Environmental stimulation on height: The story from Indonesia.

Background: Since the 19^th century, sexual dimorphism has been known to be sensitive to adverse environmental conditions. Migrants are sensitive to economic and political affluence, and tend to adjust in height towards height of their hosts. We aim to study growth, sexual dimorphism, and height of native and migrant children in three primary schools in Nabire, Papua, Indonesia. Material and Methods 1: Cross-sectional data on height were obtained from 186 children (59 and 56 native Papuan girls and boys, respectively; 38 and 33 trans-migrant girls and boys respectively; who are aged 7.0-7.7 (mean 7.45) years from three primary schools in Nabire, Papua, Indonesia. The Indonesian National Growth Charts were used as references for height. Results 1: With 118.4 cm (SD 6.7) cm, trans-migrant 7-year old boys were almost 3 cm taller compared to their native-age-matched-peers (115.7 cm (5.0 SD) cm, p < 0.05). The case was different among the girls. Trans-migrant girls were not significantly taller than native girls. Material and Method 2: We re-analyzed the height data from over 300,000 infants, children and adolescents, age 0-18 year, from 34 Indonesian provinces. The data were obtained from the latest Indonesian 2013 National Basic Health Survey (NHBS), and have previously been used to construct National Indonesian Growth Charts. St. Nicolas House Analysis was used to translate correlation matrices into network graphs and visualizing chains of associations between parameters that were multiply correlated. Results 2: St. Nicolas House Analysis suggested that the growth of male sex were more sensitive to population crowding, and that crowding contributes to the greater height dimorphism in taller populations. Conclusion: Economic prosperity and increased population density stimulate male adult height to a greater extent than female adult height, and increase the sexual dimorphism in height among the tall populations of densely populated wealthy countries.