Summary This study presents an empirical model based on a GIS approach, which was constructed to estimate the large‐scale carbon fluxes over the entire Russian tundra zone. The model has four main blocks: (i) the computer map of tundra landscapes; (ii) data base of long‐term weather records; (iii) the submodel of phytomass seasonal dynamics; and (iv) the submodel of carbon fluxes. The model uses exclusively original in situ diurnal CO2 flux chamber measurements (423 sample plots) conducted during six field seasons (1993–98). The research sites represent the main tundra biome landscapes (arctic, typical, south shrub and mountain tundras) in the latitudinal diapason of 65–74°N and longitudinal profile of 63°E−172°W. The greatest possible diversity of major ecosystem types within the different landscapes was investigated. The majority of the phytomass data used was obtained from the same sample plots. The submodel of carbon fluxes has two dependent [GPP, Gross Respiration (GR)] and several input variables (air temperature, PAR, aboveground phytomass components). The model demonstrates a good correspondence with other independent regional and biome estimates and carbon flux seasonal patterns. The annual GPP of Russian tundra zone for the area of 235 × 106 ha was estimated as −485.8 ± 34.6 × 106 tC, GR as +474.2 ± 35.0 × 106 tC, and NF as −11.6 ± 40.8 × 106 tC, which possibly corresponds to an equilibrium state of carbon balance during the climatic period studied (the first half of the 20th century). The results advocate that simple regression‐based models are useful for extrapolating carbon fluxes from small to large spatial scales.

We discuss our findings with reference to differences in mating systems between the two small-scale societies and previous findings of Western and other small-scale societies.

The androgen receptor (AR) gene polymorphism in humans is linked to aggression and may also be linked to reproduction. Here we report associations between AR gene polymorphism and aggression and reproduction in two small-scale societies in northern Tanzania (Africa)—the Hadza (monogamous foragers) and the Datoga (polygynous pastoralists). We secured self-reports of aggression and assessed genetic polymorphism of the number of CAG repeats for the AR gene for 210 Hadza men and 229 Datoga men (aged 17–70 years). We conducted structural equation modeling to identify links between AR gene polymorphism, aggression, and number of children born, and included age and ethnicity as covariates. Fewer AR CAG repeats predicted greater aggression, and Datoga men reported more aggression than did Hadza men. In addition, aggression mediated the identified negative relationship between CAG repeats and number of children born.

ObjectivesPrevious research has documented associations of physical strength and facial morphology predominantly in men of Western societies. Faces of strong men tend to be more robust, are rounder and have a prominent jawline compared with faces of weak men. Here, we investigate whether the morphometric patterns of strength-face relationships reported for members of industrialized societies can also be found in members of an African pastoralist society, the Maasai of Northern Tanzania.Materials and methodsHandgrip strength (HGS) measures and facial photographs were collected from a sample of 185 men and 120 women of the Maasai in the Ngorongoro Conservation Area. In young-adults (20–29 years; n = 95) and mid-adults (30–50 years; n = 114), we digitized 71 somatometric landmarks and semilandmarks to capture variation in facial morphology and performed shape regressions of landmark coordinates upon HGS. Results were visualized in the form of thin-plate plate spline deformation grids and geometric morphometric morphs.ResultsIndividuals with higher HGS tended to have wider faces with a lower and broader forehead, a wider distance between the medial canthi of the eyes, a wider nose, fuller lips, and a larger, squarer lower facial outline compared with weaker individuals of the same age-sex group. In mid-adult men, these associations were weaker than in the other age-sex groups.DiscussionWe conclude that the patterns of HGS relationships with face shape in the Maasai are similar to those reported from related investigations in samples of industrialized societies. We discuss differences between the present and related studies with regard to knowledge about the causes for age- and sex-related facial shape variation and physical strength associations.

The objective of this study was to estimate the CO2 exchange of a tundra ecosystem in the Russian Far East using the eddy covariance technique using closed‐chamber measurements as a reference. An eddy covariance tower was placed near the Lavrentiya settlement (Chukotskiy Peninsula, Russia, 65° 36′N, 171°04′W) within a typical tundra landscape. During the 85 d of continuous measurements [Julian days (JD) 205–289, 2000] the CO2 exchange of the studied ecosystem was found to be close to equilibrium (a carbon sink at 10.2 gC m−2). In the late summer period (JD 205–240) the ecosystem sequestered 32.1 gC m−2, whereas in autumn (JD 241–289), it was functioning as a carbon source of 21.9 gC m−2. Model‐based estimates of ecosystem respiration and gross primary production were obtained over the period of observations. These are the first eddy covariance‐based measurements performed in the Russian tundra.

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The aim of this study was to analyse the relationships between polymorphisms in four candidate genes (AR, DAT1, DRD2, and COMT) and aggression in men from a traditional society of East African pastoralists, the Datoga. Buss and Perry's Aggression Questionnaire was used to measure aggression. The number of CAG repeats in the AR gene was negatively correlated with physical aggression, anger, and hostility. Among the genes of the dopaminergic system, a significant single-gene effect was detected only for DRD2 with regard to anger. At the level of a two-gene model, a significant effect for DRD2 and a tendency for DAT1 were observed for the DAT1-DRD2 gene pair regarding hostility, and two tendencies were observed for the interaction effect of the DAT1-COMT pair regarding anger and hostility. These data suggest a probable link between physical aggression and direct fitness caused by strong sexual selection in Datoga men.

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