The chicken. Several thousand years B.C. (Before Chickens) all we had was proto-chickens. Eventually one of these chicken ancestors laid an egg, and the first chicken hatched from it. All the proto-chickens before that laid proto-chicken eggs, so the chicken came first. Of course if you believe that chickens were created by some force, then it would be easiest and most efficient for this force to create a chicken first, rather than sit on the first egg itself. Either way it looks like the chicken has it.