Which came first?

I took the kiddos to see the chicks at the feed store this morning, and they all enjoyed it. Then, later in the day Kyle was eating a hard boiled egg and we started talking about what eggs are and where they come from. Completely on her own, Abby brought up the "Which came first, the chicken or the egg?" question. I could see the wheels turning. I thought it was pretty impressive to be coming from a 5 year old.