Exploring Compersion: A Study on Polish Consensually Non-Monogamous Individuals and Adaptation of the COMPERSe Questionnaire.

Compersion is a positive emotion experienced in relation to one's partner's relationship(s) with other partner(s). Experiencing it is highly desired in communities practicing consensual non-monogamy (CNM), especially polyamory. This article presents the results of a study on compersion on Polish CNM individuals. The main goal of the study was to adapt to the Polish-speaking population the COMPERSe (Classifying Our Metamour/Partner Emotional Response Scale; Flicker et al., 2021), the first standardized quantitative scale designed to measure compersion. The analyses were performed on data obtained from 211 individuals in CNM relationships and on a comparative group of 169 people in monogamous relationships. The results of the confirmatory factor analyses suggested that the three-factor model of the original COMPERSe version did not fit well, leading to further revisions that resulted in a 7-item, two-factor solution with excellent fit, excellent internal consistency, strong divergent and convergent validity, and excellent test-retest stability. The CNM individuals were found to have higher scores on compersion and cognitive empathy and were also less jealous than the monogamous participants. Furthermore, polyamorous individuals experienced more compersion and less aversion to partner's autonomy than people in open relationships. It was also revealed that compersion indirectly predicted relationship satisfaction by decreasing jealousy and that compersion was, in turn, predicted by cognitive empathy. However, when polyamorous and open relationships were analyzed separately, compersion predicted relationship satisfaction directly, but only in polyamorous relationships; meanwhile, in open relationships, satisfaction was directly predicted by cognitive empathy.

Mating system variation and gene expression in the male reproductive tract of Peromyscus mice.

Genes involved in reproduction often evolve rapidly at the sequence level due to postcopulatory sexual selection (PCSS) driven by male-male competition and male-female sexual conflict, but the impact of PCSS on gene expression has been under-explored. Further, though multiple tissues contribute to male reproductive success, most studies have focused on the testes. To explore the influence of mating system variation on reproductive tract gene expression in natural populations, we captured adult males from monogamous Peromyscus californicus and polygynandrous P. boylii and P. maniculatus. We generated RNAseq libraries, quantified gene expression in the testis, seminal vesicle, epididymis, and liver, and identified 3627 mating system-associated differentially expressed genes (MS-DEGs), where expression shifted in the same direction in P. maniculatus and P. boylii relative to P. californicus. Gene expression variation was most strongly associated with mating behaviour in the seminal vesicles, where 89% of differentially expressed genes were MS-DEGs, including the key seminal fluid proteins Svs2 and Pate4. We also used published rodent genomes to test for positive and relaxed selection on Peromyscus-expressed genes. Though we did not observe more overlap than expected by chance between MS-DEGs and positively selected genes, 203 MS-DEGs showed evidence of positive selection. Fourteen reproductive genes were under tree-wide positive selection but convergent relaxed selection in P. californicus and Microtus ochrogaster, a distantly related monogamous species. Changes in transcript abundance and gene sequence evolution in association with mating behaviour suggest that male mice may respond to sexual selection intensity by altering aspects of sperm motility, sperm-egg binding and copulatory plug formation.

Transcriptomic changes in the posterior pallium of male zebra finches associated with social niche conformance.

Animals plastically adjust their physiological and behavioural phenotypes to conform to their social environment-social niche conformance. The degree of sexual competition is a critical part of the social environment to which animals adjust their phenotypes, but the underlying genetic mechanisms are poorly understood. We conducted a study to investigate how differences in sperm competition risk affect the gene expression profiles of the testes and two brain areas (posterior pallium and optic tectum) in breeding male zebra finches (Taeniopygia castanotis). In this pre-registered study, we investigated a large sample of 59 individual transcriptomes. We compared two experimental groups: males held in single breeding pairs (low sexual competition) versus those held in two pairs (elevated sexual competition) per breeding cage. Using weighted gene co-expression network analysis (WGCNA), we observed significant effects of the social treatment in all three tissues. However, only the treatment effects found in the pallium were confirmed by an additional randomisation test for statistical robustness. Likewise, the differential gene expression analysis revealed treatment effects only in the posterior pallium (ten genes) and optic tectum (six genes). No treatment effects were found in the testis at the single gene level. Thus, our experiments do not provide strong evidence for transcriptomic adjustment specific to manipulated sperm competition risk. However, we did observe transcriptomic adjustments to the manipulated social environment in the posterior pallium. These effects were polygenic rather than based on few individual genes with strong effects. Our findings are discussed in relation to an accompanying paper using the same animals, which reports behavioural results consistent with the results presented here.

