Epidemiology of Mycobacterium bovis infection in free-ranging rhinoceros in Kruger National Park, South Africa.

Mycobacterium bovis infection, which is a prominent cause of bovine tuberculosis, has been confirmed by mycobacterial culture in African rhinoceros species in Kruger National Park (KNP), South Africa. In this population-based study of the epidemiology of M. bovis in 437 African rhinoceros (Diceros bicornis, Ceratotherium simum), we report an estimated prevalence of 15.4% (95% CI: 10.4 to 21.0%), based on results from mycobacterial culture and an antigen-specific interferon gamma release assay from animals sampled between 2016 and 2020. A significant spatial cluster of cases was detected near the southwestern park border, although infection was widely distributed. Multivariable logistic regression models, including demographic and spatiotemporal variables, showed a significant, increasing probability of M. bovis infection in white rhinoceros based on increased numbers of African buffalo (Syncerus caffer) herds in the vicinity of the rhinoceros sampling location. Since African buffaloes are important maintenance hosts for M. bovis in KNP, spillover of infection from these hosts to white rhinoceros sharing the environment is suspected. There was also a significantly higher proportion of M. bovis infection in black rhinoceros in the early years of the study (2016­2018) than in 2019 and 2020, which coincided with periods of intense drought, although other temporal factors could be implicated. Species of rhinoceros, age, and sex were not identified as risk factors for M. bovis infection. These study findings provide a foundation for further epidemiological investigation of M. bovis, a multihost pathogen, in a complex ecosystem that includes susceptible species that are threatened and endangered.

Extracellular ATP Neurotransmission and Nicotine Sex-Specifically Modulate Habenular Neuronal Activity in Adolescence.

The recent increase in the use of nicotine products by teenagers has revealed an urgent need to better understand the impact of nicotine on the adolescent brain. Here, we sought to examine the actions of extracellular ATP as a neurotransmitter and to investigate whether ATP and nicotinic signaling interact during adolescence. With the GRABATP (G-protein-coupled receptor activation-based ATP sensor), we first demonstrated that nicotine induces extracellular ATP release in the medial habenula, a brain region involved in nicotine aversion and withdrawal. Using patch-clamp electrophysiology, we then demonstrated that activation of the ATP receptors P2X or P2Y1 increases the neuronal firing of cholinergic neurons. Surprisingly, contrasting interactive effects were observed with nicotine exposure. For the P2X receptor, activation had no observable effect on acute nicotine-mediated activity, but during abstinence after 10 d of nicotine exposure, coexposure to nicotine and the P2X agonist potentiated neuronal activity in female, but not male, neurons. For P2Y1 signaling, a potentiated effect of the agonist and nicotine was observed with acute exposure, but not following extended nicotine exposure. These data reveal a complex interactive effect between nicotinic and ATP signaling in the adolescent brain and provide mechanistic insights into extracellular ATP signaling with sex-specific alterations of neuronal responses based on prior drug exposure.SIGNIFICANCE STATEMENT In these studies, it was discovered that nicotine induces extracellular ATP release in the medial habenula and subsequent activation of the ATP purinergic receptors increases habenular cholinergic neuronal firing in the adolescent brain. Interestingly, following extended nicotine exposure, nicotine was found to alter the interplay between purinergic and nicotinic signaling in a sex-specific manner. Together, these studies provide a novel understanding for the role of extracellular ATP in mediating habenular activity and reveal how nicotine exposure during adolescence alters these signaling mechanisms, which has important implications given the high incidence of e-cigarette/vape use by youth.

One person, many changes: a socioecological qualitative analysis of the experiences of transfeminine individuals undergoing feminising gender-affirming hormone therapy.

Gender-affirming hormone therapy (GAHT) comes with many physical, psychological, and social changes that are often considered in isolation. This research uses a socioecological lens with a sample of 15 Australian transfeminine individuals to investigate the changes experienced during GAHT. Semi-structured interviews were conducted in 2022, with verbatim transcripts analysed using deductive thematic analysis with Bronfenbrenner's Socioecological Model (SEM) as a framework. Analyses revealed two themes intersecting multiple levels of the SEM. Theme 1 contained two sub-themes and broadly encapsulated how interactions with others influenced GAHT experiences. Sub-theme 1 spoke to how stigma creates positive or negative experiences (through the macrosystem, the exosystem, and proximal processes), while sub-theme 2 described how GAHT causes internal changes that promoted stronger interpersonal relationships (person and proximal processes). Theme 2 described how changes occurred over time, with some changes being temporary, and others being delayed (person and time). These themes highlight the interconnected nature of the physical, psychological, and social changes and experiences that can occur during GAHT. Best-practice care for trans people undergoing GAHT needs to be multi-faceted and holistic in order to embed support across different SEM components.

The provision of sexual and reproductive health information and services to travellers: an exploratory survey of Australian travel medicine clinicians.

BACKGROUND: International travel can increase the risk of exposure to infectious diseases including sexually transmissible infections (STI). Pre-travel medical consultation provides an opportunity for travel-related health risk assessments and advice. This study explored how travel medicine clinicians integrate sexual and reproductive health (SRH) services into clinical practice. METHODS: A convenience sample of travel medicine clinicians completed a cross-sectional survey online or via hard-copy disseminated at an annual national Australian travel medicine conference. RESULTS: Of the 67 respondents, most (n , 51; 76.1%) had a postgraduate qualification relevant to travel medicine and 55.2% (n , 37) had worked in travel medicine for over 10years. Only 22.4% (n , 15) reported conducting a SRH history/STI risk assessment for all travel patients. STI testing pre-departure was conducted on patient request (48, 71.6%), if symptomatic (32, 47.8%) or based on risk history (28, 41.8%). SRH information pre-departure was most frequently provided if prompted by patient questions (n , 42; 62.7%), or based on the patient's history (n , 37; 55.2%). Over half the sample (n , 40; 59.7%) expressed interest in further training in SRH. CONCLUSION: Providing and engaging with additional training may assist travel medicine clinicians to take a more proactive approach to SRH consultations and STI testing. Additional research is needed to explore models of care that will allow comprehensive SRH and STI services to be integrated into standard pre- and post-travel care.

Barriers to optimal management of syphilis in pregnancy and congenital syphilis in south-east Queensland: a qualitative investigation.

BACKGROUND: Australia, like many high-income countries, is experiencing a resurgence of infectious syphilis in pregnancy and congenital syphilis. Evaluations of public health notifications and clinical records suggest that healthcare systems may not be providing optimal care to women and their neonates. This study aims to explore the barriers to optimal management of syphilis in pregnancy and congenital syphilis to identify key areas for improvement. METHODS: Between 2021 and 2022, 34 healthcare workers (HCW) practicing in south-east Queensland (SEQ) Australia were recruited to complete semi-structured interviews regarding their perceptions towards management of syphilis in pregnancy and congenital syphilis. Interviews were analysed thematically. RESULTS: Thematic analysis identified four themes related to the management of syphilis in pregnancy. These included poor communication between disciplines, services, and teams from delivery through to management and post-delivery, lack of formal internal and external referral pathways, unclear and often complex maternal and congenital syphilis management procedures, and limited HCW knowledge of infectious syphilis in pregnancy and congenital syphilis. CONCLUSION: As congenital syphilis numbers continue to rise in SEQ, it is imperative that healthcare systems and HCWs identify and address gaps in the provision of health care.

Syphilis in pregnancy: a qualitative investigation of healthcare provider perspectives on barriers to syphilis screening during pregnancy in south-east Queensland.

BACKGROUND: Increasing rates of syphilis in pregnancy (SiP) in Australia and other high-income countries, has led to the resurgence of congenital syphilis. Suboptimal syphilis screening during pregnancy has been identified as a key contributing factor. METHODS: This study aimed to explore, from the perspective of multidisciplinary healthcare providers (HCPs), the barriers to optimal screening during the antenatal care (ANC) pathway. Semi-structured interviews conducted with 34 HCPs across multiple disciplines practising in south-east Queensland (SEQ) were analysed through a process of reflexive thematic analysis. RESULTS: Barriers were found to occur at the system level of ANC, through difficulties in patient engagement in care, limitations in the current model of health care delivery and limitations in the communication pathways across health care disciplines; and at the individual HCP level, through HCP knowledge and awareness of epidemiological changes in syphilis in SEQ, and adequately assessing patient risk. CONCLUSION: It is imperative that the healthcare systems and HCPs involved in ANC address these barriers to improve screening in order to optimise management of women and prevent congenital syphilis cases in SEQ.

Robot-Assisted Nasal Reconstruction: A Cadaveric Study.

OBJECTIVE: Manual contouring of cartilage for nasal reconstruction is tedious and time-consuming. The use of a robot could improve the speed and precision of the contouring process. This cadaveric study evaluates the efficiency and accuracy of a robot methodology for contouring the lower lateral cartilage of the nasal tip. METHODS: An augmented robot with a spherical burring tool attached was utilized to carve 11 cadaveric rib cartilage specimens. In phase 1, the right lower lateral cartilage was harvested from a cadaveric specimen and used to define a carving path for each rib specimen. In phase 2, the cartilage remained in situ during the scanning and 3-dimensional modeling. The final carved specimens were compared with the preoperative plans through topographical accuracy analysis. The contouring times of the specimens were compared with 14 retrospectively reviewed cases (2017-2020) by an experienced surgeon. RESULTS: Phase 1 root mean square error of 0.40±0.15 mm and mean absolute deviation of 0.33±0.13 mm. Phase 2 root mean square error of 0.43 mm and mean absolute deviation of 0.28 mm. The average carving time for the robot specimens was 14±3 minutes and 16 minutes for Phase 1 and Phase 2, respectively. The average manual carving by an experienced surgeon was 22±4 minutes. CONCLUSIONS: Robot-assisted nasal reconstruction is very precise and more efficient than manual contouring. This technique represents an exciting and innovative alternative for complex nasal reconstruction.

Digital mental health interventions: A narrative review of what is important from the perspective of LGBTQIA+ people.

OBJECTIVES: Digital mental health interventions are a promising therapeutic modality to provide psychological support to LGBTQIA+ (lesbian, gay, bisexual, trans, Queer, intersex, asexual, plus other gender, sexual, and romantic minority identities) people. The aim of this narrative review is to explore how the LGBTQIA+ community has been engaged in the design of digital mental health interventions, how content has been tailored to the LGBTQIA+ community, and features identified as important by LGBTQIA+ participants. METHODS: A total of 33 studies were included in this review from a larger yield of 1933 identified from systematic searches of five databases (PsycINFO, PubMed, Scopus, CINAHAL, and Medline). Data were analyzed narratively and using content analysis. RESULTS: Only half of the studies reported engaging the LGBTQIA+ community in intervention designs. Interventions have been tailored in a variety of ways to support LGBTQIA+ individuals-such as through affirming imagery, recruitment through LGBTQIA+ networks, and designing content to focus specifically on LGBTQIA+ issues. A range of features were identified as important for participants, namely how content was tailored to LGBTQIA+ experiences, providing connection to community, and links to other relevant LGBTQIA+ resources. While not a primary aim, results also showed that a wide range of digital modalities can significantly improve a range of mental health problems. CONCLUSION: Digital interventions are an acceptable and effective form of therapeutic intervention, but future research needs to focus on meaningful engagement of community members to inform design and implementation.

Nicotine e-cigarette vapor inhalation and self-administration in a rodent model: Sex- and nicotine delivery-specific effects on metabolism and behavior.

E-cigarettes, which deliver vaporized nicotine, have dramatically risen in popularity in recent years, despite many unanswered questions about safety, efficacy in reducing dependence, and overall impact on public health. Other factors, such as sex, also play an important role in determining behavioral and neurochemical responses to drugs of abuse. In these studies, we sought to develop a protocol for vaporized e-cigarette nicotine self-administration in rats, as a foundation to better understand the differing effects of nicotine exposure routes on behavior and physiological function. We report a novel method that elicits robust nicotine vapor self-administration in male and female rats. Our findings indicate that 5-mg/ml nicotine vape solution provides a high level of consistency in lever-pressing behavior for both males and females. Moreover, in male rats, we find that such e-cigarette nicotine vapor induces similar blood levels of nicotine's main metabolite, cotinine, as that found with intravenous nicotine self-administration. Therefore, the breathing pattern during vapor exposure in males leads to similar levels of titrated nicotine intake as with intravenous nicotine self-administration. Interestingly, a differential effect was found in the females, in which the same conditions of vapor exposure led to decreased cotinine levels with vapor compared to intravenous self-administration. Finally, differences in nicotine-mediated locomotion provide further support of the physiological effects of e-cigarette vapor inhalation. Taken together, our findings reveal important sex differences in nicotine intake based on the route of exposure, and we further establish a protocol for nicotine vapor self-administration in rats.

The Novel CYP2A6 Inhibitor, DLCI-1, Decreases Nicotine Self-Administration in Mice.

During tobacco and e-cigarette use, nicotine is mainly metabolized in the human liver by cytochrome P450 2A6 (CYP2A6). Given that a slower CYP2A6 metabolism has been associated with less vulnerability to develop nicotine dependence, the current studies sought to validate a novel CYP2A6 inhibitor, (5-(4-ethylpyridin-3-yl)thiophen-2-yl)methanamine (DLCI-1), for its effects on intravenous nicotine self-administration. Male and female mice were trained to self-administer nicotine across daily sessions. Once stable responding was achieved, DLCI-1 or vehicle control was administered prior to nicotine sessions. We found that the lower 25 mg/kg and moderate 50 mg/kg doses of DLCI-1 induced a significant decrease in nicotine intake for both males and females. DLCI-1 was further shown to be more effective than a moderate 1 mg/kg dose of bupropion on reducing nicotine intake and did not exert the adverse behavioral effects found with a high 75 mg/kg dose of bupropion. Although mice treated with DLCI-1 self-administered significantly less nicotine, similar nicotine-mediated behavioral effects on locomotion were observed. Together, along with the analysis of nicotine metabolites during self-administration, these findings support the contention that blocking hepatic nicotine metabolism would allow for similar activation of nicotinic acetylcholine receptors at lower nicotine doses. Moreover, these effects of DLCI-1 were specific to nicotine self-administration, as DLCI-1 did not result in any behavioral changes during food self-administration. Taken together, these studies validate DLCI-1 as a novel compound to decrease nicotine consumption, which may thereby promote tobacco and nicotine product cessation. SIGNIFICANCE STATEMENT: Current pharmacological approaches for nicotine and tobacco cessation have only been able to achieve limited efficaciousness in promoting long-term abstinence. In this work, we characterize the effects of a novel compound, (5-(4-ethylpyridin-3-yl)thiophen-2-yl)methanamine (DLCI-1), which inhibits the main enzyme that metabolizes nicotine, and we report a significant decrease in intravenous nicotine self-administration in male and female mice, supporting the potential of DLCI-1 as a novel tobacco cessation pharmacotherapeutic.

Adolescent Cannabinoid and Nicotine Exposure Differentially Alters Adult Nicotine Self-Administration in Males and Females.

INTRODUCTION: During adolescence, exposure to nicotine or cannabis independently induces effects on neuromaturation and later cognitive function. However, the potential effect of both drugs under co-use conditions has become of increasing concern given the prevalence of e-cigarettes, legalization of cannabis, and availability of synthetic "spice" cannabinoid agonists. AIMS AND METHODS: The current studies investigated the effects of exposure to a cannabinoid receptor agonist (WIN55,212-2) and/or nicotine over a discrete time period in mid-adolescence on later intravenous nicotine self-administration in adult male and female mice. We further examined whether cannabinoid agonist administration in adulthood would alter nicotine reinforcement, with either acute or chronic pairing across 7 days. RESULTS: We found that adult males exhibited increased nicotine self-administration at a lower, rewarding nicotine dose following adolescent cannabinoid exposure, either alone or with nicotine coadministration. In contrast, adult females demonstrated an opposing effect in which adolescent cannabinoid and nicotine coexposure resulted in decreased nicotine intake compared with the nicotine only and control groups. Furthermore, after maintaining nicotine self-administration across sessions, pretreatment with a low dose of the cannabinoid agonist decreased nicotine intake in both male and female control mice, and this lowering effect was evidenced after both acute and chronic treatment. However, the cannabinoid agonist was ineffective in altering nicotine intake in mice previously exposed to nicotine, cannabinoid agonist, or both during adolescence. CONCLUSIONS: These data provide evidence that adolescent drug exposure can alter later nicotine reinforcement in a sex-specific manner and can further modulate the effectiveness of interventions in reducing nicotine intake during adulthood. IMPLICATIONS: These studies demonstrate a significant impact of nicotine, cannabinoids, or coexposure on developmental processes during adolescence. Differential effects were observed within each sex, with opposing results found for cannabinoid exposure on nicotine intake in males and females. Intriguingly, we also evidenced resistance to the lowering effects of a cannabinoid agonist on nicotine intake in adulthood based on adolescent drug exposure. Thus, these findings have important implications for our understanding of the impact of nicotine and cannabinoids (eg, Δ9-tetrahydrocannabinol (THC) and synthetic "spice" cannabinoids) during development, with further implications for the effectiveness of therapeutic interventions based on prior drug exposure in youth.

Adapting an Outpatient Psychiatric Clinic to Telehealth During the COVID-19 Pandemic: A Practice Perspective.

As the demand for telepsychiatry increases during the COVID-19 pandemic, the strengths and challenges of telepsychiatry implementation must be articulated to improve clinical practices in the long term. Currently, observations within US contexts are lacking; therefore, we report on the rapid implementation of telepsychiatry and workflow experiences in a psychiatric practice based within a large health care system in southeast Texas with a national catchment area. We discuss the logistics of the implementation, including modes of communication, scheduling, coordination, and capacity; the psychological effects of web-based services, including both the loss of the physical therapeutic environment and the unique interpersonal dynamics experienced in the virtual environment; and postadoption patterns of engagement with our services and with other clinical functions affected by the rapid adaptation to telemedicine. Our art therapy group programming serves as an applied case study, demonstrating the value of a well-managed web-based program (eg, patients were receptive and well-engaged, and they appreciated the continuity of accessible service) as well as the challenges (eg, the need for backup plans and technological fallbacks, managing interruptions and telecommunication learning curves, and working around the difference in resources for art and music therapy between a well-stocked clinical setting versus clients' home spaces). We conclude from our experience that the overall strengths of telepsychiatry include receptive and well-engaged responses from patients as well as the expansion of boundaries, which provides a directly contextualized view into patients' home lives. Challenges and corresponding recommendations include the need for more careful safety planning for high-risk patients; maintaining professional boundaries in the newly informal virtual setting; designing the physical space to both frame the patient encounter and maintain work-life balance for the therapist; allowing for delays and interruptions (including an initial acclimation session); and preserving interprofessional care team collaboration when the physical locations that normally facilitate such encounters are not accessible. We believe that careful observations of the strengths and challenges of telepsychiatry during this pandemic will better inform practices that are considering telepsychiatry adoption both within pandemic contexts and more broadly thereafter.

Increased expression of plasminogen activator inhibitor-1 (PAI-1) is associated with depression and depressive phenotype in C57Bl/6J mice.

Plasminogen activator inhibitor 1 (PAI-1), which is elevated in numerous disease states, has been implicated as a stress-related protein involved in the pathogenesis of depression. We measured PAI-1 in the plasma of healthy and depressed individuals and assessed plasminogen activator (PA) expression and regulation by PAI-1 in cultured normal human astrocytes (NHA). Elevated plasma PAI-1 levels were found in depressed patients. Brain tissues from depressed individuals also showed stronger expression of hippocampal PAI-1 by confocal imaging in comparison to healthy individuals. Using a lipopolysaccharide-induced inflammatory model of depression in mice, we measured PAI-1 in murine plasma and brain, by ELISA and immunohistochemistry, respectively. Similar elevations were seen in plasma but not in brain homogenates of mice exposed to LPS. We further correlated the findings with depressive behavior. Ex vivo experiments with NHA treated with proinflammatory cytokines implicated in the pathogenesis of depression showed increased PAI-1 expression. Furthermore, these studies suggest that urokinase-type plasminogen activator may serve as an astrocyte PA reservoir, able to promote cleavage of brain-derived neurotrophic factor (BDNF) during stress or inflammation. In summary, our findings confirm that derangements of PAI-1 variably occur in the brain in association with the depressive phenotype. These derangements may impede the availability of active, mature (m)BDNF and thereby promote a depressive phenotype.

Online social integration is associated with reduced mortality risk.

Social interactions increasingly take place online. Friendships and other offline social ties have been repeatedly associated with human longevity, but online interactions might have different properties. Here, we reference 12 million social media profiles against California Department of Public Health vital records and use longitudinal statistical models to assess whether social media use is associated with longer life. The results show that receiving requests to connect as friends online is associated with reduced mortality but initiating friendships is not. Additionally, online behaviors that indicate face-to-face social activity (like posting photos) are associated with reduced mortality, but online-only behaviors (like sending messages) have a nonlinear relationship, where moderate use is associated with the lowest mortality. These results suggest that online social integration is linked to lower risk for a wide variety of critical health problems. Although this is an associational study, it may be an important step in understanding how, on a global scale, online social networks might be adapted to improve modern populations' social and physical health.

Formation of raiding parties for intergroup violence is mediated by social network structure.

Intergroup violence is common among humans worldwide. To assess how within-group social dynamics contribute to risky, between-group conflict, we conducted a 3-y longitudinal study of the formation of raiding parties among the Nyangatom, a group of East African nomadic pastoralists currently engaged in small-scale warfare. We also mapped the social network structure of potential male raiders. Here, we show that the initiation of raids depends on the presence of specific leaders who tend to participate in many raids, to have more friends, and to occupy more central positions in the network. However, despite the different structural position of raid leaders, raid participants are recruited from the whole population, not just from the direct friends of leaders. An individual's decision to participate in a raid is strongly associated with the individual's social network position in relation to other participants. Moreover, nonleaders have a larger total impact on raid participation than leaders, despite leaders' greater connectivity. Thus, we find that leaders matter more for raid initiation than participant mobilization. Social networks may play a role in supporting risky collective action, amplify the emergence of raiding parties, and hence facilitate intergroup violence in small-scale societies.

Ventricular global longitudinal strain is altered in children with sickle cell disease.

Cardiac disease is the primary cause of death in sickle cell disease (SCD). Right and left ventricular global longitudinal strain (RVGLS, LVGLS) are early markers of systolic dysfunction but are not well investigated among children with SCD. One hundred and forty-three patients with HbSS or HbSß0 -thalassaemia (median age 11 years, range 5-19 years) and 71 controls matched for age and sex were compared. RVGLS and LVGLS were measured and compared with conventional measures of echocardiography and markers of haemolysis and inflammation. RVGLS was higher in children with SCD than in controls (-25·72% ± 3·45% vs. -24·54% ± 2·41%, P = 0·005); LVGLS was not different. RVGLS decreased with older age in children with SCD (ρ = 0·338, P < 0·001) but not among controls. Decreased RVGLS was associated with increased left atrial end diastolic volume (ρ = 0·181, P = 0·04); RVGLS increased with cardiac output (r = -0·279, P = 0·01). RVGLS and LVGLS were not associated with disease-modifying therapies, degree of anaemia or haemolysis markers. Elevated RVGLS may indicate an early RV compensatory mechanism in response to upstream myocardial insults and elevated cardiac output. Global longitudinal strain may serve as an early marker of altered myocardial function in children with SCD.

Social networks and cooperation in hunter-gatherers.

