Chronic Stress and Severe Water Insecurity During the Historic 2022 Drought in Northern Kenya Were Associated With Inflammation Among Daasanach Seminomadic Pastoralists

OBJECTIVE

Extreme climatic events, like droughts, are increasing in frequency and severity. Droughts disrupt community livelihoods and resources with serious implications for human biology. This study investigated how chronic stress, measured by fingernail cortisol concentration (FCC), and water insecurity status were predictive of C-reactive protein (CRP), a biomarker of inflammation, during a historic drought among Daasanach seminomadic pastoralists.

METHODS

Data were collected at the height of the 2022 drought from 128 Daasanach household heads aged 16-80 years in northern Kenya using household surveys, anthropometric measurements, and dried blood spots to assess CRP levels and fingernails to assess FCC. We employed mixed-effects linear and logistic regression models to examine the relationships between log-transformed FCC, high water insecurity status measured via the Household Water Insecurity Experiences (HWISE ≥ 24) scale, and serum-equivalent CRP (log-transformed and dichotomized at mild, low-grade inflammation ≥ 1 mg/L) adjusted for covariates.

RESULTS

The mean serum-equivalent CRP was 4.1 mg/L and 56.3% of Daasanach adults had at least mild, low-grade inflammation. Linear models indicated that ln(FCC) was positively associated with ln(CRP) (β = 0.56, SE = 0.12; p < 0.001). Further, logistic models demonstrated that ln(FCC) (OR = 2.69, 95% CI: 1.84-3.95; p < 0.001) and high water insecurity (OR = 2.23, 95% CI: 1.34-3.72; p = 0.002) were both associated with greater odds of low-grade inflammation.

CONCLUSION

This study provides evidence for how chronic stress and severe water insecurity may impact inflammation levels among pastoralists during drought. Since inflammation is central to cardiometabolic disease etiology, this is an additional reason to mitigate the negative health impacts of droughts and water insecurity exacerbated by climate change.

The effects of lifestyle change on indicators of cardiometabolic health in semi-nomadic pastoralists

Background and objectives

Non-communicable disease risk and the epidemic of cardiometabolic diseases continue to grow across the expanding industrialized world. Probing the relationships between evolved human physiology and modern socioecological conditions is central to understanding this health crisis. Therefore, we investigated the relationships between increased market access, shifting subsistence patterns and cardiometabolic health indicators within Daasanach semi-nomadic pastoralists who vary in their engagement in traditional lifestyle and emerging market behaviors.

Methodology

We conducted cross-sectional socioecological, demographic and lifestyle stressor surveys along with health, biomarker and nutrition examinations among 225 (51.6% female) Daasanach adults in 2019-2020. We used linear mixed-effects models to test how differing levels of engagement in market integration and traditional subsistence activities related to blood pressure (BP), body composition and blood chemistry.

Results

We found that systolic and diastolic BP, as well as the probability of having high BP (hypertension), were negatively associated with distance to market, a proxy for market integration. Additionally, body composition varied significantly by socioeconomic status (SES), with significant positive associations between BMI and body fat and higher SES among adults.

Conclusions and implications

While evidence for evolutionary mismatch and health variation have been found across a number of populations affected by an urban/rural divide, these results demonstrate the effects of market integration and sedentarization on cardiometabolic health associated with the early stages of lifestyle changes. Our findings provide evidence for the changes in health when small-scale populations begin the processes of sedentarization and market integration that result from myriad market pressures.

Ageing and physical function in East African foragers and pastoralists

Human lifespans are exceptionally long compared with those of other primates. A key element in exploring the evolution of human longevity is understanding how modern humans grow older. Our current understanding of common age-related changes in human health and function stems mostly from studies in industrialized societies, where older adulthood is often associated with an increased incidence of chronic diseases. However, individuals who engage in different lifestyles across industrialized and non-industrialized contexts may display variance in age-related changes in health and function. Here, we explore aspects of physical function in a non-industrialized context using three objective measures of physical function. We assessed physical activity levels, walking endurance and muscle strength in two East African populations: Hadza hunter-gatherers in Tanzania and Pokot pastoralists in Kenya. Both Hadza and Pokot participants displayed significant age-related differences in most, but not all, functional measures. Our results suggest that some age-related differences in physical function seen in industrialized contexts could be consistently experienced by most humans, while other age-related differences may vary across populations. Studies of ageing should expand to include a broad range of populations so we can create a more comprehensive understanding of how senescence varies across different lifestyle contexts. This article is part of the theme issue 'Evolution of the primate ageing process'.

