一 20世纪初以来,由于青少年研究工作者们孜孜不倦的努力,青少年研究状况发生了重大的改观,青少年作为一类社会实体日益得到了承认并获得了相对稳定的地位。当然,这种发展与改观是同社会、经济、文化的高速度发展分不开的。正是由于社会经济、文化的高度发展,世界青少年普遍出现了性发育早熟的趋势。据世界卫生组织调查,欧洲女孩子月经初潮从19世纪中叶的16、17岁,在20世纪中叶提前到12—13岁。中国科学院遗传研究所80年代初期的调查表明:我国大城市女孩初潮平均年龄为12.8岁,80％城市男孩15.6岁出现遗 Since the early 20th century, with the tireless efforts of young researchers, the status of adolescent research has undergone major changes. As a social entity, adolescents have been increasingly recognized and relatively stable. Of course, such development and improvement are inseparable from the rapid development of society, economy and culture. It is precisely because of the high development of society, economy and culture that young people in the world generally have the tendency of sexual precocity. According to the World Health Organization survey, European girls menarche from the mid-19th century, 16,17 years old, early in the middle of the 20th century to 12-13 years old. According to a survey conducted by the Institute of Genetics of Chinese Academy of Sciences in the early 1980s, the average age of males in big cities in China was 12.8 years old, while that of 80% of urban boys was 15.6 years old