How the size and structure of egocentric networks change during a life transition.

While social networks are typically relatively stable in size over time, major changes in life circumstances can result in opportunities to acquire new friends. How young adults manage their relationships with their wider network of friends and family during such transitions is, however, not well understood. Using a prospective longitudinal design, we investigate changes in the size and composition of complete egocentric networks of two cohorts of young adults moving away from home to college. We show that, although networks grow rapidly due to an influx of new friends made at college, the social overload that would result is partially mitigated through the progressive loss of pre-transition friendships (but not family relationships). In addition, most of the new relationships are placed in the outermost, emotionally less close network layers that are less costly to maintain. In contrast, the more intimate inner layers of the network remain stable in size, with efforts being made to conserve these relationships. The overriding importance of face-to-face interaction in creating and maintaining ties (compared to digital media) results in the emotional quality of a tie being traded off against the constraints imposed by physical distance. The most reliable predictor of the proportion of original members with whom relationships were maintained post-transition was pre-transition network size, with weaker effects due to geographical proximity and personal popularity in the new social context. These findings have implications for managing transitions to a new environment at any life stage.

Clinical spectrum of disease and outcomes in children with Omicron SARS-COV-2 infection in Cape Town, South Africa.

INTRODUCTION: Children with underlying comorbidities and infants are most severely affected by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, including in low- and middle-income countries with a high prevalence of HIV and TB. We describe the clinical presentation of SARS-CoV-2 infection in children during the Omicron wave, in Cape Town, South Africa. METHODS: We analysed routine care data from a prospective cohort of children aged 0-13 years, with a positive SARS-CoV-2 real-time reverse-transcription polymerase chain reaction (rRT-PCR) or SARS-CoV-2 antigen test, admitted to Tygerberg Hospital between 1 November 2021 until 1 March 2022. Risk factors for severity of disease were assessed. RESULTS: Ninety-five children tested positive for SARS-CoV-2, of whom 87 (91.6%) were symptomatic. Clinical data were available for 86 children. The median age was 11 months (IQR 3.0-60.0), 37 (43.0%) were females, 21 (24.7%) were HIV-exposed and 7 (8.1%) were living with HIV (CLHIV). In total, 44 (51.2%) children had at least one underlying comorbidity. TB co-infection was seen in 11 children, 6 children were newly diagnosed and 5 children were already on TB treatment at the time of admission. CONCLUSION: There was no evidence of more severe disease in children living with HIV or TB.

INTRODUCTION: Les enfants et les nourrissons présentant des comorbidités sous-jacentes sont les plus gravement touchés par l'infection par le coronavirus-2 du syndrome respiratoire aigu sévère (SARS-CoV-2), y compris dans les pays à revenu faible ou intermédiaire où la prévalence du VIH et de la TB est élevée. Nous décrivons la présentation clinique de l'infection par le SARS-CoV-2 chez les enfants pendant la vague Omicron, au Cap, en Afrique du Sud. MÉTHODES: Nous avons analysé les données de soins de routine d'une cohorte prospective d'enfants âgés de 0 à 13 ans, avec un test positif de réaction en chaîne de la polymérase de transcription inverse en temps réel (rRT-PCR) ou d'antigène du SARS-CoV-2, admis à l'hôpital Tygerberg entre le 1er novembre 2021 et le 1er mars 2022. Les facteurs de risque de gravité de la maladie ont été évalués. RÉSULTATS: Quatre-vingt-quinze enfants ont été testés positifs au SARS-CoV-2, dont 87 (91,6%) étaient symptomatiques. Des données cliniques étaient disponibles pour 86 enfants. L'âge médian était de 11 mois (IQR 3,0­60,0), 37 (43,0%) étaient des filles, 21 (24,7%) étaient exposés au VIH et 7 (8,1%) vivaient avec le VIH (CLHIV). Au total, 44 (51,2%) enfants présentaient au moins une comorbidité sous-jacente. La co-infection par la TB a été observée chez 11 enfants, 6 enfants ont été nouvellement diagnostiqués et 5 enfants étaient déjà sous traitement antituberculeux au moment de l'admission. CONCLUSION: Il n'y a pas de preuve d'une maladie plus grave chez les enfants vivant avec le VIH ou la TB.

