Tsimane Of Bolivia Research Articles

Dementia in the Ancient Greco-Roman World Was Minimally Mentioned.

The possibility that Alzheimer's disease and related dementias (ADRD) is a modern disease arises from the minimal mention of advanced cognitive decline by ancient Greeks and Romans, who were mainly concerned with the physical frailties of older ages. Because standard medical histories of elderly health lacked mention of cognitive decline, we examined texts by Greek and Roman authors that mentioned memory loss and dementia. Primary texts of Greco-Roman authors, 8th century BCE into the 3rd century CE, that mentioned cognitive decline were identified and critically evaluated. Secondary sources were excluded. No ancient account of cognitive loss is equivalent to modern clinical data. The term dementia was occasionally used in antiquity, but not invariably linked to old age. Ancient Greeks and Romans expected intellectual competence beyond age 60. While some memory loss was acknowledged, we found only four accounts of severe cognitive loss that might represent ADRD. The possibility of modest ADRD prevalence in ancient Greece and Rome is consistent with its low prevalence in the Tsimane of Bolivia. These contemporary Amerindians live under conditions of high mortality from frequent infections and minimal cardiovascular disease with physically demanding lives. Tsimane after age 60 had increased mild cognitive impairment; the few cases of dementia were not clinically consistent with AD. The modern 'epidemic level' of advanced dementias was not described among ancient Greco-Roman elderly. The possible emergence of advanced ADRD in the Roman era may be associated with environmental factors of air pollution and increased exposure to lead. Further historical analysis may formulate critical hypotheses about the modernity of high ADRD prevalence.

Cognitive foundations for helping and harming others: Making welfare tradeoffs in industrialized and small-scale societies

For many abilities, such as vision or language, our conscious experience is one of simplicity: We open our eyes and the world appears; we open our mouths and grammatical sentences tumble out. Yet these abilities rely on immensely complex, unconscious computations. Is this also true of abilities related to cooperation or competition, like deciding whether to share food or spread gossip? We tested whether decisions like these are guided by precise psychological variables, called welfare tradeoff ratios. Welfare tradeoff ratios summarize information about multiple sources of social value (such as whether a specific other person is kin or is generous with the self) along with information about the situation (such as what's at stake or who else is watching). We evaluated these hypothesized variables in four societies: among college students in the USA and Argentina and among two groups of Amazonian forager-horticulturalists, the Shuar of Ecuador and the Tsimane of Bolivia (ns = 167, 131, 73, 23). In all societies people made a series of hypothetical decisions where they had to weigh help or harm for themselves versus others. We found strong evidence that people trade off their welfare for others with consistency—a signature of decisions being guided by precise variables in the mind. We also found evidence in three of the societies that people discriminate among different categories of others in their welfare tradeoffs (e.g., friends versus acquaintances). Although most decisions about helping or harming feel simple and intuitive, they appear to be underwritten by precise computations.

Pathway‐based genome analysis of cognitive impairment in a forager‐horticulturalist South American population

AbstractBackgroundThe genetic etiology of Cognitive Impairment (CI) is poorly understood. This is due, in part, to the complexity of diverse genetic and environmental risk factors in large, heterogeneous study populations. To overcome this obstacle, we examined a population with low genetic heterogeneity and fewer risk factors commonly found in industrialized populations ‐ the Tsimane of Bolivia (N = 353; mean age = 69 years [60–93 years]). The Tsimane are a geographically isolated forager‐horticulturalist population with high levels of physical activity and low prevalence of coronary artery disease, hypertension, and diabetes, even at advanced ages. The absence of these typical Alzheimer’s Disease (AD)‐related comorbidities provides a novel opportunity to isolate aspects of CI that are often intertwined with cardiometabolic and other non‐communicable chronic diseases.MethodCI was determined from field evaluations using a locally translated and adapted cognitive battery, mental status examination, informant interview, and neurological evaluation (CI = 31, AD = 1). Genome‐wide variation was characterized using the Infinum Multi‐Ethnic Global Array (1,754,170 SNPs) and evaluated with a novel analytic tool that uses biologic processes as the unit of analysis — Pathways of Distinction Analysis (PoDA). PoDA captures interactions across the multiple genes within a network and assesses significance via empiric resampling. A catalog of 1167 curated networks representing the diversity of biologic function was evaluated.ResultThe pathway that most significantly distinguishes individuals with CI from those without impairment is the KEGG Alzheimer’s Disease Pathway (Distance Score [DS] = 3.23; FDR‐adjusted pDS<0.001). This pathway is composed of 169 genes that capture the major processes associated with AD. Refined analysis identified a subset of 35 genes that is associated with a 6‐fold difference (OR = 6.26; pOR = 1.21×10−12) in relative risk for prevalent CI vs. no impairment. Those genes are involved in insulin signaling, calcium signaling, and mitochondrial oxidative phosphorylation subcomponents of the AD Pathway. It also includes variation within the AD risk loci APBB1 and MAPT (Figure 1).ConclusionIn a population with minimal cardiometabolic disease, pathway‐based genome analysis objectively identifies subcomponents within the AD pathway tied to cellular energy metabolism as important in CI. Following validation in larger, heterogenous populations, these components may provide targets for prevention and intervention.

