The modern chicken was believed to have descended from another closely related species of birds, the red junglefowl, but recently discovered genetic evidence suggests that the modern domestic chicken is a hybrid descendant of both the red junglefowl and the grey junglefowl. Assuming the evidence bears out, a hybrid is a compelling scenario that the chicken egg, based on the second definition, came before the chicken.

This implies that the egg existed long before the chicken, but that the chicken egg did not exist until an arbitrary threshold was crossed that differentiates a modern chicken from its ancestors. Since this arbitrary distinction cannot be made until after the egg has hatched, one would have to first find the original chicken, then from this find the first egg it laid.