Pair-bonding, romantic love, and evolution: the curious case of Homo sapiens

From molecular variations to behavioral adaptations: Unveiling adaptive epistasis in primate oxytocin system

OBJECTIVE

Our primary objective was to investigate the variability of oxytocin (OT) and the GAMEN binding motif within the LNPEP oxytocinase in primates.

MATERIALS AND METHODS

We sequenced the LNPEP segment encompassing the GAMEN motif in 34 Platyrrhini species, with 21 of them also sequenced for the OT gene. Our dataset was supplemented with primate sequences of LNPEP, OT, and the oxytocin receptor (OTR) sourced from public databases. Evolutionary analysis and coevolution predictions were made followed by the macroevolution analysis of relevant amino acids associated with phenotypic traits, such as mating systems, parental care, and litter size. To account for phylogenetic structure, we utilized two distinct statistical tests. Additionally, we calculated binding energies focusing on the interaction between Callithtrix jacchus VAMEN and Pro8OT.

RESULTS

We identified two novel motifs (AAMEN and VAMEN), challenging the current knowledge of motif conservation in placental mammals. Coevolution analysis demonstrated a correlation between GAMEN, AAMEN, and VAMEN and their corresponding OTs and OTRs. Callithrix jacchus exhibited a higher binding energy between VAMEN and Pro8OT than orthologous molecules found in humans (GAMEN and Leu8OT).

DISCUSSION

The coevolution of AAMEN and VAMEN with their corresponding OTs and OTRs suggests a functional relationship that could have contributed to specific reproductive and adaptive behaviors, including paternal care, social monogamy, and twin births, prominent traits in Cebidae species, such as marmosets and tamarins. Our findings underscore the coevolution of taxon-specific amino acids among the three studied molecules, shedding light on the oxytocinergic system as an adaptive epistatic repertoire in primates.

Effects of oxytocin receptor agonism on acquisition and expression of pair bonding in male prairie voles

There is much interest in targeting the activity in the oxytocin system to regulate social bonding. However, studies with exogenous administration of oxytocin face the caveats of its low stability, poor brain permeability and insufficient receptor specificity. The use of a small-molecule oxytocin receptor-specific agonist could overcome these caveats. Prior to testing the potential effects of a brain-penetrant oxytocin receptor agonist in clinical settings, it is important to assess how such an agonist would affect social bonds in animal models. The facultatively monogamous prairie voles (Microtus ochrogaster), capable of forming long-term social attachments between adult individuals, are an ideal rodent model for such testing. Therefore, in a series of experiments we investigated the effects of the recently developed oxytocin receptor-specific agonist LIT-001 on the acquisition and expression of partner preference, a well-established model of pair bonding, in prairie voles. LIT-001 (10 mg/kg, intraperitoneal), as expected, facilitated the acquisition of partner preference when administered prior to a 4hr cohabitation. In contrast, while animals injected with vehicle after the 4hr cohabitation exhibited significant partner preference, animals that were injected with LIT-001 did not show such partner preference. This result suggests that OXTR activation during expression of pair bonding can inhibit partner preference. The difference in effects of LIT-001 on acquisition versus expression was not due to basal differences in partner preference between the experiments, as LIT-001 had no significant effects on expression of partner preference if administered following a shorter (2hr-long) cohabitation. Instead, this difference agrees with the hypothesis that the activation of oxytocin receptors acts as a signal of presence of a social partner. Our results indicate that the effects of pharmacological activation of oxytocin receptors crucially depend on the phase of social attachments.

A comparison of domain-specific evaluations of life in predicting overall life evaluations and biological inflammation

Which domain of life evaluation is more important? Using a large-scale public sample of 1888 adults from the United States (880 males, 1008 females; Mage = 53.28), we addressed this question by comparing the predictive strength of six domains of life evaluations on overall life evaluation as well as biomarkers of inflammation. Specifically, we examined individuals' self-rated evaluations of the domains of social belonging, romantic relationships, work, subjective social status, self-esteem and finances, and we examined biological inflammation using an index of five biomarkers of inflammation: interleukin-6, fibrinogen, C-reactive protein, E-selectin and intercellular adhesion molecule 1. Adjusting for demographic variability, romantic evaluation, work evaluation, self-esteem and financial evaluation were equally and uniquely predictive of overall life evaluation. Social belonging remained predictive but was relatively weaker in magnitude, while subjective social status was no longer a significant predictor. Conversely, only financial evaluation was significantly linked to reduced biomarkers of inflammation. The findings suggest that depending on domain-specificity and whether well-being is assessed via subjective or objective indicators, links between life evaluations and well-being may show substantial nuance. In particular, financial evaluation appears to have unique links to biomarkers of inflammation even after accounting for other domains of life evaluations.

Physiological state matching in a pair bonded poison frog

More than a century ago, Charles Darwin hypothesized that the empathy-like phenotype is a phylogenetically widespread phenomenon. This idea remains contentious, due to the challenges of empirically examining emotions, and few investigations among non-mammalian vertebrates. We provide support for Darwin's hypothesis by discovering partial evidence for the most ancestral form of empathy, emotional contagion (i.e. matching another individual's emotional state), in the pair bonding mimetic poison frog, Ranitomeya imitator. We found that male corticosterone, a physiological biomarker of stress, positively correlates with female partners in experimental and semi-natural conditions. This does not appear to coincide with behavioural state-matching. However, it is specific to female partners relative to familiar female non-partners, and is independent of effects that commonly confound studies on emotional contagion. Furthermore, this physiological state-matching is irrespective of partnership longevity or lifetime reproductive output. These results physiologically indicate socially selective emotional contagion in a monogamous amphibian, and paradigms that elicit coinciding neural and behavioural indicators and morphogenic co-variation are needed for further corroboration. Further studies on ancestral forms of empathy in non-mammalian vertebrates are warranted.

Romantic relationships buffer minority stress in transgender and non-binary adults: Effects on depressive symptoms and suicidality

BACKGROUND

Transgender and non-binary (TNB) individuals are at greater risk of mental health concerns relative to their cisgender peers due to experiences of minority stress. Thus, it is critically important to identify factors that may be protective and buffer the effects of minority stress. This study examined whether romantic relationship involvement and quality buffered effects of TNB minority stress on depressive symptoms and suicidal ideation.

