Data on sex differences in mortality, morbidity, growth under conditions of environmental stress, and growth responses to environmental improvement are reviewed to test the hypothesis that males are less buffered than females against the environment during growth and development. The hypothesis predicts that males should be more affected by environmental stress, and the strongest support for this is found in studies of the prenatal period. Under stressful conditions, males have higher late fetal mortality than females, and their fetal growth generally has been found to be more retarded. Investigations of postnatal responses to environmental stress have yielded much less consistent results, in large part because of the fact that male children are given preferential treatment in many societies.

As shown in 56 human embryos and fetuses between 15 and 104 mm in crown-rump length, "adult" metacarpal-phalangeal length rankings are attained by the seventh intrauterine week and near-adult bone-to-bone ratios or proportions by the theirteenth week. Micrometric measurements of optically-projected histological hand sections show relative elongation of the distals between the 15-29 mm and 30-44 mm crown-rump range, and relative reduction to radiogrammetrically-determined adult proportions by the 90-104 mm CRL.

The physical growth of middle to upper class children of primarily European ancestry attending the private French School in L Paz, Bolivia is described and analyzed to determine how high altitude affects growth in this group of children. The sample consists of 323 children, most between the ages of 8 and 14, who reside at altitudes between 3200 and 3600 meters, but who have spent different amounts of time at high altitude. Comparisons between children who differ in their exposure to high altitude, and comparisons between French School children and other samples of high and low altitude children were used to assess the effect of high altitude on growth. Children who had lived all their lives at high altitude were found to be smaller in terms of general body size than those who had spent the shortest amount of time at high altitude, confirming the results of previous investigations of child growth in the Andes. Most studies of indigenous Andean populations have found that chest dimensions relative to stature increase with altitude, but it is not clear that this same trend exists in Bolivian French School children. Although exposure to high altitude does affect the growth of French School children, their height is essentially the same as that of Guatemalan children of high socioeconomic status. Within the age range studied, the effect of high altitude is small relative to that of other environmental factors and genetic factors, even in these children of high socioeconomic status.

Available information on mean adult male and female height, weight, sitting height, and relative sitting height for 62 groups is used to examine the relationship between anthropometric measurements and climate, geographical location, and linguistic affiliation among South American Indians. Results of correlation analysis indicate that height increases from the north to the south of the continent and is significantly negatively correlated with precipitation but is not significantly correlated with most measures of temperature. Only in females is weight significantly correlated with any of the location or climatic variables. Sitting height is correlated with both temperature and precipitation, while relative sitting height is more strongly correlated with temperature, and the direction of the correlation indicates that groups living in colder areas have relatively shorter legs. The interpretation of the correlations for sitting height and relative sitting height is complicated by the fact that the correlations of these measurements change when only the low-altitude groups in the data set are considered. There are no significant differences in male height between linguistic stocks when the analysis is limited to those stocks represented by at least five groups. In general, there appears to be more patterning in body size and shape variation in South America than there is in terms of genetic variation. The correlations between anthropometric measurements and climate in South America differ in some ways from those observed for other areas of the world.

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