Endogenous oxytocin, cortisol, and testosterone in response to group singing: "We conclude that singing together can have biological and psychological effects associated with affiliation and social bonding"

Endogenous oxytocin, cortisol, and testosterone in response to group singing. D.L. Bowling et al. Hormones and Behavior, Volume 139, March 2022, 105105. https://doi.org/10.1016/j.yhbeh.2021.105105

Highlights

• Singing and speaking were associated with decreases in salivary oxytocin concentrations, when performed together or alone.

• Salivary oxytocin concentrations decreased by less after singing together than after speaking together.

• Salivary cortisol concentrations decreased overall, but did not vary as a function of experimental conditions.

• Singing together improved self-perceived emotional status and social connectedness more than speaking together.

Abstract: Humans have sung together for thousands of years. Today, regular participation in group singing is associated with benefits across psychological and biological dimensions of human health. Here we examine the hypothesis that a portion of these benefits stem from changes in endocrine activity associated with affiliation and social bonding. Working with a young adult choir (n = 71), we measured changes salivary concentrations of oxytocin, cortisol, and testosterone from before and after four experimental conditions crossing two factors: vocal production mode (singing vs. speaking) and social context (together vs. alone). Salivary oxytocin and cortisol decreased from before to after the experimental manipulations. For oxytocin the magnitude of this decrease was significantly smaller after singing compared to speaking, resulting in concentrations that were significantly elevated after singing together compared to speaking together, after controlling for baseline differences. In contrast, the magnitude of the salivary cortisol decreases was the same across experimental manipulations, and although large, could not be separated from diurnal cycling. No significant effects were found in a low-powered exploratory evaluation of testosterone (tested only in males). At a psychological level, we found that singing stimulates greater positive shifts in self-perceived affect compared to speaking—particularly when performed together—and that singing together enhances feelings of social connection more than speaking together. Finally, measurements of heart rate made for a subset of participants provide preliminary evidence regarding physical exertion levels across conditions. These results are discussed in the context of a growing multidisciplinary literature on the endocrinological correlates of musical behavior. We conclude that singing together can have biological and psychological effects associated with affiliation and social bonding, and that these effects extend beyond comparable but non-musical group activities. However, we also note that these effects appear heavily influenced by broader contextual factors that shape social dynamics, such as stress levels, the intimacy of interactions, and the status of existing relationships.

Keywords: SpeechMusicSynchronyBondingAffectOxytocinCortisolTestosterone

4. Discussion

The hormone results described here indicate overall decreases in salivary concentrations of oxytocin and cortisol, and an absence of significant effects on salivary concentrations of testosterone in males. With respect to our experimental manipulations, vocal mode was determined to affect salivary oxytocin, with decreases being smaller after singing compared to speaking. In parallel, the survey results indicated that vocal mode and social context interacted to affect self-perceived affective status, with singing together producing the largest positive shift (see also Kreutz, 2014; Pearce et al., 2015; Schladt et al., 2017; Weinstein et al., 2016). Singing together was additionally found to be more effective than speaking together at stimulating feelings of social connectedness (see also Pearce et al., 2015; Weinstein et al., 2016). Finally, as might be expected, heart rates measured for ten participants suggested that physical exertion was highest during singing together and lowest during speaking alone. We now discuss each hormone result in turn (order-reversed from above), adding context from prior literature, exploring potential interpretations, and discussing connections with our other measures. We conclude by considering the connection between music and social bonding, as well as implications for future studies on the endocrinological correlates of musical behavior.

4.1. Testosterone

The absence of any significant effect on concentrations of testosterone in male saliva indicates that our experimental manipulations of vocal mode and social context were insufficient to systematically influence the acute regulation of testosterone in males. This is an important preliminary finding, but we emphasize caution in its interpreted because of the relatively low power of our testosterone model (observations per estimated effect =6.18). Nevertheless, we saw no indication that potential acute effects of music listening on male testosterone levels extend to singing (Fukui, 2001; Fukui and Toyoshima, 2013; Fukui and Yamashita, 2003). Future studies examining testosterone in the context of group singing or other musical behaviors should consider incorporating further factors or measurements potentially relevant to testosterone, such as the existence of interpersonal friendships, individual social status, singing skill, and competitive/cooperative group dynamics (Casto and Edwards, 2016; Edwards et al., 2006; Ponzi et al., 2016). It may also be useful to study testosterone and group singing over longer periods of time, as changes may appear gradually as participants move from forming new social bonds towards maintaining existing ones (Kornienko et al., 2016). Finally, it will be important for future studies to examine testosterone levels in females (Grant and France, 2001; van Anders, 2013), especially given that most modern choirs are majority female (Elpus, 2015).