METHODS

A large international sample (n = 1156) of TNB adults (n = 654 partnered; n = 502 single) reported on minority stress experiences, relationship status and quality, and mental health outcomes (i.e., depressive symptoms and suicidal ideation).

RESULTS

The effects of victimization and rejection on depressive symptoms and suicidal ideation were attenuated among partnered individuals. However, once relationship quality was considered, the buffering effects of relationship involvement applied only to those in more satisfying relationships; the stress-buffering effects were not observed among those in distressed relationships. Of particular importance, general interpersonal satisfaction did not act as a minority stress buffer, suggesting there may be unique stress-buffering effects of being in a satisfying romantic relationship on depressive symptoms and suicidal ideation.

LIMITATIONS

The cross-sectional nature of the current study precludes definitive conclusions regarding causation.

CONCLUSIONS

These findings suggest that romantic involvement may serve a stress-buffering role for TNB adults, but only when these relationships are satisfying. Our results have important theoretical and clinical implications, and further research is needed to investigate the utility of relationship interventions to buffer the effects of TNB minority stress on depressive symptoms and suicidality.

A general theory of consciousness III the human catastrophe

It is generally assumed that verbal communication can articulate concepts like 'fact' and 'truth' accurately. However, language is fundamentally inaccurate and ambiguous and it is not possible to express exact propositions accurately in an ambiguous medium. Whether truth exists or not, language cannot express it in any exact way. A major problem for verbal communication is that words are fundamentally differently interpreted by the sender and the receiver. In addition, intrapersonal verbal communication - the voice in our head - is a useless extension to the thought process and results in misunderstanding our own thoughts. The evolvement of language has had a profound impact on human life. Most consequential has been that it allowed people to question the old human rules of behavior - the pre-language way of living. As language could not accurately express the old rules, they lost their authority and disappeared. A long period without any rules of how to live together must have followed, probably accompanied by complete chaos. Later, new rules were devised in language, but the new rules were also questioned and had to be enforced by punishment. Language changed the peaceful human way of living under the old rules into violent and aggressive forms of living under punitive control. Religion then tried to incorporate the old rules into the harsh verbal world. The rules were expressed in language through parables: imaginary beings - the gods - who possessed the power of the old rules, but who could be related to through their human appearance and behavior.

Effects of Oxytocin Receptor Agonism on Acquisition and Expression of Pair Bonding in Male Prairie Voles

There is much interest in targeting the activity in the oxytocin system to regulate social bonding. However, studies with exogenous administration of oxytocin face the caveats of its low stability, poor brain permeability and insufficient receptor specificity. The use of a small-molecule oxytocin receptor-specific agonist could overcome these caveats. Prior to testing the potential effects of a brain-penetrant oxytocin receptor agonist in clinical settings, it is important to assess how such an agonist would affect social bonds in animal models. The facultatively monogamous prairie voles (Microtus ochrogaster), capable of forming long-term social attachments between adult individuals, are an ideal rodent model for such testing. Therefore, in a series of experiments we investigated the effects of the recently developed oxytocin receptor-specific agonist LIT-001 on the acquisition and expression of partner preference, a well-established model of pair bonding, in prairie voles. LIT-001 (10 mg/kg, intraperitoneal), as expected, facilitated the acquisition of partner preference when administered prior to a 4-hour cohabitation. In contrast, while animals injected with vehicle after the 4-hour cohabitation exhibited significant partner preference, animals that were injected with LIT-001 did not show such partner preference. This result suggests that OXTR activation during expression of pair bonding can inhibit partner preference. The difference in effects of LIT-001 on acquisition versus expression was not due to basal differences in partner preference between the experiments, as LIT-001 had no significant effects on expression of partner preference if administered following a shorter (2 hour-long) cohabitation. Instead, this difference agrees with the hypothesis that the activation of oxytocin receptors acts as a signal of presence of a social partner. Our results indicate that the effects of pharmacological activation of oxytocin receptors crucially depend on the phase of social attachments.

Emophilia: psychometric properties of the emotional promiscuity scale and its association with personality traits, unfaithfulness, and romantic relationships in a Scandinavian sample

Emophilia is a suggested stable phenomenon referring to how often and easily an individual falls in love (Jones, 2011). The current study investigated the psychometric properties of the Emotional Promiscuity Scale (EPS, i.e., a measure of emophilia) and its association with personality traits, romantic relationships, and unfaithfulness in a Scandinavian sample. The sample consisted of 2,607 participants, who were recruited through Norwegian and Swedish newspapers. Descriptive analyses of the EPS and a confirmatory factor analysis (CFA) to verify the previously obtained two-factor structure were conducted. Correlations between emophilia and the Big Five and Dark Triad traits were calculated to investigate the discriminative validity of the EPS. Lastly, negative binomial regression analyses were run in which emophilia comprised the independent variable and the number of romantic relationships and number of times being unfaithful constituted the dependent variables. The EPS had satisfactory internal reliability and the responses to the items were normally distributed. The CFA indicated a two-factor structure, although the two factors correlated highly, justifying collapsing them into one dimension. Emophilia showed satisfactory discriminant validity (r < 00.40) against the personality traits included. Lastly, emophilia was positively associated with the number of romantic relationships and times being unfaithful. Future research should aim to improve our understanding of the psychological and behavioral aspects of emophilia.

Reproductive Strategies and Romantic Love in Early Modern Europe

In Western Europe, the Early Modern Period is characterized by the rise of tenderness in romantic relationships and the emergence of companionate marriage. Despite a long research tradition, the origins of these social changes remain elusive. In this paper, we build on recent advances in behavioral sciences, showing that romantic emotional investment, which is more culturally variable than sexual attraction, enhances the cohesion of long-term relationships and increases investment in children. Importantly, this long-term strategy is considered especially advantageous when living standards are high. Here, we investigate the relationship between living standards, the emotional components of love expressed in fiction work, and behavioral outcomes related to pair bonding, such as nuptial and fertility rates. We developed natural language processing measures of "emotional investment" (tenderness) and "attraction" (passion) and computed romantic love in English plays (N = 847) as a ratio between the two. We found that living standards generally predicted and temporally preceded variations of romantic love in the Early Modern Period. Furthermore, romantic love preceded an increase in nuptial rates and a decrease in births per marriage. This suggests that increasing living standards in the Early Modern Period may have contributed to the emergence of modern romantic culture.

