The evolution of female copulation calls in primates: a review and a new model

Female copulation calls are mating-associated vocalizations that occur in some species of Old World monkeys and apes. We argue that copulation calls have two immediate functions: to encourage mating attempts by other males and to increase mate guarding by the consort male. We hypothesize that female copulation calls have evolved under the selective pressures of risk of infanticide and sperm competition. When male mate guarding is effective, copulation calls allow females to concentrate paternity in dominant males and benefit from their protection against the risk of infanticide. When mate guarding is ineffective, copulation calls may bring genetic benefits to females through facilitation of sperm competition. We present a quantitative model in which interspecific variation in females' promiscuity predicts their tendency to use copulation calls in conjunction with mating. The model predicts that in species with little female promiscuity, copulation calls should be rare and exhibited only in association with mating with dominant males. In species in which females are highly promiscuous, copulation calls should be frequent and unrelated to male dominance rank. The limited data available to test the model support its main predictions as well as the predicted relation between copulation calls and male dominance rank

Physical and Psychosocial Correlates of Facial Attractiveness

This research aimed to investigate whether and how facial attractiveness relates to physical (height and weight), social (relationship status), and psychological characteristics (personality traits, self-esteem, locus of control, self-evaluated social status, trait anxiety, and time perspective) in a sample of college students. In the first study, 231 participants (males and females) provided a standardized photo of their faces, self-rated their attractiveness, answered some anthropometric and demographic questions, and completed some psychological questionnaires. In a second study, the faces were evaluated for attractiveness by an external group of same-aged judges (N = 236). Attractiveness was negatively correlated with body mass index and with height (only in males). Attractive individuals reported being in a long-term romantic relationship more than others. Self-rated and/or other-rated attractiveness were positively correlated with self-reported social status, self-esteem, and past-positive time perspective, and negatively correlated with trait anxiety, neuroticism, and past-negative time perspective. The findings of this study suggest that more attractive individuals possess characteristics that favor psychological well-being and good mental health and that make them desirable and successful as social or romantic partners. Attractiveness may also be associated with adaptive cognitive biases that promote self-enhancement

What could assistance robots learn from assistance dogs?

These studies are part of our broader project that aims at revealing relevant aspects of human-dog interactions, which could help to develop and test robot social behaviour. We suggest that the cooperation between assistance dogs and their disabled owners could serve as a model to design successful assistance robot–human interactions. In Study 1, we analysed the behaviour of 32 assistance dog–owner dyads performing a fetch and carry task. In addition to important typical behaviours (attracting attention, eye-contact, comprehending pointing gestures), we found differences depending on how experienced the dyad was and whether the owner used a wheel chair or not. In Study 2 we investigated the reactions of a subsample of dogs to unforeseen difficulties during a retrieving task. We revealed different types of communicative and displacement behaviours, and importantly, dogs showed a strong commitment to execute the insoluble task or at least their behaviours lent a “busy” appearance to them, which can attenuate the owners’ disappointment. We suggest that assistant robots should communicate their inability to solve a problem using simple behaviours (non-verbal vocalisation, orientation alternation), and/or could show displacement behaviours rather than simply not performing the task. In sum, we propose that assistant dogs’ communicative behaviours and problem solving strategies could inspire the development of the relevant functions and social behaviours of assistance robots

Bridging gaps: how investment in public childcare affects women’s employment in Italy and Spain

This paper aims to establish whether, and to what extent, an increase in the public provision of early childhood education and care services (ECEC) has had a positive effect on women’s participation in the labour market in Italy and Spain. It does so by compiling panel data using microdata from the European Labour Force Survey (2006–2018), together with secondary sources of information on public ECEC investment made in the two countries. After controlling for unit heterogeneity and reverse causality, the estimated results indicate a positive correlation with the employment rates of women with children and the number of hours worked, in particular for those without a degree, thus indicating the need to address unequal access to publicly-provided ECEC services

Response to novel objects and foraging tasks by common marmoset (Callithrix Jacchus) female Pairs

Many studies have shown that environmental enrichment can significantly improve the psychological well-being of captive primates, increasing the occurrence of explorative behavior and thus reducing boredom. The response of primates to enrichment devices may be affected by many factors such as species, sex, age, personality and social context. Environmental enrichment is particularly important for social primates living in unnatural social groupings (i.e. same-sex pairs or singly housed animals), who have very few, or no, benefits from the presence of social companions in addition to all the problems related to captivity (e.g. increased inactivity). This study analyses the effects of enrichment devices (i.e. novel objects and foraging tasks) on the behavior of common marmoset (Callithrix jacchus) female pairs, a species that usually lives in family groups. It aims to determine which aspects of an enrichment device are more likely to elicit explorative behaviors, and how aggressive and stress-related behaviors are affected by its presence. Overall, the marmosets explored foraging tasks significantly longer than novel objects. The type of object, which varied in size, shape and aural responsiveness (i.e. they made a noise when the monkey touched them), did not affect the response of the monkeys, but they explored objects that were placed higher in the enclosure more than those placed lower down.Younger monkeys were more attracted to the enrichment devices than the older ones. Finally, stress-related behavior (i.e. scratching) significantly decreased when the monkeys were presented with the objects; aggressive behavior as unaffected. This study supports the importance of environmental enrichment for captive primates and shows that in marmosets its effectiveness strongly depends upon the height of the device in the enclosure and the presence of hidden food. The findings can be explained ifone considers the foraging behavior of wild common marmosets. Broader applications for the research findings are suggested in relation to enrichment