The effect of coronal plane angulation on patient reported outcome measures of operatively treated distal femur fractures: A multi-center prospective evaluation.

OBJECTIVES: The goal of this trial was to determine whether coronal plane angulation affects functional and clinical outcomes after the fixation of distal femur fractures. DESIGN: Multicenter, randomized controlled trial SETTING: 20 academic trauma centers PATIENTS/PARTICIPANTS: 156 patients with distal femur fractures were enrolled. 123 patients were followed 12 months. There was clinical outcome data available for 105 patients at 3 months, 95 patients at 6 months and 81 patients at one year. INTERVENTION: Lateral locked plating or retrograde intramedullary nailing MAIN OUTCOME MEASUREMENTS: Radiographic alignment, functional scoring including SMFA, Bother Index, and EQ-5D. Clinical scoring of walking ability, need for ambulatory support and ability to manage stairs. RESULTS: At 3 months, there was no difference between groups (varus, neutral or valgus) with respect to any of the clinical functional outcome scores measured. At 6 months, compared to those with neutral alignment, patients with varus angulation had a worse Stair Climbing score (4.33 vs. 2.91, p = 0.05). At 12 months, the average patient with neutral or valgus alignment needed less ambulatory support than the average patient in varus. Walking distance ability was no different between the groups at any time point. With respect to the validated patient-based outcome scores, we found no statistical difference in in the SMFA, Bother, or EQ-5D between patients with valgus or varus mal-alignment and those with neutral alignment at any time point (p > 0.05). Regardless of coronal angulation, the SMFA trended towards lower (improved) scores over time, while EQ-5D scores for patients with varus angulation did not improve over time. CONCLUSIONS: Valgus angulation and neutral angulation may be better tolerated in terms of clinical outcomes like stair climbing and need for ambulatory support than varus angulation, though patient reported outcome measures like the SMFA, Bother Index and EQ-5D show no statistical significance. Most patients with distal femur fractures tend to improve during the first year after injury but many remain significantly affected at 12 months post injury.

Incidence of self-reported tuberculosis treatment with community-wide universal testing and treatment for HIV and tuberculosis screening in Zambia and South Africa: A planned analysis of the HPTN 071 (PopART) cluster-randomised trial.