Epigenetic aging studies of pair bonding in prairie voles.

The quality of romantic relationships can predict health consequences related to aging. DNA methylation-based biomarkers of aging accurately estimate chronological age. We developed several highly accurate epigenetic aging clocks, based on highly conserved mammalian CpGs, for the socially monogamous prairie vole (Microtus ochrogaster). In addition, our dual-species human-vole clock accurately measured relative age and illustrates high species conservation of epigenetic aging effects. Next, we assessed how pair bonding impacts epigenetic aging. We did not find evidence that pair-bonded voles exhibit accelerated or decelerated epigenetic aging effects in blood, ear, liver, or brain tissue. Our epigenome wide association study identified CpGs in five genes strongly associated with pair bonding: Foxp4, Phf2, Mms22l, Foxb1, and Eif1ad. Overall, we present accurate DNA methylation-based estimators of age for a species of great interest to researchers studying monogamy in animals. We did not find any evidence that sex-naive animals age differently from pair-bonded animals.

Understanding service preferences among consensually non-monogamous individuals seeking sexual healthcare.

Despite consensually non-monogamous people being a minority population with specific healthcare needs, research on this group is minimal, especially in relation to sexual healthcare. This study explores the motivations behind consensually non-monogamous individuals' choices of sexual healthcare service options. Qualitative survey data was collected from 67 consensual non-monogamists and analysed using thematic analysis. Two key themes captured participants' perspectives on the selection of sexual healthcare services. 'Feeling Comfortable' highlighted preferences for sexually inclusive clinics and LGBT+- focused services due to perceived better quality of care and comfort. 'Practicalities' emphasised convenience, proximity and the availability of STI testing options as critical factors influencing service selection. Accordingly, this research provides insight into the specific sexual healthcare service needs, desires and motivations of those who are consensually non-monogamous. Suggestions are made for increased training and awareness when working with relationship diverse patients.

Main Partner Relationships and the HIV Care Cascade: Examining the Predictive Utility of Sexual Agreements, Partner Concordance, and Drug Use Among Sexual Minority Men Living With HIV in the USA.

BACKGROUND: The past 15 years have seen increasing attention to relationship factors among sexual minority male (SMM) couples at high risk for HIV infection. Research has largely focused on HIV prevention outcomes. Outcomes relevant to SMM living with HIV have received relatively less attention. PURPOSE: This study evaluated associations between relational covariates (relationship status, sexual agreements, and seroconcordance) and HIV care cascade outcomes (having a current antiretroviral therapy [ART] prescription, ART adherence, viral load (VL) testing, and VL detectability) above and beyond cannabis and stimulant drug use. METHODS: Adult SMM (n = 36,874) living with HIV in the USA were recruited between November 1, 2017 and March 15, 2020 through social networking applications. They completed a cross-sectional survey online. RESULTS: Nonmonogamous SMM with serodiscordant partners were most likely to have an ART prescription. Those with seroconcordant partners (regardless of sexual agreements) were least likely to be adherent. While relational covariates were not associated with VL testing, SMM in nonmonogamous relationships with serodiscordant partners were significantly more likely to have an undetectable VL. Those in monogamous relationships with seroconcordant partners were significantly less likely to have an undetectable VL. CONCLUSIONS: SMM with seroconcordant partners and monogamous sexual agreements may experience diminished interpersonal motivation for HIV care engagement. HIV care cascade retention messages that emphasize the prevention of onward transmission may have limited relevance for these SMM. Novel intervention strategies are needed to enhance HIV care outcomes in this population, ideally ones that incorporate attention to drug use.

