbed tongue. E16.
          2 fig.a A malicious or destructive person. Cf. BASILISK 2. E16.
          b A prostitute, a whore. L16–M18.

          – Shorter Oxford Dictionary

          1. Damn… I *knew* that. (tough crowd…)

            Hmmm… then those are also cockatrice eggs… and all the stuff about cocks is in the New Testament. I may have to modify my answer then:

            Matthew 26:34
            Jesus said unto him, Verily I say unto thee, That this night, before the cock crow, thou shalt deny me thrice.

            Deuteronomy 22:6
            If a bird’s nest chance to be before thee in the way in any tree, or on the ground, whether they be young ones, or eggs, and the dam sitting upon the young, or upon the eggs, thou shalt not take the dam with the young:

            So it’s definite, then. Eggs came first. Once again, the inerrant Word of God has predicted what scientismists have only been able to figure out the hard way.

  3. The egg. As already mentioned dinosaurs and lizards had hard eggs well before chickens evolved so the egg that held the first chicken came before the first chicken.

  4. These do not really answer the question. It is fine to say that chickens evolved from egg bearing animals. But you still need to answer the real question, which came first the egg or the animal?

    1. I was under the impression that it was a battle between the chicken and the egg.

      The splitting of the cell came first. 🙂

      1. I think it´s a nonsensical question because there was never a time when the first chicken appeared. The label “chicken” is a largely arbitrary discrete construct applied to a genealogical continuum.

      2. I would say that eggs evolved as the advantage of protecting expelled fertilized embryos with a membrane became selected by environmental pressures. Critter first, eggs later and more egg-like as time went on.

        1. Another way to look at it is that the very beginning of sexual reproduction involved some kind of egg, a package of genetic material from one individual being combined with a package of genetic material from another individual.

          Since sexual reproduction appears to have preceeded multi-cellular organisms, we can say that eggs came before animals.

    2. But you still need to answer the real question…

      No, that may be your question, but it is not the real question.

    3. In this case the answer is still “the egg” because the mutations that make the new animal different from the old animal happen in the chicken’s ovary and the rooster’s testes, and then as the chick is developing in the egg. So the egg always comes first.

  5. I would expecy that an almost-chicken laid an egg that was a full chicken. So the egg should have come first.

    1. surely the answer depends on whether you define “chicken egg” as “egg laid by a chicken” or “egg containing a chicken”.

  6. This is how I see it:
    The egg was first. There was an egg laying animal that evolved into the chicken.
    A chicken is a bird. Birds evolved out of dinosaurs. Dino’s laid eggs.

    If the questions was:“Which came first, the chicken or the chicken-egg?” It has to be the chicken. Something that’s not a chicken cannot lay a chicken-egg. It lays a not-really-a-chicken-yet-but-almost-indistinguishable-from-a-chicken-egg.

    1. Actually, if you’re going to attempt the impossible task of drawing a line between not-chicken and chicken, then clearly the egg came first.

      A not-chicken laid an egg. That egg contained an offspring of the egg-laying not-chicken and another not-chicken. Through mutation or sexual mixing, the offspring met whatever criteria you chose to qualify it as a chicken.

      Unless, of course, you’re going to say that the fertilized egg cell instantly became a chicken by virtue of its DNA, in which case the chicken clearly came before the egg, which formed around it inside the not-chicken.

  7. As at least two others have pointed out, eggs arrived on the scene long before chickens.

    But if we add one word to the question, make it thus:

    Which came first: the chicken or the chicken egg?

    it becomes a bit more interesting. It essentially becomes a variation on, “who was the first human?”

    The answer is that there are no hard-and-fast boundaries like that. Every child is the same species as its parent, even though, if you go back a sufficient number of generations (thousands at least, if not millions), the great-great-great…great-grandparents are a different species from their eventual descendants.

    It’s much like asking, “Where in the spectrum does blue end and green begin?” There are colors that are unquestionably blue, and others that are undoubtedly green, but there are many more colors between the two where the distinction isn’t so apparent.

