Living in Societies

Some people with HIV (PWH) experience brain changes that affect neurocognition, but little is known about how HIV impacts social cognition or related brain regions. Social cognition, the ability to perceive, understand and respond to social information, is important for maintaining relationships and quality of life. This article provides the protocol for the first comprehensive study examining social brain function in PWH and people without HIV (PWoH). With three aims, this study will: (1) examine neural circuits related to social cognition; (2) examine social cognitive performance across two social cognitive domains and (3) examine the role of social cognition in everyday social functioning. Referred to as Social Brain Health Study in HIV Study, this cross-sectional study will enrol 105 PWH and 105 demographically matched PWoH aged 18-65 years. The study administers a comprehensive assessment battery across two visits within a 2-week period. Visit 1 includes behavioural measures of social cognition (Perceiving Social Cues and Understanding Others), neurocognition and social functioning (social network size and loneliness). Visit 2 involves functional MRI procedures with three social cognitive tasks designed to activate key brain regions (ie, fusiform face area, superior temporal gyrus, temporo-parietal junction, dorsal medial prefrontal cortex). This study was funded by the National Institute of Mental Health (MH139613) and approved by the Institutional Review Board of the University of Alabama at Birmingham (IRB-300013394). Data collection is ongoing. The first results are expected to be submitted for publication in 2030. Findings of this study will be published in peer-reviewed journals and presented at local, national and international conferences as well as patient organisations such as AIDS service organisations and community talks.

Insulin-like growth factor 1 (IGF-1) seems to be involved in the neural circuits associated with social cognition and brain structure. To investigate the association of IGF-1 levels with social cognition and brain structure in Huntington's disease (HD). We evaluated social cognition using the Ekman test in 22 HD patients and 19 matched controls. Brain structure was assessed using standard volume-based voxel-based morphometry and surface-based cortical thickness pipeline. We analyzed the association of IGF-1 levels with social cognition and brain structure using adjusted regression analysis. Social cognition was worse in HD patients (P < 0.001), on antidopaminergic drugs (P=0.02), and with lower IGF-1 levels (P=0.04). In neuroimaging analyses, lower IGF-1 levels were associated with social cognition impairment and atrophy mainly in frontotemporal regions (P < 0.05 corrected). In HD, abnormal IGF-1 function seems to be associated with brain atrophy leading to clinical deficits in social cognition.

Summary 1 Long-tailed tits (Aegithalos caudatus) are a cooperatively breeding species in which helpers often invest effort in the provisioning of young that are not their own. 2 We quantified the lifetime reproductive success (LRS) and the individual fitness, lambda, of 228 long-tailed tits using 8 years of field data. Calculation of lambda took account of the effect of helpers on reproductive success, and thus lambda estimates the inclusive fitness of individuals. We examined the relationships between the fitness estimators and the provisioning effort, cohort, body size and dispersal status of individuals. 3 LRS of individuals which bred successfully varied between 0 and 13 local recruits (mean 0·71 ± 0·11 SE); lambda varied between 0 and 2·54 (mean 0·28 ± 0·04). The measures were highly correlated, and their distributions were strongly skewed. Helping by individuals contributed little to their fitness, but one-fifth of birds that accrued fitness did so only through helping. In general, individuals that gained fitness from helping did not gain fitness directly. 4 Both LRS and individual fitness were significant predictors of the number of grand-offspring that an individual had, but they accounted for only about one-third of the variation. 5 When variance in LRS was partitioned between length of breeding life span, average fecundity and offspring survival, the latter component was the most important in accounting for variance in LRS. 6 Offspring local survival was positively related to the provisioning effort of mothers, but was unrelated to that of fathers. As a result, the fitness of females was positively related to their provisioning effort. 7 Immigrant birds tended to be more reproductively successful than philopatric ones. Among females, only immigrant birds accrued any LRS or individual fitness. 8 The probability that an individual had at least one offspring recruit to the local breeding population varied among cohorts, probably as a result of variation among years in offspring local survival. This resulted in variation among cohorts in the individual fitness of females, but not in their LRS, nor in the LRS or individual fitness of males.