The majority of people living with HIV in the USA are sexual minority men (SMM). Whereas substantial work has examined HIV prevention in male couples, relatively little has examined relationship factors associated with HIV care outcomes. This study examined whether relationship status, main partner serostatus (seroconcordant vs. serodiscordant), and sexual agreements (monogamous vs. nonmonogamous) were associated with HIV care cascade outcomes (having a current antiretroviral therapy [ART] prescription, ART adherence, viral load testing, and viral load detectability) above and beyond cannabis and stimulant drug use. We surveyed adult SMM (n = 36,874) living with HIV in the USA between November 2017 and March 2020. Across outcomes where significant between-group differences were observed, results generally indicated partnered SMM with serodiscordant partners­particularly those in nonmonogamous relationships­were more likely to be retained in the HIV care cascade; meanwhile, SMM with seroconcordant partners­particularly those in monogamous relationships­were most vulnerable to attrition in the HIV care cascade. Given this pattern of findings, it is conceivable that efforts to motivate linkage and retention along the HIV care cascade have emphasized the prevention of onward transmission while failing to capitalize on or acknowledge health enhancement as an additional (and coequal) source of motivation.

Benefits of Pair-Bond Duration on Reproduction in a Lifelong Monogamous Cooperative Passerine.

AbstractLong-term social and genetic monogamy is rare in animals except birds, but even in birds it is infrequent and poorly understood. We investigated possible advantages of monogamy in a colonial, facultative cooperatively breeding bird from an arid, unpredictable environment, the sociable weaver (Philetairus socius). We documented divorce and extrapair paternity of 703 pairs over 10 years and separated effects of pair duration from breeding experience by analyzing longitudinal and cross-sectional datasets. Parts of the colonies were protected from nest predation, thereby limiting its stochastic and thus confounding effect on fitness measures. We found that 6.4% of sociable weaver pairs divorced and 2.2% of young were extrapair. Longer pair-bonds were associated with more clutches and fledglings per season and with reproducing earlier and later in the season, when snake predation is lower, but not with increased egg or fledgling mass or with nestling survival. Finally, the number of helpers at the nest increased with pair-bond duration. Results were similar for protected and unprotected nests. We suggest that long-term monogamy is associated with a better capacity for exploiting a temporally unpredictable environment and helps to form larger groups. These results can contribute to our understanding of why long-term monogamy is frequently associated with unpredictable environments and cooperation.

Tighter Constraints of Multi-Qubit Entanglement in Terms of Nonconvex Entanglement Measures LCREN and LCRENoA.

The monogamy property of entanglement is an intriguing feature of multipartite quantum entanglement. Most entanglement measures satisfying the monogamy inequality have turned out to be convex. Whether nonconvex entanglement measures obey the monogamy inequalities remains less known at present. As a well-known measure of entanglement, the logarithmic negativity is not convex. We elucidate the constraints of multi-qubit entanglement based on the logarithmic convex-roof extended negativity (LCREN) and the logarithmic convex-roof extended negativity of assistance (LCRENoA). Using the Hamming weight derived from the binary vector associated with the distribution of subsystems, we establish monogamy inequalities for multi-qubit entanglement in terms of the αth-power (α≥4ln2) of LCREN, and polygamy inequalities utilizing the αth-power (0≤α≤2) of LCRENoA. We demonstrate that these inequalities give rise to tighter constraints than the existing ones. Furthermore, our monogamy inequalities are shown to remain valid for the high-dimensional states that violate the CKW monogamy inequality. Detailed examples are presented to illustrate the effectiveness of our results in characterizing the multipartite entanglement distributions.

Evidence for individual vocal recognition in a pair-bonding poison frog, Ranitomeya imitator.

