Arithmetic means of triceps ( A,B ) and subscapular skinfolds ( C,D ) of high SES urban and low SES rural Cape Coloured children plotted against the NHANES reference (Frisancho, 1990). 

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... standard deviation) between urban and rural boys and girls. At puberty, differences increase to ∼ 15% (1 sd or more) and remain significant postpubertally. Urban children have somewhat higher pulse rates than rural children both before and after exercise. Differences are small, a few percentage points, and in some age groups insignificant, and disappear after puberty. Grip strength of both hands shows significant differences in favor of urban children in all age classes. These differences often exceed 20% (1 sd or more) and do not disappear after puberty. Differences in grip strength are greater than those in body height and arm circumference. For this reason it seems that correction of grip strength for body size would not reduce the urban- rural differences. The heights and weights of prepubertal children from the urban sample match U.S. data from the National Health and Nutrition Examination Surveys (NHANES) (Frisancho, 1990) (Figs. 2 and 3). After puberty, the means of the urban sample decline and lie between the 50th and 25th percentiles of U.S. data. This is a pattern commonly observed in developing countries. Skinfold thicknesses, however, display a somewhat different picture. The skinfolds of urban children are of similar thickness to those of the American reference, or even, especially at the subscapular site, exceed the reference means (Fig. 4). Mean heights and weights of rural children produce distance curves par- allel to those of urban children, but lying consistently 1–2 standard deviations below, thus roughly paralleling the 5th per- centile of the American data. Skinfolds of rural children, once again, lie well below those of their urban peers. The fact that the skinfolds of the urban children in this study are rather large suggests that the children are growing up in a situation of nutritional adequacy. The differences in height and weight observed between them and American youths can, therefore, hardly be inter- preted in terms of nutritional differences in as much as the quantity of energy is con- cerned. A comparison between measurements of the rural ‘‘Coloured’’ children and rural black children (Cameron and Kgamphe, 1993), namely, body height, weight, skinfold thicknesses, and arm circumference, clearly shows that the Coloured children have similar or slightly greater measurements than rural children from Ubombo and consider- ably greater measurements than children from Vaalwater. The measurements of the urban Coloured children greatly exceed both groups of black children. Comparisons of other characteristics are limited by the relative scarcity of comparative data. Comparisons of studied characteristics of higher and lower SES boys and girls reveal some general patterns. Most SES differences in somatometric characters seem to have similar magnitude of ∼ 1 sd. Differences tend to become larger at puberty and to decline after puberty. This pattern most probably reflects slower growth of lower SES individuals who experience puberty later and take longer to attain adult values. The least affected by SES seems to be head height followed by trunk length, whereas limb length differences are of the magnitude similar to height differences. It follows that different lower limb length is a principal contributor to SES differences in height. Body weight, being the sum of the mass of all tissues of the body, shows the magnitude and age pattern of SES differences similar to other somatometric characteristics. Since the higher SES participants compare rea- sonably well with American data and since the samples were selected for maximum SES contrast, it may be suggested that al- though most somatometric characteristics are significantly diminished by poor SES, the extent of such influence rarely can exceed one standard deviation. Functional characteristics such as grip strength and the time of neuromuscular reaction seem to differ between SES groups more than somatometric variables. Large differences in grip strength and NMRT between the well-off children and the impov- erished ones are more disturbing than differences in their body sizes. A relatively poor physical performance in low SES children seems to persist until late teens and thus will probably be present in adulthood. This poor performance coupled with com- paratively low levels of education in rural children may negatively influence their op- portunities in future roles within the economy, as the majority of them will probably have to be employed in various jobs re- quiring large amounts of physical labour and high levels of manual dexterity, for which rural children may be ill prepared. Longitudinal investigations are still un- derway, and the results will be available only within several years from now. Comparisons between the measurements taken on the first occasion and measurements taken on the last occasion will allow an assessment of whether the socioeconomic changes that have been occurring in South Africa during the present decade have had a positive effect on growth and development of children in the communities studied. Data on the many characteristics measured in this study are not readily available in the literature for such large sample sizes and are virtually nonexistent for South African children. The data presented can, therefore, be used as a starting database against which new studies of growth in this country can be compared. The authors express appreciation for the ongoing enthusiastic co-operation of the schools’ principals, teachers, children, and their parents. Numerous members of measuring teams participated in collection of data; among them special thanks are due to Dr. C.M.R. Warton, Ms E. Hollinshead, D. Constant, K. Mathers, M. St. James, and Messrs D. Abrahams, N. Smidt, C. Pelston, H. Exteen, and I. Adonis. Part of the data analysis was performed during the tenure of M.H. in the Department of Anatomy and Human Biology, University of the Witwatersrand in ...