4.2. Cortisol

The experimental manipulations did not differentially impact concentrations of cortisol in saliva, which decreased markedly from before to after participation regardless of condition. Whether the magnitude of the decrease that we observed was specifically related to our experiment, as opposed to natural diurnal cycling, cannot be determined with certainty. A recent meta-analysis that aggregated cortisol data from more than 18,000 individuals found an average diurnal decrease during the time at which our experiment took place of approximately 12% per 30 min (range: 3% to 20% assuming wake-times from 7:00 and 10:00; Miller et al., 2016). On the basis of this data, it may be argued that the magnitude of the cortisol decrease that we observed (30%) was too large to be explained by diurnal cycling alone, which would in turn suggest that recreational singing or speaking, together or alone, comprise particularly effective ways to relax. That said, we emphasize that testing this hypothesis would have required inclusion of a “no-treatment” control condition in which hormone levels were assessed at the same times but in the absence of any experimental manipulations. Although such control conditions are not typically included in non-clinical research, it is important that future studies aiming to identify experimental effects of group singing on cortisol levels prioritize their inclusion, particularly if measurements are made in the evening, as they were here, and as they have been in previous studies (Beck et al., 2000; Fancourt et al., 2015, Fancourt et al., 2016; Kreutz et al., 2004; Schladt et al., 2017).

With respect to previous studies, our cortisol results mostly conformed to expectations. In relatively low-stress recreational contexts like that examined here, four previous studies have reported significant cortisol decreases after group singing (ranging in magnitude from approximately 18% to 27%; Beck et al., 2000; Fancourt et al., 2015, Fancourt et al., 2016; Schladt et al., 2017), and two others have reported non-significant changes (in opposite directions; Kreutz et al., 2004; Kreutz, 2014). Although all of these studies have been conducted in the evening, some have nonetheless found experimental effects on salivary cortisol. Of particular relevance here, Schladt et al. also compared singing together with singing alone. In contrast with our results, which indicated similar decreases in salivary cortisol after singing together (29%) and singing alone (31%), Schladt et al. found a significantly greater decrease after singing together (~32%2) than after singing alone (~20%). This difference in the effects of singing alone between our study and Schladt et al. is particularly notable given that the relevant conditions were highly similar in terms of design and execution (see below). Together, these findings indicate that recreational group singing is typically associated with reduced salivary cortisol concentrations, but that the effects of singing alone are more variable.

4.3. Oxytocin

Focusing on group singing first, salivary oxytocin concentrations decreased from before to after participation in our singing-together condition (Fig. 2B). Interpreting the generality of this effect is complicated by the literature. Four previous studies have assessed changes in oxytocin from before to after group singing, all in relatively low-stress contexts. Two of these studies report decreases similar in magnitude to that found here (Fancourt et al., 2016; Schladt et al., 2017), and two report increases (Keeler et al., 2015; Kreutz, 2014). Contrasting these “decrease studies” and “increase studies” provides insight into contextual factors that may modulate the relationship between group singing and oxytocin. The decrease studies include the present one (15% reduction after a 20-min choir rehearsal, n = 37), Schladt et al. (~22% reduction after a 20-min choir rehearsal, n = 38), and Fancourt et al. (24% reduction after a 70-min choir rehearsal, n = 193, across 5 choirs). The increase studies include Kreutz (39% increase after a 30-min choir rehearsal, n = 21) and Keeler et al. (~19% increase after a 6 min bout of improvised singing in a jazz quartet, n = 4). An additional study, Grape et al. (2003), is also relevant despite not measuring group singing per se (25% increase after a 45-min private singing lesson, n = 16). We consider each of the increase studies in detail below, attempting to determine factors underlying their differential effects, relative to our study and other decrease studies.

Starting with the study most different from our own, Grape et al. examined singing lessons between adult students and a teacher with whom they had practiced for a minimum of 6 months. This context differs from all other studies considered here, not only because participants sang alone rather than in a group, but because private lessons involve more focused social interaction than choir rehearsals. This point is particularly important because the intimacy of an interaction appears to be of greater relevance for understanding oxytocin responses to social context than whether an activity is technically performed alone or together with others (Bartz et al., 2011). Additional support for this idea comes from Keeler et al.'s study of improvised singing in a jazz quartet. Although their sample of just four individuals was too small to appropriately evaluate statistical significance, the average oxytocin increase that they observed (~19%) appeared specific to improvised singing—a separate condition where the quartet sang a precomposed jazz standard was instead associated with a small oxytocin decrease (~3%). Taken together, these results suggest that focused collaborative interaction, characteristic of teaching and social improvisation, is likely an important determinant of oxytocin activity in the context of group singing.3