Sophisticated sleep improves our brains: Our advanced cognitive and social skills might derive from the evolution of improved sleep quality; today, sleep therapy could help with mental health issues and learning.

In the past decades, sleep researchers have been quietly accumulating knowledge about the physiology of sleep. Without any real health application for this knowledge, however, the public and the press have slept blissfully through most of their breakthroughs. Yet, recent findings about the evolution of sleep in humans and the effects of sleep disruption on human health seem to have finally woken the public up. A recent paper from David Samson and Charles Nunn, evolutionary anthropologists from Duke University in the USA, puts forward the hypothesis that humans have evolved more efficient sleep patterns than other primates and that this is because “[e]arly humans experienced selective pressure to fulfill sleep needs in the shortest time possible” [1]. This efficient slumber, the authors argue, might have contributed to setting our ancestors on the evolutionary path toward human civilization. The New York Times , among other newspapers, covered the publication, which follows in the wake of research indicating that human sleep patterns have stayed largely stable during the course of human evolution, from hunter‐gatherers to modern city dwellers [2]. Both of these insights provide evolutionary context for the health impact of too little sleep, with both epidemiological and clinical research showing that sleep disruption has a negative effect on health and well‐being. More recently, however, there is evidence that sleep has distinctly positive therapeutic potential to treat a variety of phobias and other psychotic conditions. The evolutionary study that attracted media attention raises interesting questions about the co‐evolution of sleep and human cognitive faculties. Samson and Nunn suggest that sleep became subject to strong selective pressures—“including increased predation risk […] threats from intergroup conflict, and benefits arising from increased social interaction” [1]—when our ancestors moved down from the trees and onto the savannah. As a result, …

Abstract 18333: Left Ventricular Systolic and Diastolic Dysfunction is an Uncommon Finding in a Pre-modern Society With High Inflammation and Low Atherosclerotic Risk Factors

Introduction: Ischemic cardiomyopathy from coronary atherosclerosis is the leading cause of mortality in developed nations. However, the natural history of cardiovascular disease in contemporary pre-industrial man is not well described. The Tsimane of Bolivia are a forager-horticulturalist population in the western Amazonian basin with high levels of inflammation and a low prevalence of atherosclerosis risk factors. We sought to define the cardiovascular health of a contemporary pre-industrial population with high inflammation and low atherosclerotic risk factors. Methods: Two-Dimensional echocardiograms with Color and Doppler were obtained on 934 Tsimane over age 40. Echocardiograms were reviewed by 2 cardiologists following the American Society of Echocardiography guidelines for interpretation. Patients had baseline clinical evaluations including age, height, weight, blood pressure, and gender. Blood was obtained for serology for inflammatory markers. Results: The average age was 53 years (SD +/- 11; range 40-90 years). 455 (48.7%) were male. The prevalences of hypertension, diabetes, and smoking were 4.8%, 0.5%, and 1.3%, respectively. Mean LVEF was 66% (SD +/- 6.1). There were 4 males with LVEF less than 52% and 11 females with LVEF less than 54%. There was no measured LVEF less than 44%. Complete diastolic data was available in 910. Normal diastolic parameters were observed in 741 (81.4%). Mild diastolic dysfunction was found in 167 (18.3%) and moderate dysfunction in 2 (0.2%). No echocardiograms showed severe diastolic dysfunction. Serologic data showed elevated CRP, ESR, and IL-6 with low high density lipoprotein (HDL) and low density lipoprotein (LDL) Conclusions: In a pre-modern population with high inflammation and low atherosclerotic risk factors, cardiovascular systolic and diastolic dysfunction was a rare finding.

Female disability disadvantage: a global perspective on sex differences in physical function and disability.

The objectives were to determine whether women always fare more poorly in terms of physical function and disability across countries that vary widely in terms of their level of development, epidemiologic context and level of gender equality. Sex differences in self-reported and objective measures of disability and physical function were compared among older adults aged 55-85 in the United States of America, Taiwan, Korea, Mexico, China, Indonesia and among the Tsimane of Bolivia using population-based studies collected between 2001 and 2011. Data were analysed using logistic and ordinary least-squares regression. Confidence intervals were examined to see whether the effect of being female differed significantly between countries. In all countries, women had consistently worse physical functioning (both self-reported and objectively measured). Women also tended to report more difficulty with activities of daily living (ADL), although differences were not always significant. In general, sex differences across measures were less pronounced in China. In Korea, women had significantly lower grip strength, but sex differences in ADL difficulty were non-significant or even reversed. Education and marital status helped explain sex differences. Overall, there was striking similarity in the magnitude and direction of sex differences across countries despite considerable differences in context, although modest variations in the effect of sex were observed.

Physiological Differences Across Populations Reflecting Early Life and Later Life Nutritional Status and Later Life Risk for Chronic Disease.

This paper addresses how indicators of early life nutrition and development and later life nutrition vary in aging populations in the U.S., England, Mexico, China, Taiwan, Indonesia, and the Tsimane of Bolivia. These populations span a wide range of current life expectancy and infant mortality when they were young. The indicators of nutritional problems are related to both current life expectancy and to levels of past infant mortality. The indicators of past and present nutrition are also related to a set of risk factors for chronic disease including the ratio of Total Cholesterol to High Density Lipoprotein Cholesterol, level of glycosylated hemoglobin, pulse pressure, and C-reactive protein. Results indicate that current obesity is associated with significantly higher levels of most risk factors in most settings. On the other hand, stunting in childhood is not related consistently to any of the indicators of current risk. Social and demographic differences in risk vary across settings. Future increases in obesity around the world are likely to be related to increasing risk for the chronic conditions of old age.

Polygyny among the Tsimane of Bolivia: an improved method for testing the polygyny-fertility hypothesis.

The polygyny-fertility hypothesis states that polygyny is associated with reduced fertility for women and is supported by a large body of literature. This finding is important, because theoretical models of polygyny often differentiate systems based on the degree to which women are forced or willingly choose to enter polygynous marriages. The fact that polygyny tends to be associated with reduced fertility has been presented as evidence that polygyny is often less favourable for women, and that women must, therefore, be pressured into accepting such arrangements. Previous studies, however, have been hampered by the non-random assignment of women into monogamous and polygynous unions (i.e. self-selection), as differences between these groups of women might explain some of the effects. Furthermore, the vast majority of such studies focus on sub-Saharan populations. We address these problems in our analysis of women's fertility in polygynous marriages among the Tsimane of Bolivia. We offer a more robust method for assessing the impact of polygynous marriage on reproductive outcomes by testing for intra-individual fertility effects among first wives as they transition from monogamous to polygynous marriage. We report a significant link between polygyny and reduced fertility when including all cases of polygyny; however, this association disappears when testing only for intra-individual effects.

Infant growth and the thymus: Data from two South American native societies

The thymus plays an important role in the development of the immune system, yet little is known about the patterns and sources of variation in postnatal thymic development. The aim of this study is to contribute cross-cultural data on thymus size in infants from two South American native populations, the Tsimane of Bolivia and the Pumé of Venezuela. Thymic ultrasonography was performed and standard anthropometric measures collected from 86 Tsimane and Pumé infants. Patterns of infant growth and thymus size were compared between the two populations and the relationship between nutritional status and thymus size was assessed. Despite nearly identical anthropometric trajectories, Tsimane infants had larger thymuses than Pumé infants at all ages. Population, infant age, and infant mid-upper arm circumference were significant predictors of thymus area in the Tsimane and Pumé infants. This finding reveals a cross-cultural difference in thymus size that is not driven by nutritional status. We suggest that future studies focus on isolating prenatal and postnatal environmental factors underlying cross-cultural variation in thymic development.

Evidence for a peak shift in a humoral response to helminths: age profiles of IgE in the Shuar of Ecuador, the Tsimane of Bolivia, and the U.S. NHANES.

BackgroundThe peak shift model predicts that the age-profile of a pathogen's prevalence depends upon its transmission rate, peaking earlier in populations with higher transmission and declining as partial immunity is acquired. Helminth infections are associated with increased immunoglobulin E (IgE), which may convey partial immunity and influence the peak shift. Although studies have noted peak shifts in helminths, corresponding peak shifts in total IgE have not been investigated, nor has the age-patterning been carefully examined across populations. We test for differences in the age-patterning of IgE between two South American forager-horticulturalist populations and the United States: the Tsimane of Bolivia (n = 832), the Shuar of Ecuador (n = 289), and the U.S. NHANES (n = 8,336). We then examine the relationship between total IgE and helminth prevalences in the Tsimane.Methodology/Principal FindingsTotal IgE levels were assessed in serum and dried blood spots and age-patterns examined with non-linear regression models. Tsimane had the highest IgE (geometric mean = 8,182 IU/ml), followed by Shuar (1,252 IU/ml), and NHANES (52 IU/ml). Consistent with predictions, higher population IgE was associated with steeper increases at early ages and earlier peaks: Tsimane IgE peaked at 7 years, Shuar at 10 years, and NHANES at 17 years. For Tsimane, the age-pattern was compared with fecal helminth prevalences. Overall, 57% had detectable eggs or larva, with hookworm (45.4%) and Ascaris lumbricoides (19.9%) the most prevalent. The peak in total IgE occurred around the peak in A. lumbricoides, which was associated with higher IgE in children <10, but with lower IgE in adolescents.ConclusionsThe age-patterning suggests a peak shift in total IgE similar to that seen in helminth infections, particularly A. lumbricoides. This age-patterning may have implications for understanding the effects of helminths on other health outcomes, such as allergy, growth, and response to childhood vaccination.

The Impact of Parents and Self-Selection on Child Survival among the Tsimane of Bolivia

The impact of the parental investment provided by a mother or father on the well-being of a child depends on many factors. The effect of fathers is of particular theoretical interest, as there has been considerable debate concerning the importance of fathers in the evolution of our species and of our reproductive strategies involving long-term pair bonds and biparental care. A common strategy for investigating the impact that parents have on child outcomes is to compare children raised in households without a mother or father to those raised in households with both parents. There is question, however, as to what degree any such effects are simply the result of covarying mortality hazards within families or through time and not necessarily a direct impact of parental absence. Here we explore the issue of self-selection in our investigation of the effects of fathers and mothers on offspring survival among the Tsimane, a forager-horticultural population of central Bolivia. We find strong associations between...

Blood lipids, infection, and inflammatory markers in the Tsimane of Bolivia

Little is known about blood cholesterol (blood-C) levels under conditions of infection and limited diet. This study examines blood-C and markers of infection and inflammation in the Tsimane of the Bolivian Amazon, indigenous forager farmers living in conditions that model preindustrial European populations by their short life expectancy, high load of infections and inflammation, and limited diets. We use multivariate models to determine the relationships between lipid levels and markers of infection and inflammation. Adult Tsimane (N = 418, age 20-84) were characterized for blood lipids, cells, and inflammatory markers in relation to individual loads of parasites and village region. Most of the Tsimane (60%) carried at least one parasite species, averaging 1.3 species per person. Serum high-density lipoprotein cholesterol (HDL-C), total cholesterol (total-C), and low-density lipoprotein cholesterol (LDL-C) were below the U.S. norms and varied inversely with markers of infection and inflammation: C-reactive protein (CRP), interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), immunoglobulin (Ig) E and eosinophil count. Although no relationship of parasite load to blood-C was found, there was an association between anemia and parasite prevalence. We conclude that the highly infected environment of the Tsimane is related to low levels of blood total-C, HDL-C, and LDL-C. This may suggest a potential reason why arterial disease is largely absent in the Tsimane.

