Human life history contains a series of paradoxes not easily explained by classical life history theory. While overall reproductive output is higher than in related primates, juvenile growth is slower and age-specific reproductive rates decline faster with age. A simple energetic model would predict that growth and reproductive rates should be positively correlated and that reproductive effort should not decelerate with age. The pattern of negative correlations in humans suggests the presence of trade-offs among peak reproductive rate, childhood growth, and reproductive rate at older ages. To address this puzzle, we propose a synthesis of reproductive ecology and behavioral ecology focused on intra-and inter-somatic energy transfers. This integration includes three concepts: the mother as final common pathway through which energy must pass to result in offspring; a distinction between direct and indirect reproductive effort, proposing the latter as a novel net energy allocation category relative to growth and direct reproductive effort; and a pooled energy budget representing the energetic contributions and withdrawals of all members of a breeding community. Individuals at all reproductive life stages are considered in light of their contributions to the pooled energy budget.

Leptin is important in a wide range of physiological processes, but logistical constraints associated with venipuncture blood collection have limited research on leptin in diverse, community-based settings. The aim of this short report is to present and validate an enzyme immunoassay method for quantifying leptin in samples of capillary whole blood collected from a simple finger prick and dried on filter paper. The method was evaluated through analysis of precision, reliability, stability, and comparisons with matched plasma and blood spot samples. We report acceptable levels of assay precision and reliability, and good agreement between results obtained from matched plasma and blood spot samples (r = 0.976, P < 0.001). Leptin concentrations begin to deteriorate after only 3 days at room temperature. Thus, care should be taken to refrigerate or freeze samples promptly. The relative ease of blood spot sample collection may facilitate research on leptin in a wider range of cultural and ecological settings.

Leptin is thought to signal energy stores, thus helping the body balance energy intake and expenditure. However, the strong relationship between leptin and adiposity in populations with adequate nutrition or common obesity is not universal across ecologic contexts, and leptin often correlates only weakly, or not at all, with adiposity in populations of lean or marginally-nourished males. To clarify whether the relationship between adiposity and leptin changes during development, this study examines leptin and body fat among children and adolescents of lowland Bolivia. Anthropometric measures of body composition and dried blood spot samples were collected from 487 Tsimane' ranging from 2 to 15 years of age. Leptin was assayed using an enzyme immunoassay protocol validated for use with blood spot samples. In this population, leptin concentrations were among the lowest reported in a human population (mean +/- SD: 1.26 +/- 0.5 and 0.57 +/- 0.3 in females and males). In addition, the relationship between leptin and adiposity follows distinct developmental trajectories in males and females. In males, leptin is weakly correlated with most measures of body composition at all ages investigated. However, in females, the level of body fat and the strength of the correlation between body fat and leptin (a measure of its strength as a signal of energy stores) both increase markedly with age. These findings suggest a more important role of leptin as a signal of energy stores among females as they approach reproductive maturity, while raising questions about the function of this hormone in lean males.

This paper presents data on selected indicators to show progress towards elimination goals and targets for hepatitis B and hepatitis C in the 31 countries of the European Union (EU) and European Economic Area (EEA). A monitoring system was developed by the European Centre for Disease Prevention and Control, which combined newly collected data from EU/EEA countries along with relevant data from existing sources. Data for 2017 were collected from the EU/EEA countries via an online survey. All countries provided responses. In 2017, most countries reporting data had not reached prevention targets for childhood hepatitis B vaccination and for harm reduction services targeting people who inject drugs (PWID). Four of 12 countries had met the target for proportion of people living with chronic HBV diagnosed and seven of 16 met this target for hepatitis C. Data on diagnosed cases treated were lacking for hepatitis B. Of 12 countries reporting treatment data for hepatitis B, only Iceland met the target. This first collection of data across the EU/EEA highlighted major issues with data completeness and quality and in the indicators that were used, which impairs a clear overview of progress towards the elimination of hepatitis. The available data, whilst incomplete, suggest that as of 2017, the majority of the EU/EEA countries were far from meeting most of the 2020 targets, in particular those relating to harm reduction and diagnosis. It is critical to improve the data collected in order to develop more effective services for hepatitis prevention, diagnosis, and treatment that are needed in order to meet the 2030 elimination targets.

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