An understanding of the drivers of individual fitness is a fundamental component of evolutionary ecology and life-history theory. Reproductive senescence, mate and mating tactic choice and latent heterogeneity in individual quality interact to affect individual fitness. We sought to disentangle the effects of these fitness drivers, where longitudinal data are required to understand their respective impacts. We used reproductive allocation and success data from a long-term (1989-2018) study of white-throated dippers Cinclus cinclus in Switzerland to simultaneously examine the effects of female and male age, mating tactic, nest initiation date and individual heterogeneity on reproductive performance. We modelled quadratic and categorical effects of age on reproductive parameters. The probability of polygyny increased with age in both sexes before declining in older age classes. Similarly, hatching probability in monogamous pairs and the number of nestlings hatched in both monogamous and polygynous pairs increased with female age before declining later in life. As predicted, offspring survival in monogamous pairs increased with male age before declining in older age classes, but male age had no effect on offspring survival in polygynous nesting attempts. Our results demonstrate that parental age, mating tactic and individual heterogeneity all affect reproductive success, and that the impacts of senescent decline are expressed across different demographic components as a function of sex-specific senescent decline and mating tactic.

I hypothesize two processes by which sexual selection may generate differential reproductive success (RS) in species with biparental care. The differential-access hypothesis posits that an individual's own desirability as a mate affects its access to potential mates. By selecting mates strategically, desirable individuals enhance quantity and/or quality of offspring produced. The differential-allocation hypothesis states that an individual's own mating attractiveness affects the amount of parental investment it is able to secure from a mate. Organisms will provide above-average (for their sex) parental investment (PI) to obtain and/or maintain relatively attractive mates. The fitness of attractive individuals can be augmented through the production of offspring that receive above-average PI; alternatively, attractive individuals can restrict their own per-offspring investment and save reproductive effort for future use. In the latter case, attractive individuals will have longer life spans and higher RS than unattractive individuals of the same sex. These two hypotheses are not mutually exclusive, though some of the predictions they generate are competing. I investigated these hypotheses using the zebra finch (Poephila guttata), a typically monogamous Australian estrildid. Attractiveness of the birds was manipulated by placing plastic bands of various colors on the legs of birds. Previous experiments had established the relative attractiveness of these colors to opposite-sex zebra finches. In the banded-male experiment (BME), males were randomly assigned bands of red (attractive to females), or green (unattractive to females), or orange (neutral, the color of zebra finch legs); females were not color-banded. In the banded-female experiment (BFE), females were randomly assigned black (attractive to males), or blue (unattractive to males), or orange bands; males were not color-banded. The duration of the BME was 22 mo, that of the BFE, 15 mo. Results of both experiments indicated a stong effect of band color (attractiveness) on RS. In the BME, attractive males achieved approximately twice the RS of other color types. In the BFE, attractive females had twice as many offspring as unattractive females; females of intermediate attractiveness had intermediate RS. The differential-allocation hypothesis predicts that attractive individuals live longer than unattractive individuals of the same sex. This occurred in both experiments. Additional evidence supporting this hypothesis is found in the tendency of attractive males to become simultaneous bigamists. It appears that attractive males are sometimes able to transcend a behavioral polygyny threshold by restricting investment in the offspring of one female sufficiently to invest in offspring of a second female. Females monogamously mated to attractive males had significantly higher RS than polygynously mated females. Attractive females showed no parallel tendency toward bigamy, a finding compatible with the fact that female zebra finches typically incur higher parental expenditure than males. Not all the results of these experiments can be explained by the differential-allocation hypothesis alone. However, the results inconsistent with this hypothesis can be explained by the differential-access hypothesis or by the simultaneous occurrence of the two. In the BME, differential RS of males did not result solely from differential survival of color types. Among males that survived past the end of the experiment, attractive males had approximately twice the number of offspring as other males. In both experiments there were trends (not always significant) for the mates of attractive individuals to have high RS. Moreover, in both experiments mortality patterns of the sex that was not color-banded were intermediate between those predicted by the two hypotheses. These experiments demonstrate the existence of considerable potential for the operation of sexual selection in typically monogamous species. Moreover, they indicate that aesthetic or arbitrary (nonfunctional) mate preferences held by individuals of both sexes (not just females) are sufficient to affect the mate-getting abilities, mortality patterns, and RS of the bearers of traits of variable attractiveness.