Love songs and serenades: a theoretical review of music and romantic relationships

In this theoretical review, we examine how the roles of music in mate choice and social bonding are expressed in romantic relationships. Darwin's Descent of Man originally proposed the idea that musicality might have evolved as a sexually selected trait. This proposition, coupled with the portrayal of popular musicians as sex symbols and the prevalence of love-themed lyrics in music, suggests a possible link between music and attraction. However, recent scientific exploration of the evolutionary functions of music has predominantly focused on theories of social bonding and group signaling, with limited research addressing the sexual selection hypothesis. We identify two distinct types of music-making for these different functions: music for attraction, which would be virtuosic in nature to display physical and cognitive fitness to potential mates; and music for connection, which would facilitate synchrony between partners and likely engage the same reward mechanisms seen in the general synchrony-bonding effect, enhancing perceived interpersonal intimacy as a facet of love. Linking these two musical functions to social psychological theories of relationship development and the components of love, we present a model that outlines the potential roles of music in romantic relationships, from initial attraction to ongoing relationship maintenance. In addition to synthesizing the existing literature, our model serves as a roadmap for empirical research aimed at rigorously investigating the possible functions of music for romantic relationships.

How Do Invested Partners Become Invested? A Prospective Investigation of Fledgling Relationship Development

Investment-the feeling that one has put considerable resources into a relationship-is theorized to play a key role in relationship persistence. Yet, the development of investment is not well-understood. We recruited 256 individuals in new dating relationships and surveyed them each week for up to 25 weeks. This design allows us to test underlying theoretical assumptions about how people become invested in new dating partners. Some assumptions, such as the idea that investment increases over time, were confirmed. Other assumptions were not supported: Feelings of investment were quite high after only a few weeks of dating and were not strongly shaped by concrete relationship milestones. Rather, feelings of investment were strongly linked to other subjective indicators of relationship development, such as feeling attached to the partner and believing that the relationship had a good future. We discuss the implications of these findings for existing models of investment.

Cognitive fossils: using cultural artifacts to reconstruct psychological changes throughout history

Psychology is crucial for understanding human history. When aggregated, changes in the psychology of individuals - in the intensity of social trust, parental care, or intellectual curiosity - can lead to important changes in institutions, social norms, and cultures. However, studying the role of psychology in shaping human history has been hindered by the difficulty of documenting the psychological traits of people who are no longer alive. Recent developments in psychology suggest that cultural artifacts reflect in part the psychological traits of the individuals who produced or consumed them. Cultural artifacts can thus serve as 'cognitive fossils' - physical imprints of the psychological traits of long-dead people. We review the range of materials available to cognitive and behavioral scientists, and discuss the methods that can be used to recover and quantify changes in psychological traits throughout history.

Validation of the Short Version (TLS-15) of the Triangular Love Scale (TLS-45) across 37 Languages

Love is a phenomenon that occurs across the world and affects many aspects of human life, including the choice of, and process of bonding with, a romantic partner. Thus, developing a reliable and valid measure of love experiences is crucial. One of the most popular tools to quantify love is Sternberg's 45-item Triangular Love Scale (TLS-45), which measures three love components: intimacy, passion, and commitment. However, our literature review reveals that most studies (64%) use a broad variety of shortened versions of the TLS-45. Here, aiming to achieve scientific consensus and improve the reliability, comparability, and generalizability of results across studies, we developed a short version of the scale-the TLS-15-comprised of 15 items with 5-point, rather than 9-point, response scales. In Study 1 (N = 7,332), we re-analyzed secondary data from a large-scale multinational study that validated the original TLS-45 to establish whether the scale could be truncated. In Study 2 (N = 307), we provided evidence for the three-factor structure of the TLS-15 and its reliability. Study 3 (N = 413) confirmed convergent validity and test-retest stability of the TLS-15. Study 4 (N = 60,311) presented a large-scale validation across 37 linguistic versions of the TLS-15 on a cross-cultural sample spanning every continent of the globe. The overall results provide support for the reliability, validity, and cross-cultural invariance of the TLS-15, which can be used as a measure of love components-either separately or jointly as a three-factor measure.

The Role of Sexual and Romantic Attraction in Human Mate Preferences

Sex differences in mate preferences are ubiquitous, having been evidenced across generations and cultures. Their prevalence and persistence have compellingly placed them in the evolutionarily adaptive context of sexual selection. However, the psycho-biological mechanisms contributing to their generation and maintenance remain poorly understood. As such a mechanism, sexual attraction is assumed to guide interest, desire, and the affinity toward specific partner features. However, whether sexual attraction can indeed explain sex differences in partner preferences has not been explicitly tested. To better understand how sex and sexual attraction shape mate preferences in humans we assessed how partner preferences differed across the spectrum of sexual attraction in a sample of 479 individuals that identified as asexual, gray-sexual, demisexual or allosexual. We further tested whether romantic attraction predicted preference profiles better than sexual attraction. Our results show that sexual attraction accounts for highly replicable sex differences in mate preferences for high social status and financial prospects, conscientiousness, and intelligence; however, it does not account for the enhanced preference for physical attractiveness expressed by men, which persists even in individuals with low sexual attraction. Instead, sex differences in physical attractiveness preference are better explained by the degree of romantic attraction. Furthermore, effects of sexual attraction on sex differences in partner preferences were grounded in current rather than previous experiences of sexual attraction. Taken together, the results support the idea that contemporary sex differences in partner preferences are maintained by several psycho-biological mechanisms that evolved in conjunction, including not only sexual but also romantic attraction.

The Effect of Income and Wealth on Behavioral Strategies, Personality Traits, and Preferences

Individuals living in either harsh or favorable environments display well-documented psychological and behavioral differences. For example, people in favorable environments tend to be more future-oriented, trust strangers more, and have more explorative preferences. To account for such differences, psychologists have turned to evolutionary biology and behavioral ecology, in particular, the literature on life-history theory and pace-of-life syndrome. However, critics have found that the theoretical foundations of these approaches are fragile and that differences in life expectancy cannot explain vast psychological and behavioral differences. In this article, we build on the theory of optimal resource allocation to propose an alternative framework. We hypothesize that the quantity of resources available, such as income, has downstream consequences on psychological traits, leading to the emergence of behavioral syndromes. We show that more resources lead to more long-term orientation, more tolerance of variance, and more investment in low marginal-benefit needs. At the behavioral level, this translates, among others, into more large-scale cooperation, more investment in health, and more exploration. These individual-level differences in behavior, in turn, account for cultural phenomena such as puritanism, authoritarianism, and innovation.

