<P> Up until the time of menstruation, girls are treated as children, and are only responsible for assisting their mothers in household work . When they approach the age of menstruation, they are sought out by males as potential wives . Puberty is not seen as a significant time period with male Yanomami children, but it is considered very important for females . After menstruating for the first time, the girls are expected to leave childhood and enter adulthood, and take on the responsibilities of a grown Yanomami woman . After a young girl gets her period, she is forbidden from showing her genitalia and must keep herself covered with a loincloth . </P> <P> The menstrual cycle of Yanomami women does not occur frequently due to constant nursing or child birthing, and is treated as a very significant occurrence only at this time . </P> <P> Yanomaman languages comprise four main varieties: Ninam, Sanumá, Waiká and Yanomamö . Many local variations and dialects also exist, such that people from different villages cannot always understand each other . Many linguists consider the Yanomaman family to be a language isolate, unrelated to other South American indigenous languages . The origins of the language are obscure . </P> <P> In early anthropological studies the Yanomami culture was described as being permeated with violence . The Yanomami people have a history of acting violently not only towards other tribes, but towards one another . </P>

Members of an ethnic group enter a society in large numbers for the first time