Individually distinctive vocalizations are widespread in nature, although the ability of receivers to discriminate these signals has only been explored through limited taxonomic and social lenses. Here, we asked whether anuran advertisement calls, typically studied for their role in territory defense and mate attraction, facilitate recognition and preferential association with partners in a pair-bonding poison frog (Ranitomeya imitator). Combining no- and two-stimulus choice playback experiments, we evaluated behavioral responses of females to male acoustic stimuli. Virgin females oriented to and approached speakers broadcasting male calls independent of caller identity, implying that females are generally attracted to male acoustic stimuli outside the context of a pair bond. When pair-bonded females were presented with calls of a mate and a stranger, they showed significant preference for calls of their mate. Moreover, behavioral responses varied with breeding status: females with eggs were faster to approach stimuli than females that were pair bonded but did not currently have eggs. Our study suggests a potential role for individual vocal recognition in the formation and maintenance of pair bonds in a poison frog and raises new questions about how acoustic signals are perceived in the context of monogamy and biparental care.

Nucleus accumbens dopamine release reflects the selective nature of pair bonds.

In monogamous species, prosocial behaviors directed toward partners are dramatically different from those directed toward unknown individuals and potential threats. Dopamine release in the nucleus accumbens has a well-established role in social reward and motivation, but how this mechanism may be engaged to drive the highly divergent social behaviors directed at a partner or unfamiliar conspecific remains unknown. Using monogamous prairie voles, we first employed receptor pharmacology in partner preference and social operant tasks to show that dopamine is critical for the appetitive drive for social interaction but not for low-effort, unconditioned consummatory behaviors. We then leveraged the subsecond temporal resolution of the fluorescent biosensor, GRABDA, to ask whether differential dopamine release might distinguish between partner and novel social access and interaction. We found that partner seeking, anticipation, and interaction resulted in more accumbal dopamine release than the same events directed toward a novel vole. Further, partner-associated dopamine release decreased after prolonged partner separation. Our results are consistent with a model in which dopamine signaling plays a prominent role in the appetitive aspects of social interactions. Within this framework, differences in partner- and novel-associated dopamine release reflect the selective nature of pair bonds and may drive the partner- and novel-directed social behaviors that reinforce and cement bonds over time. This provides a potential mechanism by which highly conserved reward systems can enable selective, species-appropriate social behaviors.

Your Happiness Is My Happiness: Predicting Positive Feelings for a Partner's Consensual Extra-Dyadic Intimate Relations.

This quantitative study tested hypotheses derived from a previous qualitative study of the factors that facilitated and hindered compersion (the positive feelings derived from one's partner's intimate relations with others) in consensually non-monogamous (CNM) relationships. A total of 255 participants recruited from online CNM and Alt-Sex communities reported on demographic and relationship characteristics as well as individual, relationship, and metamour-related variables in an online anonymous survey. In Flicker et al. (2022), we identified various factors that predicted three subtypes of compersion: contentment with one's partner's relationships with established metamours (intimate partners of one's partners), excitement sparked by one's partner's new/potentially new intimate connections, and sexual excitement elicited by thinking about one's partner with another person. The current findings were consistent with the Flicker et al. qualitative study, with some hypotheses from the previous study more strongly supported than others. The predictors of compersion most strongly supported by the current data include closeness with one's metamour and knowledge about the partner/metamour relationship, in a positive direction, as well as jealousy, envy, and attachment anxiety, in a negative direction. Individual-level predictors were weak predictors of compersion. The sexual arousal subtype of compersion was weakly endorsed by the current sample and predictors of this subtype were distinct from predictors of the other subtypes of compersion. The findings suggest that the development of new interventions that target reducing jealousy and envy and increasing attachment security within the unique context of CNM relationships could have the added benefit of increasing compersion. The development of these interventions stands to benefit a growing population of individuals involved in CNM relationships.

A Narrative Review of the Dichotomy Between the Social Views of Non-Monogamy and the Experiences of Consensual Non-Monogamous People.

