Seasonal glucocorticoid production correlates with a suite of small-magnitude environmental, demographic, and physiological effects in mandrills.

OBJECTIVES: The activation of the hypothalamic-pituitary-adrenal axis is a neuroendocrine response to external and internal changes that animals face on a predictable or unpredictable basis. Across species, variation in glucocorticoid production has been related to such changes. In this study, we investigated the predictable, seasonal sources of variation in the levels of fecal glucocorticoid metabolites (fGCM) in a large natural population of mandrills (Mandrillus sphinx) in Southern Gabon. MATERIALS AND METHODS: Using five years of regular behavioral monitoring and hormone analyses performed on 1,233 fecal samples collected on 99 individuals of both sexes and all ages and General Linear Mixed Models, we studied the three main seasonal predictors of fGCM concentrations: (i) weather conditions, (ii) number of adult males, and (iii) female reproductive status. These three predictors all vary seasonally in mandrills. RESULTS: We first showed an increase in fGCM concentrations during the short dry season while controlling for other factors. Pregnant females, which include the large majority of adult females at this time of the year, mainly drove this increase, although a combination of other small-magnitude, season-related effects linked to climatic events and demographic changes also partly explained this seasonal trend. Indeed, fGCM concentrations increased with both low temperatures (and low rainfall) and high numbers of adult males present in the group. These seasonal changes, while correlated, held true throughout the studied years and when restricting our analyses to a given season. Finally, we found that older mandrills showed on average higher fGCM concentrations than younger ones and that medium-ranked females exhibited the highest levels of fGCMs. DISCUSSION: The observed patterns suggest that plasticity in mandrills' metabolism in the form of glucocorticoid production allows them to adjust to predictable changes in climatic, demographic and physiological conditions by mobilizing and redirecting energetic resources toward appropriate, calibrated seasonal responses.

Women's attractiveness is linked to expected age at menopause.

A great number of studies have shown that features linked to immediate fertility explain a large part of the variance in female attractiveness. This is consistent with an evolutionary perspective, as men are expected to prefer females at the age at which fertility peaks (at least for short-term relationships) in order to increase their reproductive success. However, for long-term relationships, a high residual reproductive value (the expected future reproductive output, linked to age at menopause) becomes relevant as well. In that case, young age and late menopause are expected to be preferred by men. However, the extent to which facial features provide cues to the likely age at menopause has never been investigated so far. Here, we show that expected age at menopause is linked to facial attractiveness of young women. As age at menopause is heritable, we used the mother's age at menopause as a proxy for her daughter's expected age of menopause. We found that men judged faces of women with a later expected age at menopause as more attractive than those of women with an earlier expected age at menopause. This result holds when age, cues of immediate fertility and facial ageing were controlled for. Additionally, we found that the expected age at menopause was not correlated with any of the other variables considered (including immediate fertility cues and facial ageing). Our results show the existence of a new correlate of women's facial attractiveness, expected age at menopause, which is independent of immediate fertility cues and facial ageing.

Sibship effects on dispersal behaviour in a pre-industrial human population.

Understanding dispersal behaviour and its determinants is critical for studies on life-history maximizing strategies. Although many studies have investigated the causes of dispersal, few have focused on the importance of sibship, despite that sibling interactions are predicted to lead to intrafamilial differences in dispersal patterns. Using a large demographic data set from pre-industrial Finland (n = 9000), we tested whether the sex-specific probability of dispersal depended on the presence of same-sex or opposite-sex elder siblings who can both compete and cooperate in the family. Overall, following our predictions, the presence of same-sex elder siblings increased the probability of dispersal from natal population for both sexes, whereas the number of opposite-sex siblings had less influence. Among males, dispersal was strongly linked to access to land resources. Female dispersal was mainly associated with competition over availability of mates but likely mediated by competition over access to wealthy mates rather mate availability per se. Besides ecological constraints, sibling interactions are strongly linked with dispersal decisions and need to be better considered in the studies on the evolution of family dynamics and fitness maximizing strategies in humans and other species.

Assortative mating based on cooperativeness and generosity.

Cooperative behaviour and generosity towards nonkin represent costly and risky behaviour that could be used as a signal of mate quality. Therefore, cooperative traits could serve as criteria in mate choice, leading to assortative mating for those traits. There is evidence of similarity in couples for altruistic traits. However, the literature is based on self-reports and does not provide conclusive proof of either a convergence across time or mating preferences. Here, we report a field experiment, conducted in rural villages in Senegal, showing that husbands and wives are similar with respect to their contributions to a public good and their charity donations. Further analyses suggest that this similarity is due to initial assortment rather than convergence of phenotypes.

Ritual fights and male reproductive success in a human population.