The impact of romantic relationships on deception detection: Exploring the gender differences and the mediating role of mentalizing

In evolution, romantic relationships serve as the foundation for breeding and producing offspring. The ability to detect deception in these relationships can safeguard the investment and cultivation of descendants, leading to greater chances of survival and reproduction. However, barely any research has been carried out within this domain. The current study investigated the preliminary relationship between romantic relationships, mentalizing ability, and deception detection ability through an empirical experiment. Participants were primed by their romantic experiences and neutral experiences, and then went through a Reading the Mind in the Eyes (RTM) task and the deception detecting task for real person crime-type videos. Results showed that romantic relationships can improve participants' emotion recognition ability toward negative emotions, and females performed better in the deception detection task than males did. Most importantly, romantic relationships can improve participants' deception detection ability through the mediator of mentalizing ability. Though gender difference was not statistically significant in the RTM task, the results lay a solid foundation for further investigation into females' mentalizing ability and disclose the evolutionary meaning of romantic relationships.

Being Female and in a Romantic Relationship Enhances the Association between Satisfaction with Love Life and Capacity to Love

This study aims to evaluate if the relation between love life satisfaction, assessed by the satisfaction with love life scale (SWLLS), and capacity to love, assessed by the capacity to love inventory (CTL-I), is moderated by gender and by being or not in a romantic relationship, in a Portuguese sample. To this end, the adaptation and validation of CTL-I for this population were carried out through an exploratory factorial analysis (EFA) followed by a Robust Maximum Likelihood (MLR) confirmatory factorial analysis (CFA). A multi-group analysis for measurement invariance depending on being in a romantic relationship or not was assessed. The model's reliability was also evaluated. The associations between SWLLS and CTL-I were tested by correlations, regressions and moderations. At last, differences between means and distributions concerning sociodemographic variables were determined. The results showed that a good model fit for the Portuguese version of the CTL-I was found, as well as good psychometric properties. Results also showed that satisfaction with love life contributes to explaining the capacity to love and all its dimensions, and that gender and being in a romantic relationship moderate the association between love life satisfaction and the capacity to love. Being female and being in a romantic relationship make the relationship between love life satisfaction and the capacity to love stronger and more meaningful.

Romantic love evolved by co-opting mother-infant bonding

For 25 years, the predominant evolutionary theory of romantic love has been Fisher's theory of independent emotion systems. That theory suggests that sex drive, romantic attraction (romantic love), and attachment are associated with distinct neurobiological and endocrinological systems which evolved independently of each other. Psychological and neurobiological evidence, however, suggest that a competing theory requires attention. A theory of co-opting mother-infant bonding sometime in the recent evolutionary history of humans may partially account for the evolution of romantic love. I present a case for this theory and a new approach to the science of romantic love drawing on human psychological, neurobiological, and (neuro)endocrinological studies as well as animal studies. The hope is that this theoretical review, along with other publications, will generate debate in the literature about the merits of the theory of co-opting mother-infant bonding and a new evolutionary approach to the science of romantic love.

What are Romantic Relationships Good for? An Explorative Analysis of the Perceived Benefits of Being in a Relationship

Forming long-term intimate relationships is a human universal, with most people across different times and cultures doing so. Such relationships should be associated with important benefits otherwise individuals would not engage in them, with the current research aiming to identify what people consider as beneficial in a long-term intimate relationship. More specifically, Study 1 employed qualitative research methods in a sample of 221 Greek-speaking participants, and identified 82 perceived benefits. Study 2 employed quantitative research methods in a sample of 545 Greek-speaking participants, and classified these benefits into 10 broad factors and two broader domains. Experiencing positive emotions, including love and passion, as well as having someone to provide support and do things together, were considered among the most important benefits. Although there were a few significant differences, the evaluations of the perceived benefits of intimate relationships were generally consistent across participants of different sex, age, and relationship status.

Attachment across the lifespan: Examining the intersection of pair bonding neurobiology and healthy aging

Increasing evidence suggests that intact social bonds are protective against age-related morbidity, while bond disruption and social isolation increase the risk for multiple age-related diseases. Social attachments, the enduring, selective bonds formed between individuals, are thus essential to human health. Socially monogamous species like the prairie vole (M. ochrogaster) form long-term pair bonds, allowing us to investigate the mechanisms underlying attachment and the poorly understood connection between social bonds and health. In this review, we explore several potential areas of focus emerging from data in humans and other species associating attachment and healthy aging, and evidence from prairie voles that may clarify this link. We examine gaps in our understanding of social cognition and pair bond behavior. Finally, we discuss physiologic pathways related to pair bonding that promote resilience to the processes of aging and age-related disease. Advances in the development of molecular genetic tools in monogamous species will allow us to bridge the mechanistic gaps presented and identify conserved research and therapeutic targets relevant to human health and aging.

What's love got to do with jealousy?

Romantic love and jealousy seem antagonistic, but the expression of both emotions have evolutionary functions that can go in the same direction of maintaining a relationship. Considering natural selection designed adaptations to solve the problems surrounding reproduction, then love and romantic jealousy are emotions aimed at staying cooperative for a period of time, where love solves the adaptive challenges of promoting pair bonding, cooperation, and protecting offspring; and jealousy is triggered by a threat or the loss of a valuable cooperative relationship, either on behalf of descendants in need of resources, or a close romantic bond. Consequently, understanding love and romantic jealousy points in the same adaptive functional domain of protecting a romantic pair bond. Specifically, love can be comprehended in two different ways and in regard to jealousy. First, conceiving love as the attachment to significant others one develops throughout lifetime, and secondly, it contemplates affective dependence. Results from a sample of single and committed individuals (n = 332) show the predicted positive correlation between attachment and jealousy as stable traits, consistent with previous literature. In addition, there is a non-significant and low correlation, respectively, between attachment and love as a measure of dependence. Furthermore, in the single participants group, jealousy was associated with love. The discussion emphasizes the need for expanding a functional account of love and jealousy as complementary emotions of our human affective endowment. Finally, it would be informative to study attachment as a relational trait and love as a specific affection for a romantic partner that could be manipulated to elucidate the functional design of jealousy.

