Chinanews, Beijing, December 10 – Due to the improved living conditions and the change of environment, the starting age of bone development of Chinese youths has become 2-3 years earlier than in the 1960s.The information was disclosed in a research paper on bone age identification of adolecents, written by Professor Zhu Guangyou, who has studied 1,897 young Chinese aged between 11 and 21, from Henan, Zhejiang and Hainan provinces. Zhu took X-ray pictures of the six big joints in their bodies to check the 24 indexes of bone development.Documents show that the closing of epiphysis in the palms started the age around 18 in the 1960s, and the ossification of the connection between the collarbone and sternum of boys started around the age of 18 -20 at that time. The age of the complete closing of the epiphysis of the lilac crest of boys was around 20 – 25.Zhu’s research shows that the age of closing of the epiphysis in the palms of boys today is around 16, and that of girls is around 15. The ossification of the connection between the collarbone and sternum of boys begins as early as they are 15 years old, and the complete closing of the epiphysis of the lilac crest of boys can be found on boys aged around 18.