The first public showing of the face of the boy pharaoh Tutankhamun, last week, exposed more than cracked, leathery skin and his buckteeth. (Gene Tierney’s overbite was much more fetching.) Archaeologists also detected a new feature, the hint of a Tut smile, transfiguring a regal mummy from antiquity into a human being with emotions perhaps like those of people today. The first reaction of Zahi Hawass, Egypt’s head of antiquities, was unscientific. The face, he said, “has magic; it has mystery; it has beauty.” The search for identifiable affinities, if only a smile, with people long ago may account for...