The last increase study—Kreutz (2014)—is also the most similar to our own (and the other decrease studies). There are, however, a number of potentially important differences. A first difference is that whereas we and others have examined choirs that existed prior to the initiation of study, Kreutz examined a choir that was specifically formed for their study. Whereas many of the members of our choir had pre-existing friendships and previous experience singing together (often over multiple semesters), the members of Kreutz’s choir presumably had little such relations. This difference in social context is directly relevant to the value of affiliative behavior and potential for social bonding. A second difference is that the choir in our study was made-up entirely of members of the same age cohort (mean = 22 years, range = 17–28), whereas the choir in Kreutz included a greater mix of ages (mean ~ 49, range ~ 18–65). Schladt et al.'s choir was similar to ours in participant age (mean = 23 years, range = 19–29); Fancourt et al.'s was older (mean = 59 years) but still relatively narrow in age range (SD ~ 12). Given that extra-familial social bonds are biased towards members of the same age group (Nahemow and Lawton, 1975), the difference in age diversity of the choir studied by Kreutz may have similarly led to differences in affiliative value and bonding potential. Kreutz (2014) is also unique for its connection to a local television station, which ran advertisements to recruit participants, filmed rehearsals for a short documentary feature, and televised a final concert. This televised aspect may have led to a systemic difference in the personality traits of participants, potentially favoring group-level differences in individual oxytocin biology (Li et al., 2015). Finally, the music sung by Kreutz’s choir (e.g., the 1960s pop song “California Dreaming”) was more popular than the relatively obscure choral music used in our study and other decrease studies. Effects of music type on changes in salivary oxytocin concentrations after listening have been reported, and may be attributable to acoustic parameters conveying different types of affect (Ooishi et al., 2017).

A summary of these findings is that group singing in the context of choir rehearsals is primarily associated with decreases in salivary oxytocin concentrations, but that this effect can be modulated to the point of reversal by a variety of factors related to the broader social context in which singing occurs. The intimacy of the social interactions that take place during singing appears to be among the most important of these factors, with more intimate, direct, collaborative interactions potentially driving higher oxytocin activity than more anonymous, diffuse, independent interactions. Related to this, the nature of existing social relationships between group members also appears important, as it sets the stage for differences in the relative value of affiliative behavior and potential for social bonding. Finally, cultural and affective connotations of the specific music being sung may contribute further to differences in the effects of group singing on oxytocin.

Turning to our experimental manipulation of musical versus non-musical vocal production, we found evidence of a smaller decrease in salivary oxytocin concentration after speaking compared to singing (35% vs. 15% respectively; Fig. 2C). This novel comparison suggests that singing may sustain relatively higher levels of oxytocin activity than speaking, a similar vocal behavior that is also used for communication and that also involves high levels of interpersonal coordination. Psychologically, vocal production mode also influenced self-perceived affective status, with singing stimulating greater positive shifts in affect, particularly when performed together with others, as well as greater feelings of social connectedness. What is the basis for these differences in the biological and psychological effects of singing and speaking?

Despite broad similarities, singing and speaking are obviously characterized by a variety of neural, behavioral, and acoustic differences, any of which could be investigated as a potential basis for the differential effects that we observed. One straight-forward approach to understanding the different of effects singing versus speaking on salivary oxytocin is focused on potential differences in physical activity between them. Physical exertion can increase salivary oxytocin concentrations as well as feelings of affiliation (Anshel and Kipper, 1988; de Jong et al., 2015; Tarr et al., 2015). Just 10 min of jogging, for example, was found to increase salivary oxytocin by ~320% on average (de Jong et al., 2015). Accordingly, singing may increase salivary oxytocin concentrations more than speaking because it requires higher levels of physical exertion. Albeit preliminary, our heart rate data do not generally support this possibility. The largest and smallest estimated changes in salivary oxytocin occurred in conditions with approximately equal mean heart rates: salivary oxytocin decreased by 42% after speaking together, where mean heart rate was 94.8 bpm (SD = 11.3), but only decreased by 15% after singing alone, despite a similar mean heart rate of 92.8 bpm (SD = 14.0; cf. Figs. 2B and 7B). Nevertheless, further experiments are required to fully rule out physical exertion as a potential driver of differential effects of singing and speaking on salivary oxytocin.

Another approach to explaining the observed differential effects is focused on oxytocin's role in mitigating the effects of HPA axis activation (Gibbs, 1986; Neumann, 2002; Schladt et al., 2017). The idea here is that oxytocin activity is upregulated in response to stress, being released alongside cortisol and acting as an anxiolytic (Brown et al., 2016). Accordingly, if singing stimulated greater HPA axis activity than speaking, proportional oxytocin activity may underlie the differential effects that we observed. This interpretation is not supported by our salivary cortisol results, which showed a stable decrease in concentrations across conditions rather than an increase (or smaller decrease) after singing. This suggests that the singing and speaking conditions had similar effects on HPA axis activation. Furthermore, although salivary oxytocin and cortisol concentrations were significantly correlated across all of our measurements, we did not find evidence that these factors changed together over the course of our study. It is therefore unlikely that differential effects of singing versus speaking on salivary oxytocin are explained by differences in activation of the HPA-axis between conditions.