In Defense of Moderate Romantic Curiosity and Information Avoidance: A Conceptual Outlook of Balanced Curiosity

Curiosity, which is the human motive to seek information, is extremely valuable, since it enables people to widen their horizons and develop their capacities. However, there are many cases in which curiosity is harmful and not learning more information is preferable. In the romantic realm, this complexity is particularly relevant. Although knowledge is valuable in romantic relationships, there are circumstances in which ignorance and avoidance of information may be more beneficial. I suggest the restriction of central virtues of romantic love, such as curiosity and sensitivity, while giving some limited weight to oft-called vices in romantic relationships, such as ignorance and indifference. This suggestion has significant implications for the nature of romantic relationships, and in particular, for enhancing flexibility and diversity of such relationships, and the ongoing need to find an optimal balance.

Possible effects of pair bonds on general cognition: Evidence from shared roles of dopamine

Pair bonding builds on preexisting dopamine connectivity to help form and maintain the bond. The involvement of dopaminergic pathways in pair bonding has stimulated research linking pair bonds to other dopamine-dependent processes, like addiction and social cognition (Burkett & Young, 2012; Yetnikoff, Lavezzi, Reichard, & Zahm, 2014). Less studied is the relationship of pair bonding to non-social cognitive processes. The first half of this review will provide an overview of pair bonding and the role of dopamine within social processes. With a thorough review of the literature, the current study will identify the ways the dopaminergic pathways critical for pair bonding also overlap with cognitive processes. Highlighting dopamine as a key player in pair bonds and non-social cognition will provide evidence that pair bonding can alter general cognitive processes like attention, working memory, cognitive flexibility, and impulse control.

Love Culturally: How Does Culture Affect Intimacy, Commitment & Love

This paper, relying on a thematic review of the literature, aimed to explore the influence of culture on human relations, particularly on love. We highlighted the innate need of humans to belong and be part of a community and, moreover, partake in an intimate relationship. Most humans yearn for intimacy, and thus it was defined and described. In our Western culture, intimacy is often found in marriage, usually built on love. Love, if not nurtured, may fade, and so we described what happens when it does. Romantic relationships, where love is usually expressed and actualized, were examined, including how it is shown, how time affects love, and what causes love relationships to be marred by loneliness. The main part of the paper is devoted to examining the effect of culture on love, its expression, and on romantic relationships. While love may be universal, its development, expression, and importance in intimate relationships differ depending on the culture and era in which it occurs.

Male-male relationships in chimpanzees and the evolution of human pair bonds

The evolution of monogamy has been a central question in biological anthropology. An important avenue of research has been comparisons across "socially monogamous" mammals, but such comparisons are inappropriate for understanding human behavior because humans are not "pair living" and are only sometimes "monogamous." It is the "pair bond" between reproductive partners that is characteristic of humans and has been considered unique to our lineage. I argue that pair bonds have been overlooked in one of our closest living relatives, chimpanzees. These pair bonds are not between mates but between male "friends" who exhibit enduring and emotional social bonds. The presence of such bonds in male-male chimpanzees raises the possibility that pair bonds emerged earlier in our evolutionary history. I suggest pair bonds first arose as "friendships" and only later, in the human lineage, were present between mates. The mechanisms for these bonds were co-opted for male-female bonds in humans.

Initial compatibility during a "Speed-Dating" test predicts postpairing affiliation in titi monkeys (Plecturocebus cupreus)

Behavioral compatibility plays a critical role in shaping how potential mates interact with and evaluate each other and whether they choose to pursue a relationship. Compatibility is especially important for mate choice and relationship quality in pair-bonding species that form long-term attachments between mates. Although this process has been studied in humans and birds, relatively few studies have investigated it in non-human primates. In this study, we investigated whether pairing titi monkeys (Plecturocebus cupreus) based on initial compatibility increased postpairing affiliation between mates. Subjects were 12 unpaired adult titi monkeys (two cohorts of three males and three females). We determined each subject's initial interest in each opposite-sex potential mate in their cohort across a series of six 30-min interaction periods (i.e., "speed-dates"). To determine initial compatibility, we used the Social Relations Model to calculate relationship effects in initial interest (how much each subject uniquely preferred each potential mate beyond their own affiliative disposition and their partner's popularity). We then paired monkeys in a way that maximized net relationship effects between pairs, and measured longitudinal pair affiliation (Proximity, Contact, Tail Twining, and Combined Affiliation) for 6 months postpairing using daily scan-sample observations and monthly home-cage video recordings. Multilevel models showed that, on average, the six speed-dating pairs exhibited higher levels of Tail Twining (determined from scan-sample observations; β = 0.31) compared to a group of 13 age-matched colony pairs that were determined quasi-randomly without quantifying compatibility. The degree of initial compatibility within speed-dating pairs also predicted higher levels of Combined Affiliation (determined from video recordings) at earlier post-pairing time points, with the association peaking at 2 months postpairing (β = 0.57). These findings suggest that initial compatibility facilitates pair bonding in titi monkeys. We conclude by discussing how the speed-dating design can be used for colony management to inform pair-housing decisions.

The Effect of Asymmetric Intersexual Selection Power Perception on the Choice Deferral Behavior of Men and Women

Consumers always delay their choices, which can cause companies to suffer tremendous losses. One reason for such delay is a lack of confidence. Confidence in consumer decision-making can stem from many sources, including social power. In this research, we find that selection power with regard to choosing a romantic mate increases consumers' decision confidence and, in turn, decreases choice deferral. We define the concept of intersexual selection power (ISP), and propose certain factors that can induce individuals' asymmetric ISP. We conducted four studies to explore four factors that could influence consumers' ISP perceptions (sex, mating cues, sex ratio, and mate value) and the effects of such power perception on choice deferral. The results showed that individuals with high ISP perception have more decision confidence and a lower choice deferral rate than individuals with low ISP perception regardless of the way in which choice deferral is measured.

The Neurobiology of Love and Pair Bonding from Human and Animal Perspectives

Love is a powerful emotional experience that is rooted in ancient neurobiological processes shared with other species that pair bond. Considerable insights have been gained into the neural mechanisms driving the evolutionary antecedents of love by studies in animal models of pair bonding, particularly in monogamous species such as prairie voles (Microtus ochrogaster). Here, we provide an overview of the roles of oxytocin, dopamine, and vasopressin in regulating neural circuits responsible for generating bonds in animals and humans alike. We begin with the evolutionary origins of bonding in mother-infant relationships and then examine the neurobiological underpinnings of each stage of bonding. Oxytocin and dopamine interact to link the neural representation of partner stimuli with the social reward of courtship and mating to create a nurturing bond between individuals. Vasopressin facilitates mate-guarding behaviors, potentially related to the human experience of jealousy. We further discuss the psychological and physiological stress following partner separation and their adaptive function, as well as evidence of the positive health outcomes associated with being pair-bonded based on both animal and human studies.

