The egg. The egg that hatched the first chicken. 😉
Hi Sirius. Evolution is a gradual process, that comes about through the slow accumulation of mutations. In the past there will have been chicken-like birds that we wouldn’t quite call “chickens”, but at some point, completely at random, one of these birds’ eggs will get a mutation that takes the offspring from “almost chicken”, to “actual chicken”.
But the egg needs to come first.
I know its controversial but hear me out. Could it be that the mutation happened in the chick, perhaps causing it to grow the red wobbly thing under the chickens mouth, thus turning it into a true chicken? I know there is zero evidence for this but it could be possible 🙂