Dogs are believed to be the earliest creatures domesticated by humans, and the central role they played in many ancient cultures has led to their depiction in a variety of forms. In Ancient Greek and Roman societies, they were kept as pets, as well as being used for household security, hunting, and even military combat. In Ancient Egypt, the god Anubis is often depicted as having the head of a jackal, and was believed to oversee the embalming process and the passage of souls to the underworld.