    So while one might naively suggest that, at some point in the distant past, a non-chicken hen laid a chicken egg, that simply wan’t the case. A bird-like dinosaur laid eggs of bird-like dinosaurs, and each bird-like dinosaur chick was as like its parents as any child is — and as different. And, over time, those differences drifted in various ways, with some cousins more closely resembling their ancestors and others going their separate ways. But the cousins still had children that resembled the parents!

    And if you were to trace one particular family tree of that bird-like dinosaur, you’d find this branch over here became more and more bird-like and less and less dinosaur-like, and this branch became more chicken-like (while this other branch we’re ignoring for the moment became more eagle-like and this other one became more ostrich-like and so on), and eventually that branch leads to the hen who laid the eggs you had for breakfast and whose flesh is headed for the stew pot for dinner.

    And who knows what sorts of organisms her chick’s chick’s chick’s…chick’s chicks will be like? (Assuming her line doesn’t die out before then — which, of course, is what almost all branches do.)



    1. Right.

      Either the answer is simply “the egg”, for reasons explained by others, or the question itself is meaningless because there was no “first” chicken.

      1. Exactly, a better question is “what’s a chicken?” and is it really an important question? It seems the question just plays on the human need for classification.

          1. “Species” are real only to human language. An entity that happens to be associated with “chicken” would probably identify itself as existing (“real”) if it actually had the facility to assert as such. 🙂

            1. There’s something approximating them (and I know it is complicated) because of the “observed” fact of failure to produce offspring, though. And yes, this only applies to sexual organisms.

              1. I suspect that was not a sudden point either but rather varying degrees chance of reproductive success between variants leading to a subsequent point of not being able to reproduce at all, genetically (0 chance) as the variants “grow” distant. I could be wrong but thats how I understand it.

            1. Good point. In the early pages of Speciation by Coyne & Orr, they identify, as I recall, two scientific characterizations of species, then specify which they use and continue.

              It’s an expensive way to answer the question, but it may be available through Inter Library Loan if not in your local library.

    2. What if we take the complete genome of a modern chicken. Can’t we see from what point on, back in time, a modern chicken couldn’t procreate with its ancestor?

      1. How many of its ancestors would it need to be incompatible with to count? What if it was incompatible with all ancestors more than, say 1000 generations before it, but compatible with all of its contemporaries in the extant lineage (who would also be incompatible with said ancestors)?

      2. What if we take the complete genome of a modern chicken. Can’t we see from what point on, back in time, a modern chicken couldn’t procreate with its ancestor?

        No, we can’t, for many reasons. First, we have no way of determining the order of mutations along an unbroken branch of the evolutionary tree. All you could say at most is that an event happened somewhere between the split between chickens and their closest relatives (green jungle fowl, assuming we think chickens are the same species as red jungle fowl) and the earliest split within the extant chicken population. (It’s even more complicated than that, considering that a species isn’t a single lineage, with a uniform genome at any slice of time, that mutations happen in individuals and take time to spread through the population, and that this spread may take longer than the age of the species.)

        Second, we don’t have that good a handle on what makes procreation likely or unlikely, so just looking at genomes won’t help much.

        Third, chickens will quite happily, under the proper conditions and especially in captivity, procreate with various other species in their own genus and even other genera in their family. The divisions between species aren’t as simple and clearcut as you might imagine. Not between species around today and even more between hypothetical extinct ancestors.

        We also have to define what a chicken egg is: is it an egg laid by a chicken or an egg that hatches to become a chicken? And we also have to decide, if we’re going down that route, is what one mutation is crucial to our definition of “chicken”. Or perhaps it’s a particular combination of alleles. In either case, that’s the only way you can have a first chicken or a first chicken egg, distinct from an evolving population that collectively passes through some vague line between chicken-ness and non-chicken-ness.

    3. Well, since humans have decided that both chickens and eggs are delicious, AND we can grow them on farms, I’d say the chicken is about as safe from extinction has humans are.

