Nutritional status of Efe pygmies and Lese horticulturists

We assessed the nutritional status of 90 pygmies (Efe) and 211 members of a neighboring horticultural Lese in the Ituri forest in northeast Zaire. Clinical signs of iron and iodine deficiency were highly prevalent, but the frequency of these and other clinical signs of nutritional deficiency did not differ between the two groups. Infectious diseases such as yaws, cellulitis, and filiariasis were common. Absolute heights and weights of both Efe males and females aged 2–18 years were less than the 5th percentile of the National Center for Health Statistics standards. Weights for height of both groups were within the normal range. Weights and heights, expressed as percentages of the 50th percentile for age and sex, were significantly lower (P < .001) in Efe males and females than among Lese males and females, but weights for height did not differ significantly. Z-Scores of height and weight were also significantly lower in Efe males and females than among their Lese counterparts. The differences in weight and height, expressed either as a percentage of the 50th percentile or as Z-scores, were most apparent in older adolescents and persisted among adults. The normal weight for height among both populations indicated that acute undernutrition did not exist at the time of the survey. Despite comparable levels of adult fatness, measured by triceps skinfold thickness, heights of Efe males and females were lower than those of the Lese. These observations support the hypothesis that genetic differences account for the short stature of the Ituri pygmy. However, because the environments shared by the two groups are not identical and because other practices differ, nutritional effects cannot be excluded.     

Research on the Efe and Lese populations of the Ituri forest,Zaire

Since 1980, as part of the Ituri Project, researchers have been studying numerous aspects of the biology, health, economy, and social relations of Efe (Pygmies) and Lese villagers living in the Ituri Forest region of north-eastern Zaire. The Efe are seminomadic people who hunt and gather forest resources for their own consumption and for exchange with sedentary subsistence farmers. The Lese are Sudanic-speaking subsistence farmers who practice shifting slash-and-burn horticulture and live in semipermanent villages. Relations between the Efe and Lese have been close for many generations and extend beyond economic exchange to include most aspects of ritual and social life. This paper serves as an introduction to five subsequent papers that report findings from research on these two forest-living populations. It provides background information concerning the ecology and history of human occupation of the Ituri region of central Africa; it describes the study area and the study populations; it discusses how the annual subsistence cycles of the Efe and Lese relate to rainfall and food availability; and it provides further information concerning Ituri Project research during the last 7 years.     

Historical trends in forager and farmer exchange in the Ituri rain forest of northeastern Zaïre

Using oral histories, archival materials, and observations of present behavior, a largely hypothetical historical reconstruction of the natural resource exploitation and subsistence practices of Lese farmers and Efe foragers in the Ituri Forest of northeastern Zaïre is presented. Distinct epochs associated with the advent of forest agriculture, Belgian colonization, and post-independence economic collapse have resulted in changes in local population density, the range of forest resources exploited, and the spatial distribution and intensity of resource use. Broadly speaking, there has been a historical trend toward sedentism, spatial clumping of settlements, localization of resource exploitation, reduced importance of forest carbohydrates in the diet, and an increased reliance on agricultural products. Over time the Efe and Lese exchange system has changed, in relation to the items traded and the relative dependence of each partner on the exchange relationship. Involvement in this alliance has had a considerable impact on Efe settlement pattern, diet, and probably fecundity. It ultimately placed the Lese in a position of power over the Efe, and provided the farmers with means to enter a transient monetary economy. By providing a retrospective on Efe and Lese subsistence, we hope to demonstrate that to decipher the relative benefits and constraints of this contemporary exchange relationship, we must understand their historical etiology.     

The ecology of birth seasonality among agriculturalists in central Africa.

The Lese are subsistence farmers living in the Ituri Forest of north-east Za?re. They exhibit significant birth seasonality, with lowest frequencies of conception when food production is least, nutritional status is low and ovarian function, as measured by salivary steroid hormone levels, is reduced. Efe pygmy foragers, who live in the same geographical area but are less dependent on cultivated foods and have a more flexible life style, do not exhibit frequent fluctuations in nutritional status nor significant birth seasonality. These findings support a model of birth seasonality relating climatic variables to variation in fertility through a causal chain linking rainfall to food production to energy balance to ovarian function to fertility. The model, which emphasises an ecological approach to the study of human reproduction, should have broad applicability since seasonality of food production and energy balance is widespread geographically and across a wide variety of economies and cultures.     