Body condition may predict individual fitness because those in better condition have more resources to allocate towards improving their fitness. However, the hypothesis that condition indices are meaningful proxies for fitness has been questioned. Here, we ask if intraspecific variation in condition indices predicts annual reproductive success and survival. We monitored a population of Neochmia phaeton (crimson finch), a sedentary, tropical passerine, for reproductive success and survival over four breeding seasons, and sampled them for commonly used condition indices: mass adjusted for body size, muscle and fat scores, packed cell volume, hemoglobin concentration, total plasma protein, and heterophil to lymphocyte ratio. Our study population is well suited for this research because individuals forage in common areas and do not hold territories such that variation in condition between individuals is not confounded by differences in habitat quality. Furthermore, we controlled for factors that are known to impact condition indices in our study population (e.g., breeding stage) such that we assessed individual condition relative to others in the same context. Condition indices that reflect energy reserves predicted both the probability of an individual fledging young and the number of young produced that survived to independence, but only during some years. Those that were relatively heavy for their body size produced about three times more independent young compared to light individuals. That energy reserves are a meaningful predictor of reproductive success in a sedentary passerine supports the idea that energy reserves are at least sometimes predictors of fitness. However, hematological indices failed to predict reproductive success and none of the indices predicted survival. Therefore, some but not all condition indices may be informative, but because we found that most indices did not predict any component of fitness, we question the ubiquitous interpretation of condition indices as surrogates for individual quality and fitness.

The common features of autism-spectrum disorder (ASD), a highly-heritable pervasive developmental disorder with a significant heterogeneity and multiple-genetic factors, are characterized by severe dysfunction in social reciprocity, abnormalities in social-brain regions, and disproportionately low probability in females. On the other hand, a certain domain of mental function such as emotional memory and social reciprocity shows a significant sex-difference. In addition, recent neuroimaging studies have shown significant sexually-dimorphisms in neuroanatomical correlates of social cognition and behavior. Recently, some sexuallydimorphic factors such as oxytocin have been paid attention because of its possible contribution to mental development especially in social cognitive and behavioral domain. Taken together, it is hypothesized that a sexuallydimorphic factor associating with social function could affect dysfunction in social reciprocity, abnormalities in social-brain regions, and disproportionately low probability in females of ASD. This review article overviewed sexually-dimorphisms in clinical feature of ASD, in normal social cognition, and in social brain function and structure. The association of oxytocin with sexually-dimorphisms, social reciprocity, neural correlates of social congition, and the pathogenesis of ASD were further summarized.

Social cognition develops through a complex interplay between neural maturation and environmental factors, yet the neurobehavioral mechanisms underlying this process remain unclear. Using a naturalistic fMRI paradigm, we investigated the effects of age and parental caregiving on social brain development and Theory of Mind (ToM) in 34 mother-child dyads. The functional maturity of social brain networks was positively associated with age, while mother-child neural synchronization during movie viewing was related to dyadic relationship quality. Crucially, parenting and child factors interactively shaped social cognition outcomes, mediated by ToM abilities. Our findings demonstrate the dynamic interplay of neurocognitive development and interpersonal synchrony in early childhood social cognition, and provide novel evidence for neurodevelopmental plasticity and reciprocal determinism. This integrative approach, bridging brain, behavior, and parenting environment, advances our understanding of the complex mechanisms shaping social cognition. The insights gained can inform personalized interventions promoting social competence, emphasizing the critical importance of nurturing parental relationships in facilitating healthy social development.

Human interactions are increasingly taking place from a distance through methods of remote interpersonal communication like video chatting and social media. While remote interpersonal communication has existed for millennia—with the first postal system arising in ∼2400 B.C.—accelerated advances in technology and the recent global COVID-19 pandemic have led to a dramatic increase in remote interpersonal communication use in daily life. Remote interpersonal communication presents a challenge to the field of social-cognitive neuroscience, as researchers seek to understand the implications of various types of remote interpersonal communication for the “social brain.” The present paper reviews our current understanding of the social-cognitive neural network and summarizes critical differences between the neural correlates of social cognition in remote vs. face-to-face interactions. In particular, empirical and theoretical work is reviewed that highlight disparities in the neural mechanisms of social perception, evaluation of social stimuli, human motivation, evaluation of social reward, and theory of mind. Potential impacts of remote interpersonal communication on the development of the brain’s social-cognitive network are also discussed. Finally, this review closes with future directions for research on social-cognitive neuroscience in our digital technology-connected world and outlines a neural model for social cognition in the context of remote interpersonal communication. For the field of social-cognitive neuroscience to advance alongside of the ever-evolving society, it is crucial for researchers to acknowledge the implications and concepts suggested for future research in this review.