      Unless we all suddenly develop an egg allergy. Then, no more chickens.

    4. “Which came first: the chicken or the chicken egg?”

      Then it depends whether you define “a chicken egg” as “an egg laid by a chicken” or “an egg from which a chicken hatches”.

      If the first, the chicken must come first, if the second, the egg. But you asked a different question, so you shouldn’t be surprised that it can yield a different answer.

      1. It really doesn’t matter how you define it, because the dividing line is nowhere near so narrow as to be able to pin down to a single individual.

        “Measure with micrometer. Mark with chalk. Cut with axe.”

        That’s what we’re doing here.

        G. gallus and G. varius have a common ancestor about 8.5 MYA. Is there really anybody here who could say with a straight face that the several-million-times-great grandancestor of a particular chicken was the first?

        Again, population genetics doesn’t work like that. There was no first chicken, no first chicken egg. Just as there was no first human, no first redwood tree, no first anything. No single rain of rice added to the collection turns it into a pile of rice, either, and no single drop turns a pond into a lake or a lake into an ocean. There is no temperature at which water stops being cold and starts being hot.

        Those are all superbly useful labels, but you’e gotta be more than a bit nuts to use them for precision work of any kind.

        If you really need to do that sort of thing, drop the fuzzy words and use precise and quantifiable objective measures. This water is 76.43°F. This body of water has an historical average surface area and volume of such-and-such, and you can find it on the map at these coordinates. There are 738 grains of rice in this collection.

        And there’s a rather pretty hen named, “Jerry,” in my parents’s back yard and anybody who wishes to do a genomic analysis on her is welcome to do so — or on any of the five other hens you’ll find there. But watch out for Etta…she’s ornery.



  8. Hmm. I’m embarrassed that I don’t know the answer to this.

    I would think they both come about at they same time; probably evolving from some other creature that laid eggs. And that creature, in turn, probably gradually evolved giving birth to some amorphous blob that gradually evolved a harder shell for protection.

    So, by the time the chicken came along, it was laying eggs.

    That’s my best guess.

  9. Isn’t this like asking who came first Elizabeth I or Elizabeth II? There was Elizabeth, until Elizabeth II was crowned, then Elizabeth I was recognized; therefore, I say the chicken came first, only to realize is must have hatched from a chicken egg… virgin birth?

    1. No, it is quite different. The Lizzies are distinct and individual persons. “The chicken” and “the egg” are linguistic tricks in that they sound like they refer to particular discrete individual creatures (because that is how we generally understand the “the” part). But we are really talking about all eggs and all chickens. And, as pointed out above, the answer must be either “eggs, because there were eggs long before anything called a “chicken” existed, or the question is a bad one because it assumes the existence of a “first chicken”. There was no “first chicken”. There was a first queen named “Elizabeth”.

      1. But she wasn’t Elizabeth I until the existance of Elizabeth II. This is actually a good way to think about the problem, except without the additional complication that reproductive incompatibility is not absolute.

      2. Something in the above is not quite right, because we also say “the hydrogen atom has a single proton”, for example. Can’t quite put my finger on it, though.

  10. The mindset that this question comes from is one I heard Kathy Ireland, a model, express on Bill Maher’s show years ago: “Kind comes from kind. So how can one species come from a different species?”

    What I always wanted to ask her was, “Just how many men were in your bedroom the night your daughter was conceived?” I’m pretty sure it was just two individuals, not a collective endeavor.

    Judging what the boundaries of a species are can’t be all that easy, and we don’t know for certain that Kathy Ireland’s daughter is a member of the same species as her mother. Suppose the daughter becomes an astronaut, part of the colonization of Mars, and bears some mutation that makes her offspring more likely to survive and reproduce on Mars. At some point, the Mars population diverges enough to become a separate species. If we trace back to the original source of the mutation, Ireland fille, what would we say about which species she belongs to?

    So, of course, the egg came first. That’s the opportunity for new genetic combinations.

