The egg, the chicken, and evolution

A question from

“Who came first, the egg or the chicken?!”

The egg, of course! Reptiles were laying eggs before the first bird was even around. Now, if you’re specifically talking about a chicken egg, it gets a little more complicated. I was going to create my own explanation, but I think Wikipedia already does quite a nice job:

Since DNA can be modified only before birth, a mutation must have taken place at conception or within an egg such that an animal similar to a chicken, but not a chicken, laid the first chicken egg.[8][9] In this light, both the egg and the chicken evolved simultaneously from birds that were not chickens and did not lay chicken eggs but gradually became more and more like chickens over time.

However, a mutation in one individual is not normally considered a new species. A speciation event involves the separation of one population from its parent population, so that interbreeding ceases; this is the process whereby domesticated animals are genetically separated from their wild forebears. The whole separated group can then be recognized as a new species.

The modern chicken was believed to have descended from another closely related species of birds, the red junglefowl, but recently discovered genetic evidence suggests that the modern domestic chicken is a hybrid descendant of both the red junglefowl and the grey junglefowl.[10] Assuming the evidence bears out, a hybrid is a compelling scenario that the chicken egg, based on the second definition, came before the chicken.

There you go – a scientific answer to an age-old question! Of course, the Biblical viewpoint is that the chicken came first, since God created birds on the fourth day and made no mention of eggs. Guess proving the Bible wrong again is the cherry on top.


  1. says

    it drives me crazy when people say things like “that’s a real chicken-and-egg dilemma” – I’ve always maintained that evolution gives us a simple answer of the egg coming first! :-)

  2. javamann says

    I’ve always maintained that evolution gives us a simple answer that the chicken came first.

  3. says

    I love that wikipedia page! I thought that question wasn’t worthwhile the time of somebody, but wikipedia editors don’t think that way.

  4. DataJack says

    The rooster – Ha! Seriously, it can only be the egg, as Wiki explains. Something not-quite-a-chicken laid the first chicken egg. Although this technically answers the question, it is really a non-answer, because all living organisms are transitional forms :)

  5. Hbk743 says

    “The egg, of course! Reptiles were laying eggs before the first bird was even around.”I’ve been using that answer since I was about 12. Unfortunately, my heavily-baptist family wasn’t really buying it. ~Raiki

  6. Zenlite says

    A point to which Dawkins devotes an entire chapter in ‘The Greatest Show on Earth’ which was an absolutely wonderful read.

  7. Rhb says

    Holycrap: this is a similar problem to the chickeneggchickeneggch.. and one that was answered definitively in (I think) a B.C. cartoon (anyway something involving cavemen) many years ago. It was the chicken zigging at rightangles then zagging (also at rightangles) that was followed by the decision “THAT’s where we’ll build the road”

  8. says

    I had already reasoned that one out for myself, but a few months ago I heard the entire argument summed up in the pithy four-word answer:”eggs laid by proto-chickens”Yep, that’s pretty much it.

  9. Kaleberg says

    I even found out why the chicken crossed the road, thanks to the internet. (Apparently it was for some fowl purpose.)

  10. says

    I think it it possible for the mutation to occur during the time when a sperm is formed. The mutant sperm then fertilizes the normal egg and a new species – chicken – emerges.So my answer is neither, because a sperm is neither an egg nor chicken.The question becomes: which scenario is more likely, mutated sperm or mutated egg? And what is the probability of each scenario?

  11. says

    I think it’d depend on how you define the species of an egg. It could be 1) the species it contains 2) the species that lays it or 3) the species whose tissue forms the egg. By 1, the egg came first. By two, the chicken came first. By 3 (which I prefer), the chicken came before the egg, because the eggshell is laid down by the mother (and therefore the first chicken hatched from a non-chicken egg).Incidentally, that means that you couldn’t possibly have cloned dinosaurs hatching from eggs, but I think that’s one of the simpler problems to solve before we have Jurassic Park.

  12. Metal_Warrior says

    “The egg, of course! Reptiles were laying eggs before the first bird was even around.”That answer I gave my granddad with around 7 – he never asked me the question again :D

  13. libraboy says

    Well, in mammals the answer is pretty obvious. Since the males keep their balls on the outside, they are more subject to mutation. I’m not sure where roosters store their gonads…

  14. Gus Snarp says

    I like to think of it this way: If I plant zucchini and pumpkins in my garden, and I save the seeds from the pumpkins and zucchinis, then the pumpkins and zucchinis are the eggs, and they came from pumpkin and zucchini plants. But the plants will have cross pollinated and whatever grows from the seeds will likely be neither zucchini nor pumpkin. Sure, the difference between a velociraptor and a chicken is greater than that between a zucchini and a pumpkin, but the difference between a male not-quite-a-chicken and a female proto-chicken is close enough.

  15. KarateMonkey says

    That reminds me of one of my favorite jokes.A chicken and an egg are lying in bed the chicken is looking smug and smoking a cigarette. The egg says in an annoyed tone, “Well, I guess we answered THAT question.”

  16. D. Carney says

    How about… The Egg. Since the egg represents a ‘potential chicken’ and the chicken an ‘actual chicken’ and since potentiality comes before actuality.P.S. Your post about Disney World was so awesome Jen.

  17. Beingofsoundmind says

    Really, saying that evolution proves that the egg came first is all a matter of your own interpretation of what constitutes a (chicken) egg. That first egg to be hatched by “proto” chicken that contained an actual chicken (to simplify matters somewhat I concur, but allow me to continue) can be labled a chicken egg or a proto chicken egg, depending on what creatre you attribute the … eggness to. If we say the egg is a chicken egg because a chicken laid it, the chicken came first. If we say an egg is a chicken egg because it contains a chicken, then the egg came first.So to look at the question from a non evolutionionary perspective it boils down to a more general view of labeling or classification. The correct question to ask is,”What makes an egg a type of egg The creature that produced it or the creature it contains?”Blame getting high on this entire comment. I just had to write this even though I am completely baked…

  18. Valhar2000 says

    I would say that, in light of what we now know about biology, that question is simply wrong. You cannot point to one animal that was a proto-chicken and then point to its offspring that was a chicken. It just doesn’t work that way, but that is the only type of scenario in which the question would be anything other than non-sense.

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