This ancient riddle has plagued countless sufferers into the mind numbing cycle of ” the egg came from chicken…but the chicken came from an egg…but the egg was laid by a chicken…ughhh”. With a little help of modern day biology this seemingly never ending question can finally be cracked open.
From an evolutionary prospective the egg predates the chicken. Animals like turtles and alligator and even dinosaur birds have been laying eggs long before there were even chickens clucking around on this earth. But that is a cop out. The question that everyone is really trying to answer is which came first, the chicken or the chicken egg.
A good place to begin is with the chicken egg itself. To produce a chicken egg there needs to be the protein OV-17 (ovocledidin-17). This protein is necessary in the formation of the specialized hard egg shell which protects the delicate yolk and fluids while the chick grows inside. Chicken ovaries are the only place this protein occurs in nature. From this it appears there needs to be chicken ovaries–ergo a whole chicken–in order to produce the chicken egg. Looks like a win for the chicken…but not so quick.
Through DNA replication and fertilization there are many possibilities for not only variations but mutations, as we have been learning in class. These small changes play a role in natural selection. As Darwin stated, individuals with favorable DNA will live long enough to reproduce and provide this DNA to its offspring. Over thousands of generations, this passing down process leads to the evolution of new features and eventually an all new species.
Using this, scientists infer that a creature very similar to a chicken mated with another creature with similar genetic make up as a chicken. These two almost-chicken creatures created a zygote with a mutation. The mutant zygote was then, in reality, the first chicken. This first chicken, though, had to come from an egg. So after all it looks like the egg really did come first.
That being said, no single fertilization event can create a whole new species. It was not like “Bam! Now there is a chicken”. Evolution is such a gradual process that it was over many generations of chicken-like species reproducing that simply evolved into what we now know as the common chicken. Dr Colin Freeman, from Sheffield University’s Department of Engineering Materials, even noted, “It’s very interesting to find that different types of avian species seem to have a variation of [OV-17] that does the same job”, implying that many egg laying creatures could share the same ancestor since they have similar chemical processes.
So in a nutshell (or an eggshell), two birds that were not really chickens created a chicken egg, and hence, there was an egg laid first, and then a chicken was hatched.
But so what? The answer to this seemingly juvenile question has actually been a significant discovery and is being put to real use. Professor John Harding from Sheffield University’s Department of Engineering Materials, explained, “Understanding how chickens make egg shells is fascinating in itself but can also give clues towards designing new materials and processes… Nature has found innovative solutions that work for all kinds of problems in materials science and technology”.
Enjoy this video about the topic: