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In large, complex societies, assorting with others with similar social norms or behaviors can facilitate successful coordination and cooperation. The ability to recognize others with shared norms or behaviors is thus assumed to be under selection. As a medium of communication, human art might reflect fitness-relevant information on shared norms and behaviors of other individuals thus facilitating successful coordination and cooperation. Distinctive styles or patterns of artistic design could signify migration history, different groups with a shared interaction history due to spatial proximity, as well as individual-level expertise and preferences. In addition, cultural boundaries may be even more pronounced in a highly diverse and socially stratified society. In the current study, we focus on a large corpus of an artistic tradition called kolam that is produced by women from Tamil Nadu in South India (N = 3, 139 kolam drawings from 192 women) to test whether stylistic variations in art can be mapped onto caste boundaries, migration and neighborhoods. Since the kolam art system with its sequential drawing decisions can be described by a Markov process, we characterize variation in styles of art due to different facets of an artist's identity and the group affiliations, via hierarchical Bayesian statistical models. Our results reveal that stylistic variations in kolam art only weakly map onto caste boundaries, neighborhoods, and regional origin. In fact, stylistic variations or patterns in art are dominated by artist-level variation and artist expertise. Our results illustrate that although art can be a medium of communication, it is not necessarily marked by group affiliation. Rather, artistic behavior in this context seems to be primarily a behavioral domain within which individuals carve out a unique niche for themselves to differentiate themselves from others. Our findings inform discussions on the evolutionary role of art for group coordination by encouraging researchers to use systematic methods to measure the mapping between specific objects or styles onto groups.

The rapid adoption of lightweight activity tracking sensors demonstrates that precise measures of physical activity hold great value for a wide variety of applications. The corresponding growth of physical activity data creates an urgent need for methods to integrate such data. In this paper, we demonstrate methods for 1) synchronizing accelerometer and Global Positioning System (GPS) data with optimal corrections for device-related time drift, and 2) producing principled estimates of step counts from GPS data. These methods improve the accuracy of time-resolved physical activity measures and permit pedestrian travel from either sensor to be expressed in terms of a common currency, step counts. We show that sensor-based estimates of step length correspond well with expectations based on independent measures, and functional relationships between step length, height, and movement speed expected from biomechanical models. Using 123 person-days of data in which Hadza hunter-gatherers wore both GPS devices and accelerometers, we find that GPS-based estimates of daily step counts have a good correspondence with accelerometer-recorded values. A multivariate linear model predicting daily step counts from distance walked, mean movement speed, and height has an R2 value of 0.96 and a mean absolute percent error of 16.8% (mean absolute error = 1,354 steps; mean steps per day = 15,800; n = 123). To best represent step count estimation error, we fit a Bayesian model and plot the distributions of step count estimates it generates. Our methods more accurately situate accelerometer-based measures of physical activity in space and time, and provide new avenues for comparative research in biomechanics and human movement ecology.

In post-industrial settings, apolipoprotein E4 (APOE4) is associated with increased cardiovascular and neurological disease risk. However, the majority of human evolutionary history occurred in environments with higher pathogenic diversity and low cardiovascular risk. We hypothesize that in high-pathogen and energy-limited contexts, the APOE4 allele confers benefits by reducing innate inflammation when uninfected, while maintaining higher lipid levels that buffer costs of immune activation during infection. Among Tsimane forager-farmers of Bolivia (N = 1266, 50% female), APOE4 is associated with 30% lower C-reactive protein, and higher total cholesterol and oxidized LDL. Blood lipids were either not associated, or negatively associated with inflammatory biomarkers, except for associations of oxidized LDL and inflammation which were limited to obese adults. Further, APOE4 carriers maintain higher levels of total and LDL cholesterol at low body mass indices (BMIs). These results suggest that the relationship between APOE4 and lipids may be beneficial for pathogen-driven immune responses and unlikely to increase cardiovascular risk in an active subsistence population., eLife digest Genes contain the instructions needed for a cell to make molecules called proteins, which perform various roles in the body. Different variants of a gene can affect how the protein works, and in some cases, can increase a person’s risk to develop certain diseases. For example, people who carry a version of the apolipoprotein E gene called APOE4 have a greater risk of developing Alzheimer’s disease or heart disease. Individuals with two copies of this genetic variant have a 45% higher risk of heart disease and 12 times higher risk of Alzheimer’s disease. Studies in industrialized countries suggest this increased risk may be the result of higher cholesterol and inflammation in people with APOE4. But if APOE4 is harmful, why does it continue to be so common worldwide? One potential explanation is that APOE4, which has been around since before modern humans, may be beneficial in some contexts. Cholesterol is essential for many vital tasks in the body. In physically demanding environments where parasitic infections are common – conditions similar to those experienced by early humans – APOE4 might be beneficial. Under those circumstances, having more cholesterol might help fuel metabolic activities, fight infections, or reduce inflammation caused by infections. Garcia et al. investigated the link between the APOE4 genetic variant, cholesterol and inflammation in 1,266 Indigenous Tsimane people from 80 villages in Bolivia. Tsimane people live an active lifestyle foraging and farming for food. Parasite infections are a common problem in their communities, but obesity rates are very low. Garcia et al. found that Tsimane people with at least one copy of the APOE4 have lower levels of inflammation and higher levels of cholesterol than those who have two copies of the APOE3 version of the gene. Very lean people with APOE4 had especially high levels of the so called “bad” low density lipoprotein (LDL) cholesterol compared to people with APOE3 only. However, in this situation, storing a little extra cholesterol may not be so bad. The findings contradict other studies that have linked obesity to higher LDL levels and APOE4 to higher levels of inflammation. For the majority of human history, humans lived in more physically strenuous and calorically restrictive environments, with less access to clean water. Garcia et al. suggest that the harmful effects of APOE4 seen in studies in more industrialized societies – where people tend to be more sedentary and have less exposure to pathogens – may reflect a mismatch between a person’s environment and their genes. More studies that capture the diversity of environmental conditions under which people live will help clarify the role of APOE4 health and disease.