Love and affectionate touch toward romantic partners all over the world

Touch is the primary way people communicate intimacy in romantic relationships, and affectionate touch behaviors such as stroking, hugging and kissing are universally observed in partnerships all over the world. Here, we explored the association of love and affectionate touch behaviors in romantic partnerships in two studies comprising 7880 participants. In the first study, we used a cross-cultural survey conducted in 37 countries to test whether love was universally associated with affectionate touch behaviors. In the second study, using a more fine-tuned touch behavior scale, we tested whether the frequency of affectionate touch behaviors was related to love in romantic partnerships. As hypothesized, love was significantly and positively associated with affectionate touch behaviors in both studies and this result was replicated regardless of the inclusion of potentially relevant factors as controls. Altogether, our data strongly suggest that affectionate touch is a relatively stable characteristic of human romantic relationships that is robustly and reliably related to the degree of reported love between partners.

People with higher relationship satisfaction use more humor, valuing, and receptive listening to regulate their partners' emotions

The emotional experiences you have with a romantic partner shape how satisfied you are in your relationship. Engaging in attempts to make a romantic partner feel better is linked with better relationship outcomes. However, it is not yet clear which specific processes people use to regulate their partners' emotions, nor which processes are most strongly linked with relationship satisfaction. In the current study of 277 individuals (55% female), we tested the extent to which eight extrinsic emotion regulation processes (expressive suppression, downward social comparison, humor, distraction, direct action, reappraisal, receptive listening, and valuing) predict relationship satisfaction. Six of the eight processes showed significant positive correlations with relationship satisfaction, with the strongest associations for valuing (r = .43), humor (r = .33), and receptive listening (r = .27). Relative weights were significant only for valuing, humor, and receptive listening, suggesting that these are the most important predictors of relationship satisfaction. Results are discussed in terms of the distinction between intrinsic and extrinsic regulation processes and the potential importance of motives for regulation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12144-023-04432-4.

Dual Mating Strategies Observed in Male Clients of Female Sex Workers

Humans have a complex and dynamic mating system, and there is evidence that our modern sexual preferences stem from evolutionary pressures. In the current paper we explore male use of a dual mating strategy: simultaneously pursuing both a long-term relationship (pair-bonding) as well as short-term, extra-pair copulations (variety-seeking). The primary constraint on such sexual pursuits is partner preferences, which can limit male behavior and hence cloud inferences about male preferences. The aim of this study was to investigate heterosexual male mating preferences when largely unconstrained by female partner preferences. In service of this goal, female full-service sex workers (N = 6) were surveyed on the traits and behaviors of their male clients (N = 516) and iterative cluster analysis was used to identify male mating typologies. Two clusters emerged: clients seeking a pair-bonding experience and clients seeking a variety experience. Results also suggested that romantically committed men were more likely to seek a variety experience than a relationship experience. We conclude that men desire both pair-bonding and sexual variety, and that their preference for one might be predicted by fulfilment of the other. These findings have implications for relationships, providing insight into motivations for male infidelity.

Genetic and epigenetic effects on couple adjustment in context of romantic relationship: A scoping systematic review

Introduction: Couples' relationships defined by a complex interaction between the two partners and their intrapersonal traits. Romantic; relationships and love are associated with marital satisfaction and stability, as well as couples' happiness and health. Personality traits influence romantic relationships and, personality influenced by genetical and non-genetically factors. The roles of non-genetically factors such as socioeconomic position and external appearance have revealed in determining the quality of romantic relationships. Methods: We; performed a scoping systematic review to assess the association between genetics and epigenetic factors and romantic relationship. Relevant articles were identified by PubMed, EMBASE, Web of Science, Scopus, and the APA PsycInfo searching between inception and 4 June 2022. Results: Different studies evaluated the associated polymorphisms in 15 different genes or chromosomal regions. In the first step; we classified them into four groups: (1) Oxytocin-related signaling pathway (OXTR, CD38, and AVPR1A); (2) Serotonin-related signaling pathway (SLC6A4, HTR1A, and HTR2A); (3) Dopamine and catecholamine-related signaling pathway (DRD1, DRD2, DRD4, ANKK1, and COMT); and (4) other genes (HLA, GABRA2, OPRM1, and Y-DNA haplogroup D-M55). Then, we evaluated and extracted significant polymorphisms that affect couple adjustment and romantic relationships. Discussion: Overall, the findings suggest that genetic and epigenetics variants play a key role in marital adjustment and romantic relationships over time.

How Sexual Information Sources are Related to Emerging Adults' Sex-Positive Scripts and Sexual Communication

Prior research suggests that parents, peers, and media are popular sources of sexual information and beliefs among emerging adults. Sex-positivity is an orientation toward sex that emphasizes open-minded beliefs and communication about varying sexual behaviors, preferences, and orientations. The current study investigated whether these sexual information sources were associated with emerging adults' endorsement of sex-positive and sexual orientation-related sexual scripts, and if these sources and scripts were associated with sexual communication among a sample of college students ages 18-22 (n = 341). Results indicate that learning from television was positively related to sex-positive sexual script endorsement, and that sex-positive scripts were associated with more positive sexual communication. An interaction also emerged between gender and learning from television on sex-positive script endorsement, and between gender and learning from social media on sexual orientation-related script endorsement. The implications of these findings are contextualized within emerging adults' sexual agency and behavior. Future directions of research are also discussed.