BACKGROUND: HIV is a potent risk factor for tuberculosis (TB). Therefore, community-wide universal testing and treatment for HIV (UTT) could contribute to TB control, but evidence for this is limited. Community-wide TB screening can decrease population-level TB prevalence. Combining UTT with TB screening could therefore significantly impact TB control in sub-Saharan Africa, but to our knowledge there is no evidence for this combined approach. METHODS AND FINDINGS: HPTN 071 (PopART) was a community-randomised trial conducted between November 2013 to July 2018; 21 Zambian and South African communities (with a total population of approximately 1 million individuals) were randomised to arms A (community-wide UTT and TB screening), B (community-wide universal HIV testing with treatment following national guidelines and TB screening), or C (standard-of-care). In a cohort of randomly selected adults (18 to 44 years) enrolled between 2013 and 2015 from all 21 communities (total size 38,474; 27,139 [71%] female; 8,004 [21%] HIV positive) and followed-up annually for 36 months to measure the population-level impact of the interventions, data on self-reported TB treatment in the previous 12 months (self-reported TB) were collected by trained research assistants and recorded using a structured questionnaire at each study visit. In this prespecified analysis of the trial, self-reported TB incidence rates were measured by calendar year between 2014 and 2017/2018. A p-value ≤0.05 on hypothesis testing was defined as reaching statistical significance. Between January 2014 and July 2018, 38,287 individuals were followed-up: 494 self-reported TB during 104,877 person-years. Overall incidence rates were similar across all arms in 2014 and 2015 (0.33 to 0.46/100 person-years). In 2016 incidence rates were lower in arm A compared to C overall (adjusted rate ratio [aRR] 0.48 [95% confidence interval (95% CI) 0.28 to 0.81; p = 0.01]), with statistical significance reached. In 2017/2018, while incidence rates were lower in arm A compared to C, statistical significance was not reached (aRR 0.58 [95% CI 0.27 to 1.22; p = 0.13]). Among people living with HIV (PLHIV) incidence rates were lower in arm A compared to C in 2016 (RR 0.56 [95% CI 0.29 to 1.08; p = 0.08]) and 2017/2018 (RR 0.50 [95% CI 0.26 to 0.95; p = 0.04]); statistical significance was only reached in 2017/2018. Incidence rates in arms B and C were similar, overall and among PLHIV. Among HIV-negative individuals, there were too few events for cross-arm comparisons. Study limitations include the use of self-report which may have been subject to under-reporting, limited covariate adjustment due to the small number of events, and high losses to follow-up over time. CONCLUSIONS: In this study, community-wide UTT and TB screening resulted in substantially lower TB incidence among PLHIV at population-level, compared to standard-of-care, with statistical significance reached in the final study year. There was also some evidence this translated to a decrease in self-reported TB incidence overall in the population. Reduction in arm A but not B suggests UTT drove the observed effect. Our data support the role of UTT in TB control, in addition to HIV control, in high TB/HIV burden settings. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01900977.

Structural and Cognitive Mechanisms of Group Cohesion in Primates.

Group-living creates stresses that, all else equal, naturally lead to group fragmentation, and hence loss of the benefits that group-living provides. How species that live in large stable groups counteract these forces is not well understood. I use comparative data on grooming networks and cognitive abilities in primates to show that living in large, stable groups has involved a series of structural solutions designed to create chains of 'friendship' (friends-of-friends effects), increased investment in bonding behaviours (made possible by dietary adjustments) to ensure that coalitions work effectively, and neuronally expensive cognitive skills of the kind known to underpin social relationships in humans. The first ensures that individuals synchronise their activity cycles; the second allows the stresses created by group-living to be defused; and the third allows a large number of weak ties to be managed. Between them, these create a form of multilevel sociality based on strong versus weak ties similar to that found in human social networks. In primates, these strategies appear successively at quite specific group sizes, suggesting that they are solutions to 'glass ceilings' that would otherwise limit the range of group sizes that animals can live in (and hence the habitats they can occupy). This sequence maps closely onto the grades now known to underpin the Social Brain Hypothesis and the fractal pattern that is known to optimise information flow round networks.

Lifehistory Trade-Offs Influence Women's Reproductive Strategies.

Objective: In a UK national census sample, women from the upper and lower socioeconomic (SES) classes achieve parity in completed family size, despite marked differences in both birth rates and offspring survival rates. We test the hypothesis that women adopt reproductive strategies that manipulate age at first reproduction to achieve this. Methods: We use a Monte-Carlo modeling approach parameterized with current UK lifehistory data to simulate the reproductive lifehistories of 64,000 individuals from different SES classes, with parameter values at each successive time step drawn from a statistical distribution defined by the census data. Results: We show that, if they are to achieve parity with women in the higher socioeconomic classes, women in lower socioeconomic classes must begin reproducing 5.65 years earlier on average than women in the higher SES classes in order to offset the higher class-specific mortality and infertility rates that they experience. The model predicts very closely the observed differences in age at first reproduction in the census data. Conclusions: Opting to delay reproduction in order to purse an education-based professional career may be a high risk strategy that many lower SES women are unwilling and unable to pursue. As a result, reproducing as early as possible may be the best strategy available to them.

Why did doctrinal religions first appear in the Northern Subtropical Zone?

Doctrinal religions that involve recognised gods, more formal theologies, moral codes, dedicated religious spaces and professional priesthoods emerged in two phases during the Neolithic. Almost all of these appeared in a narrow latitudinal band (the northern Subtropical Zone). I suggest that these developments were the result of a need to facilitate community bonding in response to scalar stresses that developed as community sizes increased dramatically beyond those typical of hunter-gatherer societies. Conditions for population growth (as indexed by rainfall patterns and the difference between pathogen load and the length of the growing season) were uniquely optimised in this zone, creating an environment of ecological release in which populations could grow unusually rapidly. The relationship between latitude, religion and language in contemporary societies suggests that the peculiar characteristics of the northern (but not the southern) Subtropical Zone were especially favourable for the evolution of large scale religions as a way of enforcing community cohesion.

Laughter and its role in the evolution of human social bonding.

In anthropoid primates, social grooming is the principal mechanism (mediated by the central nervous system endorphin system) that underpins social bonding. However, the time available for social grooming is limited, and this imposes an upper limit on the size of group that can be bonded in this way. I suggest that, when hominins needed to increase the size of their groups beyond the limit that could be bonded by grooming, they co-opted laughter (a modified version of the play vocalization found widely among the catarrhine primates) as a form of chorusing to fill the gap. I show, first, that human laughter both upregulates the brain's endorphin system and increases the sense of bonding between those who laugh together. I then use a reverse engineering approach to model group sizes and grooming time requirements for fossil hominin species to search for pinch points where a phase shift in bonding mechanisms might have occurred. The results suggest that the most likely time for the origin of human-like laughter is the appearance of the genus Homo ca 2.5 Ma. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

Nonverbal Auditory Cues Allow Relationship Quality to be Inferred During Conversations.

The claim that nonverbal cues provide more information than the linguistic content of a conversational exchange (the Mehrabian Conjecture) has been widely cited and equally widely disputed, mainly on methodological grounds. Most studies that have tested the Conjecture have used individual words or short phrases spoken by actors imitating emotions. While cue recognition is certainly important, speech evolved to manage interactions and relationships rather than simple information exchange. In a cross-cultural design, we tested participants' ability to identify the quality of the interaction (rapport) in naturalistic third party conversations in their own and a less familiar language, using full auditory content versus audio clips whose verbal content has been digitally altered to differing extents. We found that, using nonverbal content alone, people are 75-90% as accurate as they are with full audio cues in identifying positive vs negative relationships, and 45-53% as accurate in identifying eight different relationship types. The results broadly support Mehrabian's claim that a significant amount of information about others' social relationships is conveyed in the nonverbal component of speech. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10919-021-00386-y.

Use of interactive messaging to reduce pre-diagnosis loss to follow-up for TB care.

OBJECTIVE: To investigate the uptake and usage of a WhatsApp-based interactive communication strategy to avert pre-diagnosis loss to follow-up (LTFU) from TB care in a high-incidence setting.METHODS: We enrolled adults (≥18 years) who underwent routine sputum TB testing in two primary healthcare clinics in Khayelitsha, Cape Town, South Africa. The intervention consisted of structured WhatsApp-based reminders (prompts) sent prior to a routine clinic appointment scheduled 2-3 days after the diagnostic visit. Pre-diagnosis LTFU was defined as failure to return for the scheduled appointment and within 10 days.RESULTS: We approached 332 adults with presumptive TB, of whom 103 (31%) were successfully enrolled; 213 (64%) did not own a WhatsApp-compatible phone. Of 103 participants, 74 (72%) actively responded to WhatsApp prompts; 69 (67%) opted to include a close contact in group communication to co-receive reminders. Pre-diagnosis LTFU was low overall (n = 7, 6.8%) and was not associated with failure to respond to WhatsApp prompts.CONCLUSION: In this high-incidence setting, enrolment in a WhatsApp-based communication intervention among adults with presumptive TB was low, mainly due to low availability of WhatsApp-compatible phones. Among participants, we observed high message response rates and low LTFU, suggesting potential for interactive messaging services to support pre-diagnosis TB care.

Managing the stresses of group-living in the transition to village life.

Group living is stressful for all mammals, and these stresses limit the size of their social groups. Humans live in very large groups by mammal standards, so how have they solved this problem? I use homicide rates as an index of within-community stress for humans living in small-scale ethnographic societies, and show that the frequency of homicide increases linearly with living-group size in hunter-gatherers. This is not, however, the case for cultivators living in permanent settlements, where there appears to be a 'glass ceiling' below which homicide rates oscillate. This glass ceiling correlates with the adoption of social institutions that allow tensions to be managed. The results suggest (a) that the transition to a settled lifestyle in the Neolithic may have been more challenging than is usually assumed and (b) that the increases in settlement size that followed the first villages necessitated the introduction of a series of social institutions designed to manage within-community discord.

How Audiences Engage With Drama: Identification, Attribution and Moral Approval.

Fictional storytelling has played an important role in human cultural life since earliest times, and we are willing to invest significant quantities of time, mental effort and money in it. Nonetheless, the psychological mechanisms that make this possible, and how they relate to the mechanisms that underpin real-world social relationships, remain understudied. We explore three factors: identification (the capacity to identify with a character), moral approval and causal attribution with respect to a character's behaviour in live performances of two plays from the European literary canon. There were significant correlations between the extent to which subjects identified with a character and their moral approval of that character's behaviour that was independent of the way the play was directed. However, the subjects' psychological explanations for a character's behaviour (attribution) were independent of whether or not they identified with, or morally approved of, the character. These data extend previous findings by showing that moral approval plays an important role in facilitating identification even in live drama. Despite being transported by an unfolding drama, audiences do not necessarily become biased in their psychological understanding of why characters behaved as they did. The psychology of drama offers significant insights into the psychological processes that underpin our everyday social world.

Laughter influences social bonding but not prosocial generosity to friends and strangers.

Humans deploy a number of specific behaviours for forming social bonds, one of which is laughter. However, two questions have not yet been investigated with respect to laughter: (1) Does laughter increase the sense of bonding to those with whom we laugh? and (2) Does laughter facilitate prosocial generosity? Using changes in pain threshold as a proxy for endorphin upregulation in the brain and a standard economic game (the Dictator Game) as an assay of prosociality, we show that laughter does trigger the endorphin system and, through that, seems to enhance social bonding, but it does not reliably influence donations to others. This suggests that social bonding and prosociality may operate via different mechanisms, or on different time scales, and relate to different functional objectives.

Cochlear SGN neurons elevate pain thresholds in response to music.

The C-tactile (CLTM) peripheral nervous system is involved in social bonding in primates and humans through its capacity to trigger the brain's endorphin system. Since the mammalian cochlea has an unusually high density of similar neurons (type-II spiral ganglion neurons, SGNs), we hypothesise that their function may have been exploited for social bonding by co-opting head movements in response to music and other rhythmic movements of the head in social contexts. Music provides one of many cultural behavioural mechanisms for 'virtual grooming' in that it is used to trigger the endorphin system with many people simultaneously so as to bond both dyadic relationships and large groups. Changes in pain threshold across an activity are a convenient proxy assay for endorphin uptake in the brain, and we use this, in two experiments, to show that pain thresholds are higher when nodding the head than when sitting still.

Blocking mu-opioid receptors inhibits social bonding in rituals.

Religious rituals are universal human practices that play a seminal role in community bonding. In two experiments, we tested the role of mu-opioids as the active factor fostering social bonding. We used a mu-opioid blocker (naltrexone) in two double-blind studies of rituals from different religious traditions. We found the same effect across both studies, with naltrexone leading to significantly lower social bonding compared with placebo. These studies suggest that mu-opioids play a significant role in experiences of social bonding within ritual contexts.

Structure and function in human and primate social networks: implications for diffusion, network stability and health.

