Limb proportions in South Africans : secular changes population differences and implications for stature estimation

Abstract

In order to provide accurate methods for stature estimations, ancestry differences and secular changes in stature and limb proportions need to be noted. Stature and limb proportion changes in human population groups are influenced by various genetic and environmental factors. The purpose of this study was to evaluate ancestry differences and secular changes in stature and limb proportions of South African population groups and to assess how these variables differ between individuals from southern and northern hemispheres. The sample comprised of osteometric and anthropometric data from modern black and white South Africans (17 and 68 years), North American and white European (Dutch and Swiss) populations. The sample was divided into birth cohorts of 5 years or 10 years to observe secular trends. Ancestry differences and secular trends in stature and limb proportions between South African population groups were compared. Also, differences and secular trends in stature and limb proportions were compared between white North American and European groups to determine whether differences exist between the southern and northern hemisphere groups. Additionally, the differences in stature between black and white South African and North American groups were compared. It was found that white South Africans were significantly taller than their black South African counterparts. Significant positive secular trends in stature were observed in black South African males while non-significant increases were observed in white South African males and white and black South African females. The secular trends in European samples are significantly greater than those observed in white South African males. Black South African groups had greater limb and distal limb lengths than white South African groups. Proximal limb ratios increased while the distal limb ratios decreased which suggests that regression formulae to estimate stature need to be regularly updated. The upper limb ratio and arm ratios were significantly higher in white South African groups compared to white North American groups. Secular changes are constantly taking place due to a combination of various factors such as climate, nutrition. Overall, secular changes in limb proportions indicate a trend where South African groups are becoming more similar to each other.