Chicken Or The Egg

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.
• Science
The theory of evolution states that species change over time via mutation and natural 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.