Ritual fights are widespread across human populations. However, the evolutionary advantage associated with this behaviour is unclear because these fights rarely provide direct benefits such as territory, resources or mates. Here, the reproductive success of men competing in a traditional ritual fight, Sereer wrestling, was investigated for the first time. Involvement in wrestling had a significant positive effect on men's number of offspring and a marginally significant effect on polygyny, controlling for age, body condition and socio-economic status. These positive effects suggest that being involved in wrestling competition provides prestige, facilitating access to mates and thereby increasing fecundity. However, when women were interviewed on their preference concerning qualities of potential mates, the quality 'being involved in wrestling competition' was poorly ranked. This discrepancy may arise either from deceptive reports or from discordance between parents and daughters in the choice of a husband.

Why are some people left-handed? An evolutionary perspective.

Since prehistoric times, left-handed individuals have been ubiquitous in human populations, exhibiting geographical frequency variations. Evolutionary explanations have been proposed for the persistence of the handedness polymorphism. Left-handedness could be favoured by negative frequency-dependent selection. Data have suggested that left-handedness, as the rare hand preference, could represent an important strategic advantage in fighting interactions. However, the fact that left-handedness occurs at a low frequency indicates that some evolutionary costs could be associated with left-handedness. Overall, the evolutionary dynamics of this polymorphism are not fully understood. Here, we review the abundant literature available regarding the possible mechanisms and consequences of left-handedness. We point out that hand preference is heritable, and report how hand preference is influenced by genetic, hormonal, developmental and cultural factors. We review the available information on potential fitness costs and benefits acting as selective forces on the proportion of left-handers. Thus, evolutionary perspectives on the persistence of this polymorphism in humans are gathered for the first time, highlighting the necessity for an assessment of fitness differences between right- and left-handers.

Crystal structure of the CheA histidine phosphotransfer domain that mediates response regulator phosphorylation in bacterial chemotaxis.

The x-ray crystal structure of the P1 or H domain of the Salmonella CheA protein has been solved at 2.1-A resolution. The structure is composed of an up-down up-down four-helix bundle that is typical of histidine phosphotransfer or HPt domains such as Escherichia coli ArcB(C) and Saccharomyces cerevisiae Ypd1. Loop regions and additional structural features distinguish all three proteins. The CheA domain has an additional C-terminal helix that lies over the surface formed by the C and D helices. The phosphoaccepting His-48 is located at a solvent-exposed position in the middle of the B helix where it is surrounded by several residues that are characteristic of other HPt domains. Mutagenesis studies indicate that conserved glutamate and lysine residues that are part of a hydrogen-bond network with His-48 are essential for the ATP-dependent phosphorylation reaction but not for the phosphotransfer reaction with CheY. These results suggest that the CheA-P1 domain may serve as a good model for understanding the general function of HPt domains in complex two-component phosphorelay systems.

[Effect of 2 beta-blockers on arterial hypertension during pregnancy. Results of a prospective study on 56 pregnant hypertensive women treated with atenolol and labetalol]. / Action de deux bêta-bloquants sur l'hypertension artérielle pendant la grossesse. Résultats d'une étude prospective sur 56 femmes enceintes hypertendues traitées par Aténolol et Labétalol.

This study reports the results that were obtained in 56 cases of arterial hypertension in pregnancy solely by beta-blocking with Atenolol or Labetalol. Any pregnant woman whose arterial blood pressure rises to or exceeds 140/90 mm mercury in two successive examinations at intervals of 8 days with rest is considered to be hypertensive. As soon as treatment is started mothers' supervision is assured regularly by clinical and biological examinations and the dose of drug is adapted to each case. Fetal monitoring is ensured by ultrasound, cardiac rhythm tracings and hormone estimations. As far as the newborn is concerned, blood sugar and electrocardiogram measurements are taken to add to the normal examination at birth. Finally plasma levels of beta-blockers are estimated at birth in the mother and in the cord blood. The analysis of these results shows: for the mother: a fairly constant antihypertensive effect which is about the same for either drug in pregnancy. Further complementary injection therapy was needed, however, in 8 cases in labour. There were alterations in the method of delivery and in particular the Caesarean section rate rose to 12.5% and induction had to be carried out more frequently, triggered off by the slightest sign of fetal distress. As far as the child was concerned: 2 died in utero, the Apgar score was comparable to a control series, there was no bradycardia or broncho-spasm or teratogenic effect, mean weight at birth was significantly higher with Labetalol (3280 g +/- 555) than with Atenolol (2750 g +/- 630), the blood sugar levels at birth were in six cases lower than 1.4 mmol (0.25 g/l) but these were easily pu right by transfusion. The plasma levels of beta-blockers showed that there was a linear relationship between the maternal and fetal concentrations which confirmed that the two molecules pass through the placenta. This study confirms therefore that it is worth while using beta-blockers in cases of hypertension in pregnancy so long as careful observation is carried out, and it seems that the alpha constituent of Labetalol has advantages over the other.