A final issue to consider in accounting for the differential effects of singing versus speaking on salivary oxytocin is focused on baseline differences. Careful inspection of Fig. 2 shows that salivary oxytocin concentrations measured before the speaking conditions were relatively elevated compared to those measured before the singing conditions. Thus, the interaction between time and vocal mode that we observed is confounded with baseline differences in salivary oxytocin between conditions. To test whether or not baseline differences (rather than experimental effects) are responsible for the observed interaction, we fit an alternate oxytocin model that incorporated baseline salivary oxytocin concentrations as a covariate in predicting post-experiment salivary oxytocin concentrations. This “baseline” oxytocin model was a significantly better predictor of post-experiment oxytocin concentrations than a parallel null model (χ2 = 7.85, d.f. =3, p = 0.049), and post-hoc tests indicated that the two-way interaction between vocal mode and social context was significant (estimate ± s.e. =0.38 ± 0.16; χ2 = 98.7, d.f. =1, p = 0.016). Specifically, oxytocin concentrations were estimated to be significantly higher after singing together compared to speaking together (72.7 pg/ml [c.i. =64.1–83.1] vs. 56.0 pg/ml [48.4–64.9], t(100.5) = −2.497, p = 0.014), but not after singing alone compared to speaking alone (62.8 [52.5-74.5] vs. 71.0 [59.2-85.6], t(100.5) =0.919, p = 0.360). Thus, post-experiment salivary oxytocin concentrations were found to differ as a function of vocal mode after specifically accounting for the influence of baseline differences. This reflects marked differences in the magnitudes of salivary oxytocin decreases across conditions in our original model, and indicates that the corresponding experimental effect is not an artifact of unexplained differences in baseline salivary oxytocin concentrations (see Supplementary Text 1 for further details).

Last, we come to our manipulation of social context. Whereas our original oxytocin model indicates that the effect of vocal mode on salivary oxytocin was not impacted by social context (Fig. 2B), the baseline oxytocin model just described indicates that post-experiment salivary oxytocin concentrations were affected by social context, which interacted with vocal mode. In fact, the pattern of results for singing versus speaking performed together was reversed for singing and speaking performed alone (although the difference was not significant). Nevertheless, in both models, singing together was similarly associated with relatively higher levels of oxytocin activity than speaking together. This is reflected by smaller decreases in salivary oxytocin concentrations from before to after singing versus speaking together in our original model, and higher salivary oxytocin concentrations after singing versus speaking together when controlling for baseline differences in the baseline model. Insight into the disruption of this pattern for singing versus speaking alone in the baseline model can be found by comparing our results with Schladt et al. (2017), who also examined singing together versus singing alone. Although Schladt et al.'s results were similar to ours for singing together (we found an average decrease of 15%, compared to their average decrease of ~22%), their results were markedly different for singing alone (we again found an average decrease of 15%, but they found an average increase of ~10%, Fig. 2B). As noted above in our discussion of discrepant cortisol results between alone conditions in our study and Schladt et al., this suggests that the endocrine effects of singing together are more stable than those of singing alone. This appears to be true despite a high level of procedural similarity between the alone conditions in our study and Schladt et al. In both studies, amateur young-adult chorists were provided with written instructions leading them through a short vocal warm-up followed by practice of their choir's repertoire, for a total duration of 20 min. Additionally, both studies found that singing alone produced positive shifts in self-perceived affect. Hormone changes in response to singing alone thus appear quite sensitive to more subtle differences between individuals and/or contexts (e.g., differences in stress and anxiety, or external performance pressures). Conversely, singing together with others seems to be capable of overriding individual or contextual differences to induce hormonal responses that are more similar across individuals.

We close this section on oxytocin with a brief discussion of our finding that male participants had higher salivary oxytocin concentrations than female participants (by 1.7 times on average). Importantly, this results does not reflect simple methodological error: our experimental procedures were the same for females and males, and their saliva samples were equally distributed across assays. We also emphasize that although oxytocin has often been associated with female-specific behaviors and effects—e.g., in the context of mothering, parturition, and lactation—it clearly functions in social behavior and cognition (as well as metabolism, cardiovascular function, and bone regeneration) across both females and males, with evidence of overlapping effects, as well as female- and male-specificity (Caldwell, 2018; Quintana and Guastella, 2020). Simple rules about oxytocin and sex differences remain “very difficult” to state (Caldwell, 2018), and evidence that oxytocin responses and reactions can be more pronounced in males is not unusual (Dumais et al., 2016; Feldman et al., 2010; Herzmann et al., 2013; Lynn et al., 2014; Rilling et al., 2014; Theodoridou et al., 2013). Nevertheless, our finding of higher salivary oxytocin concentrations in males contrasts with at least one other result in the human oxytocin literature. In their study of male and female medical staff at an Italian hospital (n = 90, 45 female), Marazziti et al. (2019) found that blood oxytocin concentrations were ~ 2.8 times higher in females compared to males. In considering this sex difference together with our own, it is apparent that neither Marazziti et al. nor the present study examined random samples. This leads to two hypotheses about the sex difference that we observed. One is that male chorists are a “special” group that exhibits higher levels of oxytocin activity (reflected in salivary concentrations). Modern choirs tend to be female-biased, and relative to males who are not in choirs, males in choirs tend to be more accepting of atypical gender behavior and identify less with gender stereotypes like “guys are physical” and “girls are feminine” (Nannen, 2017), potentially reflecting differences in trait empathy. A second hypothesis is that male oxytocin activity is specifically sensitive to variation in opportunities to affiliate with females. Our choir was 63% female (n = 71, 45 female) and young (mean age = 23). These circumstances may have led males to feel relatively safe and sociable in support of affiliation and courtship (some may have even have been “in love”). Although most previous endocrine studies of group singing have not included sex as predictor, some insight into evaluating these two hypotheses comes from Schladt et al. (2017). Despite looking, Schladt et al. did not find a significant sex difference in salivary oxytocin in their choir, which was more balanced in terms of participant sex at 55% female (n = 38, 21 female). This is a strike against the ‘male chorists are special’ hypothesis, but not necessarily the ‘affiliative opportunity’ hypothesis. If male chorists generally have higher levels of oxytocin activity, this should have been apparent also in Schladt et al. (2017), despite the more balanced choir. In contrast, if male oxytocin activity partially reflects male-female ratios that favor opportunities for males to affiliate with females, the absence of a sex difference in Schladt et al. (2017) would be predicted on the basis of their more balanced choir. Accordingly, we favor increased opportunities for males to affiliate with females as a preliminary explanation of the sex difference that we observed. However, we emphasize that the two hypotheses described above are not mutually exclusive, and that more research on salivary and blood oxytocin concentrations in the general population is needed before the sex differences found here and elsewhere can be interpreted in broader context.