Monogamy is deeply rooted in most Western societies, shaping how people construe and behave in romantic relationships. These normative views facilitate the emergence of negative perceptions and evaluations when people choose not to adhere to mononormativity. Even though people in consensual non-monogamous (CNM) relationships are targets of stigmatization, research shows a dichotomy between these negative views and the relational experiences of CNM people. Indeed, people in CNM and monogamous relationships have comparable relationship functioning and quality and struggle with similar relationship problems. One of the differences is that CNM relationships afford people to explore their sexuality and fulfill their needs with multiple partners, without agreed-upon extradyadic behavior being perceived as infidelity or having deleterious consequences to relationship maintenance. These positive experiences notwithstanding, CNM people are continuously pressured by mononormativity and stigmatization, increasing the risk of internalized CNM negativity and worse personal and relational outcomes. One possible way to counteract CNM stigmatization and improve the lives of CNM people is by changing discourses surrounding non-monogamy and improving acceptance, not only in professional settings but also in the general population. Another strategy is to understand how the relationship beliefs and scripts of younger generations can help promote more inclusive and diverse societies.

Examining the Role of Mononormative Beliefs, Stigma, and Internalized Consensual Non-Monogamy Negativity for Dehumanization.

Interest in consensually non-monogamous (CNM) relationships has been increasing in the general population in recent years. However, given the cultural dominance of monogamy and the normative expectations often imposed through socialization (i.e., mononormativity), people in CNM relationships may experience negativity, which can become internalized and harm their individual and relationship health. The present study investigated if mononormativity beliefs and CNM relationship stigma were associated with more dehumanization and if internalized CNM negativity was an underlying mechanism for these associations. Results showed that participants who endorsed more mononormative beliefs and CNM relationship stigma also reported more internalized CNM negativity. In turn, participants who experienced more internalized CNM negativity attributed more negative (vs. positive) emotions to themselves and treated their partners as more immature, unrefined, exploitable, and emotionless. These results show that mononormativity and internalized negativity can shape the attitudes, perceptions, and behaviors of CNM individuals toward themselves and their partners.

Polygamous Interest in a Mononormative Nation: The Roles of Sex and Sociosexuality in Polygamous Interest in a Heterosexual Sample from the UK.

Polygamy is a form of "one-sided" consensually non-monogamous relationship where one person has multiple committed partners, each of whom is only involved with that one person. It was likely a reoccurring feature of ancestral mating that posed adaptive problems for our ancestors. Yet polygamy, and multi-partnering more generally, is understudied in Western cultures, raising questions about the existence of polygamous interest and whether this is calibrated adaptively to personal conditions. In two studies, we examined polygamous interest in two heterosexual online samples from the UK. In Study 1 (N = 393), modest interest was found for polygamous relationships overall. Men were six times more open to polygyny than women, but there was little sex difference in openness to polyandry. Further analysis revealed that all forms of multi-partnering were undesirable relative to singlehood and monogamy; however, consensual multi-partner relationships were less undesirable than non-consensual ones. Sex differences were largest for polygyny and arrangements where men had agreed access to a casual partner alongside a committed one, yet these were two of the most acceptable forms of multi-partnering when men and women's responses were combined. Sociosexuality positively predicted interest in most forms of multi-partnering. Study 2 (N = 735) focused on polygyny and added status-linked traits as predictors. The results of Study 1 were broadly replicated, though the status-linked traits did not predict polygynous interest specifically. Instead, sociosexuality and male intrasexual competitiveness uniquely predicted general interest in multi-partner relationships. Overall, interest in polygamy appears to emerge despite social discouragement and sex differences in interest track the relative costs and benefits associated with it. However, there is no strong evidence that polygamous interest is uniquely calibrated to personal conditions when compared to other forms of multi-partnering.

Initial Motivations for Engaging in Polyamorous Relationships.