Fitness and Oxygen uptake of children in the Ituri forest. Natural selection or adaptation to the environment?

For the inhavitants of an isolated niche like the Ituri rain forest of N-E Zaire, the interplay of natural selection and conditioning by daily physical activity should influence the physical development of growing children, provided general health and nutrition stay within acceptable limits. The general health of 389 children between 5 and 15 years of age (207 Lese villagers and 182 Efe Pygmies) living in that area, appears to be fairly good, although the hematocrite is low (37 and 34% respectively). Tuberculine reaction is positive in over 50%, intestinal parasites generally present while more than 50% are free of dental caries. Efe children stand peristently some 10 cm smaller and weigh 5 to 6 kg less than Lese of the same age, who reach only the 3rd percentile of European children (Tanner-Whithouse 1963). In the motorfitness, Efe score better than Lese for balance and flexibility tests. Both appear superior to European children of the same age, they are equal or better for strength, even when adjusted for body size. Against this background, the Oxygen uptake (VO₂) at increasing work load on the step test of 58 Lese and 56 Efe indicates similar efficiency. The Efe reach a fixed VO₂ with higher Heart Rate (HR), which is consistent with their smaller size, hence smaller heart and stroke volume. The difference disappears when adjusted for body size. Children living in the Ituri forest tend to be fitter than Europeans notwithstanding their health condition. This belies any Energy Proteine Malnutrition (EPM) form earky childhood on, and supports the thesis that the small body size of the Efe follows genetic factors and does not result from poor health or chronic EPM in childhood.     

Dental Health Diet and Social Status among Central African Foragers and Farmers

An oral health survey of African pygmies and Bantu revealed significant contrasts that can be explained by differences in diet, social status, and oral hygiene. Pygmy men have fewer carious lesions and less tooth loss than pygmy women. Ethnographic data suggest that this results from sex differences in eating habits and access to cariogenic foods. Pygmy "leaders" have much better dental health than "nonleaders." This status difference appears to be explained by social and dietary variables.     

Ten categories of statistical errors: a guide for research in endocrinology and metabolism

A simple framework is introduced that defines ten categories of statistical errors on the basis of type of error, bias or imprecision, and source: sampling, measurement, estimation, hypothesis testing, and reporting. Each of these ten categories is illustrated with examples pertinent to research and publication in the disciplines of endocrinology and metabolism. Some suggested remedies are discussed, where appropriate. A review of recent issues of American Journal of Physiology: Endocrinology and Metabolism and of Endocrinology finds that very small sample sizes may be the most prevalent cause of statistical error in this literature.     

Can Dietary Nitrates Enhance the Efficiency of Mitochondria?

A decline in mitochondrial function occurs in many conditions. A report in this issue of Cell Metabolism (Larsen et al., 2011) shows that dietary inorganic nitrates enhance muscle mitochondrial efficiency. It is an attractive hypothesis that dietary changes enhance energy efficiency, but its potential application depends on long-term studies investigating net benefits versus adverse effects.     

Fat-induced inflammation unchecked

Increased dietary saturated fat intake can lead to detrimental effects on human health. In this issue of Cell Metabolism, Lichtenstein et?al. (2010) show that by inhibiting lipoprotein lipase (LPL) activity in mesenteric lymph nodes, Angiopoietin-like protein 4 (Angptl4) protects resident macrophages from dietary saturated fatty acid (SFA)-induced inflammation.     

Fly-let biology and the high protein/low carb diet

In Drosophila, a simple network of nutrient-sensing neuroendocrine cells, analogs of pancreatic islet alpha and beta cells, regulates carbohydrate metabolism. Work presented in this issue of Cell Metabolism (Buch et al., 2008) shows that signals from these cells control expression of a glycogen-specific glucosidase in response to dietary protein and carbohydrate.     

