Evolutionary mutation occurred in a fertilized egg laid by a proto-chicken, so the first true chicken emerged from an egg before chickens existed as a species. In the broader biological sense, eggs also predate chickens by hundreds of millions of years.

CURRENT STATE

The evidence overwhelmingly supports the evolutionary-biology answer that the egg came first: amniotic eggs appeared about 312–340 million years ago, while chickens evolved far later from red junglefowl through domestication and genetic change. The OC-17 argument supports 'chicken first' only if the question is narrowly defined as a fully formed chicken laying a chicken eggshell, but other evidence states the first chicken hatched from an egg laid by a non-chicken ancestor.

Have your own question?