  11. Chicken egg came before chicken. Evolutionary changes occur during the formation and fertilization of the egg. The line of where to separate an almost chicken from a chicken is arbitrary but, once that line is drawn the first occurrence necessarily needs to be within the egg. The animal that laid the first chicken egg wasn’t a chicken.

    1. +1

      I didn’t notice you answer before I posted mine. Of course, simplifying assumptions have to be made in order to answer this question in the first place, but once those are in place, this is the only possible answer.

    2. The line of where to separate an almost chicken from a chicken is arbitrary but, once that line is drawn the first occurrence necessarily needs to be within the egg.

      The problem is that that line can’t be drawn.

      Ignoring the case of surrogate wombs, in no instance will a parent ever birth offspring of a different species.

      (Plants are a bit weirder, of course, but they reproduce differently.)



      1. The problem is that that line can’t be drawn.

        I believe that the main problem with the simplified approach (“drawing a line”) is not that in reality the evolutionary change is gradual (after all, the definition of a species is to some extent arbitrary, thus also requiring drawing a line), but that it occurs in populations rather than in individuals. A single chicken doesn’t make a new species, it’s the allele frequency in a population that changes.

      2. My teacher used to take that argument away from me by telling me to choose the most correct answer on multiple guess questions.

        Which is more correct:
        a) The chicken came first.
        b) The egg containing a chicken came first.

        I advise you to select carefully as my next question is directed to Baihu.
        Can you draw a line between master and slave?

        Lastly, how will you ever get through the classification of your Coleoptera?

        1. Sorry. I don’t do multiple guess any more. I’m not interested in satisfying the petty power fantasizes of lazy educators who love false dichotomies.

          If I ever find myself in the classroom again, on either side of the podium, all multiple-guess questions would be treated as essay questions, with a correct answer being one which provides all reasonable arguments both for and against all logically valid interpretations of all options.

          As to your next question, yes. There are multiple lines on the floor, indeed, between me and my master.

          And for your last question? I think the answer has something to do with the gold plate with scarab beetle relief figures she gave to Antony before Caesar found them out.



  12. this was a question posed in my law school at one time: “what came first, the chicken or its egg?” Does the chicken own the egg in which it was hatched, and/or the egg it hatches? So what is “its” egg? Clearly, if “the egg” of the question above is the particular egg of that chicken, I assume others here can answer whether any of the egg is formed inside a chicken before fertilization occurs. If “the egg” is the egg a chicken will lay, then she came before. If the question is directed broadly to eggs and chickens in general, then the fist question is whether we are talking chicken eggs or any eggs. If the latter, the reptile egg came first. If the former, this question can be asked as to whether the species of chicken was evolved by the time eggs were used for reproduction, which I assume is the case, meaning the prior species of the chicken probably used eggs, meaning by the time the species we call chicken arrived, chicken eggs were on the scene, so they came at the same time.

    1. Parents are obliged to be caregivers but, it is problematic when they see their children as possessions that they own.

  13. If we ignore for a moment the (by no means trivial) issue that speciation doesn’t happen in one generation and assume, for simplicity, that a new species differs from the old species by one final mutation (or a set of mutations that occurred in the same generation), the answer to the question “chicken or chicken egg?” comes clear: it was the egg.

    Evolution consists of random mutations plus natural selection. Since the only mutations that matter in the evolutionary sense happen in the germ line (as opposed to somatic mutations elsewhere in the body, which are not passed on to the next generation), the final mutation(s) that completed the evolutionary change from pre-chicken to chicken must have occurred during egg formation in the pre-chicken ovary or during sperm formation in the rooster. The resulting fertilized egg had the genetic makeup of the new species. Thus, the pre-chicken laid the first chicken egg. From that egg, the first chicken developed.

    1. Going with the assumption you already pointed out (speciation by one final mutation) there still is some wiggle room, depending on how you define the terms.

      If you ask: What came first, the “chicken” or the “chicken-egg”?