Mental health is biological health: Why tackling "diseases of the mind" is an imperative for biological anthropology in the 21st century

The germ theory of disease and the attendant public health initiatives, including sanitation, vaccination, and antibiotic treatment, led to dramatic increases in global life expectancy. As the prevalence of infectious disease declines, mental disorders are emerging as major contributors to the global burden of disease. Scientists understand little about the etiology of mental disorders, however, and many of the most popular psychopharmacological treatments, such as antidepressants and antipsychotics, have only moderate-to-weak efficacy in treating symptoms and fail to target biological systems that correspond to discrete psychiatric syndromes. Consequently, despite dramatic increases in the treatment of some mental disorders, there has been no decrease in the prevalence of most mental disorders since accurate record keeping began. Many researchers and theorists are therefore endeavoring to rethink psychiatry from the ground-up. Anthropology, especially biological anthropology, can offer critical theoretical and empirical insights to combat mental illness globally. Biological anthropologists are unique in that we take a panhuman approach to human health and behavior and are trained to address each of Tinbergen's four levels of analysis as well as culture. The field is thus exceptionally well-situated to help resolve the mysteries of mental illness by integrating biological, evolutionary, and sociocultural perspectives.

Positive effects of refugee presence on host community nutritional status in Turkana County, Kenya

OBJECTIVES

Refugee camps are often assumed to negatively impact local host communities through resource competition and conflict. We ask instead whether economic resources and trade networks associated with refugees have benefits for host community health and nutrition. To address this question we assess the impacts of Kakuma Refugee Camp in northwest Kenya, comparing anthropometric indicators of nutritional status between Turkana communities in the region.

METHODS

Participants were recruited at four sites in Turkana County (N = 586): Kakuma Town, adjacent to Kakuma Refugee Camp; Lorugum, an area with sustained economic development; Lokichoggio, formerly host to international NGOs, and now underdeveloped; and Lorengo, an undeveloped, rural community. We evaluated nutritional status using summed skinfold thickness and body mass index (BMI). Structured interviews provided contextual data.

RESULTS

Age-controlled multiple regression models reveal two distinct skinfold thickness profiles for both sexes: comparatively elevated values in Kakuma and Lorugum, and significantly lower values in Lorengo and Lokichoggio. BMI did not vary significantly by location. Despite better nutritional status, a large proportion of Kakuma residents still report worries about basic needs, including hunger, health, and economic security.

CONCLUSIONS

Kakuma Refugee Camp is associated with better host community energetic status indicators, compared to other relevant, regional sites varying in development and resources. Based on global nutritional standards, observed differences likely represent meaningful disparities in overall health. We suggest that access to cereals via refugee trade networks and employment might mediate this relationship. However, perceptions of refugees as illegitimate interlopers maintain a high psychological burden.

The nutritional consequences of pregnancy sickness : A critique of a hypothesis

The purpose of this paper is to assess Profet's (1992) and others' hypothesis that nausea and vomiting in pregnancy (NVP) is adaptive. A number of studies have found an association between NVP and a decreased risk for early fetal loss (<20 weeks). It is assumed that the adaptive benefits of improved survivorship associated with NVP outweigh the minimal nutritional consequences. However, in populations that experience marginal levels of nutrition, NVP may have important nutritional consequences. To test these potential consequences, a study on NVP, nutritional status, and pregnancy outcome was conducted among Turkana pastoralists, who experience seasonal and chronic nutritional stress. Interviews and anthropometric assessments were conducted on 68 pregnant Turkana women of Kenya during a 1993-1994 field season. The results from the case study suggest that women who experience NVP do encounter nutritional consequences in the later stages of pregnancy and are more likely to experience poor pregnancy outcomes. These results suggest that NVP may not be adaptive in all environmental settings, particularly among marginally nourished populations.