Consistency of Eye Coloration Across Different Relationship Partners

Studies have indicated that people are attracted to partners who resemble themselves or their parents, in terms of physical traits including eye color. We might anticipate this inclination to be relatively stable, giving rise to a sequential selection of similar partners who then represent an individual's "type". We tested this idea by examining whether people's sequential partners resembled each other at the level of eye color. We gathered details of the eye colors of the partners of participants (N = 579) across their adult romantic history (N = 3250 relationships), in three samples, comprising two samples which made use of self-reports from predominantly UK-based participants, and one which made use of publicly available information about celebrity relationship histories. Recorded partner eye colors comprised black (N = 39 partners), dark brown (N = 884), light brown (N = 393), hazel (N = 224), blue (N = 936), blue green (N = 245), grey (N = 34), and green (N = 229). We calculated the proportion of identical eye colors within each participant's relationship history, and compared that to 100,000 random permutations of our dataset, using t-tests to investigate if the eye color of partners across an individual's relationship history was biased relative to chance (i.e., if there was greater consistency, represented by higher calculated proportions of identical eye colors, in the original dataset than in the permutations). To account for possible eye color reporting errors and ethnic group matching, we ran the analyses restricted to White participants and to high-confidence eye color data; we then ran the analyses again in relation to the complete dataset. We found some limited evidence for some consistency of eye color across people's relationship histories in some of the samples only when using the complete dataset. We discuss the issues of small effect sizes, partner-report bias, and ethnic group matching in investigating partner consistency across time.

Couples relationship standards and satisfaction in Pakistani couples

Relationship standards are beliefs about what is important in a satisfying couple relationship, which vary considerably between cultures, and might mean that what couples seek from couple therapy differs across cultures. We assessed the standards of n = 49 Pakistani couples and whether those standards predicted couple satisfaction. To provide referents for the Pakistani standards, we also assessed selfreported relationship standards in n = 33 Western couples and n = 30 Chinese couples. Pakistani couples endorsed couple bond standards (e.g., expressions of love) as similarly important, and family responsibility (e.g., extended family relations) standards as more important, than Western or Chinese couples. In Pakistani couples, Couple Bond predicted couples' relationship satisfaction, but family responsibility and Religion predicted only wives' satisfaction. Modest sample sizes necessitate caution in interpreting results but suggest existing couple therapies might need modification to address the distinctive relationship standards of Pakistani couples.

The price of love: an investigation into the relationship between romantic love and the expression of obsessive-compulsive disorder

BACKGROUND

The present study explored the influence of romantic love on the expression of several obsessive-compulsive disorder (OCD) characteristics, including symptom severity, symptom dimensions, age at onset, sensory phenomena (SP), and developmental course, as well as other related comorbid disorders. It was hypothesized that love-precipitated OCD would be associated with a set of distinct characteristics and exhibit greater rates of comorbid disorders.

METHODS

The analyses were performed using a large sample (n = 981) of clinical patients with a primary diagnosis of OCD (Females = 67.3%, M age = 35.31).

RESULTS

Love-precipitated OCD was associated with greater severity of SP and later age at onset of obsessions. However, symptom severity, symptom dimension, developmental course, and psychiatric comorbidities were not associated with love-precipitated OCD.

CONCLUSION

It was concluded that romantic love does shape the expression of OCD, especially with regard to SP and onset age. These findings encourage further exploration to determine its clinical significance as a phenotype.

Women's Estrus and Extended Sexuality: Reflections on Empirical Patterns and Fundamental Theoretical Issues

How do women's sexual interests change across their ovulatory cycles? This question is one of the most enduring within the human evolutionary behavioral sciences. Yet definitive, agreed-upon answers remain elusive. One empirical pattern appears to be robust: Women experience greater levels of sexual desire and interest when conceptive during their cycles. But this pattern is not straightforward or self-explanatory. We lay out multiple possible, broad explanations for it. Based on selectionist reasoning, we argue that the conditions that give rise to sexual interests during conceptive and non-conceptive phases are likely to differ. Because conceptive and non-conceptive sex have distinct functions, the sexual interests during conceptive and non-conceptive phases are likely to have different strategic ends. We discuss provisional evidence consistent with this perspective. But the exact nature of women's dual sexuality, if it exists, remains unclear. Additional empirical research is needed. But perhaps more crucially, this topic demands additional theory that fruitfully guides and interprets future empirical research.

Towards a theory of brand love in services: the power of identity and social relationships

Purpose

Building meaningful relationships between consumers and service brands has received significant attention. This paper aims to explore how brand love in services – a relationship between the consumer and the service brand – is created through relationships between the consumer and other people. Specifically, we explore how brand love is created through the social relationships consumers form with other consumers.

Design/methodology/approach

This conceptual paper synthesizes the literature on consumer-brand relationships, brand community, social support and service providers, psychological ownership and brand love in the context of services.

Findings

This paper suggests that consumers love brands that are meaningful to them. Brands can become more meaningful to consumers by facilitating interpersonal connections and helping consumers define their identity. The connection between social relationships with other consumers and brand love is mediated by the consumer's level of perceived membership in the community. For some consumers, perceived membership grows to the point of becoming perceived psychological ownership of the community, where the consumer feels a sense of responsibility for the brand's and the community's well-being.

Originality/value

This paper advances theoretical understanding of how brand love operates in services and how it can be enhanced through services’ management.

Couple Communication Behaviors During Sexual and Nonsexual Discussions and Their Association with Relationship Satisfaction

The quality of communication between romantic partners has consistently been found to be associated with relationship well-being and stability. Studies on sexual and nonsexual communication, however, have typically assessed communication skills and behaviors using self-report measures. The use of observational methods has several advantages, including the ability to capture and allow for the independent coding of both partners' communication behaviors. With few exceptions, research applying observational methods has not distinguished between sexual and nonsexual communication behaviors. In the present study, we asked 126 young, mixed-sex couples to engage in sexual and nonsexual conflict discussions. The two 7-min discussions were videotaped and rated by trained coders on nine behavioral dimensions using an adaptation of the specific affect coding system (Gottman & Krokoff, 1989) and the system for coding interactions and family functioning (Lindahl & Malik, 2001). Coder ratings applied to the discussion as a whole. Analyses included factor analysis on the behavioral dimensions and multilevel modeling incorporating the actor-partner interdependence model (APIM). We found significant differences in how couples interacted during the two discussions, with more positive (affectionate and validating) and less negative behaviors during sexual discussions as compared to nonsexual discussions. In both women and men, expressions of positivity during the two types of conflict discussions were associated with higher relationship satisfaction. Gender differences were found in the association between negative behaviors during sexual discussions and relationship satisfaction, with men but not women's negative behaviors being associated with lower relationship satisfaction. These findings point at distinct qualities of sexual communication and its association with couples' relational well-being and contribute to a better scientific understanding, with clinical relevance, of sexual and nonsexual communication.