Polyamory is a relationship style in which partners consensually agree to engage in sexual and/or emotional relationships with concurrent partners. Compared with other forms of consensual non-monogamy (CNM), polyamory practitioners tend to report greater relationship satisfaction and less jealousy. However, the unique motivations leading people to engage with polyamory are less understood. Previous research has examined motivations for engaging in CNM relationship styles, in general, but no research has focused exclusively on the motivations of polyamory practitioners. The present study draws on the open-ended responses of 63 U.S. American adults who reported previous or current engagement in at least one consensually polyamorous relationship. Thematic analyses revealed four themes guiding participants' initial motivations for polyamory engagement: values alignment, relationship factors, external triggers, and sexuality. The study's themes are discussed in the context of self-determination theory and situated in the existing body of CNM and polyamory research. Directions for future research provide next steps for examining outcomes associated with specific polyamory motivations.

Primate social organization evolved from a flexible pair-living ancestor.

Explaining the evolution of primate social organization has been fundamental to understand human sociality and social evolution more broadly. It has often been suggested that the ancestor of all primates was solitary and that other forms of social organization evolved later, with transitions being driven by various life history traits and ecological factors. However, recent research showed that many understudied primate species previously assumed to be solitary actually live in pairs, and intraspecific variation in social organization is common. We built a detailed database from primary field studies quantifying the number of social units expressing different social organizations in each population. We used Bayesian phylogenetic models to infer the probability of each social organization, conditional on several socioecological and life history predictors. Here, we show that when intraspecific variation is accounted for, the ancestral social organization of primates was inferred to be variable, with the most common social organization being pair-living but with approximately 10 to 20% of social units of the ancestral population deviating from this pattern by being solitary living. Body size and activity patterns had large effects on transitions between types of social organizations. As in other mammalian clades, pair-living is closely linked to small body size and likely more common in ancestral species. Our results challenge the assumption that ancestral primates were solitary and that pair-living evolved afterward emphasizing the importance of focusing on field data and accounting for intraspecific variation, providing a flexible statistical framework for doing so.

A superação à família monogâmica é pela coletividade! Parentalidades não-monogâmicas de pessoas sexo-gênero-diversas / The overcoming of the monogamous family is through the community! Non-monogamous parenting of sex-gender-diverse people

Resumo Pessoas sexo-gênero-diversas e que são não-monogâmicas tensionam a cisnormatividade e a mononormatividade. Em termos científicos, há uma nebulosidade quanto aos arranjos parenterais dessas pessoas. Assim, esta etnografia objetiva compreender a percepção de pessoas sexo-gênero-diversas não-monogâmicas sobre parentalidades. O referencial teórico utilizado partiu dos estudos não-monogâmicos, amor e sexualidade das Ciências Sociais e Humanas em Saúde da Saúde Coletiva, e o metodológico da etnografia digital. O trabalho de campo ocorreu entre 2021 e 2022, em um grupo on-line do WhatsApp. A observação participante foi empregada no grupo e foram realizadas entrevistas on-line semiestruturadas. Emergiram duas categorias: a) Os nós das parentalidades não-monogâmicas e b) As parentalidades coletivas. Na primeira, se explora a importância do vínculo nas redes afetivas e expõe as barreiras desses arranjos familiares. Já na segunda, se descreve a importância do viver em comunidade, bem como o resgate à ancestralidade indígena e negra. O resgate à ancestralidade e às formas de se viver em comunidade ganham relevo à medida que se compreende a importância que estes possuem na vivência das parentalidades de pessoas sexo-gênero-diversas e que são não-monogâmicas.

Abstract Sex-gender-diverse and non-monogamous strain cisnormativity and mononormativity. In scientific terms, the parenting arrangements of these people are uncertain. Thus, this ethnography aims to understand the perception of non-monogamous sex-gender-diverse people about parenting. The theoretical framework adopted is derived from non-monogamous studies, love and sexuality from the Social and Human Sciences in Public Health and the digital ethnography methodological framework. Fieldwork occurred from 2021 to 2022 through an online WhatsApp group. Participant observation was employed in the group, and semi-structured online interviews were held. Two categories emerged: a) The non-monogamous parenting nodes and b) Collective parenting. In the first, the importance of bonds in affective networks is explored, and the barriers to these family arrangements are exposed. The second describes the importance of living in a community, and Indigenous and Black ancestry is revived. The revived ancestry and ways of living in a community gain importance as we understand their relevance in the experience of parenting for sex-gender-diverse people who are non-monogamous.

