Basically, many, many moons ago there was a chicken-like bird. It was genetically close to a chicken, but wasn’t a full-blown chicken yet. Krulwich calls it a proto-chicken. So proto-hen laid an egg, and proto-rooster fertilized it. But when the genes from ma and pa almost-chicken fused, they combined in a new way, creating a mutation that accidently made the baby different from its parents. Although it would take millennia for the difference to be noticed, that egg was different enough to become the official progenitor of a new species, now known as … the chicken! So in a nutshell (or an eggshell, if you like), two birds that weren’t really chickens created a chicken egg, and hence, we have an answer: The egg came first, and then it hatched a chicken.