Age-related changes in testosterone and SHBG among Turkana males

To determine age-related changes in biologically available testosterone (T) among men in a subsistence society and their relationship to energetic status, T, sex hormone binding globulin (SHBG) and anthropometric measures were compared among nomadic and settled Turkana pastoralists of northern Kenya. Hormonal measures were available for 104 nomadic men and 72 settled men, estimated ages 20-90 years. Comparison of the two subpopulations revealed significantly higher blood T (32.7+/- 15.1 vs. 23.4+/-15.2 nM) and SHBG (53.8+/- 19.5 vs. 39.7+/- 20.nM) but not free testosterone index (FTI) (65.6+/- 39.3 vs.66.3+/- 45.9) among the nomads. Total blood T did not exhibit a significant linear decline with age in either subgroup, while SHBG values showed a significant linear increase among the nomads. When controlled for energetic status, FTI showed a significant decrease with age among the nomads, but not the settled males. Total blood T was negatively associated with waist circumference among the nomads, but not the settled males. FTI showed a marginally significant negative association with waist circumference, suprailiac skinfold, and % body fat among the nomads but no associations with body composition among the settled group. These results add additional evidence that T is related to energetic status under conditions of negative energy balance and suggest that cross-population variation in the slope of age-related declines in free serum T and salivary T may be related to energetic status through the effects of SHBG.

Evolutionary health promotion

Health promotion's promise is enormous, but its potential is, as yet, unmatched by accomplishment. Life expectancy increases track more closely with economic prosperity and sanitary engineering than with strictly medical advances. Notable achievements in the past century--the decreased incidences of epidemic infections, dental caries, and stomach cancer--are owed to virologists, dentists, and (probably) refrigeration more than to physicians. Prevention speaks against tobacco abuse with a single voice, but in many other areas contradictory research findings have generated skepticism and even indifference among the general public for whom recommendations are targeted. Health promotion's shortcomings may reflect lack of an overall conceptual framework, a deficiency that might be corrected by adopting evolutionary premises: (1) The human genome was selected in past environments far different from those of the present. (2) Cultural evolution now proceeds too rapidly for genetic accommodation--resulting in dissociation between our genes and our lives. (3) This mismatch between biology and lifestyle fosters development of degenerative diseases. These principles could inform a research agenda and, ultimately, public policy: (1) Better characterize differences between ancient and modern life patterns. (2) Identify which of these affect the development of disease. (3) Integrate epidemiological, mechanistic, and genetic data with evolutionary principles to create an overarching formulation upon which to base persuasive, consistent, and effective recommendations.

A comparison of health complaints of settled and nomadic Turkana men

This article examines the health complaints of settled and nomadic Ngisonyoka Turkana of northwest Kenya. Samples of 152 nomadic and 124 settled men, aged 14 and over, were surveyed about their health status. The general pattern of disease reported concurs with previous studies of health among Turkana; that is, the primary complaints are respiratory tract infections and eye infections. The settled Turkana reported more severe complaints and higher rates of infectious disease than the nomads, including a significantly higher frequency of cold with cough, eye infection, and chest infection. Although the settled males as a group had slightly higher body mass index and other measures of body fat than the nomadic group, none of these indicators of body composition were predictive of health complaints. Observed differences in health patterns are possibly related to differences in dietary composition, exposure to pathogens associated with population density and environmental pollution, physical activity patterns, and psychosocial stress.

Seasonal ecology and nutritional status of women and children in a Tanzanian pastoral community

Anthropometric dimensions for 180 women and 347 individual children (0-18 years) from a seminomadic population of Datoga pastoralists living in the Eyasi and Yaeda basins of northern Tanzania are used to assess the nutritional status of the population and the magnitude and prevalence of changes between late wet season and late dry season sampling periods (1989-1991). Results reveal high prevalence of undernutrition among both women and children. Almost one-half of all women were chronically energy deficient (BMI < 18.5) and were estimated to have very low fat stores. Moderate seasonal decreases in fat stores were observed in longitudinal, and also inferred in cross-sectional, samples of the women. The decreases were more marked among lactating individuals. Almost one-half of all children showed evidence of growth retardation due to undernutrition. There was some limited evidence of decreased adiposity among children in the dry period relative to the wet period. Although drier ecological conditions are associated with decreased fat stores among both women and children, the change is of small magnitude. Am. J. Hum. Biol. 12:758-781, 2000. Copyright 2000 Wiley-Liss, Inc.

Pregnancy outcome for nomadic Turkana pastoralists of Kenya

The outcome of an individual pregnancy is a key component of overall reproductive success and is strongly influenced by environmental, behavioral, and biological variation within populations. This prospective study examined the outcomes of 68 pregnancies among nomadic Turkana of Kenya from July 1993 to July 1994. A total of 12 women experienced pregnancy losses, and 3 women experienced live births with a subsequent perinatal death. The following characteristics are associated with increased risk for experiencing a fetal or perinatal death: severe morbidity episodes, shorter nonpregnant intervals, lower third-trimester weight, higher third-trimester summed skinfolds but limited third-trimester reduction in summed skinfolds, and higher activity levels late in gestation. Turkana newborns measured within 48 hr of birth (n = 19) weighed an average of 2,860 +/- 640 g and had a mean ponderal index of 2.72 +/- 0.46. Variation in birth weight was predicted by preterm delivery, delivery during the wet season, and maternal morbidity levels. Birth length averaged 50.8 +/- 6.8 cm and was positively influenced by full term delivery, better maternal health, and birth during the dry season. These results suggest complicated pathways linking the physical environment, subsistence requirements, heterogeneity in maternal fitness, behavior, and pregnancy outcome. The results augment the larger picture of reproductive success for Turkana nomads who live in a highly variable savanna environment.