4.4. Caveats

The most important caveat here concerns our evolving understanding of the oxytocin system and the aspects of its function that may be assessed in saliva. The principal neural sources of oxytocin—magnocellular and parvocellular neurons in the hypothalamus—exert their effects through at least three different release mechanisms. These include neurosecretory release from magnocellular neurons into peripheral circulation via projections to the neurohypophysis, somato-dendritic release into central extracellular and/or cerebrospinal fluid from magnocellular neurons for paracrine action in the central nervous system, and release from magnocellular and parvocellular projections onto specific central targets in the forebrain, hypothalamus, brainstem, and spinal cord (Jirikowski, 2019; Jurek and Neumann, 2018; Knobloch et al., 2012; Lewis et al., 2020; Ludwig and Leng, 2006; Menon et al., 2018). These mechanisms may act alone or in concert with the others to exert a diversity of influences on social function in different contexts (Jurek and Neumann, 2018; Landgraf and Neumann, 2004). Recent evidence from mice indicates that central synaptic release of oxytocin onto dopaminergic neurons in the reward system is particularly important for understanding affiliation in “consociate” (non-reproductive) relationships (Dölen et al., 2013; Gunaydin et al., 2014; Hung et al., 2017), which may thus provide an appropriate model for relationships between chorists in our study. If comparable central oxytocin projections are similarly key to human consociate affiliation, detection of their activity in saliva seems dubious. Related to this issue, it should be noted that oxytocin's mode of entry into saliva is poorly understood (MacLean et al., 2019; Martin et al., 2018). Like other hydrophilic peptides, oxytocin does not easily cross the blood brain barrier. This can create differences in oxytocin concentrations between the central nervous system and the periphery (McEwen, 2004; Neumann and Landgraf, 2012). Salivary oxytocin is typically interpreted as an indicator of peripheral levels—presumably on the basis of correlations with oxytocin concentrations in blood (Grewen et al., 2010; White-Traut et al., 2009), and because saliva also lies outside the blood brain barrier—but the matter is contested. In particular, two studies conducted in critically ill patients have reached different conclusions, one finding moderate to strong correlations between oxytocin concentrations measured in saliva and cerebrospinal fluid (Martin et al., 2018), and the other indicating very weak correlations (except in the morning; Kagerbauer et al., 2019). The above points about oxytocin and the oxytocin system emphasize that our experimental effects on salivary oxytocin concentrations should be interpreted with caution, as their relation to central oxytocin mechanisms remains unclear. A second caveat concerns the absolute salivary oxytocin concentrations observed in our study (mean = 112 pg/ml across all 200 measurements; see Table 1). Although these concentrations are consistent with those reported by previous studies that have used the same Arbor Assays oxytocin ELISA (e.g., Akimoto et al., 2018; Erickson et al., 2020; Leeds et al., 2020), they are considerable higher than most results in the literature. For example, the absolute oxytocin concentrations in saliva measured using another popular oxytocin ELISA (originally produced by Assay Designs Inc., now Enzo Life Sciences Inc.) are more typically in the 5–20 pg/ml range (e.g., Blagrove et al., 2012; Feldman et al., 2010; Grewen et al., 2010; Holt-Lunstad et al., 2011). The reason for the order of magnitude difference between concentrations reported using these two oxytocin ELISAs is unclear. They use different antibodies and protocols. Both now recommend and specify procedures for extracting samples, though it should be noted that these procedures are designed for blood rather than saliva. In a recent review of the challenges faced in measuring oxytocin, MacLean et al. (2019) propose that discrepant results in the literature are due to different methods of sample preparation and measurement being differentially sensitive to “diverse conformational states of the oxytocin molecule” (see also Brandtzaeg et al., 2016; Gnanadesikan et al., 2021). This would indicate that differences in the absolute concentrations of oxytocin reported using different methods reflect real differences in oxytocin biochemistry, rather than the relative validity or invalidity of particular assays. In accord with this perspective, and in defense of our results, we provide the following rationale in support of our oxytocin data having value for examining relative concentration changes across our experimental conditions, despite ongoing debate over absolute values. First, we used the same procedure for all oxytocin measurements; second, the correlation between different measurements of the same participant was r = 0.83; and third, the patterns of change that we report are quite similar to those reported by several other recent studies of group singing of similar design (Fancourt et al., 2016; Schladt et al., 2017). A final caveat is that singing and speaking may result in differences in salivary flow rate that could potentially influence measures of salivary oxytocin. Although we are not aware of any evidence that singing and speaking differ in this way, future endocrine studies of group singing that use salivary assays should record the volumes of collected samples so that flow rates may be determined.

