In the cemetery of Egypt's earliest rulers, archaeologists were shocked to find the carefully buried corpses of baboons, jackals, leopards and even a hippopotamus. Forensic evidence shows these animals were not native to Egypt, and were captured at faraway locations. Why did these ancient Egyptians treat these animals like honored guests, even burying them with the royal family? New revelations show that this "world's first zoo" may have been the foundation for the ancient Egyptian religion – and the source of Egypt's mysterious animal-headed gods.