Social networks show striking structural regularities, and both theory and evidence suggest that networks may have facilitated the development of large-scale cooperation in humans. Here, we characterize the social networks of the Hadza, a population of hunter-gatherers in Tanzania. We show that Hadza networks have important properties also seen in modernized social networks, including a skewed degree distribution, degree assortativity, transitivity, reciprocity, geographic decay and homophily. We demonstrate that Hadza camps exhibit high between-group and low within-group variation in public goods game donations. Network ties are also more likely between people who give the same amount, and the similarity in cooperative behaviour extends up to two degrees of separation. Social distance appears to be as important as genetic relatedness and physical proximity in explaining assortativity in cooperation. Our results suggest that certain elements of social network structure may have been present at an early point in human history. Also, early humans may have formed ties with both kin and non-kin, based in part on their tendency to cooperate. Social networks may thus have contributed to the emergence of cooperation.

A 61-million-person experiment in social influence and political mobilization.

Human behaviour is thought to spread through face-to-face social networks, but it is difficult to identify social influence effects in observational studies, and it is unknown whether online social networks operate in the same way. Here we report results from a randomized controlled trial of political mobilization messages delivered to 61 million Facebook users during the 2010 US congressional elections. The results show that the messages directly influenced political self-expression, information seeking and real-world voting behaviour of millions of people. Furthermore, the messages not only influenced the users who received them but also the users' friends, and friends of friends. The effect of social transmission on real-world voting was greater than the direct effect of the messages themselves, and nearly all the transmission occurred between 'close friends' who were more likely to have a face-to-face relationship. These results suggest that strong ties are instrumental for spreading both online and real-world behaviour in human social networks.

Familial social structure and socially driven genetic differentiation in Hawaiian short-finned pilot whales.

Social structure can have a significant impact on divergence and evolution within species, especially in the marine environment, which has few environmental boundaries to dispersal. On the other hand, genetic structure can affect social structure in many species, through an individual preference towards associating with relatives. One social species, the short-finned pilot whale (Globicephala macrorhynchus), has been shown to live in stable social groups for periods of at least a decade. Using mitochondrial control sequences from 242 individuals and single nucleotide polymorphisms from 106 individuals, we examine population structure among geographic and social groups of short-finned pilot whales in the Hawaiian Islands, and test for links between social and genetic structure. Our results show that there are at least two geographic populations in the Hawaiian Islands: a Main Hawaiian Islands (MHI) population and a Northwestern Hawaiian Islands/Pelagic population (FST and ΦST p < .001), as well as an eastern MHI community and a western MHI community (FST p = .009). We find genetically driven social structure, or high relatedness among social units and clusters (p < .001), and a positive relationship between relatedness and association between individuals (p < .0001). Further, socially organized clusters are genetically distinct, indicating that social structure drives genetic divergence within the population, likely through restricted mate selection (FST p = .05). This genetic divergence among social groups can make the species less resilient to anthropogenic or ecological disturbance. Conservation of this species therefore depends on understanding links among social structure, genetic structure and ecological variability within the species.

The evolution of overconfidence.

Confidence is an essential ingredient of success in a wide range of domains ranging from job performance and mental health to sports, business and combat. Some authors have suggested that not just confidence but overconfidence--believing you are better than you are in reality--is advantageous because it serves to increase ambition, morale, resolve, persistence or the credibility of bluffing, generating a self-fulfilling prophecy in which exaggerated confidence actually increases the probability of success. However, overconfidence also leads to faulty assessments, unrealistic expectations and hazardous decisions, so it remains a puzzle how such a false belief could evolve or remain stable in a population of competing strategies that include accurate, unbiased beliefs. Here we present an evolutionary model showing that, counterintuitively, overconfidence maximizes individual fitness and populations tend to become overconfident, as long as benefits from contested resources are sufficiently large compared with the cost of competition. In contrast, unbiased strategies are only stable under limited conditions. The fact that overconfident populations are evolutionarily stable in a wide range of environments may help to explain why overconfidence remains prevalent today, even if it contributes to hubris, market bubbles, financial collapses, policy failures, disasters and costly wars.