From 2021... Self-domestication/selective migration hypothesis: Cultural differences along the individualism–collectivism dimension are driven by the out-migration of individualists from collectivist core regions of states to peripheral frontier areas

From 2021... The origins of cultural divergence: evidence from Vietnam. Hoang-Anh Ho, Peter Martinsson & Ola Olsson. Journal of Economic Growth volume 27, pages45–89. Aug 20 2021. https://link.springer.com/article/10.1007/s10887-021-09194-x

Abstract: Cultural norms diverge substantially across societies, often within the same country. We propose and investigate a self-domestication/selective migration hypothesis, proposing that cultural differences along the individualism–collectivism dimension are driven by the out-migration of individualistic people from collectivist core regions of states to peripheral frontier areas, and that such patterns of historical migration are reflected even in the current distribution of cultural norms. Gaining independence in 939 CE after about a thousand years of Chinese colonization, historical Vietnam emerged in the region that is now north Vietnam with a collectivist social organization. From the eleventh to the eighteenth centuries, historical Vietnam gradually expanded its territory southward to the Mekong River Delta through repeated waves of conquest and migration. Using a nationwide household survey, a population census, and a lab-in-the-field experiment, we demonstrate that areas annexed earlier to historical Vietnam are currently more prone to collectivist norms, and that these cultural norms are embodied in individual beliefs. Relying on many historical accounts, together with various robustness checks, we argue that the southward out-migration of individualistic people during the eight centuries of the territorial expansion is an important driver, among many others, of these cultural differences.

Conclusion

The individualism–collectivism dimension has been found to be a powerful predictor of economic and democratic development in a large sample of countries (Gorodnichenko & Roland, 2011, 2015, 2017). Thus, why some societies have become more collectivistic or individualistic than others is a crucial question in understanding long-run comparative development. In the present paper, we propose and investigate the selective migration hypothesis, stating that cultural differences along the individualism–collectivism dimension are driven by the out-migration of individualistic people from collectivist societies to settle down in frontier areas, and that such patterns of historical migration are reflected even in the current distribution of cultural norms. We use the territorial expansion of historical Vietnam from the eleventh to the eighteenth centuries as an ideal setting to empirically examine this hypothesis. During this period, historical Vietnam gradually expanded its territory southward along the coast from the Red River Delta to the Mekong River Delta through various waves of conquest and migration to form the country as it is today.

Our empirical analysis focuses on the ability to solve collective action problems, which is the main feature of collectivism in related economic models, by using data on voluntary contributions to public goods, which is the most typical collective action in daily living in Vietnam. Using a household survey, we find that areas annexed earlier to historical Vietnam currently have higher levels of voluntary labor contribution to public goods production. Using a population census, we also find that households in districts that were annexed earlier have a higher percentage of households with grandchildren living in them and a lower prevalence of divorced households, which are two other standard measures of individualism–collectivism traits. Conducting a public goods experiment with high school students, we find that subjects from areas annexed earlier to historical Vietnam contribute substantially more to the public good compared to subjects from areas annexed later, and that the result is mainly driven by the belief about the contributions of other subjects. Relying on various Vietnamese historical accounts, together with various robustness checks, we show that the southward out-migration of individualistic people during eight centuries of territorial expansion of historical Vietnam is an important driver behind these cultural differences.

Despite our efforts, we recognize, however, that in the current study, it is empirically challenging to completely isolate the effects of selective migration from a crowding-in of collectivist norms by a strong state or the pre-existence of individualist norms in the periphery. We leave it for future research on other areas, with access to more detailed data on historical migration patterns and attitudes, to potentially shed further light on the relative contributions of each of these interrelated mechanisms.

We believe that the present paper makes a contribution by offering an extended conceptual framework and an empirical strategy combining survey and experimental evidence for understanding long-run cultural divergence. First and foremost, the migration patterns in the distant past played a crucial role in explaining cultural differences across modern societies. As time goes on, similar processes may continue to enhance cultural differences across societies. These cultural differences may, in turn, have important implications for future levels of comparative development.