      It comes down to whether you define “chicken-egg” as the egg *containing* a chicken, or the egg *laid by* a chicken.

      If the former, then the answer is egg. If the latter, then the answer is chicken.

      Of course, the assumptions we made to get here are ones that don’t actually play out (in that there never was a “not-chicken to chicken” generational change) so the difference in definition never comes up outside of this thought experiment – as there never is a time when the two are different.

      1. If the latter, then the answer is chicken.

        The only way a chicken could lay a chicken egg is if the one doing the laying was a chicken in an egg before it became a chicken that laid an egg. However, an almost chicken could lay an egg that contained a chicken.

      2. It comes down to whether you define “chicken-egg” as the egg *containing* a chicken, or the egg *laid by* a chicken.

        I always understood that “a chicken-egg” is an egg containing a chicken. Same as “a chicken embryo”. In other words, a very young chicken.

        And of course, this is only a thought experiment – and a risky one in the context of science education, because it may perpetuate a misunderstanding of the true nature of speciation.

        But if we remain within the parameters of this thought experiment, there is only one correct answer.

        1. In the past, I would have defined “chicken egg” that way too (as one CONTAINING a chicken).

          However, if I go to the supermarket and buy eggs – they are definitely thought of as “chicken eggs” even though they do NOT contain a chicken. In that case, they seem to be considered “chicken eggs” simply by virtue of being laid by a chicken.

          In reality, this makes their contents “less chicken” than our mythical “non-chicken, and only one mutation away from being chicken, ancestor” from the thought experiment – so one cannot argue they are chicken eggs because they “contain” a chicken. (They’re just a container of biological material with 50% the DNA necessary for a chicken. Our “non-chicken ancestor” is presumably 99%+ “chicken”)

          I’m still on the fence as to how to define it. I can make a case either way. I think it has less to do with biology than it does with linguistics. 🙂

    2. Okay, let’s say that a species differs from an old species by one mutation. And some individual gets that mutation. Presto, it’s the new species. Now that organism finds a mate, reproduces, and only half of its offspring get the new mutation. So half of its offspring are chickens, and half have reverted back to the old species. And on and on, so that you have a breeding population all mixed up between chickens and non-chickens.

      I’m with Ben Goren. There’s no dividing line between chicken and non-chicken, so there’s no answer to the chicken-egg question. You just have to understand that it’s a gradual process.

  14. Goslings, like Chicks, should know the answer. Check out “Chickens have a lot to say about evolution.”

  15. Why complicate the issue when the answer is so obvious: God created all extant species in their current forms, so the first chicken gave rise to the first egg. QED.

      1. Actually, it wasn’t God; it was Mabel.

        And it wasn’t chicken and eggs; it was cake and frosting. And Mabel only made the cake; her sister, Louise, made the frosting. And they made it all at the same time.

        This was all last Tuesday, as I understand it.

        Hope that clears it all up….


        1. You all don’t get it, do you? My revelation is superior to you all’s because I have a holy book to back me up. You have diddly squat.


          1. Ah, yes.

            But your holy book is written on processed dead tree carcasses, whilst my holy book is woven into the very fabric of existence itself.

            So there.


            1. Ouch…good one!

              Hey, I actually learned something useful by playing devil’s advocate this time.

              Believers always whip out the “Holy Book” argument on me like it’s a trump card. Now I have a good retort:”the universe itself is my “holy” book”.

              Good stuff!

            2. Ouch…good one!

              Hey I actually learned something useful by playing devil’s advocate this time!

              Believers always whip out the “Holy Book” argument on me like it’s a trump card. Now I have a good retort:”the universe itself is my “holy” book”.

              Good stuff!

      2. You don’t get it do you? My revelation is superior to yours because I have a holy book to back it up. You have diddly squat.


        1. Oh yeah? Well my God can beat up your God with one hand tied behind his back, any day of the week. So there.

  16. Sexual reproduction likely began with single cell creatures and as time moved on multi-celled creatured entered the scene with sexual reproduction already in place. The specific forms of this reproduction, idk. But it seems likely (perhaps an expert knows this) that egg formation was one manner of sexual reproduction early on when animals first developed. Certainly fish have eggs and then it is rather easy to envision the extension to chickens.