Reproducibility is integral to science, but difficult to achieve. Previous research has quantified low rates of data availability and results reproducibility across the biological and behavioural sciences. Here, we surveyed 560 empirical publications, published between 1955 and 2018 in the social learning literature, a research topic that spans animal behaviour, behavioural ecology, cultural evolution and evolutionary psychology. Data were recoverable online or through direct data requests for 30% of this sample. Data recovery declines exponentially with time since publication, halving every 6 years, and up to every 9 years for human experimental data. When data for a publication can be recovered, we estimate a high probability of subsequent data usability (87%), analytical clarity (97%) and agreement of published results with reproduced findings (96%). This corresponds to an overall rate of recovering data and reproducing results of 23%, largely driven by the unavailability or incompleteness of data. We thus outline clear measures to improve the reproducibility of research on the ecology and evolution of social behaviour.

Poverty is bad for health. People living in poverty are more likely to struggle to afford nutritious food, lack access to health care, or be overworked or stressed. This may make them susceptible to chronic diseases, contribute to faster aging, and shorten their lifespans. In high-income countries, there is growing evidence to suggest that a person’s ‘rank’ in society also impacts their health. For example, individuals who have a lower position in the social hierarchy report worse health outcomes, regardless of their incomes. But it is unclear why living in an unequal society or having a lower social status contributes to poorer health. One possibility is that inequalities in society are creating a stressful environment that leads to worse physical and mental outcomes. It is thought that this stress largely comes from how humans evolved to prioritize reaching a higher social status over having a long and healthy life. If this is the case, this would mean that the link between social status and health would also be present in non-industrialized communities where social hierarchies tend to be less pronounced. To test this, Jaeggi, Blackwell et al. studied the Indigenous Tsimane population in Bolivia who live in small communities and forage and farm their own food. The income and relative wealth of 870 households from 40 Tsimane communities were compared against various outcomes, including symptoms associated with depression, stress hormone levels, blood pressure, self-rated health and several diseases. Jaeggi, Blackwell et al. found poverty and inequality did not negatively impact all of the health outcomes measured as has been previously reported for industrialized societies. However, blood pressure was higher among people with lower incomes or those who lived in more unequal communities. But because the Tsimane people generally have low blood pressure, the differences were too small to have much effect on their health. People who lived in more unequal communities were also three times more likely to have respiratory infections, but the reason for this was unclear. This shows that social determinants such as a person’s wealth or inequality can affect health, even in communities with less rigid social hierarchies. In industrial societies the effect may be worse in part because they are compounded by lifestyle factors, such as diets rich in fat and sugar, and physical inactivity which can also increase blood pressure. This information may help policy makers reduce health disparities by addressing some of the social determinants of health and the lifestyle factors that cause them.

In post-industrial settings,APOE4is associated with increased cardiovascular and neurological disease risk. However, the majority of human evolutionary history occurred in environments with higher pathogenic diversity and low cardiovascular risk. We hypothesize that in high-pathogen and energy-limited contexts, theAPOE4allele confers benefits by reducing baseline innate inflammation when uninfected, while maintaining higher lipid levels that buffer costs of immune activation during infection. Among Tsimane forager-farmers of Bolivia (N=1266),APOE4is associated with 30% lower C-reactive protein, and higher total cholesterol and oxidized-LDL. Blood lipids were either not associated, or negatively associated with inflammatory biomarkers, except for associations of oxidized-LDL and inflammation which were limited to obese adults. Further,APOE4carriers maintain higher levels of total and LDL cholesterol at low BMIs. These results suggest the relationship betweenAPOE4and lipids is likely beneficial for pathogen-driven immune responses, and unlikely to increase cardiovascular risk in an active subsistence population.

National audience; Background: Atrial fibrillation is the most common arrhythmia in post-industrialized populations. Older age, hypertension, obesity, chronic inflammation, and diabetes are significant atrial fibrillation risk factors, suggesting that modern urban environments may promote atrial fibrillation.Objective: Here we assess atrial fibrillation prevalence and incidence among tropical horticulturalists of the Bolivian Amazon with high levels of physical activity, a lean diet, and minimal coronary atherosclerosis, but also high infectious disease burden and associated inflammation.Methods: Between 2005–2019, 1314 Tsimane aged 40–94 years (52% female) and 534 Moseten Amerindians aged 40–89 years (50% female) underwent resting 12-lead electrocardiograms to assess atrial fibrillation prevalence. For atrial fibrillation incidence assessment, 1059 (81% of original sample) Tsimane and 310 Moseten (58%) underwent additional ECGs (mean time to follow up 7.0, 1.8 years, respectively).Findings:Only one (male) of 1314 Tsimane (0.076%) and one (male) of 534 Moseten (0.187%) demonstrated atrial fibrillation at baseline. There was one new (female) Tsimane case in 7395 risk years for the 1059 participants with >1 ECG (incidence rate = 0.14 per 1,000 risk years). No new cases were detected among Moseten, based on 542 risk years.Conclusion: Tsimane and Moseten show the lowest levels of atrial fibrillation ever reported, 1/20 to ~1/6 of rates in high-income countries. These findings provide additional evidence that a subsistence lifestyle with high levels of physical activity, and a diet low in processed carbohydrates and fat is cardioprotective, despite frequent infection-induced inflammation. Findings suggest that atrial fibrillation is a modifiable lifestyle disease rather than an inevitable feature of cardiovascular aging.

Reproducibility is integral to science, but difficult to achieve. We surveyed 560 empirical publications, published between 1955 and 2018 in the social learning literature, a research topic that spans animal behaviour, behavioural ecology, cultural evolution, and evolutionary psychology. Data was recoverable online or through direct data requests for 30% of this sample. Moreover, data recovery declines exponentially with time since publication, halving every 6 years, and up to every 9 years for human experimental data. When data for a publication can be recovered, we estimate a high probability of subsequent data usability (87%), analytical clarity (97%), and agreement of published results with reproduced findings (96%). This corresponds to an overall rate of recovering data and reproducing results of 23%, largely driven by unavailability or incompleteness of data. We thus outline clear measures to improve reproducibility of research on the ecology and evolution of social behaviour.

Storytelling can affect wellbeing and fitness by transmitting information and reinforcing cultural codes of conduct. Despite their potential importance, the development and timing of storytelling skills, and the transmission of story knowledge have received minimal attention in studies of subsistence societies that more often focus on food production skills. Here we examine how storytelling and patterns of information transmission among Tsimane forager-horticulturalists are predicted by the changing age profiles of storytellers' abilities and accumulated experience. We find that storytelling skills are most developed among older adults who demonstrate superior knowledge of traditional stories and who report telling stories most. We find that the important information transmitted via storytelling typically flows from older to younger generations, and stories are primarily learned from older same-sex relatives, especially grandparents. Our findings suggest that the oral tradition provides a specialized late-life service niche for Tsimane adults who have accumulated important experience and knowledge relevant to foraging and sociality, but have lost comparative advantage in other productive domains. These findings may help extend our understanding of the evolved human life history by illustrating how changes in embodied capital predict the development of information transmission services in a forager-horticulturalist economy.

The Tsimane Health and Life History Project, an integrated bio-behavioral study of the human life course, is designed to test competing hypotheses of human life-history evolution. One aim is to understand the bidirectional connections between life history and social behavior in a high-fertility, kin-based context lacking amenities of modern urban life (e.g. sanitation, banks, electricity). Another aim is to understand how a high pathogen burden influences health and well-being during development and adulthood. A third aim addresses how modernization shapes human life histories and sociality. Here we outline the project's goals, history, and main findings since its inception in 2002. We reflect on the implications of current findings and highlight the need for more coordinated ethnographic and biomedical study of contemporary nonindustrial populations to address broad questions that can situate evolutionary anthropology in a key position within the social and life sciences.

Persistent interest lies in gender inequality, especially with regard to the favouring of sons over daughters. Economists are concerned with how privilege is transmitted across generations, and anthropologists have long studied sex-biased inheritance norms. There has, however, been no focused cross-cultural investigation of how parent–offspring correlations in wealth vary by offspring sex. We estimate these correlations for 38 wealth measures, including somatic and relational wealth, from 15 populations ranging from hunter–gatherers to small-scale farmers. Although small sample sizes limit our statistical power, we find no evidence of ubiquitous male bias, at least as inferred from comparing parent–son and parent–daughter correlations. Rather we find wide variation in signatures of sex bias, with evidence of both son and daughter-biased transmission. Further, we introduce a model that helps pinpoint the conditions under which simple mid-point parent–offspring wealth correlations can reveal information about sex-biased parental investment. Our findings are relevant to the study of female-biased kinship by revealing just how little normative descriptors of kinship systems, such as patrilineal inheritance, capture intergenerational correlations in wealth, and how variable parent–son and parent–daughter correlations can be.This article is part of the theme issue ‘The evolution of female-biased kinship in humans and other mammals'.

Whitehouse, et al. have recently used the Seshat archaeo-historical databank to argue that beliefs in moralizing gods appear in world history only after the formation of complex “megasocieties” of around one million people. Inspection of the authors’ data, however, shows that 61% of Seshat data points on moralizing gods are missing values, mostly from smaller populations below one million people, and during the analysis the authors re-coded these data points to signify the absence of moralizing gods beliefs. When we confine the analysis only to the extant data or use various standard imputation methods, the reported finding is reversed: moralizing gods precede increases in social complexity. We suggest that the reported “megasociety threshold” for the emergence of moralizing gods is thus solely a consequence of the decision to re-code nearly two-thirds of Seshat data from unknown values to known absences of moralizing gods.

Cognitive performance is characterized by at least two distinct life course trajectories. Many cognitive abilities (e.g., "effortful processing" abilities, including fluid reasoning and processing speed) improve throughout early adolescence and start declining in early adulthood, whereas other abilities (e.g., "crystallized" abilities like vocabulary breadth) improve throughout adult life, remaining robust even at late ages. Although schooling may impact performance and cognitive "reserve," it has been argued that these age patterns of cognitive performance are human universals. Here we examine age patterns of cognitive performance among Tsimane forager-horticulturalists of Bolivia and test whether schooling is related to differences in cognitive performance over the life course to assess models of active versus passive cognitive reserve. We used a battery of eight tasks to assess a range of latent cognitive traits reflecting attention, processing speed, verbal declarative memory, and semantic fluency (n = 919 individuals, 49.9% female). Tsimane cognitive abilities show similar age-related differences as observed in industrialized populations: higher throughout adolescence and only slightly lower in later adulthood for semantic fluency but substantially lower performance beginning in early adulthood for all other abilities. Schooling is associated with greater cognitive abilities at all ages controlling for sex but has no attenuating effect on cognitive performance in late adulthood, consistent with models of passive cognitive reserve. We interpret the minimal attenuation of semantic fluency late in life in light of evolutionary theories of postreproductive life span, which emphasize indirect fitness contributions of older adults through the transfer of information, labor, and food to descendant kin. (PsycINFO Database Record

The apolipoprotein E4 (E4) allele is present worldwide, despite its associations with higher risk of cardiovascular morbidity, accelerated cognitive decline during aging, and Alzheimer’s disease (AD). The E4 allele is especially prevalent in some tropical regions with a high parasite burden. Equatorial populations also face a potential dual burden of high E4 prevalence combined with parasitic infections that can also reduce cognitive performance. We examined the interactions of E4, parasite burden, and cognitive performance in a traditional, nonindustrialized population of Amazonian forager-horticulturalists (N = 372) to test whether E4 protects against cognitive decline in environments with a heavy pathogen burden. Contrary to observations in industrial populations, older adult E4 carriers with high parasite burdens either maintained or showed slight improvements in cognitive performance, whereas non-E4 carriers with a high parasite burden showed reduced cognitive performance. Being an E4 carrier is the strongest risk factor to date of AD and cognitive decline in industrial populations; it is associated with greater cognitive performance in individuals facing a high parasite and pathogen load, suggesting advantages to the E4 allele under certain environmental conditions. The current mismatch between postindustrial hygienic lifestyles and active parasite-rich environs may be critical for understanding genetic risk for cognitive aging.—Trumble, B. C., Stieglitz, J., Blackwell, A. D., Allayee, H., Beheim, B., Finch, C. E., Gurven, M., Kaplan, H. Apolipoprotein E4 is associated with improved cognitive function in Amazonian forager-horticulturalists with a high parasite burden.

Author(s): Gurven, Michael D; Trumble, Benjamin C; Stieglitz, Jonathan; Yetish, Gandhi; Cummings, Daniel; Blackwell, Aaron D; Beheim, Bret; Kaplan, Hillard S; Pontzer, Herman | Abstract: ObjectivesResting metabolic rate (RMR) reflects energetic costs of homeostasis and accounts for 60 to 75% of total energy expenditure (TEE). Lean mass and physical activity account for much RMR variability, but the impact of prolonged immune activation from infection on human RMR is unclear in naturalistic settings. We evaluate the effects of infection on mass-corrected RMR among Bolivian forager-horticulturalists, and assess whether RMR declines more slowly with age than in hygienic sedentary populations, as might be expected if older adults experience high pathogen burden.Materials and methodsRMR was measured by indirect calorimetry (Fitmate MED, Cosmed) in 1,300 adults aged 20 to 90 and TEE was measured using doubly labeled water (n = 40). Immune biomarkers, clinical diagnoses, and anthropometrics were collected by the Tsimane Health and Life History Project.ResultsTsimane have higher RMR and TEE than people in sedentary industrialized populations. Tsimane RMR is 18 to 47% (women) and 22 to 40% (men) higher than expected using six standard prediction equations. Tsimane mass-corrected TEE is similarly elevated compared to Westerners. Elevated leukocytes and helminths are associated with excess RMR in multivariate regressions, and jointly result in a predicted excess RMR of 10 to 15%. After age 40, RMR declines by 69 kcal/decade (p l .0001). Controlling for lean mass and height accounts for 71% of age-related RMR decline, and adding indicators of infection minimally affects the age slope. The residual level of age-related decline from age 40 is 1.2% per decade.ConclusionHigh pathogen burden may lead to higher metabolic costs, which may be offset by smaller body mass or other energy-sparing mechanisms.

Author(s): Ross, Cody T; Mulder, Monique Borgerhoff; Oh, Seung-Yun; Bowles, Samuel; Beheim, Bret; Bunce, John; Caudell, Mark; Clark, Gregory; Colleran, Heidi; Cortez, Carmen; Draper, Patricia; Greaves, Russell D; Gurven, Michael; Headland, Thomas; Headland, Janet; Hill, Kim; Hewlett, Barry; Kaplan, Hillard S; Koster, Jeremy; Kramer, Karen; Marlowe, Frank; McElreath, Richard; Nolin, David; Quinlan, Marsha; Quinlan, Robert; Revilla-Minaya, Caissa; Scelza, Brooke; Schacht, Ryan; Shenk, Mary; Uehara, Ray; Voland, Eckart; Willfuhr, Kai; Winterhalder, Bruce; Ziker, John | Abstract: With apologies, an incorrect author list was given in the article. An additional author, Chris von Rueden, (Jepson School of Leadership Studies, University of Richmond) also contributed to this work. Author Ryan Schacht's affiliation was out-of-date. His correct affiliation is: Department of Anthropology, East Carolina University.

© 2018 The Author(s) Published by the Royal Society. All rights reserved. Monogamy appears to have become the predominant human mating system with the emergence of highly unequal agricultural populations that replaced relatively egalitarian horticultural populations, challenging the conventional idea - based on the polygyny threshold model - that polygyny should be positively associated with wealth inequality. To address this polygyny paradox, we generalize the standard polygyny threshold model to a mutual mate choice model predicting the fraction of women married polygynously. We then demonstrate two conditions that are jointly sufficient to make monogamy the predominant marriage form, even in highly unequal societies. We assess if these conditions are satisfied using individual-level data from 29 human populations. Our analysis shows that with the shift to stratified agricultural economies: (i) the population frequency of relatively poor individuals increased, increasing wealth inequality, but decreasing the frequency of individuals with sufficient wealth to secure polygynous marriage, and (ii) diminishing marginal fitness returns to additional wives prevent extremely wealthy men from obtaining as many wives as their relative wealth would otherwise predict. These conditions jointly lead to a high population-level frequency of monogamy.

The physiology of fatherhood is a growing field of study, and variability in hormonal mediators of reproductive effort (e.g. testosterone, cortisol) can predict variability in paternal investment. Studies often find that lower testosterone levels are associated with increased paternal investment, though most studies are conducted under relatively stable ecological conditions. In this paper, we examine parental physiological correlates of crop loss and family health problems among Tsimane forager-horticulturalists following a catastrophic flood in lowland Bolivia. Immediately after a devastating 2014 flood that impacted75% of Tsimane communities, we conducted structured interviews examining crop losses and morbidity, and collected saliva specimens from 421 parents (n = 292 households) to analyze cortisol and testosterone. Over 98% of interviewees reported horticultural losses, with the average family losing 88% of their crops, while 80% of families reported flood-induced injuries or illnesses. Controlling for age, body mass index, and time of specimen collection, men's testosterone was negatively associated with both absolute cropland losses (Std. β = -0.16, p = 0.037), and percent of cropland lost (Std. β = -0.16, p = 0.040). Female testosterone was not associated with crop losses. Using the same control variables, both male and female cortisol was negatively associated with a composite measure of child health burden (fathers: Std. β = -0.34, p 0.001; mothers: Std. β = -0.23, p = 0.037). These results are discussed in the cultural context of a strong sexual division of labor among Tsimane; we highlight the physiological and psychosocial costs of experiencing a natural disaster, especially for paternal caregivers in a nutritionally and pathogenically stressed subsistence population where cultigens provide the majority of calories in the diet.

Evolutionary theories of aging posit that greater reproductive effort causes somatic decline given a fundamental trade-off between investing energy in reproduction and repair. Few studies in high fertility human populations support this hypothesis, and prob- lems of phenotypic correlation can obscure the expected trade-off between reproduction and somatic condition. This cross-sectional study investigates whether greater reproductive effort is associated with reduced calcaneal bone mineral density (BMD) among female Tsimane forager-farmers of lowland Bolivia. We also investigate whether female Tsimane BMD values are lower than sex- and age-matched US reference values, despite the fact that Tsimane engage in higher physical activity lev- els that can increase mechanical loading. To measure calcaneal BMD, quantitative ultrasonography was per- formed on 130 women (mean 6 SD age 5 36.6 6 15.7, range 5 15-75) that were recruited regardless of past or current reproductive status. Anthropometric and demo- graphic data were collected during routine medical exams. As predicted, higher parity, short inter-birth interval, and earlier age at first birth are associated with reduced BMD among Tsimane women after adjust- ing for potential confounders. Population-level differen- ces are apparent prior to the onset of reproduction, and age-related decline in BMD is greater among Tsimane compared with American women. Greater cumulative reproductive burden may lower calcaneal BMD individu- ally and jointly with other lifestyle and heritable factors. Fitness impacts of kin transfers in adulthood may deter- mine the value of investments in bone remodeling, and thus affect selection on age-profiles of bone mineral loss.

Summary Background Conventional coronary artery disease risk factors might potentially explain at least 90% of the attributable risk of coronary artery disease. To better understand the association between the pre-industrial lifestyle and low prevalence of coronary artery disease risk factors, we examined the Tsimane, a Bolivian population living a subsistence lifestyle of hunting, gathering, fishing, and farming with few cardiovascular risk factors, but high infectious inflammatory burden. Methods We did a cross-sectional cohort study including all individuals who self-identified as Tsimane and who were aged 40 years or older. Coronary atherosclerosis was assessed by coronary artery calcium (CAC) scoring done with non-contrast CT in Tsimane adults. We assessed the difference between the Tsimane and 6814 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). CAC scores higher than 100 were considered representative of significant atherosclerotic disease. Tsimane blood lipid and inflammatory biomarkers were obtained at the time of scanning, and in some patients, longitudinally. Findings Between July 2, 2014, and Sept 10, 2015, 705 individuals, who had data available for analysis, were included in this study. 596 (85%) of 705 Tsimane had no CAC, 89 (13%) had CAC scores of 1–100, and 20 (3%) had CAC scores higher than 100. For individuals older than age 75 years, 31 (65%) Tsimane presented with a CAC score of 0, and only four (8%) had CAC scores of 100 or more, a five-fold lower prevalence than industrialised populations (p≤0·0001 for all age categories of MESA). Mean LDL and HDL cholesterol concentrations were 2·35 mmol/L (91 mg/dL) and 1·0 mmol/L (39·5 mg/dL), respectively; obesity, hypertension, high blood sugar, and regular cigarette smoking were rare. High-sensitivity C-reactive protein was elevated beyond the clinical cutoff of 3·0 mg/dL in 360 (51%) Tsimane participants. Interpretation Despite a high infectious inflammatory burden, the Tsimane, a forager-horticulturalist population of the Bolivian Amazon with few coronary artery disease risk factors, have the lowest reported levels of coronary artery disease of any population recorded to date. These findings suggest that coronary atherosclerosis can be avoided in most people by achieving a lifetime with very low LDL, low blood pressure, low glucose, normal body-mass index, no smoking, and plenty of physical activity. The relative contributions of each are still to be determined. Funding National Institute on Aging, National Institutes of Health; St Luke's Hospital of Kansas City; and Paleocardiology Foundation.

Son preference predominates in China, yet there are patterned exceptions to this rule. In this paper, we test whether lineality (patrilineal versus matrilineal inheritance and descent) is associated with son versus daughter preference among the ethnic Mosuo (Na) of Southwest China. Our results show (i) an increased probability of continued fertility among matrilineal women after having a son compared with a daughter and (ii) an increased probability of continued fertility among patrilineal women after having a daughter compared with a son. These results are consistent with son preference among patrilineal Mosuo and more muted daughter preference among the matrilineal Mosuo. Furthermore, we show (iii) the lowest probability of continued fertility at parity 2 once women have one daughter and one son across both systems, suggesting that preferences for at least one of each sex exist alongside preferences for the lineal sex. The Mosuo are the only known small-scale society in which two kinship systems distinguish sub-groups with many otherwise shared cultural characteristics. We discuss why this, in conjunction with differences in subsistence, may shed light on the evolutionary underpinnings of offspring sex preferences.

Women exhibit greater morbidity than men despite higher life expectancy. An evolutionary life history framework predicts that energy invested in reproduction trades-off against investments in maintenance and survival. Direct costs of reproduction may therefore contribute to higher morbidity, especially for women given their greater direct energetic contributions to reproduction. We explore multiple indicators of somatic condition among Tsimane forager-horticulturalist women (Total Fertility Rate = 9.1; n = 592 aged 15–44 years, n = 277 aged 45+). We test whether cumulative live births and the pace of reproduction are associated with nutritional status and immune function using longitudinal data spanning 10 years. Higher parity and faster reproductive pace are associated with lower nutritional status (indicated by weight, body mass index, body fat) in a cross-section, but longitudinal analyses show improvements in women’s nutritional status with age. Biomarkers of immune function and anemia vary little with parity or pace of reproduction. Our findings demonstrate that even under energy-limited and infectious conditions, women are buffered from the potential depleting effects of rapid reproduction and compound offspring dependency characteristic of human life histories.

BackgroundAmazonian populations are exposed to diverse parasites and pathogens, including protozoal, bacterial, fungal and helminthic infections. Yet much knowledge of the immune system is based on industrialised populations where these infections are relatively rare.AimThis study examines distributions and age-related differences in 22 measures of immune function for Bolivian forager-horticulturalists and US and European populations.Subjects and methodsSubjects were 6338 Tsimane aged 0-90 years. Blood samples collected between 2004-2014 were analysed for 5-part blood differentials, C-reactive protein, erythrocyte sedimentation rate (ESR) and total immunoglobulins E, G, A and M. Flow cytometry was used to quantify naïve and non-naïve CD4 and CD8 T cells, natural killer cells, and B cells.ResultsCompared to reference populations, Tsimane have elevated levels of most immunological parameters, particularly immunoglobulins, eosinophils, ESR, B cells, and natural killer cells. However, monocytes and basophils are reduced and naïve CD4 cells depleted in older age groups.ConclusionTsimane ecology leads to lymphocyte repertoires and immunoglobulin profiles that differ from those observed in industrialised populations. These differences have consequences for disease susceptibility and co-vary with patterns of other life history traits, such as growth and reproduction.

Objectives Growth standards and references currently used to assess population and individual health are derived primarily from urban populations, including few individuals from indigenous or subsistence groups. Given environmental and genetic differences, growth may vary in these populations. Thus, there is a need to assess whether international standards are appropriate for all populations, and to produce population specific references if growth differs. Here we present and assess growth references for the Tsimane, an indigenous population of Bolivian forager-horticulturalists. Methods Mixed cross-sectional/longitudinal anthropometrics (9,614 individuals; 30,118 observations; ages 0–29 years) were used to generate centile curves and Lambda-Mu-Sigma (LMS) tables for height-for-age, weight-for-age, body mass index (BMI)-for-age, and weight-for-height (WFH) using Generalized Additive Models for Location Shape and Scale (GAMLSS). Velocity curves were generated using SuperImposition by Translation and Rotation (SITAR). Tsimane ≤5 years were compared to World Health Organization (WHO) standards while those >5 years were compared to WHO school age references. All ages were compared to published references for Shuar forager-horticulturalists of the Ecuadorian Amazon. Results Tsimane growth differs from WHO values in height and weight, but is similar for BMI and WFH. Tsimane growth is characterized by slow height velocity in childhood and early adolescent peak height velocity at 11.3 and 13.2 years for girls and boys. Tsimane growth patterns are similar to Shuar, suggesting shared features of growth among indigenous South Americans. Conclusions International references for BMI-for-age and WFH are likely appropriate for Tsimane, but differences in height-for-age and weight-for-age suggest Tsimane specific references may be useful for these measures.

Studying fitness consequences of variable behavioural, physiological and cognitive traits in contemporary populations constitutes the specific contribution of human behavioural ecology to the study of human diversity. Yet, despite 30 years of evolutionary anthropological interest in the determinants of fitness, there exist few principled investigations of the diverse sources of wealth that might reveal selective forces during recent human history. To develop a more holistic understanding of how selection shapes human phenotypic traits, be these transmitted by genetic or cultural means, we expand the conventional focus on associations between socioeconomic status and fitness to three distinct types of wealth—embodied, material and relational. Using a model selection approach to the study of women's success in raising offspring in an African horticultural population (the Tanzanian Pimbwe), we find that the top performing models consistently include relational and material wealth, with embodied wealth as a less reliable predictor. Specifically, child mortality risk is increased with few household assets, parent nonresidency, child legitimacy, and one or more parents having been accused of witchcraft. The use of multiple models to test various hypotheses greatly facilitates systematic comparative analyses of human behavioural diversity in wealth accrual and investment across different kinds of societies.

Social organisms sometimes depend on help from reciprocating partners to solve adaptive problems [1], and individual cooperation strategies should aim to offer high supply commodities at low cost to the donor in exchange for high-demand commodities with large return benefits [2, 3]. Although such market dynamics have been documented in some animals [4-7], naturalistic studies of human cooperation are often limited by focusing on single commodities [8]. We analyzed cooperation in five domains (meat sharing, produce sharing, field labor, childcare, and sick care) among 2,161 household dyads of Tsimane' horticulturalists, using Bayesian multilevel models and information-theoretic model comparison. Across domains, the best-fit models included kinship and residential proximity, exchanges in kind and across domains, measures of supply and demand and their interactions with exchange, and household-specific exchange slopes. In these best models, giving, receiving, and reciprocating were to some extent shaped by market forces, and reciprocal exchange across domains had a strong partial effect on cooperation independent of more exogenous factors like kinship and proximity. Our results support the view that reciprocal exchange can provide a reliable solution to adaptive problems [8-11]. Although individual strategies patterned by market forces may generate gains from trade in any species [3], humans' slow life history and skill-intensive foraging niche favor specialization and create interdependence [12, 13], thus stabilizing cooperation and fostering divisions of labor even in informal economies [14, 15].

Parasitic worms influence human fecundity Parasitic worms infect 2 billion people globally. Mostly, such infections are symptomless and individual worm burdens are low. Blackwell et al. monitored the fecundity of Tsimane women in Bolivia. These women have on average of 10 children in their lifetimes. However, if they had successive hookworm infections, lifetime births dropped to 7. Surprisingly, if the women were chronically infested with roundworm, they had as many as 12 children. These effects may relate to the balance of immune responses that the different worms induce, rather than to the physiological costs of parasitism. Science , this issue p. 970

Thoracic aortic calcium (TAC) is thought to be a manifestation of atherosclerosis with risk factors similar to those for CAD. To better understand TAC, we examined the Tsimane, a remote Bolivian Amazonian population with few CV factors and the lowest recorded levels of coronary artery calcium (CAC

Human culture is widely believed to undergo evolution, via mechanisms rooted in the nature of human cognition. A number of theories predict the kinds of human learning strategies, as well as the population dynamics that result from their action. There is little work, however, that quantitatively examines the evidence for these strategies and resulting cultural evolution within human populations. One of the obstacles is the lack of individual-level data with which to link transmission events to larger cultural dynamics. Here, we address this problem with a rich quantitative database from the East Asian board game known as Go. We draw from a large archive of Go games spanning the last six decades of professional play, and find evidence that the evolutionary dynamics of particular cultural variants are driven by a mix of individual and social learning processes. Particular players vary dramatically in their sensitivity to population knowledge, which also varies by age and nationality. The dynamic patterns of opening Go moves are consistent with an ancient, ongoing arms race within the game itself.

Author(s): Beheim, Bret A; Baldini, Ryan | Abstract: Beginning with the Price equation, recent work has developed the method of evolutionary decomposition, an exact partitioning of mean phenotypic change into underlying demographic processes. We present a method of evolutionary decomposition for human cultural change, and a demonstration of this method on three centuries of half-decadal census records collected from a simulated island population. By decomposing phenotypic trajectories, we can develop and evaluate suitable hypotheses of the driving mechanisms of cultural evolution.

We consider patterns in the evolution of canoe technology in the eastern Pacific relative to three general processes: movement of canoe traits along the Polynesian settlement sequence, adaptations to local island environment, and post-settlement interaction between island groups. Using model selection methods on the distributions of canoe technology, we show that social and ecological covariates together consistently outperform each considered individually, though knowledge of island area and post-settlement trading spheres does not add explanatory power. In particular, decorative canoe traits are not effectively explained by either our ecological or transmission models. We also estimate negative effects from both settlement sequence and island geomorphology, consistent with the die-off of particular canoe designs on resource-rich high island groups such as Hawaii and New Zealand. This decline in measured traits may be owing to the lifting of ecological constraints on population size or building materials.