Overall, women appear to accomplish their sexual goals in digital dating arenas more than men do given a surplus of male demand

Is Dating Behavior in Digital Contexts Driven by Evolutionary Programs? A Selective Review. Jorge Ponseti, Katharina Diehl and Aglaja Valentina Stirn. Front. Psychol., February 28 2022. https://doi.org/10.3389/fpsyg.2022.678439

Abstract: In recent years, millions of citizens all over the world have used digital dating services. It remains unknown to what extent human sexuality will be changed by this. Based on an evolutionary psychological perspective, we assume that sexual selection shaped behavioural tendencies in men and women that are designed to increase the reproductive fitness. These tendencies are referred to as sexual strategies. Males and females sexual strategies differ according to sex-dimorphic reproductive investments. We assume that this inheritance will affect human sexuality also in a digital future. To evaluate this assumption, we conducted a selective review of studies on digital dating services. Based on sexual selection theory, we derived a number of hypotheses regarding how men and women will use digital dating services typically and how the use of digital dating services might affect sexual wellbeing. Out of an initial data set of 2,568 records, we finally reviewed a set of 13 studies. These studies provided support for the notion that men and women act in the digital dating area according to sex-typical strategies. However, sometimes the circumstances of digital dating affect communication flow, e.g., in that men are even more active in establishing contacts than they are in real world conditions. Overall, women appear to accomplish their sexual goals in digital dating arenas more than men do given a surplus of male demand. Our results suggest that future human sexuality will be impacted by an interaction of both: sex-dimorphic ancient sexual strategies and new technologies.

Discussion

This selective review evaluated a total of 13 cross-sectional studies on digital dating services. Evolutionary psychological reasoning and some hypotheses, which we drew from this, drove our analysis. Taken together, our selective review supports the notion that human sexuality is not going to change fundamentally on account of the rising popularity of digital dating services. The hypotheses that led our review covered four broader topics: (a) female mating preferences, (b) male mating preferences, (c) interactions between male and female mating preferences and finally, and (d) sexual wellbeing. The reviewed studies provided supporting evidence particular to hypotheses regarding mating preferences (a–c), which were derived from evolutionary psychological reasoning. Our hypotheses regarding sexual wellbeing received only partial support.

Female Mating Preferences

Some of the reviewed studies provided findings that are in accord with evolutionary psychological reasoning. These studies report that women in the digital mating market appreciate men of higher education and of white colour. Both attributes are associated with higher socio-economic status in many countries. High-status men in turn look for younger women, as one study reported. This indicates that high-status men in digital mating markets are aware of female mating preferences. Both findings (preference for high-status males and pursuit of younger women by high-status men) have previously been found in non-digital mating markets (Buss, 1989b; Grammer, 1992; Buss and Shackelford, 2008; Iredale et al., 2008; Vohs et al., 2014; Ponseti et al., 2018). One of the reviewed studies concluded that men try to look taller and more powerful as they orient their selfies more often from below (Sedgewick et al., 2017). In fact, women prefer males who are physically more powerful and taller (particularly in a short-term mating context). Again, this has been found already in the non-digital mating market before (Frederick and Haselton, 2007). Obviously, men act according to female preferences for physical dominance and display as much as possible of this trait. This in turn is sexually rewarded: physically powerful men report more sexual partners than less powerful men do (Frederick and Haselton, 2007).

We assume that female mating preferences (like male mating preferences as well) are shaped by sexual selection and modulated by culture and actual conditions of the mating marked (in terms of demand and supply). The findings discussed so far indicate that humans act according to female mating preferences in (sometimes anonymous) digital dating arenas more or less similar to real-world encounters.

Male Mating Preferences

According to sexual selection theory, males have more fitness benefits from having numerous sexual partners than females do. Therefore, males are predicted to pursue more sexual partners than females. In humans, this is particularly evident when looking at gender differences regarding interest in short-term sex (Clark and Hatfield, 1989; Voracek et al., 2005; Gueguen, 2011). This has been found outside the digital market area previously and appears to be true in the digital dating market in the same manner (Harris and Aboujaoude, 2016; Martins et al., 2016). Male fitness benefits from high numbers of sex partners and from having young sex partners given that the reproductive capacity of a young female is higher than that of an older female. Therefore, men appreciate youthfulness in their female partners much more than vice versa (Buss, 2008, S. 114). Again, what has been found in real-word mating with respect to male mating preferences is mirrored in the digital mating market (Bruch and Newman, 2018).

Interaction of Male and Female Sexual Strategies

A striking gender difference was reported by the study of Bruch and Newman in that 80% of first messages were sent by men (Bruch and Newman, 2018). Given that in the study of Bruch and Newman the numbers of male and female participants were roughly similar, the reported difference cannot be due to a limited female supply. It rather suggests that males are much more active, if not impatient, in establishing contacts. This male over-activity might be the result of both, (i) the possibility to anonymously interact with several women at the same time (driven by the strategy to find as many mates as possible and the lack of social control) and (ii) the lack of concealed signals from women that help men to focus on those mates with prospect of success. Male over-activity in turn puts females in a more comfortable position, allowing them to define the rules of the game more according to their own needs. One possible consequence of this is that women are more self-centred in their profiles and communication (Davis and Fingerman, 2016). A pattern that is pronounced in high attractive women. These women respond even less to male requests than less attractive women (Bruch and Newman, 2018). These findings are in accord with sexual selection theory predicting the higher investing sex to be choosier and the lower investing sex to be more competitive in its efforts to sexually access the higher investing sex. We predicted the respective findings for the digital mating arena because similar observations have been made in real-world scenarios previously – and, of course, because of our overall hypothesis that important variances in human mating strategies have been shaped in ancient times. However, interactions between male and female mating strategies are complicated and require a closer look, even though the data of our selective review on this was scarce. In real-word scenarios, the supply of males is an importance factor that modulates the female inclination to engage in short-term sex. If there are fewer males than females in a given mating market, females tend to be more willing to engage in short-term sex; “sex becomes cheap” (Barber, 2000; Schmitt, 2005; Xing et al., 2016). Conversely, “sex becomes expensive” when there is more male demand. Possibly, the observed self-centredness of women in digital dating markets is caused by the dynamic between supply and demand. As noted above, a surplus of male demand can be experienced in a mating market even if absolute numbers of males and females are equal simply because one sex is more impatient in its efforts to establish contacts.