    I think the development of sexual reproduction and how it manifest would be a very interesting topic to study further.

    But the semial answer is that the creature came first and sexual reproduction came next. And while the chicken and egg came along together, back when the creature came before the egg!

  17. The question is silly, but it’s a good way to explain why questions like, “if evolution is true, why don’t we see dogs giving birth to cats?” are ridiculous. Ben’s answer above is a good one, using the light spectrum as an example of gradual change. Ring species may also be helpful. This question is actually a good chance to teach kids some real biology.

    1. And an opportunity to teach the pitfalls of thinking in binary terms. Let them read Ben on a shades-of-gray (Not the book!) approach.

          1. 50 Shades of Wretched has been swooned over by a lot of people, some of whom were middle-aged women. Why pick out middle aged women, particularly?

              1. I think instead of “middle aged women” it should say “the sexually repressed.” I personally haven’t read it, but I hear it’s very popular in Utah.

              2. Nah. Not sexually repressed. Not everyone does sex the same way–that really is the context of 50 Shades, and one of the things that makes the series, as badly written as it is, important.

                50 Shades will change the publishing industry, permanently, and all writers, especially those who self-publish, will be beneficiaries.

              3. See, you probably just trebled my knowledge of the subject. I thought it was a single book, not a series; it wouldn’t even have occurred to me that it was self-published; and I suspected but didn’t actually know that it was badly written. And I thought it was just its explicit nature that was causing all the ruckus, not that it’s apparently explicitly about something other than male / female missionary-position sex.

                Then again, this is already more serious thought than I ever would have thought I’d have given to it….


  18. OT but this reminds me of a linguistic trick I used to play on my kids when they were younger:

    “Birds fly like bees but fruit flies like bananas.”

    In my children’s opinion, I repeated this to them about ten thousand times too many.

    1. That should be:

      “Time flies like an arrow; fruit flies like a banana.”

      Birds, by the way, do not fly like bees.

    2. Interestingly (or not), in a book by Hofstadter/Sander, I learned a word that labels the kind of word play present in the your sentence. It’s zeugmas (or syllepsis). This is off topic, of course.

  19. 1) If one insists on a literal chicken as one of the outcomes, then the answer is that the egg came first. One does not have to go all the way back to the non-avian dinosaur ancestors of birds, but only to the point where a non-chicken laid an egg that hatched the most recent ancestor of chickens. If one means “domestic chickens”, that date is more recent.

    2) If the focus is on the broader question of “which came first, eggs or mature animals”, then the answer is the chicken equivalent, since there were animals before there were (shelled) eggs. This is also the case if one broadens the definition of egg to include the larger of two gametes, since there were organisms before gametes. In this scenario, it’s chickens all the way down.

    1. At some point there were chemical constituents that combined to produce something that could be considered life. So, the chemicals that produced a chicken had to be combined before the chicken was produced. It’s dirt, water, and chemistry all the way down.

  20. The chicken ovum is fertilized, making a chicken zygote. The egg is then built around it, is layed and eventually hatches, revealing the chick. But the chicken was there throughout the existence of the egg, so that came first.

  21. Tsk, Jerry, as a foodie I would expect you to know the answer to this one:

    You eat the egg for breakfast and the chicken for lunch or dinner. So the egg comes first.

  22. Since the chicken is a domesticated Southeast Asian jungle fowl (if I remember correctly), you need to put a (semi-)Intelligent Designer in the mix — Homo sapiens. Would you ask “Which came first–the ova or the dog?” while ignoring human domestication of the wolf, or some wolves’ self-domestication to create a new ecological niche of “wolves that are commensal with Homo sapiens?”

  23. The amniote egg came millions of years before the chicken which is an avion dinosaur which did not show up on the scene until acouple hundred million years later.

