Hunter-gatherer child and adolescent height and tricep skinfold measures

Despite agreement that humans have evolved to be unusually fat primates, adipose patterning among hunter-gatherers has received little empirical consideration. Here we consider the development of adiposity among four contemporary groups of hunter-gatherers, the Aka, Savanna Pumé, Ju’/Hoansi and Agta using multi-level generalized additive mixed modeling (GAMM) to characterize growth of tricep skinfolds from early childhood through adolescence. In contrast to references, hunter-gatherers show several consistent patterns: 1) children are lean with little fat accumulation; 2) no adiposity rebound at 5 years is evident; 3) girls on average build 90% of their body size, and reach menarche when adiposity is at its maximum velocity; 4) a metabolic tradeoff is evident in young, but not older children, such that both boys and girls prioritize skeletal growth during middle childhood, a tradeoff that diminishes during adolescence when height velocity increases in pace with fat accumulation. Consistent results across hunter-gatherers living in diverse environments suggests that these patterns reflect a general forager pattern of development. The findings provide a valuable baseline for adipose development not apparent from reference populations. We emphasize both generalized trends among hunter-gatherers, and that inter-populational differences point to the plasticity with which humans organize growth and development.

Methods
Study Populations

The data include tricep skinfolds and height from four foraging populations: the Savanna Pumé (Venezuela), the Ju/’Hoansi (Nambia), Agta (Philippines), and the Aka (Congo).  These data were collected by independent research teams as part of broad, long-term anthropological research programs. The data collection for these projects were all subject to institutional review boards at the PI’s respective institutions.  The Ju/’Hoansi data come from a publicly available repository at the university of Toronto.

Anthropometric measures

Skinfolds and height were obtained using conventional anthropometric techniques. Tricep skinfolds are a noninvasive measure, and a reliable indicator of children’s nutritional status and overall fat reserves [1,2]. Skinfolds are widely reported in the cross-cultural literature, and the standard for measuring adiposity in remote areas without electricity or medical facilities.  Given Dryad policy of publishing no more than three indirect identifiers, all quantitative variables have been binned into appropriate ranges.

References

1. Sen J, Mondal N, Dey S. 2011 Assessment of the nutritional status of children aged 5–12 years using upper arm composition. Ann Hum Biol 38, 752–759. (doi:10.3109/03014460.2011.610358)

2. Chowdhury SD, Ghosh T. 2009 The upper arm muscle and fat area of Santal children: An evaluation of nutritional status. Acta Paediatrica, International Journal of Paediatrics 98, 103–106. (doi:10.1111/J.1651-2227.2008.01072.X)