One should note that the question of who was first, the chicken or the egg, was considered purely philosophical. However, at least in a literal reading, the issue can be considered relatively resolved today. According to current paleontological data, the first oviparous animals were early amniotes that appeared at the end of the Carboniferous period. Many millions of years later, birds are separated from their dinosaur ancestors as far back as the Mesozoic era.
If the answer to the question is relatively unambiguous in such a literal reading, it can have many more nuances in other senses. What if it is supposed to be the question, «what came first, the first chicken or the first chicken’s egg»? In this case, it would be logical to turn to Darwinian evolution. There was once a particular population of direct ancestors of chickens, which could be called proto-chickens. The population gradually accumulated genetic changes, and in the end, one of the proto-chickens laid an egg from which a real chicken hatched.
Nevertheless, at each moment, the new generation belonged to the same species as the ancestral one. In particular, the importance and significance of Hox genes are directly related to the development of the animal’s body (Larsen 69). In other words, there can be no egg without a chicken due to genes controlling the structure and functions of organisms. Genetics and genomics suggest that an organism lives as a single cell and a zygote that creates identical copies (Larsen 59). Mitosis is a necessary process that most vividly explains the essence of live birth and the origin of chickens.
However, from a paleontological perspective, the accumulated changes led to the formation of new species. Biology species are not discrete; in the course of evolution, they smoothly flow from one to another. Thus, the “first” chicken never existed, just as the last one will never exist unless, of course, they die out.
The philosophical dilemma of the primacy of the chicken or the egg is essentially the paradox of Theseus’ ship. If somebody gradually replaces all the boards on the ship, will it still be the same ship? Furthermore, if not, at what point does the old ship cease to exist and a new one form? The answer to the primacy of a chicken or an egg directly depends on the preferred solution to the paradox of Theseus’ ship. Suppose that after the reconstruction, it is still the same ship. In this case, all the ancestors of chickens from the beginning of life, as well as all their subsequent descendants, should be considered chickens.
In this case, chickens appeared earlier because, historically, egg-laying arose at some point when life had already existed for quite a long time. However, people must come to terms with the fact that a bunch of molecules and a modern chicken are the same, which is not. For instance, if a ship is two different ships at different times, it is worth deciding at what point the ship becomes new.
Work Cited
Larsen, Clark Spencer. Essentials of Biological Anthropology. 5th ed., W. W. Norton & Company, 2021.