Behavioral studies have shown that, at a population level, women perform better on tests of social cognition and empathy than men. Furthermore Autism Spectrum Disorders (ASDs), which are characterized by impairments in social functioning and empathy, occur more commonly in males than females. These findings have led to the hypothesis that differences in the functioning of the social brain between males and females contribute to the greater vulnerability of males to ASD and the suggestion that ASD may represent an extreme form of the male brain. Here we sought to investigate this hypothesis by determining: (i) whether males and females differ in social brain function, and (ii) whether any sex differences in social brain function are exaggerated in individuals with ASD. Using fMRI we show that males and females differ markedly in social brain function when making social decisions from faces (compared to simple sex judgements) especially when making decisions of an affective nature, with the greatest sex differences in social brain activation being in the inferior frontal cortex (IFC). We also demonstrate that this difference is exaggerated in individuals with ASD, who show an extreme male pattern of IFC function. These results show that males and females differ significantly in social brain function and support the view that sex differences in the social brain contribute to the greater vulnerability of males to ASDs.

In group-living mammals, an individual's fitness depends, in part, on the quality of social relationships it has with others. Among species of nonhuman primates in which one sex is philopatric, individuals of that sex often develop strong social bonds and alliances with closely related kin. Less is known regarding the social processes used by dispersing adults to form stable bonds with nonkin in their new group. From May to December 2009, April to August 2010, September to December 2011, and February to May 2012, we collected data on grooming interactions in wild Tibetan macaques (Macaca thibetana), a female philopatric species, at Mt. Huangshan, China. Our goal was to compare social interactions and bond formation between resident males, recent immigrant males, and resident females. Our results indicate that recent immigrant males formed stable partner relationships with a small number of resident females and groomed these females more frequently or for longer than they received grooming. In contrast, resident males switched female grooming partners more frequently, received more grooming than they gave, and formed relationships with a greater number of female partners. We argue that the ability of recent immigrant male Tibetan macaques to maintain strong and persistent social bonds with a small set of resident adult females is a primary factor that enables them to establish residence in a new multimale-multifemale group. The present study provides new and important insights into the integrated social strategies used by dispersing males and resident females to maintain group stability.

In many vertebrates, body size is an important driver of variation in male reproductive success. Larger, more fit individuals are more likely to dominate mating opportunities, skewing siring success and resulting in lower effective population sizes and genetic diversity. The mating system of the gopher tortoise (Gopherus polyphemus) has been characterized as both female-defense and scramble-competition polygyny. Mating systems are typically not fixed and can be influenced by factors such as population density, demographic structure, and environmental conditions; however, most populations will have a predominant strategy that results from local conditions. We assessed how male body size influences patterns of paternity and reproductive success in a natural population of gopher tortoises in Florida, United States. Using microsatellites, we assigned parentage of 220 hatchlings from 31 nests collected during 2 reproductive seasons. Larger males were significantly more likely to sire offspring and sired more offspring than smaller males; however, the likelihood of a clutch being multiply sired was unrelated to male body size. We also found evidence of mate fidelity across years. Although paternity patterns in this high-density population are more consistent with defense polygyny, female monopoly by males was incomplete, with both large and small males contributing to multiply sired clutches. Additional behavioral data are needed to clarify the role of female mate selection in paternity outcomes. The context-dependence of mating systems underscores the need to compare parentage patterns across populations and to recognize the potential for more than 1 strategy to be employed within a single population.

Summary: The brain has evolved to understand and interact with other people. We are increasingly learning more about the neurophysiological basis of social cognition and what is known as the social brain, that is the network of brain regions involved in understanding others. This chapter focuses on how the social brain develops during adolescence. Adolescence is a time characterised by change - hormonally, physically, psychologically and socially. Yet until recently this period of life was neglected by cognitive neuroscience. In the past decade, research has shown that the brain develops both structurally and functionally during adolescence. Large scale structural MRI studies have demonstrated development during adolescence in white matter and grey matter volumes in regions within the social brain. Activity in some of these regions, as measured using fMRI, also shows changes between adolescence and adulthood during social cognition tasks. Finally, I will present evidence that theory of mind usage is still developing late in adolescence. © 2011 John Wiley & Sons, Ltd.

ABSTRACT. Variation in mating success among individuals is the basis for sexual selection and the evolution of elaborate secondary sexual traits. In socially monogamous species, variation in mating success is generally thought to be small, but a skewed adult sex ratio, differences in female fecundity, and extrapair fertilizations that arise from matings outside the social pair bond can increase variance in reproductive success. We investigated how these factors generate the opportunity for sexual selection in the socially monogamous White-crowned Sparrow (Zonotrichia leucophrys pugetensis). We found a 38% increase in the standardized actual variance in reproductive success compared to the apparent standardized variance of males because of the contribution of extrapair fertilizations to total reproductive success. However, partitioning variance into within-pair and extrapair components showed that the majority of variance in male reproductive success was attributable to within-pair success and a skewed adu...

Emotion recognition and theory of mind are related to gray matter volume of the prefrontal cortex in schizophrenia