This study describes the hemoglobin concentration ([Hb]) and hematocrit (HCT) of over 1,000 Tibetan and Han children, adolescents, and young adults who were born and raised at 3,200 m, 3,800 m, or 4,300 m in Qinghai Province, western China. At 3,200 m, no altitude effect is evident in the hematological characteristics of either group. At 3,800 m and 4,300 m, both groups show [Hb] and HCT values that are above low-altitude norms. At both altitudes, Tibetan and Han children show no differences in the pattern of hematological response up to age 13. Among adolescents and young adults, however, the [Hb] and HCT of Han males and females are elevated compared to Tibetans. This indicates that the adolescent period may involve a divergence in the responses to hypoxia made by some individuals in these two groups. Also, many other adolescents and young adults in both groups show similar hematological characteristics, indicating that many Tibetans and Han share similar hematological responses to hypoxia.

Although genetic similarities cannot be ruled out, comparable dietary stress is a likely explanation for the similar and slow morphological growth of Han and Tibetans at high altitude. However, Han-Tibetan differences in thorax dimensions are likely a consequence of population (genetic) differences in the response to hypoxia during growth.

This study compares the stature, weight, skinfolds, upper arm muscle area, and chest dimensions of Tibetan children, adolescents, and young adults who were born and raised, or who had lived from infancy, at 3,200 m, 3,800 m, and 4,300 m in Qinghai Province, People's Republic of China. While the individuals measured in Qinghai are among the tallest and heaviest Tibetans reported in the literature, they are nevertheless smaller and lighter than well-off children living at low altitude. The pattern of size variation among Tibetan males and females measured at the three high altitudes, along with evidence of a secular trend at 4,300 m, suggests that nutrition may significantly effect growth at high altitude. Only minor differences in thorax dimensions exist between Tibetan males and females measured at 3,200 m and 3,800 m. However, Tibetan males at 4,300 m possess slightly narrower and deeper chests (during and after adolescence) than males at 3,200 m and 3,800 m. Since individuals from 3,800 m and 4,300 m belong to the same local populations, this characteristic is unlikely to be genetically determined. However, it may be related to differences in the degree of hypoxia or to the influences of other environmental conditions.

This study compares the morphological characteristics of Han children, adolescents, and young adults who were born at 250 m near Beijing and at three high altitudes in Qinghai Province, Peoples Republic of China (3,200 m, 3,800 m, and 4,300 m). From ages 6 through 15, Han children growing up at high altitudes are significantly shorter, lighter, have less fat, and are less muscular than Han children growing up at low altitude. However, older adolescents and young adults show no such altitude differences. Younger adolescents and children in this study were all born after the government economic reforms of 1978. These reforms had a greater impact on the growth of children in and around large cities than on those in more remote areas. Therefore, the altitude differences in size among Han children ages 15 and younger may be a consequence of regional variation in health and nutrition, rather than due to the influence of hypoxia. There are no altitude-related differences in thorax dimensions among Han children, adolescents, or young adults. This suggests that hypoxia does not affect the thorax growth of Han children. Am. J. Hum. Biol. 12:665-681, 2000. Copyright 2000 Wiley-Liss, Inc.

Forced vital capacity (FVC), forced expiratory volume at 1 second (FEV(1)), and FEV(1)/FVC ratios were determined for 531 individuals of Han Chinese descent living at low altitude (250 m) near Beijing and for 592 individuals of Han descent who were born and raised at three high altitudes (3,200 m, 3,800 m, 4,300 m) in Qinghai Province, P.R.C. The study included males and females, ages 6-51 years. Thorax widths, depths, and circumferences of Han females and males born and raised at high altitude are similar to those of low-altitude Han. On the other hand, high-altitude children and adolescents have larger relative sitting heights, indicating greater thorax lengths. After adjusting for this variation in morphology, mean FVC values among 6-21 year-old Han at high altitude are only between 136 mL (for females) and 173 ml (for males) greater than those determined at low altitude but the differences are statistically significant and are maintained consistently throughout the growth period. These data indicate that growth at high altitude produces small-to-moderate increases in lung volumes (about 6%) relative to genetically similar groups growing up at low altitude. In addition, there is no evidence that lung volume growth is accelerated relative to morphological growth among Han children born and raised at high altitude. Adults, 22-51 years, also show greater FVC values at high altitude but the size of the increase relative to Han at low altitude is variable (3% in males and 11% in females). Greater lung function at high altitude is unlikely to result from increased activity or lower pollution, and thus appears to be primarily a result of development in a hypoxic environment. Differences in FVC and FEV(1) at 3,200 m, 3,800 m, and 4,300 m are generally not significant, so that living at altitudes between 3,200 m and 4,300 m appears to have little additional effect on volumetric growth.