This study investigates variation in body growth (cross-sectional height and weight velocity) among a sample of 22 small-scale societies. Considerable variation in growth exists among hunter-gatherers that overlaps heavily with growth trajectories present in groups focusing more on horticulture. Intergroup variation tends to track environmental conditions, with societies under more favorable conditions displaying faster growth and earlier puberty. In addition, faster/earlier development in females is correlated with higher mortality. For example, African "Pygmies," Philippine "Negritos," and the Hiwi of Venezuela are characterized by relatively fast child-juvenile growth for their adult body size (used as a proxy for energetic availability). In these societies, subadult survival is low, and puberty, menarche, and first reproduction are relatively early (given their adult body size), suggesting selective pressure for accelerated development in the face of higher mortality. In sum, the origin and maintenance of different human ontogenies may require explanations invoking both environmental constraints and selective pressures.

The Yanomamo Indians are an unacculturated tribe inhabiting the tropical equatorial rain forest of northern Brazil and southern Venezuela who do not use salt in their diet. The group therefore presented an unusual opportunity to study the hormonal regulation of sodium metabolism in a culture with life-long extreme restriction of dietary sodium, with parallel observations on blood pressure. Blood pressures increased from the first to second decade but, in constrast to civilized populations, do not systematically increase during subsequent years of life. In twenty-four hour urine collections on adult male Indians, excretion of sodium averaged only 1 plus or minus 1.5 (SD) mEq. Simultaneous plasma renin activities were elevated and comparable to those of civilized subjects placed for brief periods on 10 mEq sodium diets. Similarly, excretion rates of aldosterone equaled those of acculturated subjects on low sodium diets. The findings suggest that the hormonal adjustments to life-long low sodium intakes are similar to those achieved in acute sodium restriction of civilized man. Parenthetically, these elevated levels of aldosterone and renin were probably the norm for man during much of human evolution and suggest that the values observed in civilized controls are depressed by an excessive salt intake in contemporary diets.

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These findings, combined with animal model data, support the hypothesis that uric acid has a key role in the pathogenesis of early onset essential hypertension, and may unify some of the disparate theories of the origins of essential hypertension.

Uric acid has historically been viewed as a purine metabolic waste product excreted by the kidney and gut that is relatively unimportant other than its penchant to crystallize in joints to cause the disease gout. In recent years, however, there has been the realization that uric acid is not biologically inert but may have a wide range of actions, including being both a pro- and anti-oxidant, a neurostimulant, and an inducer of inflammation and activator of the innate immune response. In this paper, we present the hypothesis that uric acid has a key role in the foraging response associated with starvation and fasting. We further suggest that there is a complex interplay between fructose, uric acid and vitamin C, with fructose and uric acid stimulating the foraging response and vitamin C countering this response. Finally, we suggest that the mutations in ascorbate synthesis and uricase that characterized early primate evolution were likely in response to the need to stimulate the foraging “survival” response and might have inadvertently had a role in accelerating the development of bipedal locomotion and intellectual development. Unfortunately, due to marked changes in the diet, resulting in dramatic increases in fructose- and purine-rich foods, these identical genotypic changes may be largely responsible for the epidemic of obesity, diabetes and cardiovascular disease in today’s society.