Why and How Did Narrative Fictions Evolve? Fictions as Entertainment Technologies

Narrative fictions have surely become the single most widespread source of entertainment in the world. In their free time, humans read novels and comics, watch movies and TV series, and play video games: they consume stories that they know to be false. Such behaviors are expanding at lightning speed in modern societies. Yet, the question of the origin of fictions has been an evolutionary puzzle for decades: Are fictions biological adaptations, or the by-products of cognitive mechanisms that evolved for another purpose? The absence of any consensus in cognitive science has made it difficult to explain how narrative fictions evolve culturally. We argue that current conflicting hypotheses are partly wrong, and partly right: narrative fictions are by-products of the human mind, because they obviously co-opt some pre-existing cognitive preferences and mechanisms, such as our interest for social information, and our abilities to do mindreading and to imagine counterfactuals. But humans reap some fitness benefits from producing and consuming such appealing cultural items, making fictions adaptive. To reconcile these two views, we put forward the hypothesis that narrative fictions are best seen as entertainment technologies that is, as items crafted by some people for the proximate goal to grab the attention of other people, and with the ultimate goal to fulfill other evolutionary-relevant functions that become easier once other people's attention is caught. This hypothesis explains why fictions are filled with exaggerated and entertaining stimuli, why they fit so well the changing preferences of the audience they target, and why producers constantly make their fictions more attractive as time goes by, in a cumulative manner.

An Evolutionary Perspective on Appearance Enhancement Behavior

Researchers have highlighted numerous sociocultural factors that have been shown to underpin human appearance enhancement practices, including the influence of peers, family, the media, and sexual objectification. Fewer scholars have approached appearance enhancement from an evolutionary perspective or considered how sociocultural factors interact with evolved psychology to produce appearance enhancement behavior. Following others, we argue that evidence from the field of evolutionary psychology can complement existing sociocultural models by yielding unique insight into the historical and cross-cultural ubiquity of competition over aspects of physical appearance to embody what is desired by potential mates. An evolutionary lens can help to make sense of reliable sex and individual differences that impact appearance enhancement, as well as the context-dependent nature of putative adaptations that function to increase physical attractiveness. In the current review, appearance enhancement is described as a self-promotion strategy used to enhance reproductive success by rendering oneself more attractive than rivals to mates, thereby increasing one's mate value. The varied ways in which humans enhance their appearance are described, as well as the divergent tactics used by women and men to augment their appearance, which correspond to the preferences of opposite-sex mates in a heterosexual context. Evolutionarily relevant individual differences and contextual factors that vary predictably with appearance enhancement behavior are also discussed. The complementarity of sociocultural and evolutionary perspectives is emphasized and recommended avenues for future interdisciplinary research are provided for scholars interested in studying appearance enhancement behavior.

Imaginary worlds through the evolutionary lens: Ultimate functions, proximate mechanisms, cultural distribution

We received several commentaries both challenging and supporting our hypothesis. We thank the commentators for their thoughtful contributions, bringing together alternative hypotheses, complementary explanations, and appropriate corrections to our model. Here, we explain further our hypothesis, using more explicitly the framework of evolutionary social sciences. We first explain what we believe is the ultimate function of fiction in general (i.e., entertainment) and how this hypothesis differs from other evolutionary hypotheses put forward by several commentators. We then turn to the proximate features that make imaginary worlds entertaining and, therefore, culturally successful. We finally explore how these insights may explain the distribution of imaginary worlds across time, space, age, and social classes.

Neural Representations of the Committed Romantic Partner in the Nucleus Accumbens

Having an intimate romantic relationship is an important aspect of life. Dopamine-rich reward regions, including the nucleus accumbens (NAcc), have been identified as neural correlates for both emotional bonding with the partner and interest in unfamiliar attractive nonpartners. Here, we aimed to disentangle the overlapping functions of the NAcc using multivoxel pattern analysis, which can decode the cognitive processes encoded in particular neural activity. During functional MRI scanning, 46 romantically involved men performed the social-incentive-delay task, in which a successful response resulted in the presentation of a dynamic and positive facial expression from their partner and unfamiliar women. Multivoxel pattern analysis revealed that the spatial patterns of NAcc activity could successfully discriminate between romantic partners and unfamiliar women during the period in which participants anticipated the target presentation. We speculate that neural activity patterns within the NAcc represent the relationship partner, which might be a key neural mechanism for committed romantic relationships.

Relationship Match: The Neural Underpinnings of Social Feedback in Romantic Couples

Romantic love involves an evaluative process in which couples weigh similarities and differences that facilitates pair bonding. We investigated neural attentive processes (P3) during evaluative relationship feedback within existing romantic couples using the Relationship Match Game. This paradigm included participant-driven expectations about relationship matching and relationship feedback from an expert panel of fictive peers and their romantic partner. In total, 49 couples participated who had dated less than one year. Participants showed significantly larger P3s in anticipation of feedback when they expected a mismatch, especially when supported by panel feedback. P3 amplitudes were also greater when participants received feedback from their partner congruent with their own assessment of compatibility. This was moderated by relational ambiguity, or one’s preference to keep the relationship’s status vague. We discuss how insecurity about the relationship is costly in terms of attentional resources contributing to over-alertness to cues of relationship evaluation.

Sexual Desire Mediates the Relationship-Promoting Effects of Perceived Partner Mate Value

Although sexual desire for one's partner is theorized to serve as a gut-level indicator of partner mate value that motivates investment in valued partners, there is scant empirical evidence to support this hypothesis. Five studies addressed this possibility, examining whether experiencing sexual desire encouraged the enactment of relationship-promoting behaviors and whether perceptions of partner mate value motivated this proposed process. In a pilot study and Study 1, participants relived an activity they experienced with their partner, which was either sexual or non-sexual. Then, participants rated their desire to engage in sex and other non-sexual relationship-promoting activities with their partner (pilot study) and their partner's responsiveness to personal disclosures. Participants' enacted responsiveness was also evaluated by judges (Study 1). Results showed that experiences of desire enhanced relationship-promoting tendencies. Using experimental, daily experiences, and longitudinal methods, Studies 2-4 extended these findings, indicating that both manipulated and perceived partner mate value predicted desire, which, in turn, was associated with engagement in relationship-promoting behaviors. These findings demonstrate that sexual desire functions as a mechanism encouraging investment in partners who are perceived to be worth pursuing and retaining.