Bonding against the odds: Male prairie vole response to the "widow effect" among females.

Although pair bonding is the preferred mating tactic among socially monogamous prairie voles, naturalistic observations have demonstrated many males remain non-bonded. Moreover, although males readily re-bond after the loss of a partner, females do not (i.e., the "widow effect'). Few studies have attempted to address why so many males remain non-bonded or if a reluctance of re-bonding in females contributes to this outcome. We investigate how female bonding history impacts male pair bond formation. Specifically, we test two alternative hypotheses for how sexually naïve males will behave when paired with widow females. The fecundity hypothesis predicts males will avoid bonding with widow females and be more receptive to novel bond-naïve females. The preference to bond hypothesis predicts males will choose to bond and express a partner preference, irrespective of if a pair-mate is a widow or sexually naïve. Our results demonstrated that males expressed a partner preference for females regardless of their social history. These data support the preference to bond hypothesis and suggest natural variation in bonding may not be strongly due to males forgoing bonding opportunities.

Varied impacts of social relationships on neuroendocrine state.

Social relationships, affiliative social attachments, are important for many species. The best studied types of relationships are monogamous pair bonds. However, it remains unclear how generalizable models of pair bonding are across types of social attachments. Zebra finches are a fascinating system to explore the neurobiology of social relationships because they form various adult bonds with both same- and opposite-sex partners. To test whether different bonds are supported by a single brain network, we quantified individuals' neuroendocrine state after either 24 h or 2 weeks of co-housing with a novel same- or opposite-sex partner. We defined neuroendocrine state by the expression of 22 genes related to 4 major signaling pathways (dopamine, steroid, nonapeptide, and opioid) in six brain regions associated with affiliation or communication [nucleus accumbens (NAc), nucleus taeniae of the amygdala (TnA), medial preoptic area (POM), and periaqueductal gray (PAG), ventral tegmental area, and auditory cortex]. Overall, we found dissociable effects of social contexts (same- or opposite-sex partnerships) and duration of co-housing. Social bonding impacted the neuroendocrine state of four regions in males (NAc, TnA, POM, and PAG) and three regions in females (NAc, TnA, and POM). Monogamous pair bonding specifically appeared to impact male NAc. However, the patterns of gene expression in zebra finches were different than has previously been reported in mammals. Together, our results support the view that there are numerous mechanisms regulating social relationships and highlight the need to further our understanding of how social interactions shape social bonds.

Descent, marriage, and residence practices of a 3,800-year-old pastoral community in Central Eurasia.

Our understanding of prehistoric societal organization at the family level is still limited. Here, we generated genome data from 32 individuals from an approximately 3,800-y-old burial mound attributed to the Bronze Age Srubnaya-Alakul cultural tradition at the site of Nepluyevsky, located in the Southern Ural region of Central Eurasia. We found that life expectancy was generally very low, with adult males living on average 8 y longer than females. A total of 35 first-degree, 40 second-degree, and 48 third-degree biological relationships connected 23 of the studied individuals, allowing us to propose a family tree spanning three generations with six brothers at its center. The oldest of these brothers had eight children with two women and the most children overall, whereas the other relationships were monogamous. Notably, related female children above the age of five were completely absent from the site, and adult females were more genetically diverse than males. These results suggest that biological relationships between male siblings played a structural role in society and that descent group membership was based on patrilineality. Women originated from a larger mating network and moved to join the men, with whom they were buried. Finally, the oldest brother likely held a higher social position, which was expressed in terms of fertility.