The chicken or the egg causality dilemma is commonly stated as "which came first, the chicken or the egg?" To ancient philosophers, the question about the first chicken or egg also evoked the questions of how life and the universe in general began.
Cultural references to the chicken and egg intend to point out the futility of identifying the first case of a circular cause and consequence. It could be considered that in this approach lies the most fundamental nature of the question. A literal answer is somewhat obvious, as egg-laying species pre-date the existence of chickens. However, the metaphorical view sets a metaphysical ground to the dilemma. To better understand its metaphorical meaning, the question could be reformulated as: "Which came first, X that can't come without Y, or Y that can't come without X?"
An equivalent situation arises in engineering and science known as circular reference, in which a parameter is required to calculate that parameter itself. Examples are Van der Waals equation and the famous Colebrook equation.
History of the dilemma
A chick hatching from an egg
Ancient references to the dilemma are found in the writings of classical philosophers. Their writings indicate that the proposed problem was perplexing to them and was commonly discussed by others of their time as well.
Aristotle (384–322 BC) was puzzled by the idea that there could be a first bird or egg and concluded that both the bird and egg must have always existed:
If there has been a first man he must have been born without father or mother – which is repugnant to nature. For there could not have been a first egg to give a beginning to birds, or there should have been a first bird which gave a beginning to eggs; for a bird comes from an egg.
The same he held good for all species, believing, with Plato, that everything before it appeared on earth had first its being in spirit."
Plutarch (46–126 AD) referred to a hen rather than simply a bird. In volume 8 of the Moralia, in the books entitled Table-talk, Plutarch discussed a series of arguments based on questions posed in a symposium. Under the section entitled "Whether the hen or the egg came first", the discussion is introduced in such a way suggesting that the origin of the dilemma was even older:
...the problem about the egg and the hen, which of them came first, was dragged into our talk, a difficult problem which gives investigators much trouble. And Sulla my comrade said that with a small problem, as with a tool, we were rocking loose a great and heavy one, that of the creation of the world..."
Macrobius (395–423 AD), a Roman philosopher, found the problem to be interesting:
You jest about what you suppose to be a triviality, in asking whether the hen came first from an egg or the egg from a hen, but the point should be regarded as one of importance, one worthy of discussion, and careful discussion at that."
Stephen Hawking and Christopher Langan argue that the egg came before the chicken, though the real importance of the question has faded since Darwin's On the Origin of Species and the accompanying Theory of Evolution, under which the egg must have come first, assuming the question intended the egg to mean an egg in general or an egg that hatches into a chicken.[7][8]
Responses to the dilemma
Proteins
Professor Mark Rodger and Dr David Quigley, from the University of Warwick, who helped develop a recent study with colleagues from Sheffield University, point out that in fact a key chicken protein, ovocleidin-17, which helps in the formation of the egg's hard shell, actually comes both before and after the egg shell. They say that this chemical quirk actually makes the question of which came first even more pointless than before. As Professor Mark Rodger says "Does this really prove the chicken came before the egg? Well this actually further underlines that it's a fun but pointless question. This science does however give new insight into an efficient and fast method of crystallisation. It will help in research to devise better synthetic bone and research into how to store/sequester CO2 as limestone."
However, this may contradict a previous analysis which came to another conclusion. Professor John Brookfield and Professor David Papineau argue since there was "first" chicken, it must have come from an egg which pre-dated that chicken. Biologist PZ Myers points out a further flaw in this argument, in that other birds make use of different kinds of proteins for producing eggs, and that the evolution of ovocleidin was not coincident with the evolution of eggs; ovocleidin developed from prior proteins, which were used to form eggs since before birds branched away evolutionarily from reptiles.
Mathematical
An alternative solution utilizing Granger causality was proposed by Thurman and Fisher. In their paper, they examined US egg production and chicken population from 1930 to 1983. Granger causality looks to see if data in one time series can predict data in another time series. By looking at the annual number of eggs produced, and comparing it with the total number of chickens, Thurman and Fisher sought to see if the chicken population predicted the number of eggs laid, or if the number of eggs predicted the chicken population, or both. It was found that information present in the egg time series predicted the number of chickens, but there was no reciprocal prediction of the number of eggs from the number of chickens. Thurman and Fisher conclude that the egg came first.
Evolution
Darwin's theory of evolution states that species change over time via mutation and selection. Since DNA can be modified only before birth, a mutation must have taken place at conception or within an egg such that an animal similar to a chicken, but not a chicken, laid the first chicken egg. In this light, both the egg and the chicken evolved simultaneously from birds that were not chickens and did not lay chicken eggs but gradually became more and more like chickens over time.
However, a mutation in one individual is not normally considered a new species. A speciation event involves the separation of one population from its parent population, so that interbreeding ceases; this is the process whereby domesticated animals are genetically separated from their wild forebears. The whole separated group can then be recognized as a new species.
The modern chicken was believed to have descended from another closely related species of birds, the red junglefowl, but recently discovered genetic evidence suggests that the modern domestic chicken is a hybrid descendant of both the red junglefowl and the grey junglefowl. Assuming the evidence bears out, a hybrid is a compelling scenario that the chicken egg, based on the second definition, came before the chicken.
Theology
Judeo-Christian writings indicate God's creation of birds along with the rest of the universe. The Judeo-Christian story of creation describes God creating birds, and commanding them to multiply, but makes no direct mention of eggs. According to Genesis 1:
19 And the evening and the morning were the fourth day. 20 And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven. 21 And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good. 22 And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth.
A literal historic account of Genesis would place the chicken before the egg.
In Hindu writings, creation of birds (and other life forms) by God through superhuman beings is stated in Purāṇas and Dharmaśāstras. However, if one broadens one's definition of "an egg" to include non-chicken egg, the Hindu mythology also mentions a "cosmic egg" from which the universe as known to humans originated. In this sense this supreme egg comes before all creatures, including chickens and chicken eggs. This egg is known as Brahmanda: "Brahma: creator" and "anda": egg. The primordial egg is also depicted as a Lingam.
Cyclical view of time
In Buddhism there is the belief of the wheel of time which regards time as cyclical and with repeating ages, as some other cultures such as Mesoamerican (Aztecs, Mayan) and some native American Indians believe. Their idea of time gives a different answer to the question of "who is first" when combined with the concept of eternal return which is well known in the Western culture through the writings of Nietzsche. The assumption is that time is eternally repetitive and therefore, there is no "first" in eternity, there is no creation. The answer then becomes: None is first. There is no "first" in a cyclical view of time.
Definition of the chicken egg
An overlooked method of approaching the question is to base the answer from the definition of the chicken egg. Is the chicken egg an egg that was directly laid by a chicken, or an egg that resulted directly in the birth of a chicken (chick)? Consequently by definition, according to the former, the chicken came first. If however, the definition was based on the latter, then the chicken egg came first. However, it would seem that this method attempts to answer a slightly different question than the one posed by philosophers, as the former attempts to determine whether a certain egg came before or after a chicken, while the latter attempts to determine whether eggs universally came before chickens, or vice versa.
