2007 Volume 53 Issue 2 Pages 215-230
In this study an attempt was made to demonstrate the changes in height growth in two recent periods of the Mongols, one of the ethnic groups in China, by comparing the height growth in adolescence in this group in the years 1985 and 2005. Nearly all previous analyses have used growth distance curves, with analysis of the velocity curve based on the difference value in the amount of annual growth. This method may show that young people are becoming larger, but there is no guarantee that this method objectively demonstrates early maturation. The present study applied the wavelet interpolation method proposed by Fujii (2006), and specified the age of maximum peak velocity (MPV) in growth during puberty from the height growth velocity curve. Then, based on age at MPV and annual changes in MPV, early maturation in height growth and time changes in the velocity curve in Chinese Mongols was demonstrated. The data used were height data for Mongols and Han Chinese (boys and girls 7–18 years of age) in the Inner Mongolia Autonomous Region, extracted from national surveys of student physique and health in China conducted in the years 1985 and 2005. The data used for Japan were growth data from the Survey of Physical Strength and Athletic Ability conducted by the Ministry of Education, Culture, Sports, Science and Technology in the years 1985 and 2005. The results did not reveal any marked changes in the growth of Japanese boys and girls between these two periods. However, a tendency for earlier age at MPV was seen in both boys and girls in Han and Mongol Chinese. This tendency was particularly marked in Mongols, and maturity was clearly earlier. The trend in these recent 20 years from 1985 to 2005 in Inner Mongolia is thought to be similar to the past phenomenon of earlier maturation in Japanese that was influenced by high socioeconomic growth. The factors for the change seen in Mongols are assumed to be considerable improvements in recent years in the dietary habits and environment of Mongols in the Inner Mongolia Autonomous Region of China, and improvements in their social and economic environment.
