A secret women's language: Nüshu, a written language passed on to women in China's Hunan Province, is one of the world's oldest languages--and the only exclusively female language known. Researchers found that the calligraphy has more than 2,000 characters and that "the content of nüshu writings have proved to be revealing about society, history, nationality and culture... It is, however, a written language only. Women formed their own written symbols to represent the words in their local dialect. Hence men can usually understand nüshu if they hear it read aloud." Read more here.