Anthropometric data indicate nutritional homogeneity in Hadza foragers of Tanzania

Abstract

We analyzed body mass index (BMI = wt/height²) and percent body fat (BF%) in adults of the Hadza, an egalitarian society with a strong food-sharing ethic, to examine variation in energetic status in relation to sex, age, and time of year. Data collected from 26 camps over six field seasons gave a cross-sectional sample of 238 males and 235 females and a small longitudinal sample (n = 54). We found that mean BMI showed no sex difference [20.1 ± 1.6 (SD) kg/m² for males and 20.3 ± 2.2 kg/m² for females] and remained similar, regardless of age or time of year. Mean BF% showed a significant sex difference, as expected [10.6 ± 3.2 (SD) % for males and 19.0 ± 7.0% for females (P < 0.0001)], with two significant age departures from uniformity: (1) males in the prime age group (30–45 years, n = 79) had a higher mean BF% (11.7%) compared to other ages (P < 0.03), and (2) females in the extreme elderly age group (> 75 years, n = 11) had a lower mean BF% (11.3%) compared to other ages (P < 0.004). In the longitudinal sample, we found no significant change over time in mean BMI or BF%. However, relative change in BF% fluctuated within individuals by as much as 20% of initial values for both sexes. Taken collectively, our results support the idea of broad nutritional homogeneity among the Hadza, but indicate that subtle, potentially important differences in energetic condition exist as well. Am. J. Hum. Biol. 19:107–118, 2007. © 2006 Wiley-Liss, Inc.