Abstract Attractive facial features in women are assumed to signal fertility, but whether facial attractiveness predicts reproductive success in women is still a matter of debate. We investigated the ...association between facial attractiveness at young adulthood and reproductive life history—number of children and pregnancies—in women of a rural community. For the analysis of reproductive success, we divided the sample into women who used contraceptives and women who did not. Introducing two-dimensional geometric morphometric methodology, we analysed which specific characteristics in facial shape drive the assessment of attractiveness and covary with lifetime reproductive success. A set of 93semi landmarks was digitized as two-dimensional coordinates in postmenopausal faces. We calculated the degree of fluctuating asymmetry and regressed facial shape on facial attractiveness at youth and reproductive success. Among women who never used hormonal contraceptives, we found attractive women to have more biological offspring than less attractive women. These findings are not affected by sociodemographic variables. Postmenopausal faces corresponding to high reproductive success show more feminine features—facial characteristics previously assumed to be honest cues to fertility. Our findings support the notion that facial attractiveness at the age of mate choice predicts reproductive success and that facial attractiveness is based on facial characteristics, which seem to remain stable until postmenopausal age.
Abstract There is more to female attractiveness than a pretty face. Human mate choice decisions are guided by different cues, which in combination may give a better estimate of a general condition. ...We hypothesized that such signal redundancy might be true for vocal and visual cues of human female attractiveness. To test this we used photographs of women's faces, recorded their voices and asked men to rate both types of stimuli on attractiveness. We found a significant relationship between males' ratings of female faces and voices. Moreover, low levels of fluctuating asymmetry of women's bodies and faces were associated with high ratings on facial and vocal attractiveness. Applying the Geometric Morphometric Methodology we performed a multivariate regression analysis of attractiveness ratings with landmark data obtained from women's faces. We found similar facial shape changes for ratings of facial and vocal attractiveness that are both negatively related to facial and body FA. Findings suggest that females with an attractive face also tend to have an attractive voice and that this redundant information is reflected in female facial shape.
Prosociality in a despotic society Bhattacharjee, Debottam; Cousin, Eythan; Pflüger, Lena S. ...
iScience,
05/2023, Letnik:
26, Številka:
5
Journal Article
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Prosociality is the intent to improve others’ well-being. Existing hypotheses postulate that enhanced social tolerance and inter-individual dependence may facilitate prosocial preferences, which may ...favor the evolution of altruism. While most studies are restricted to “tolerant” (cooperatively breeding and self-domesticated) species, despotic societies provide an alternative opportunity to investigate prosociality due to nepotism and ample inter-individual dependencies. Japanese macaques live in hierarchical matrilineal societies, with strong kin bonds. Besides, tolerance among non-kin may persist through reciprocity. Using a group service food-provision paradigm, we found prosocial preferences in a semi free-ranging group of Japanese macaques. The extent of provisioning was at levels comparable to tolerant species. Dyadic tolerance predicted the likelihood and magnitude of provisioning, while kinship predicted the magnitude. We emphasize the role of a complex socio-ecology fostering individual prosocial tendencies through kinship and tolerance. These findings necessitate a framework including different forms of interdependence beyond the generally tolerant species.
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•Conventionally, research on prosociality is restricted to tolerant societies•We show despotic semi free-ranging Japanese macaques have prosocial preferences too•Dyadic social tolerance and kinship positively predict prosocial provisioning•Selective prosocial preferences may be maintained by inter-individual dependencies
Biological sciences; Zoology; Evolutionary biology
We assessed individual differences in visual attention toward faces in relation to their attractiveness via saccadic reaction times. Motivated by the aim to understand individual differences in ...attention to faces, we tested three hypotheses: (a) Attractive faces hold or capture attention more effectively than less attractive faces; (b) men show a stronger bias toward attractive opposite-sex faces than women; and (c) blue-eyed men show a stronger bias toward blue-eyed than brown-eyed feminine faces. The latter test was included because prior research suggested a high effect size. Our data supported hypotheses (a) and (b) but not (c). By conducting separate tests for disengagement of attention and attention capture, we found that individual differences exist at distinct stages of attentional processing but these differences are of varying robustness and importance. In our conclusion, we also advocate the use of linear mixed effects models as the most appropriate statistical approach for studying inter-individual differences in visual attention with naturalistic stimuli.
