Like other hunter-gatherers, Hadza are quite short. They are not particularly thin; men are quite muscular (Photograph 16.1), and most women have substantial subcutaneous fat. Adult Hadza women (aged 18–60) were 150.7 cm tall and weighed 46 kg on average. Men (aged 20–60) were 160.6 cm tall and weighed 51.3 kg. Body mass index (BMI) (kg/m2) is widely used to assess obesity, and international reference standards have been publicized. Only three Hadza met the Centers for Disease Control and Prevention (CDC) criterion for “overweight,” and Hadza are not excessively thin (Figure 16.1).

Hadza children are small but very active. Jelliffe et al. (1962) continued the earlier quote, “… in particular, the syndromes of kwashiorkor and nutritional marasmus, rickets, infantile scurvy, and vitamin B deficiency syndromes were not seen.” Some might argue that this was because the sick could not endure the harsh forager life long enough to be observed in a brief visit. However, Jeliffe also noted the balanced diet on which Hadza children are raised. The broad patterns of development are similar to those anywhere. Chubby babies and toddlers (Photograph 16.2) grow into active and skinny “stick people” in middle childhood (Photographs 16.3, 16.4), and in the mid- to late teenage years are transformed into shapely young women and muscular young men. My data show general features of Hadza size and growth in close agreement with the descriptions of independently collected data by Marlowe (2010, pp. 141–149, table 6.1). Many aspects of Hadza growth could be explored with our data, perhaps best in combination with Lars Smith's data from 1977, and Frank Marlowe's from 1995 to 2010.

Here I primarily direct my attention to growth as another dependent variable, as a possible proxy for fitness. Height, weight, and upper arm circumference are commonly predictors of mortality and morbidity, and thus are possible proxies for fitness of the measured individual. In later chapters, I look for effects of helpers on growth as a reflection of the help children are receiving. Growth is likely to be a more sensitive measure than mortality. There are several reasons for treating the under-five-year-olds as special targets of helpers. I have shown in Chapter 12 that their survival is especially significant to population growth (and to natural selection).