  24. I always thought this question was rhetorical, a way of saying “Here’s a repeating cycle in which A leads to B which leads to A again & so on indefinitely. It is pointless to ask which came first:
    A or B.” Like a lot of folk observations, it doesn’t stand up to close scrutiny.

    1. Jerry specifically called this an evolutionary question. In the context of evolution, this is not a repeating cycle.

  25. When someone has a problem understanding the answer to this question, I sometimes think it is useful to bring out the sorites paradox.

    It is no easier to identify the exact point at which the animal became a chicken than it is to identify the exact point at which the sand became a heap. It is also not really very important. It is also not a problem for the theory of evolution.

  26. I think…
    No matter where you draw the arbitrary line separating chicken from non-chicken, you are separating the non-chicken parent from its chicken egg. Egg first. A non-chicken did not, in Lamarckian fashion, turn into a chicken. It laid eggs with variations, one of which contained the first chicken (in the arbitrary sense). This is understanding, of course, that the changes accumulated not in a single individual, per se, but in a population, which complicates everything. Still, if you could tell us exactly what single mutation put the lineage “over the line,” then it might be theoretically traceable to a single individual. Or not.

  27. The first egg with the exact DNA sequence that spells “c-h-i-c-k-e-n” would have been laid by a hen with DNA that spelled “a-l-m-o-s-t-c-h-i-c-k-e-n” so the egg came first.

    (though that hen probably tasted like chicken)

    1. Except, of course, there is no exact DNA sequence that spells “c-h-i-c-k-e-n.”

      There is a population of DNA sequences that collectively form an interfertile group that we attach the “chicken” label to. But there exists no Platonic ideal chicken DNA, not even in principle.



      1. Lady’s example also doesn’t really answer the question, as it could be the case that an egg with “almostchicken” DNA in it suffered some developmental abnormality that lead to it producing a “chicken.”

        1. This is generally a silly line of thought. Which chicken, they are all different. The most sensible thought is that chickens came along together. As chickens are bred they all produce eggs for reproduction.

          The first chicken did not appear from an egg of a creature that was nothing like a chicken. And all the chickens are differnt.

          More interesting is when did egg bearing creature come about and what were they? Did it happen more than once? And further when did sexual reproduction come along and did that happen more than once? The child asked the question and thus the opportunity to help the child examime than answer and ask more questions.

      2. There is, however, an amino acid sequence that spells “c-h-i-c-k-e-n”: cysteine, histidine, isoleucine, cysteine, lysine, glutamic acid, asparagine.

        Whether this amino acid sequence occurs in any proteins produced by chickens is left as an exercise for the reader.

  28. It’s all about definitions. The whole chicken-egg thing has been done to death, but we could also turn this into a number of more general questions:

    “Which came first, the animal or the egg?”

    “Which came first, the organism or the egg?”

    And we still have to deal with definitions. What’s an egg? Generally, it’s considered to be a megaspore, in a species in which haploid gametes are divided into both megaspores and microspores, the difference being that the macrospore is packed with raw materials for cell division and the microspore, not so much, but is usually motile (sperm, e.g.). In which case, the answer to the first question is “the egg”, as megaspores exist in a variety of protists. (I don’t actually know, but I’m betting that they are known in the sister group of animals, choanoflagellates.) Then again, the answer to the first question is “the organism”, since megaspores are a eukaryote thing, and eukaryotes are fairly recent organisms, being less than half as old as life.

    Anyway, eggs are older than chickens, older than reptiles, older than vertebrates, and older than animals. Depending on how you define “egg”.

    1. *After the fact footnote: It turns out that nobody knows how sexual reproduction in choanoflagellates works; nobody has ever observed meiosis or gametes. But since they have the package of genes needed in meiosis and nowhere else, they must do it some time. Out of sight, though.

  29. While the egg evolved in more advanced forms of sex, I find it humorous that some claims forms of sex was always with us in the form of fission-fusion cycles of the ill defined early compartments that led up to and through the LUCA cells.