Adaptations in humans for assessing physical strength from the voice

Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength from the voice. We found that subjects accurately assessed upper-body strength in voices taken from eight samples across four distinct populations and language groups: the Tsimane of Bolivia, Andean herder-horticulturalists and United States and Romanian college students. Regardless of whether raters were told to assess height, weight, strength or fighting ability, they produced similar ratings that tracked upper-body strength independent of height and weight. Male voices were more accurately assessed than female voices, which is consistent with ethnographic data showing a greater tendency among males to engage in violent aggression. Raters extracted information about strength from the voice that was not supplied from visual cues, and were accurate with both familiar and unfamiliar languages. These results provide, to our knowledge, the first direct evidence that both men and women can accurately assess men's physical strength from the voice, and suggest that estimates of strength are used to assess fighting ability.

The multiple dimensions of male social status in an Amazonian society

While social-status hierarchies are common to all human societies, status acquisition is relatively understudied in small-scale societies lacking significant material wealth or intergenerational inheritance. Among the Tsimane of Bolivia, a small-scale Amazonian society, we employ a photo-ranking methodology to determine the important predictors of four measures of male social status: success in dyadic physical confrontation, getting one's way in a group, community-wide influence, and respect. The predictors evaluated include age, physical size, skill in food production, level of acculturation, prosocial personality, and social support. We find that physical size best predicts rankings of dyadic fighting ability while social support best predicts getting one's way in a group, community-wide influence, and respect. Level of acculturation, furthermore, is an independent predictor of influence but not respect, and skill in food production is an independent predictor of respect but not influence. The lack of a linear relationship between age and the polyadic social-status measures is evaluated in light of the increasing exposure of the Tsimane to market economies and public education among recent age cohorts. To our knowledge, this study is the first multivariate analysis of social status that considers different determinants of status simultaneously.

Aging and Inflammation in Two Epidemiological Worlds

Humans evolved in a world with high levels of infection resulting in high mortality across the life span and few survivors to advanced ages. Under such conditions, a strong acute-phase inflammatory response was required for survival; however, inflammatory responses can also promote chronic diseases of aging. We hypothesize that global historical increases in life span at older ages are partly explained by reduced lifetime exposure to infection and subsequent inflammation. To begin a test of this hypothesis, we compare C-reactive protein (CRP); levels in two populations with different epidemiological environments: the Tsimane of Bolivia and persons in the United States. High CRP is significantly more prevalent among the Tsimane up through middle age; by age 35, the Tsimane have spent more years with high CRP than have Americans at age 55. Further testing of the links among infection, inflammation, and chronic diseases of aging among the Tsimane requires collection of age-specific indicators of atherosclerosis and cardiac function.

Female intrasexual competition and reputational effects on attractiveness among the Tsimane of Bolivia

This study, conducted among Tsimane women of Bolivia, investigates the relationship between reputational reports and ratings of individual attractiveness. Reputations are, at least in part, created and maintained through linguistic avenues between group members and are thus open to manipulation by others. Taking this into account, we hypothesized that individuals might have the ability to influence the attractiveness of others indirectly by influencing their reputations. The data collected among Tsimane women show that reporting positive or negative information about other group members significantly predicts the rankings of attractiveness assigned to those group members. We found that characteristics surrounding motherhood, trustworthiness, housekeeping abilities, social intelligence, and wealth or status to be the most influential reputational reports on attractiveness. We found that reports of promiscuity had no significant affect on perceived attractiveness. Overall, the results demonstrate that attractiveness ratings reflected a significant reputational component.

Rethinking Polygyny: Co-Wives, Codes, and Cultural Systems [and Comments and Reply

Rethinking Polygyny: Co-Wives, Codes, and Cultural Systems [and Comments and Reply