Age, sex and anthropometric status of children in an African pastoral community

The study objective was to explore sex differences in anthropometric status of children from a semi-nomadic population of Datoga pastoralists living in northern Tanzania and test the hypothesis that any differences would be related to age- and gender-specific work activities. Anthropometric measurements made on 438 individual children (0-18 years) were used to assess the association of various anthropometric measures of achieved growth status with age, sex and season of measurement. There was a high overall prevalence of indicators of undernutrition but the risk of undernutrition was not uniformly distributed within the child population. Comparison of cross-sectional mean anthropometric scores suggested that children over 5 years, girls 5-8 years, boys 9-12 years and teenagers were found to be at highest risk of undernutrition as assessed by various indicators. Although the prevalence of all indicators of undernutrition showed a significant increase with age, the prevalence of indicators of undernutrition did not show a statistically significant sex difference within any age group. There was little evidence of sex-preferential treatment of children or strongly biased sex ratios or mortality rates. Taken together, these results indicate that the anthropometric status of children may be associated with the age- and gender-specific pattern of work activities typical of this population. Possible mechanisms through which anthropometric status may be influenced by work activities are hypothesized.

An alternative method for assessing early mortality in contemporary populations

Biological anthropologists are interested in a population's early mortality rates for a variety of reasons. Early mortality (infant or juvenile) is of obvious importance to those interested in demography, but early mortality statistics are useful for life history analysis, paleodemography, and human adaptability studies, among others. In general, the form of mortality statistics is derived from demography, where chronological age is the gold standard for statistical calculation and comparison. However, there are numerous problems associated with the collection, analysis, and interpretation of early mortality statistics based on age, particularly for anthropological research, which is often conducted in small or non-calendrical-age numerate populations. The infant mortality rate (IMR), for example, is notoriously difficult to determine in populations where accurate accounting of age is not routine, and yet it is widely used in demography, public health, medicine, and social science research. Here we offer an alternative to age-based early mortality statistics that makes use of human biologists' interest in, and skill at, assessing human growth and development. Our proposal is to use developmental stages of juveniles instead of relying exclusively on age as the basis for mortality statistics. Death or survival according to a developmental stage (such as crawling or weaning) may provide more accurate data that are also more closely related to the cause of death. Developmental stages have the added advantage of putting infants and children back at the center of the discussion of early mortality by focusing on their activities in relation to their environment. A case study from the Turkana population of Kenya illustrates the use of developmental stages in describing early mortality.

Sedentism and child health among Rendille pastoralists of northern Kenya

Many nomadic pastoralists of Africa are settling near towns and famine-relief centers in response to drought-induced livestock loss, loss of pasture land, increased involvement in market economies and political turmoil including civil war. The present study uses measurements of child health, particularly morbidity, dietary and growth patterns, to evaluate the consequences of sedentism for three Rendille communities of northern Kenya. A nutritional and health survey utilizing interviews, anthropometric measurements, physical examinations and hemoglobin measurements was conducted for 105 mothers and their 174 children under six years of age in three Rendille communities, one fully nomadic and two sedentary, in July 1990, a year of above average rainfall, and again in June 1992, a drought year. Results indicate that while the nomadic Rendille community of Lewogoso shares similar morbidity patterns with its sedentary counterparts and had similar numbers of malnourished children during the wet year, the sedentary communities had significantly more malnutrition among children under six during the dry year. Moreover, the children in the settled town of Korr had significantly higher levels of anemia. Differences in malnutrition are attributed to distinctive dietary regimes: during the drought, nomadic children consumed three times as much milk as the sedentary children, while settled children's diets concentrated on starches, fat and sugar. This study suggests that the pastoral nomadic diet, particularly one dependent on camels' milk, offers children better resistance to the pressures of drought and supports findings that the subsistence base of mixed-species pastoralism is superior to sedentary alternatives with respect to child health.