Comments on Mpeta et al. (2018) : black living standards in South Africa before democracy

Abstract

Mpeta et al. recently published a paper in which they used secular trends in stature of South Africans to make inferences about living standards. The use of documentation of living standards and the fluctuations thereof as a result of economic growth to explain the secular changes observed in height is a viable approach. The authors gave an excellent review of the history of South Africa and the differences in living conditions that existed between the population groups. However, we believe the biological data were incorrectly used, in order to support inferences regarding the socio-economic situation. The average stature of a population group indeed has a direct relationship with the living conditions and the per capita income of the individuals. For example, decreased stature may be an indicator of nutritional deprivation as a result of a lower income. However, it is important to note that there are many other factors that can influence stature. The size and shape of human bodies vary considerably among population groups across the world and body size is not fixed. Changes in height are continually taking place. In this study the authors repeatedly imply that the living standards can be explained by differences and changes in height, e.g. ‘by analysing the mean height…, we shed light on the standard of living’ (p. 1); ‘black living standards as measured by height’ (p. 1). Height should not be used simplistically to indicate the standard of living or socioeconomic status as it is influenced by too many other variables such as climate, diet, genetics/gene flow, family size and urbanisation. Rather, standard of living should be used, as one of many possible factors, to explain the observed differences in height.