A new paper in PLoS One suggests that we humans may be afraid of the dark and associate evil goings on with the full moon because that is when lions try to eat us.
Nocturnal carnivores are widely believed to have played an important role in human evolution, driving the need for night-time shelter, the control of fire and our innate fear of darkness. . .African lions are as sensitive to moonlight when hunting humans as when hunting herbivores and that lions are most dangerous to humans when the moon is faint or below the horizon. . .most lion attacks occur in the first weeks following the full moon. . .
Random facts of note from the description of their database, it appears there are about 50 reported attacks on people by lions per year in Tanzania (1000 over 20 years).