What Came First – Chicken or Egg?

October 25, 2015 / Animal Factoids, Paradox / 0 Comments /
header image of a chicken

It is an age old puzzle – a chicken must have come from an egg, but, for an egg to exist, a chicken must have laid it, so which came first? Neither seems be be able to exist without the other before it, but we know that at some point in time one must have come first as part of the natural order of things. So, lets look at the different ways to approach the question.



First of all, the question needs to be clarified, because eggs have been laid for many many of years before chickens existed. We know that most dinosaurs laid eggs, and so if you are asking which came first a generic egg, or a chicken, the answer is very obviously the egg.

However, most people understand the question to be which a chicken egg and a chicken, and so this is what we will look at here.


Approach 1 – what is a chicken egg?

A chicken egg can be defined as 1 of three:

  • An egg laid by a chicken
  • An egg containing a chicken
  • An egg laid by a chicken which also contains a chicken

However, most people will agree that a chicken egg would be an egg laid by a chicken. If you can imagine going to buy some eggs from the supermarket, all the eggs are called chicken eggs because they are laid by a chicken, regardless of what genetic alterations there may have been to the embryo inside the egg. Imagine if a chicken laid an egg that contained pigeon, you would still call the egg a chicken egg, but the offspring would be a pigeon.

Following this approach then, a pseudo- chicken (something similar to a chicken, but not quite a chicken) must have laid a pseudo-chicken egg, which contained the genetically altered pseudo-chicken, that we all call a chicken. This chicken then went on to lay chicken eggs, and so the chicken came first.

Granted, this is open to interpretation. If you define a chicken egg as an egg which contains a chicken, then the egg must have come first, so lets look at the science.


Approach 2 – Science

Research have identified a protein in a chicken egg shell called OC-17 which is critical to the egg forming process, and can only be made chicken ovaries. So even if an egg laid by a pseudo-chicken contains a chicken, it is still a pseudo-chicken egg, because a chicken egg contains the OC-17 protein, which can only be made is a chicken’s ovaries.  With this in mind a chicken egg cannot have been layen without a chicken, and so again, the chicken must have come first.


Approach 3 – Apply it to another situation

I would say this approach isn’t very accurate than the above approaches, but it can sometimes be useful to approach the problem from a different angle.

You can also apply this question to humans, because we humans also produce eggs (they just aren’t laid), and you could ask “what came first, a human, or a human egg“. In this scenario, you would have a pseudo-human with a egg in their ovaries, which is fertilised by a pseudo-human sperm. It is possible that the genetic material needed to create a human is in the sperm, and the egg is 100% perfect pseudo-human genes, which makes the egg beyond doubt a pseudo-human egg. Only once the egg is fertilised is the human created, at which point it is an embryo, not an egg. By this logic, the human came first, not the egg, and so if we apply the conclusion back into the original question, we get the same answer – the chicken came first.



When approaching the puzzle logically and scientifically, the conclusions are the same – the chicken must have come first, because a chicken egg cannot be created without a chicken, but a chicken can be created by genetic mutations from a pseudo-chicken.

Image courtesy of Rob and Stephanie Levy

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

Due to genetic research, it would apear that the chicken had to come first, in order for a chicken egg to be layed. The chicken came from a pseudo-chicken type creatures egg.