Diet-Related Buccal Dental Microwear Patterns in Central African Pygmy Foragers and Bantu-Speaking Farmer and Pastoralist Populations

Pygmy hunter-gatherers from Central Africa have shared a network of socioeconomic interactions with non-Pygmy Bantu speakers since agropastoral lifestyle spread across sub-Saharan Africa. Ethnographic studies have reported that their diets differ in consumption of both animal proteins and starch grains. Hunted meat and gathered plant foods, especially underground storage organs (USOs), are dietary staples for pygmies. However, scarce information exists about forager–farmer interaction and the agricultural products used by pygmies. Since the effects of dietary preferences on teeth in modern and past pygmies remain unknown, we explored dietary history through quantitative analysis of buccal microwear on cheek teeth in well-documented Baka pygmies. We then determined if microwear patterns differ among other Pygmy groups (Aka, Mbuti, and Babongo) and between Bantu-speaking farmer and pastoralist populations from past centuries. The buccal dental microwear patterns of Pygmy hunter-gatherers and non-Pygmy Bantu pastoralists show lower scratch densities, indicative of diets more intensively based on nonabrasive foodstuffs, compared with Bantu farmers, who consume larger amounts of grit from stoneground foods. The Baka pygmies showed microwear patterns similar to those of ancient Aka and Mbuti, suggesting that the mechanical properties of their preferred diets have not significantly changed through time. In contrast, Babongo pygmies showed scratch densities and lengths similar to those of the farmers, consistent with sociocultural contacts and genetic factors. Our findings support that buccal microwear patterns predict dietary habits independent of ecological conditions and reflect the abrasive properties of preferred or fallback foods such as USOs, which may have contributed to the dietary specializations of ancient human populations.     

Leucing weight with a futile cycle

The essential amino acid leucine serves as a signal that activates protein synthesis. A new study by She et al. (2007) in this issue of Cell Metabolism shows that raising circulating leucine by blocking leucine breakdown drives a futile cycle of protein synthesis and degradation that contributes to higher-energy expenditure, resistance to dietary obesity, and improved insulin sensitivity.     

Weighing on autophagy

Comment on: Coupé B, et al. Cell Metab 2012; 15:247–55, Kaushik S, et al. EMBO Rep 2012; 13:258-65 and Quan W, et al. Endocrinology 2012; 153: In press     

An IRKO in the Podo: impaired insulin signaling in podocytes and the pathogenesis of diabetic nephropathy

Despite its high prevalence, the mechanisms causing diabetic kidney disease remain poorly understood. In this issue of Cell Metabolism, Welsh et al. (2010) show that elimination of insulin receptors from the glomerular podocyte, a cell that is central to the pathogenesis of proteinuric renal diseases, recapitulates many features of human diabetic nephropathy.     

Location, location, location..

Intra-abdominal fat is an established risk factor for the metabolic syndrome. In this issue of Cell Metabolism, Tran et al. (2008) test the cell-autonomous and location-related properties of transplanted intra-abdominal and subcutaneous fat depots. While subcutaneous fat seems to confer metabolic benefits, species differences in adipose biology justify caution in interpreting the results.     

Taranabant Cuts the Fat: New Hope for Cannabinoid-Based Obesity Therapies?

Endocannabinoid/cannabinoid receptor signaling acts centrally and peripherally to govern appetite and energy balance. While system stimulation promotes eating and energy storage, receptor blockade can reduce food intake and facilitate weight loss. In this issue of Cell Metabolism, Addy et al. (2008) test the therapeutic antiobesity potential of taranabant, a cannabinoid 1 receptor inverse agonist.     

Bringing together linguistic and genetic evidence to test the Bantu expansion

The expansion of Bantu languages represents one of the most momentous events in the history of Africa. While it is well accepted that Bantu languages spread from their homeland (Cameroon/Nigeria) approximately 5000 years ago (ya), there is no consensus about the timing and geographical routes underlying this expansion. Two main models of Bantu expansion have been suggested: The 'early-split' model claims that the most recent ancestor of Eastern languages expanded north of the rainforest towards the Great Lakes region approximately 4000 ya, while the 'late-split' model proposes that Eastern languages diversified from Western languages south of the rainforest approximately 2000 ya. Furthermore, it is unclear whether the language dispersal was coupled with the movement of people, raising the question of language shift versus demic diffusion. We use a novel approach taking into account both the spatial and temporal predictions of the two models and formally test these predictions with linguistic and genetic data. Our results show evidence for a demic diffusion in the genetic data, which is confirmed by the correlations between genetic and linguistic distances. While there is little support for the early-split model, the late-split model shows a relatively good fit to the data. Our analyses demonstrate that subsequent contact among languages/populations strongly affected the signal of the initial migration via isolation by distance.     

