Historically, many cultures have practiced this form of body modification. In Bali, teeth were filed down because it was thought that the teeth represented anger, jealousy, and other similar negative emotions. The teeth were also sharpened as a rite of passage for adolescents.  Teeth filing was also used by Aborigines for spiritual reasons, as did assorted Vietnamese and Sudanese tribes. In Mayan culture, the teeth were sharpened, and sometimes had designs carved into them, to distinguish those in the upper-classes. Many cultures would sharpen their teeth to imitate animals, such as the Wapare of intertropical Africa, who sharpened their teeth to imitate sharks, as well as kicking out some of the lower teeth during puberty. In Ancient China, a group called Ta-ya Kih-lau ("Kih-lau which beat out their teeth") had every woman about to wed knock out two of her front teeth to "prevent damage to the husband's family." Some cultures have distinctions between which sex does what to their teeth. In the central Congo region, the Upoto tribe has men file only the upper row, and women file both the upper and lower rows.