The human social world is orders of magnitude smaller than our highly urbanized world might lead us to suppose. In addition, human social networks have a very distinct fractal structure similar to that observed in other primates. In part, this reflects a cognitive constraint, and in part a time constraint, on the capacity for interaction. Structured networks of this kind have a significant effect on the rates of transmission of both disease and information. Because the cognitive mechanism underpinning network structure is based on trust, internal and external threats that undermine trust or constrain interaction inevitably result in the fragmentation and restructuring of networks. In contexts where network sizes are smaller, this is likely to have significant impacts on psychological and physical health risks.

Physical Contact and Loneliness: Being Touched Reduces Perceptions of Loneliness.

OBJECTIVE: This article addresses the connection between loneliness and physical contact. Evolutionary and psychological research has shown that touch is an important part of bond-building and emotion communication; loneliness is intimately related to these elements as well. In this paper, we ask whether physical contact reduces feelings of loneliness -which might derive from evolutionary ancient bonding mechanisms-despite a cultural context that is relatively non-tactile. METHOD: An experimental study (40 participants, 13 males) tested for observable effects of touch on loneliness scores in a low-contact culture to analyse whether they respond positively to that stimulus despite cultural training against it. RESULTS: Participants exposed to physical contact reported significantly lower neglect scores from their close relationships in a short loneliness scale, thus suggesting that there is an underlying mechanism that persists despite enculturation. The effects were particularly strong among single people, which could mean that lower loneliness among married people might be partly explained by the regular availability of physical contact. Participants in the experimental condition also showed a faster reduction in heart rate, interpreted as a sign of physiological wellbeing. CONCLUSIONS: These findings help to specify mechanisms within the evolutionary theoretical framework of loneliness that link internal feelings to environmental cues. This article aims at contributing to a more complex discussion on the interactions between emotions, cultural practices and psychological well-being.

Relating size and functionality in human social networks through complexity.

Extensive empirical evidence suggests that there is a maximal number of people with whom an individual can maintain stable social relationships (the Dunbar number). We argue that this arises as a consequence of a natural phase transition in the dynamic self-organization among N individuals within a social system. We present the calculated size dependence of the scaling properties of complex social network models to argue that this collective behavior is an enhanced form of collective intelligence. Direct calculation establishes that the complexity of social networks as measured by their scaling behavior is nonmonotonic, peaking around 150, thereby providing a theoretical basis for the value of the Dunbar number. Thus, we establish a theory-based bridge spanning the gap between sociology and psychology.

Closing the reporting gap for childhood tuberculosis in South Africa: improving hospital referrals and linkages.

SETTING: A referral hospital in Cape Town, Western Cape Province, Republic of South Africa. OBJECTIVE: To measure the impact of a hospital-based referral service (intervention) to reduce initial loss to follow-up among children with tuberculosis (TB) and ensure the completeness of routine TB surveillance data. DESIGN: A dedicated TB referral service was established in the paediatric wards at Tygerberg Hospital, Cape Town, in 2012. Allocated personnel provided TB education and counselling, TB referral support and weekly telephonic follow-up after hospital discharge. All children identified with TB were matched to electronic TB treatment registers (ETR.Net/EDRWeb). Multivariable logistic regression was used to compare reporting of culture-confirmed and drug-susceptible TB cases before (2007-2009) and during (2012) the intervention. RESULTS: Successful referral with linkage to care was confirmed in 267/272 (98%) and successful reporting in 227/272 (84%) children. Children with drug-susceptible, culture-confirmed TB were significantly more likely to be reported during the intervention period than in the pre-intervention period (OR 2.52, 95%CI 1.33-4.77). The intervention effect remained consistent in multivariable analysis (adjusted OR 2.62; 95%CI 1.31-5.25) after adjusting for age, sex, human immunodeficiency virus status and the presence of TB meningitis. CONCLUSIONS: A simple hospital-based TB referral service can reduce initial loss to follow-up and improve recording and reporting of childhood TB in settings with decentralised TB services.