The answer to the question "Which came first, the chicken or the egg?" depends on the perspective taken—philosophical, evolutionary, or scientific. From an evolutionary biology standpoint, the egg came first. Eggs, as a reproductive structure, existed long before chickens evolved. The first amniote eggs appeared around 312 million years ago, while chickens as a species emerged only about 8,000 to 10,000 years ago through domestication and evolutionary changes in wild jungle fowl ancestors. The first true chicken likely hatched from an egg laid by a proto-chicken that was not exactly a modern chicken but very close genetically. Hence, the "chicken egg" in the genetic sense came before the chicken itself.
From a scientific protein-formation perspective, some argue the chicken came first because a protein essential for forming the hard shell of a chicken egg (ovocleidin-17) is produced only by hens. This suggests the first modern chicken to produce this protein laid the first true "chicken egg".
Philosophically, the question is an ancient paradox about cause and effect without a clear starting point, often illustrative of infinite regress or circular causality, with thinkers like Aristotle describing it as an infinite sequence.
In summary, biologically and evolutionarily, the egg (in general and the chicken egg specifically) came before the chicken, but some scientific views highlight the critical role of the chicken itself in forming the egg. Philosophically, the question highlights a causality dilemma that may not have a simple answer.