To produce offspring early in life is energetically demanding and depends greatly on environmental conditions. In female primates, age at first reproduction (AFR) has been associated with social ...parameters (e.g., population density and social rank), food availability and meteorological conditions (e.g., photoperiod, rainfall patterns, and temperature). Regarding the latter, less attention has been given to the influence of sunshine. In nonhuman primates, including the northern‐most distributed Japanese macaque (Macaca fuscata), sunbathing is an effective thermoregulatory strategy to maintain sufficient energy intake during harsh winter months. Furthermore, the energetic value of sunshine and its role in the synthesis of essential vitamins important for sexual development and overall fertility is well investigated using human and animal models. In the present study, we hypothesized that female's AFR is influenced by the amount of sunshine in a semi‐free‐ranging, provisioned a group of Japanese macaques. To test this, we gathered data on sunshine duration in the year females theoretically experienced the onset of puberty. This phase of the female life cycle is particularly prone to the effects of environmental conditions. In addition to the investigation of sunshine duration and other meteorological conditions (i.e., rainfall and temperature) we controlled for social parameters (i.e., group size and sex ratio) as potential covariates. We found a clear effect of sunshine duration on female AFR: Females who entered puberty in years with more sunshine reproduced for the first time at significantly younger ages than females who experienced less sunshine during this specific period of their development. Possible mechanisms for how the sunshine influences sexual maturation in Japanese macaques are discussed.
Longer sunshine duration in the year of puberty lowers female age at first reproduction in Japanese macaques.
Research highlights
We investigated the influence of sunshine during the year of puberty onset on a female's age at first reproduction (AFR).
We used 20 years of birth data from a semi‐free‐ranging group of Japanese macaques and meteorological data provided online by local weather stations
We controlled for the influence of other meteorological conditions as well as for group size and socionomic sex ratio
Higher mean sunshine duration in the year of puberty onset significantly decreased females’ AFR.
The self‐initiated split of a social group, known as fission, is a challenge faced by many group‐living animals. The study of group fission and the social restructuring process in real time provides ...insights into the mechanism of this biologically important process. Previous studies on fission in Japanese macaques (Macaca fuscata) assigned individuals to newly reorganized groups mainly using behavioral observations and group attendance records based on periods before or after fission itself. Here, we present a novel framework for group classification during the process of fission that uses quantifiable behavioral variables and statistical analyses. The framework was tested on a group fission process at Affenberg Landskron (Austria), a park that housed around 160 semi‐free‐ranging Japanese macaques. The behavioral data were collected for 26 days during fission. We analyzed three behavioral developments recurrent in fissions in Japanese macaques, that is, independence of behavior, participation in group movements, and separation of nomadic ranges. These analyses were combined to assign individuals to different groups. Our study resulted in one main group (N = 33), one subgroup (N = 36) and 56 individuals whose group membership was still undefined. The demographic characteristics of these newly formed groups were comparable with those of fissioned groups in wild populations. Furthermore, we found that these newly forming groups showed early social dynamics of fission five months before group level movements, that is: grouping based on spatial proximity and spatial withdrawal of the subgroup to the periphery. These results underline the validity of our novel framework to study social dynamics in Japanese macaques during the process of fission. It represents an important addition to existing methods, and we recommend testing its scope in other primate societies.
Graphical overview of a novel methodological framework for group classification during fission in Japanese macaques (Macaca fuscata).
