Scientists resolve the eternal debate about the chicken and the egg

Paleontologists and biologists have explained why in the age-old debate about the chicken and the egg, the egg came first. Eggs appeared long before birds, and the first chicken hatched from an egg laid by birds that were not fully chickens. Evolutionary biology provides a concrete answer.

Paleontologists and biologists have resolved the age-old debate about the chicken and the egg, concluding that the egg came first. Eggs as a form of reproduction existed on Earth hundreds of millions of years ago, long before the appearance of birds and certainly before domestic chickens. The first chicken did not arise suddenly—it was the result of a long process of evolution and domestication of the red junglefowl. At some point, two birds that were not yet modern chickens produced offspring, and in one of the eggs, a combination of genetic changes occurred from which the first true chicken hatched. Thus, the chicken came from an egg laid by birds that were not fully chickens. From an evolutionary perspective, the boundary between ancestor and new species is conditional, but the egg is in any case first.