Individual differences in puberty onset in girls: Bayesian estimation of heritabilities and genetic correlations

We report heritabilities for individual differences in female pubertal development at the age of 12. Tanner data on breast and pubic hair development in girls and data on menarche were obtained from a total of 184 pairs of monozygotic and dizygotic twins. Genetic correlations were estimated to determine to what extent the same genes are involved in different aspects of physical development in puberty. A Bayesian estimation approach was taken, using Markovchain Monte Carlo simulation to estimate model parameters. All three phenotypes were to a significant extent heritable and showed high genetic correlations, suggesting that a common set of genes is involved in the timing of puberty in general. However, gonadarche (menarche and breast development) and adrenarche (pubic hair) are affected by different environmental factors, which does not support the three phenotypes to be regarded as indicators of a unitary physiological factor. © 2006 Springer Science+Business Media, Inc

Personality of wild male crested macaques (Macaca nigra).

Animal personalities, i.e. consistent differences in behavior across time and/or context, have received increased attention of behavioral biologists over the last years. Recent research shows that personalities represent traits on which natural and sexual selection work and which can have substantial fitness consequences. The aim of this study is to establish the personality structure of crested macaque (Macaca nigra) males as foundation for future studies on its adaptive value. We collected behavioral data through focal animal sampling and additionally conducted two sets of playback experiments. Results of a factor analysis on the behavioral data revealed a four factor structure with components we labeled Anxiety, Sociability, Connectedness and Aggressiveness. Results from the experiments revealed an additional and independent Boldness factor but the absence of Neophilia. Overall, this structure resembles other macaque and animal species with the exception of Connectedness, which might be a consequence of the species' tolerant social style. Our results thus not only form the basis for future studies on the adaptive value of personality in crested macaques but also contribute an important data point for investigating the evolution of personality structure from a comparative perspective by refining, for example, which personality factors characterized the last common ancestor of hominids and macaques

Testosterone, cortisol, and status-striving personality features: A review and empirical evaluation of the dual hormone hypothesis

Decades of research in behavioral endocrinology has implicated the gonadal hormone testosterone in the reg- ulation of mating effort, often expressed in primates in the form of aggressive and/or status-striving behavior. Based on the idea that neuroendocrine axes influence each other, recent work among humans has proposed that links between testosterone and indices of status-striving are rendered conditional by the effects of glucocorti- coids. The Dual Hormone hypothesis is one particular instance of this argument, predicting that cortisol blocks the effects of testosterone on dominance, aggression, and risk-taking in humans. Support for the Dual Hormone hypothesis is wide-ranging, but considerations of theoretical ambiguity, null findings, and low statistical power pose problems for interpreting the published literature. Here, we contribute to the development of the Dual Hormone hypothesis by (1) critically reviewing the extant literature—including p-curve analyses of published findings; and, (2) “opening the file drawer” and examining relationships between testosterone, cortisol, and status-striving personality features in seven previously published studies from our laboratories (total N = 718; median N per feature = 318) that examined unrelated predictions. Results from p-curve suggest that published studies have only 16% power to detect effects, while our own data show no robust interactions between tes- tosterone and cortisol in predicting status-striving personality features. We discuss the implications of these results for the Dual Hormone hypothesis, limitations of our analyses, and the development of future research

Familiarity bias and physiological responses in contagious yawning by dogs support link to empathy

In humans, the susceptibility to yawn contagion has been theoretically and empirically related to our capacity for empathy. Because of its relevance to evolutionary biology, this phenomenon has been the focus of recent investigations in nonhuman species. In line with the empathic hypothesis, contagious yawning has been shown to correlate with the level of social attachment in several primate species. Domestic dogs (Canis familiaris) have also shown the ability to yawn contagiously. To date, however, the social modulation of dog contagious yawning has received contradictory support and alternative explanations (i.e., yawn as a mild distress response) could explain positive evidence. The present study aims to replicate contagious yawning in dogs and to discriminate between the two possible mediating mechanisms (i.e., empathic vs. distress related response). Twenty-five dogs observed familiar (dog’s owner) and unfamiliar human models (experimenter) acting out a yawn or control mouth movements. Concurrent physiological measures (heart rate) were additionally monitored for twenty-one of the subjects. The occurrence of yawn contagion was significantly higher during the yawning condition than during the control mouth movements. Furthermore, the dogs yawned more frequently when watching the familiar model than the unfamiliar one demonstrating that the contagiousness of yawning in dogs correlated with the level of emotional proximity. Moreover, subjects’ heart rate did not differ among conditions suggesting that the phenomenon of contagious yawning in dogs is unrelated to stressful events. Our findings are consistent with the view that contagious yawning is modulated by affective components of the behavior and may indicate that rudimentary forms of empathy could be present in domesticated dogs