There is still considerable skepticism regarding my conclusion that the chicken comes first. Many of the objections are simply due to different interpretations of the question, interpretations which I consider unfaithful to the original purpose of the chicken-egg dilemma.
Fundamentally, this question is supposed to represent a causality dilemma. When there is a causal dependency between any two objects, A and B, we can ask ourselves, "which came first, A or B?" An object C could have caused B, and thus triggered the recursive relation C→B→A→B→A... Of course, it could just as easily have been A that was caused first.
To properly answer this question, we must reduce the abstract objects A and B to concrete objects and apply our scientific knowledge to ground the recursion. Using chickens and eggs as our objects, we have to precisely define what chickens and what eggs to consider.
The question "which came first, chickens or any type of egg?" is not a causal dilemma at all, and further is not faithful to the original purpose of the question. The ancient Greeks that first posed this question had no concept of evolution and no inkling that chickens could have any relationship to other egg types, so they would not have asked, "which came first, the chicken or the fish egg?" To the ancient Greeks, such a question isn't a dilemma, it's complete nonsense. Thus, the paper linked in my last post is invalid.
The more precise and faithful phrasing of the dilemma is, "which came first, the chicken or the chicken egg?", or more generally, "which came first, species Sn or it's reproductive mechanism Rn?"
Sn and Rn are in the appropriate recursive relation to form a causal dilemma, and we can ground it in biology and chemistry. The very first single-celled organism did not form by mitosis, thus the first single-celled organism, S∅ preceded its own reproduction mechanism, R∅. Thus, the dominoes fall, ie. the first egg-laying species was not hatched from an egg, thus it too preceded its own reproductive mechanism, and so on, ad infinitum.
Eventually, we reach chickens and chicken eggs, and the conclusion is simply, that the chicken necessarily came before its egg.