Has there been any serious scientific inquiries into answering this age old question?

  • 2
    $\begingroup$ -1 as the attempts at answers show this question needs to be much more constrained to be answerable. $\endgroup$
    – DQdlM
    Mar 12, 2012 at 22:51
  • $\begingroup$ Perhaps the question can be better worded as: "Are there any scientific inquiries to the Chicken or the Egg question?" $\endgroup$
    – bobthejoe
    Mar 13, 2012 at 7:35
  • 1
    $\begingroup$ This question is invalid but it's such a known question that it's worth putting forth, if only to give an opportunity to point out why it's invalid. $\endgroup$
    – john-jones
    Apr 5, 2012 at 11:52
  • $\begingroup$ This question is more a philosophical question. The chicken or egg dilemma is not really framed in the proper way according to our understanding of biology today, it's more than 2000 years old. $\endgroup$ Apr 5, 2012 at 18:57
  • $\begingroup$ Since the egg carries new mutations and recombination in each generation, and grow (usually) with the same DNA to the adult chicken/cock, we may assume the egg always comes first. In other words, the theropod lays an egg a little more avian than itself. It IS a philosophical question that, as many others, has perfectly viable biological approaches. I vote to reopen it. We should stop being so closed to "strange" questions. $\endgroup$
    – Rodrigo
    Mar 12, 2017 at 12:38

4 Answers 4


Most theories about origin of life say that unicellular organisms were first and multicellularity (like chicken) evolved much later, so in that meaning egg (single cell)* was first. Also, almost all chicken ancestors lay eggs (primitive birds, non-avian reptiles, amphibians, fishes and so on...) so eggs existed much earlier than chickens.

*in the meaning of zygote. The development of chicken embryo starts in hen's oviducts, so it's not a single cell at the moment when hen lays it (Gilbert, 2000).

  • $\begingroup$ @Hermann_Ingjaldsson Thanks, I've fixed it. Is it better now? $\endgroup$
    – Marta Cz-C
    Apr 6, 2012 at 14:54

This is a classic case of "it depends on the context."

  • The Egg: As Marta Cz-C points out, the amniotic eggs that chickens lay were inherited virtually unmodified from their theropod dinosaur ancestors. So when considering the type of eggs, the egg came first.
  • The Chicken: From a systematic perspective, you must first have an animal that you would call a chicken before it can lay a "chicken" egg. So considering the animal, the chicken.

The question makes the false assumption that chicken and eggs are different life forms.
A life form at stage x is not a different life form than that very life form at stage y.
You might as well ask of which came first, a 7 year old kid or an 8 year old kid.

But they are the same thing and therefore this question is invalid.


Dunno about any serious scientific inquiries into the answer but I always thought the answer is egg. At some point the modern chicken has come into being as the progeny of two pre-modern chickens, however it had to be an egg before it could be a chicken and its parents couldn't have been modern chickens.

However, all that presupposes that you can draw a line in the evolutionary history of the modern (extant) chicken and say this is modern and what goes before is not. I dunno if that really can be done.

Edit: came across this guardian article: http://www.guardian.co.uk/science/2006/may/26/uknews

"Whether chicken eggs preceded chickens hinges on the nature of chicken eggs," said panel member and philosopher of science David Papineau at King's College London.

"I would argue it's a chicken egg if it has a chicken in it. If a kangaroo laid an egg from which an ostrich hatched, that would surely be an ostrich egg, not a kangaroo egg. By this reasoning, the first chicken did indeed come from a chicken egg, even though that egg didn't come from chickens."

And from Prof. Brookfield of the University of Nottingham:

The first chicken must have differed from its parents by some genetic change, perhaps a very subtle one, but one which caused this bird to be the first ever to fulfil our criteria for truly being a chicken; Thus the living organism inside the eggshell would have had the same DNA as the chicken that it would develop into, and thus would itself be a member of the species of chicken

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    $\begingroup$ Evolution does not happen over the course of a generation. You are confounding evolution of a species with mutations of a single individual. $\endgroup$
    – nico
    Mar 12, 2012 at 19:40
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    $\begingroup$ That's why I wrote I don't think its possible to draw a line in the evolutionary history and say this is an extant version of a chicken and the previous generation is not. $\endgroup$ Mar 13, 2012 at 12:13

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