    Such a generic but long term mechanism of incomplete lineage isolation would predict the seen early intense horizontal gene transfer without the need of special mechanisms.* [“A Unifying Scenario on the Origin and Evolution of Cellular and Viral Domains”, Bandea -09.]

    In that sense, the “egg” may have been concurrent. =D

    *Instead they, of course, want to or maybe even have to rely on special mechanisms for isolation later. The ref uses early parasitism, that later became viruses.

  30. Presumably the parents are not “chicken”.
    At fertilization the resultant DNA is “chicken”.
    What we commonly call the “egg” then subsequently forms around the zygote.
    Therefore the chicken came first??
    Then the egg(hard shell kind) then the chicken again. Unless of course the prerequisite mutations took place in the maternal ovum then it is egg(ovum) to chicken(zygote) to egg(shelled) to chicken(hatchling)

  31. I know these comments go on and on and they have as usual.Forget the chicken and egg, Twinkies are coming back in about 4 days.

  32. Depends on what “the egg” and “the chicken” mean.

    If “the egg” means “the first chicken egg”, then then answer is that the chicken came first, as eggs are named after whatever laid them. The first chicken hatched from an egg laid by a non-chicken, hence that egg was not a chicken egg.

    If, otoh, the terms are generic in significance, then clearly the first egg ever laid by any species came before the first organism we can call “a chicken”.

  33. The question I want to know the answer to is : How would the answer to this question about which came first, the chicken or the egg, help this student understand evolution better? There are better questions, ones whose answers would clarify the understanding of some area of evolution. The trick is to ask a good question.

  34. However we define the DNA cutoff point of a chicken, that chicken came from an egg. Hence, egg came first.

    1. I don’t see how “DNA cutoff” or boundary between a species and one its evolutionary ancestors cab be as thinly defined as a single egg or a singular shuffling and mixing of two organisms’ DNA.

  35. In one sense, obviously there were kinds of eggs before chickens existed.

    But if we think of the problem as most people do, and address the paradox of how can there be a chicken egg without a chicken, or how can there be a chicken without a chicken egg, then we have to answer that neither the chicken or the chicken egg came first.

    Since speciation occurs on a population over a broad space and time, not on an individual or a single lineage, there is no mathematical way to order individual eggs and chickens and say one came before the other.

  36. I think species are real. I am an ichthyologist who has a lot of experience identifying living species of fish. Mostly it can be done, although there is a large literature about fish hybrids. I also think one cannot observe speciation in today’s world except for some of the instantaineous methods seen mostly in plants.

    On the other hand I can picture a nest of dinsosaur eggs. After the eggs hatch, some sort of vicarience event divides the brood into ancestors of more dinosaurs similar to mama and papa on the one hand, and the ancestors of domestic chickents on the other. But, if you were there, you would have no idea that was what you were seeing.

  37. Chickens have eggs, humans have eggs, the last common ancestor of humans and chickens had eggs – and that was long before humans or chickens existed. The egg wins by a few hundred million years.

    1. Uhmmm. Clearly chickens and eggs came along together there is no meaning to asking which is first for these animals. But going back in time clearly creatures existed before eggs. So clearly creatures came first and eggs were a later development. So the egg loses and came after, by how long, I have no idea.

      1. Whether your claim is true depends on what you mean by “creature”. And on what you mean by “egg”. Please clarify.

  38. It occurred to me that the chicken/egg question is really just a kind of variation on the irreducible complexity argument.

    It’s like asking which came first, the eye or sight, where by sight I mean the neurological/brain components of vision that depend on the eye.

    It’s a similar kind of conundrum, and it seems the only conceivable answer is a gradual coevolution through many interdependent transitions from lesser to greater complexity, via a feedback process: a minimally light sensitive cell or cells give rise to neurological growth connecting the light signals to behaviors that confer slight advantages, followed by increased advantages for any increase in light sensitivity leading to more complex light sensitive neurally stimulated behavior and so on and so forth.

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