However, it is not self-evident that a surplus of male demand in the digital (as well as in the real-world) market is only driven by male’s (ancient) strategy to find as quickly as possible as many mates as possible. In a seminal review, Baumeister and Twenge (2002) showed convincing evidence that women work together to restrict male’s sexual access to females (in order to get as much as possible in exchange for sex). One strategy is to hide, respectively, to obscure a female’s own sexual interest. Women are influenced by other women (mothers, sisters, girlfriends, etc.) which makes them feel uncomfortable when openly showing their own sexual needs. This cultural force, in addition to adaptations shaped by sexual selection and the specific conditions of anonymous digital dating, might be one further reason why 80% of first messages were sent by men.

Effects of Digital Dating Services on Sexual Wellbeing

Contrary to our expectations, we found no studies that reported high numbers of persons being victims of sexual deception (as described above). However, we found no study that investigated this topic from an evolutionary psychology viewpoint directly. Taken together, the reviewed studies provided mixed information about whether using digital dating services might lead to increased sexual wellbeing or not. In Tinder users, feelings of loneliness or low self-esteem were found quite often (Rochat et al., 2019); others reported a willingness to engage in infidelity or unprotected sex, particularly in male users of some other data bases (Harris and Aboujaoude, 2016); however, Tsai et al. (2019) found no evidence for this in their systematic review. Moreover, a systematic comparison of couples who have met online vs. offline based on a large representative sample reported no difference regarding the quality of the relationship. That is, differences concerning sexual wellbeing between the online and offline dating world might not be as big as they were sometimes assumed, maybe with the exception that some individuals with specific problems might be attracted by particular dating services. We propose that the specific interactions between personality characteristics and characteristics of certain dating services that may lead to problems of sexual wellbeing should be investigated in future research. It is possible that the benefits of digital dating services are underestimated as well. It was found that online couples are not better off than offline couples. However, it is possible that many people are in a stable relationship or experience sexual intimacy thanks to the use of digital dating.

General Limitations

The findings of this selective review are limited by the fact that the studies included in our review were not designed to test evolutionary psychological hypotheses. This has led to a type of methodological cherry-picking in the sense that we just looked at the reviewed studies for evidence that seemed to match with (or contradict) our expectations. One problem with this approach is that the samples of the reviewed studies were of quite different origins. Some studies were based on representative samples of the general population, whereas others focussed on particular individuals, e.g., Tinder users or individuals in committed relationships. Moreover, our review covers different types of dating services; some of them offer opportunities for short-term dating, whereas others focus on long-term dating. These aspects also influence the operational sex ratio. There is ample evidence in evolutionary psychology that people experience different sexual preferences and apply different strategies depending on whether they are looking for a short-term mate or a long-term mate and depending on whether there is a surplus of males or females in a given mating arena. This leads to some limitation in the reported findings given that our hypotheses were found to be proved sometimes in one sample type but not in another sample, and vice versa. In most cases this was influenced by the fact that not all studies we reviewed provided information regarding all our hypotheses.

Factors that contribute to the maintenance or decline of relationship satisfaction

Factors that contribute to the maintenance or decline of relationship satisfaction. Francesca Righetti, Ruddy Faure, Giulia Zoppolat, Andrea Meltzer & James McNulty. Nature Reviews Psychology, Feb 21 2022. https://www.nature.com/articles/s44159-022-00026-2

Abstract: The quality of romantic relationships influences physical and mental health. However, maintaining happy and healthy relationships is challenging; relationship satisfaction declines over time, and relationship dissolution is frequent. This raises the question of which factors contribute to the maintenance versus decline of relationship satisfaction. In this Review, we examine the key factors that have been linked to relationship satisfaction in both cross-sectional and longitudinal studies. Specifically, we describe how self-reported perceptions (subjective perceptions of the self, the partner or the relationship), implicit evaluations (automatic evaluations of one’s partner assessed indirectly) and objective indexes (demographics, life events, communication patterns and biological indexes) relate to relationship satisfaction. This synthesis suggests that self-reported perceptions are not always the most reliable predictors of longitudinal changes in relationship satisfaction. Thus, to uncover why some relationships flourish and others struggle over time, future research should not solely focus on self-reported perceptions, but also on implicit evaluations, demographics, life events, communication patterns and biological factors, and their combination.