Research Highlights
We studied semi‐free‐ranging Japanese macaques during group fission
Our applied methodology uses multiple behavioral variables for group classification
Our framework represents an important addition to existing methods used to study fission
Sequence variations in genes of the monoamine neurotransmitter system and their common function in human and non-human primate species are an ongoing issue of investigation. However, the COMT gene, ...coding for the catechol-O-methyltransferase, has not yet attracted much scientific attention regarding its functional role in non-human primates. Considering that a polymorphism of the human COMT gene affects the enzyme activity and cortisol level in response to a social stressor, this study investigated the impact of COMT on endocrine stress and behavioural parameters in Japanese macaques (Macaca fuscata). The species exemplifies a despotic hierarchy in which males' social rank positions require an adaptation of behaviour strategies. During the mating period steroid secretion and the frequency of aggressive encounters between males increase. We addressed i) whether this species exhibits potential functional COMT variants, ii) whether these variants are associated with faecal cortisol excretion of males, iii) how they are distributed among different social rank positions and iv) whether they are associated with behavioural strategies during times of mate competition. By genotyping 26 males we identified three COMT haplotypes (HT), including a putative splice mutant (HT3). This variant was associated with increased cortisol excretion. Given the observed inverse correlation between cortisol and physical aggression, we assume that different COMT haplotypes may predispose individuals to pursue more or less aggressive strategies. How these gene-stress effects might favour a specific social role is discussed. Our study of non-invasive genotyping in combination with behavioural and endocrine parameters represents an important step towards the understanding of gene-stress effects in a hierarchically organised primate society.
•We addressed variants of COMT and cortisol excretion in male Japanese macaques.•A putative COMT splice mutant (HT3) was associated with increased cortisol excretion.•This haplotype was widely distributed among males.•Cortisol excretion was inversely correlated with physical aggression.•No correlation between cortisol and social rank was found.
Cooperation occurs amongst individuals embedded in a social environment. Consequently, cooperative interactions involve a variety of persistent social influences such as the dynamics of partner ...choice and reward division. To test for the effects of such dynamics, we conducted cooperation experiments in a captive population of Japanese macaques (Macaca fuscata, N = 164) using a modified version of the loose-string paradigm in an open-experiment design. We show that in addition to becoming more proficient cooperators over the course of the experiments, some of the macaques showed sensitivity to the presence of potential partners and adjusted their behavior accordingly. Furthermore, following an unequal reward division, individuals receiving a lesser reward were more likely to display aggressive and stress-related behaviors. Our experiments demonstrate that Japanese macaques have some understanding of the contingencies involved in cooperation as well as a sensitivity to the subsequent reward division suggestive of an aversion to inequity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Animals experience stressful situations, from predation to social conflicts, but mostly deal with them successfully. This adaptive mechanism, coping, reduces the adverse effects of stressors, and its ...failure may result in reduced fitness. Substantial inter-individual variation in coping is observed, yet little is known about how behavioral, physiological and genetic drivers regulate coping holistically and contribute to such variations. We assessed behavioral coping styles (n=30), emotional arousal (n=12), and personalities (n=32) of long-tailed macaques (Macaca fascicularis) and also investigated the association of coping with a valine/methionine polymorphism encoded by a critical human stress regulatory gene, catechol-O-methyltransferase (COMT) (n=26). Personality and the human equivalent COMT Val/Met polymorphism were associated with “nonaggression-based” and “aggression-based” coping styles. Compared to nonaggression-based, aggression-based copers maintained higher average facial temperatures, indicating potentially lower emotional arousal, as measured using infrared thermography. These findings demonstrate a complex interplay of various proximate mechanisms governing coping in a non-human primate.
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•Long-tailed macaques exhibit “aggression-” and “nonaggression-based” coping styles•Behavioral coping styles show consistency with emotional arousal•A human equivalent COMT Val/Met polymorphism is present in long-tailed macaques•Personality and COMT Val/Met polymorphism are linked to coping in long-tailed macaques
Evolutionary biology; Genetics; Zoology
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