A simple question that almost all of us are familiar with. But who has actually spent more than a few seconds of thought trying to work out this conundrum. Most will probably get a headache after a few iterations of the chicken-egg cycle and truth be told this is a very interesting concept indeed. I'm going to work specifically on the 'chicken' and 'egg' problem and I'm not going to tackle any of the more philosophical notions like: "If X depends on Y and Y depends on X, X is different from Y and they can not happen simultaneously. Thus, which came first, X or Y?"
I started to think about this during class, I can't remember what was the subject of discussion, but the teacher said "it's like the old chicken and egg question..." to which I replied with a proud tone in my voice: "It was the egg! The egg came first!". My colleagues, hearing this, instinctively adopted the opposite belief. I held a quick argument with them that evening but not much to show for. It was the day after that I elaborated and refined the proof for which the egg came first.
For those of you that are simply searching the internet for a answer to this question my opinion is this: The egg came first. Now for the proof:
Suppose that chickens evolved from reptiles (could have been dinosaurs for all I care) and that the only distinction between a bird and a reptile is the existence of feathers (the proof accepts further differentiation, but for the sake of simplicity let's just use feathers). Now, the reptiles were living happily when a mutation occurred and they started developing feathers. At first, this is called a mutation because the evolving feathers don't provide a sufficient increase in survival chances. So in the course of millions of years there were reptiles with feathers and reptiles without them (i.e. some generations had feathers and others didn't). Now suppose that we define a chicken to be the animal coated with feathers after 1000 consecutive generations of feather-bearing reptiles. We do this in order to eliminate the possibility of mutations: the fact that even then, individuals still have feathers means that they have an increased survival chance compared to their feather-less cousins. Ok, so the 999th egg is laid and a reptile with feathers comes out, that reptile in turn lays the 1000th egg. From that egg a chicken hatches (being the individual that corresponds to our definition). So, basically the first chicken appeared from an egg, and thus the egg was first.
Good, now you might consider our definition: the 1000th member with feathers, the idea is to strictly define the difference between a chicken and a reptile. You can use any definition you like, it's fundamental property is to classify all of the egg-laying animals into two categories: chickens and non-chickens. Once you have that it is easy to rebuild the proof.
So there you go, proof that the egg came before the chicken. I came up with this in the course of an evening, about a week ago. The big surprise came then I searched the internet today and found that I was right: according to evolution, the egg DID in fact come first.