GTP-binding protein-independent potentiation by mastoparan of IL-1β-induced nitric oxide release from insulin-secreting HIT-T15 cells

Our recent data implicated small molecular weight G-proteins (e.g., H-Ras) in interleukin 1beta (IL 1beta)-induced metabolic dysfunction and apoptotic demise of the islet beta cell (Tannous et al., Biochem Pharmacol 2001; 62:1459-1468, Kowluru and Morgan, Biochem Pharmacol, 2002; 63:1027-1035, Chen et al. Biochem Pharmacol, 2003; 66:1681-1694). Recently, we have shown that mastoparan, a tetradecapeptide from wasp venom, has been shown to directly activate islet endogenous G-proteins and regulate islet function (Amin et al., Endocrinology 2003; 144: 4508-4518). Herein, we investigated potential contributory roles, if any, of mastoparan (Mas)-sensitive G-proteins in IL-induced nitric oxide (NO) release from insulin-secreting HIT-T15 cells. While, ineffective by itself, Mas significantly potentiated IL-induced NO release from HIT-T15 cells. Interestingly, Mas-17, an inactive analog of Mas, also potentiated IL-induced NO release, suggesting that the potentiating effect of Mas may not involve activation of specific G-proteins. Such potentiating effects on IL-induced NO release were also demonstrable in the presence of another polycationic compound, melittin. Together, these findings suggest that Mas-induced potentiation of IL-induced NO release may in part be due to its amphiphilic and polycationic nature. These data also warrant caution in the use of Mas to study its regulation of cellular function without the use of an appropriate negative control, such as Mas-17.     

Mitochondrial DNA diversity in two ethnic groups in Southeastern Kenya: Perspectives from the northeastern periphery of the bantu expansion

The Bantu languages are widely distributed throughout sub‐Saharan Africa. Genetic research supports linguists and historians who argue that migration played an important role in the spread of this language family, but the genetic data also indicates a more complex process involving substantial gene flow with resident populations. In order to understand the Bantu expansion process in east Africa, mtDNA hypervariable region I variation in 352 individuals from the Taita and Mijikenda ethnic groups was analyzed, and we evaluated the interactions that took place between the Bantu‐ and non‐Bantu‐speaking populations in east Africa. The Taita and Mijikenda are Bantu‐speaking agropastoralists from southeastern Kenya, at least some of whose ancestors probably migrated into the area as part of Bantu migrations that began around 3,000 BCE. Our analyses indicate that they show some distinctive differences that reflect their unique cultural histories. The Taita are genetically more diverse than the Mijikenda with larger estimates of genetic diversity. The Taita cluster with other east African groups, having high frequencies of haplogroups from that region, while the Mijikenda have high frequencies of central African haplogroups and cluster more closely with central African Bantu‐speaking groups. The non‐Bantu speakers who lived in southeastern Kenya before Bantu speaking groups arrived were at least partially incorporated into what are now Bantu‐speaking Taita groups. In contrast, gene flow from non‐Bantu speakers into the Mijikenda was more limited. These results suggest a more complex demographic history where the nature of Bantu and non‐Bantu interactions varied throughout the area. Am J Phys Anthropol 150:482–491, 2013. © 2013 Wiley Periodicals, Inc.     

Nck links nephrin to actin in kidney podocytes

Two papers, one in Nature (Jones et al., 2006) and the other in the Journal of Clinical Investigation (Verma et al., 2006) show that Nck adaptor proteins connect phosphorylated nephrin with actin polymerization in podocyte foot processes, structures important for slit-diaphragm formation in the kidney. Their results further our understanding of podocyte development and repair in glomerular disease.