Although increasing evidence highlights genetic contributions to male sexual orientation, our current understanding of contributory loci is still limited, consistent with the complexity of the trait

Genome-Wide Linkage Study Meta-Analysis of Male Sexual Orientation. Alan R. Sanders, Gary W. Beecham, Shengru Guo, Judith A. Badner, Sven Bocklandt, Brian S. Mustanski, Dean H. Hamer & Eden R. Marti. Archives of Sexual Behavior, Jun 2 2021. https://link.springer.com/article/10.1007%2Fs10508-021-02035-3

Abstract: Male sexual orientation is a scientifically and socially important trait shown by family and twin studies to be influenced by environmental and complex genetic factors. Individual genome-wide linkage studies (GWLS) have been conducted, but not jointly analyzed. Two main datasets account for > 90% of the published GWLS concordant sibling pairs on the trait and are jointly analyzed here: MGSOSO (Molecular Genetic Study of Sexual Orientation; 409 concordant sibling pairs in 384 families, Sanders et al. (2015)) and Hamer (155 concordant sibling pairs in 145 families, Mustanski et al. (2005)). We conducted multipoint linkage analyses with Merlin on the datasets separately since they were genotyped differently, integrated genetic marker positions, and combined the resultant LOD (logarithm of the odds) scores at each 1 cM grid position. We continue to find the strongest linkage support at pericentromeric chromosome 8 and chromosome Xq28. We also incorporated the remaining published GWLS dataset (on 55 families) by using meta-analytic approaches on published summary statistics. The meta-analysis has maximized the positional information from GWLS of currently available family resources and can help prioritize findings from genome-wide association studies (GWAS) and other approaches. Although increasing evidence highlights genetic contributions to male sexual orientation, our current understanding of contributory loci is still limited, consistent with the complexity of the trait. Further increasing genetic knowledge about male sexual orientation, especially via large GWAS, should help advance our understanding of the biology of this important trait.

Discussion

Our primary analysis for this investigation was the joint analysis of multipoint linkage from the Hamer and MGSOSO datasets (Mustanski et al., 2005; Sanders et al., 2015), to which each dataset contributed some peaks (Fig. 1, Supplementary Figs. 1 and 2). Overall, the maximum multipoint peaks increased little in height, though the pericentromeric chromosome 8 peak was broadened (Fig. 2). Chromosomes 8 and X retained the highest multipoint peaks genome-wide, mostly arising from the larger (MGSOSO) dataset (Fig. 2). The joint analysis gives a more comprehensive picture of shared and heterogeneous linkage regions (e.g., at pericentromeric chromosome 8), the studies share overlapping peaks (possibly suggesting heterogeneity, perhaps with different genes involved in the different datasets), and the evidence broadens the search. The secondary analyses on summary statistics using MSP and GSMA to incorporate all three (Hamer, MGSOSO, Canadian) GWLS datasets showed no genome-wide significant results though suggestive findings remained present. The joint analysis of multipoint linkage (Fig. 1) extracted the available positional information from collaborating GWLS, though previous GWLS findings were not much further strengthened in these analyses. Nevertheless, this provides information to complement other approaches, such as helping prioritize findings from GWAS. Linkage and association studies measure different genetic properties (i.e., segregation of a region within families, vs. correlation of alleles in a population), both of which provide clues about underlying trait genetics. Thus, since GWLS are different from GWAS, we were unable to directly combine any GWAS (e.g., Ganna et al., 2019) with the studied GWLS in our GWLS meta-analysis. Limitations include those inherent to linkage (as opposed to GWAS) of traits with complex genetics (e.g., their limited utility for phenotypes with contributions from more than one or a few genes); on the other hand, linkage retains some advantages over association approaches, such as being robust to allelic heterogeneity (Lipner & Greenberg, 2018). Accumulating genetic studies of the trait such as by much enlarged GWAS (e.g., Ganna et al., 2019) will be especially useful, given its successful application in the study of other phenotypes manifesting complex genetics (e.g., Fig. 3b in Sullivan et al. (2018)).

Relational turbulence (external changes to the relational environment compel romantic partners to navigate transitions by establishing new daily routines as interdependent couples) in COVID-19

Relational turbulence from the COVID-19 pandemic: Within-subjects mediation by romantic partner interdependence. Alan K. Goodboy et al. Journal of Social and Personal Relationships, March 17, 2021. https://doi.org/10.1177/02654075211000135

Abstract: Relational turbulence theory posits that external changes to the relational environment compel romantic partners to navigate transitions by establishing new daily routines as interdependent couples. The COVID-19 pandemic is an unprecedented transition fraught with difficult changes that have the potential to be especially disruptive to romantic partners’ daily routines as couples alter their patterns of interdependence and adapt their everyday lives. To study the pandemic’s effect as a relational transition, college students in romantic relationships (N = 314) completed measures of partner facilitation and interference, negative emotions, and relational turbulence as they recalled what their relationships were like prior to the pandemic (January, 2020) and then reported on their relationships during the peak of the first wave of the pandemic in the U.S. (April, 2020). On average, negative emotions (i.e., anger, fear, sadness) toward interacting with partners and relational turbulence both increased from before to during the pandemic, and partner interference was positively correlated, whereas facilitation was inversely correlated, with negative emotions during the pandemic. Results of a within-subjects mediation model revealed that changes in relational turbulence were explained, in part, by a decrease in partner interdependence due to the pandemic. A direct effect of the pandemic on increases in relational turbulence was also discovered.

Keywords: COVID-19, interdependence, negative emotions, relational turbulence model, relational turbulence theory

Discussion

In an effort to better understand how dating relationships are affected by the COVID-19 pandemic, this study provided tests consistent with the RTM/RTT and demonstrated that this pandemic affected college students’ interdependence in their romantic relationships, their experience of negative emotions in those relationships, and ultimately the stability of those relationships. Specifically, compared to how romantic relationships were recalled before the pandemic, during the pandemic, on average, interference and facilitation from a partner in everyday routines declined, negative emotions toward the partner were amplified, and relational turbulence became more prevalent. Collectively, these results confirm RTT’s claim that transitions create changes to relational environments that modify patterns of interdependence, which ultimately give rise to more chaotic relational states (Solomon et al., 2016).

The decrease in partner interdependence might be explained by college students’ restrictions for contact during the pandemic. That is, their partner’s ability to facilitate or interfere with daily routines becomes less influential if their overall contact and time spent together has decreased due to pandemic-related constraints. Put simply, romantic partners might see each other less, providing fewer opportunities to interfere or facilitate. A post-hoc analysis provided evidence for this explanation of decreased interdependence; on average, partners saw each other 4.400 times a week before the pandemic (SD = 2.199), which decreased to an average of 3.220 times a week during the pandemic (SD = 2.496); t(300) = 7.305, p < .001, d = .420. This limited contact explanation could explain the decreases in interdependence from before to during the pandemic. For instance, some students might have moved back home and now live with a parent or parents after college campuses discontinued in-person educational offerings and switched to online instruction (Sahu, 2020). Post-hoc descriptive statistics revealed additional evidence for this limited contact explanation as partners reported increases in geographical separation after the pandemic started. Prior to the pandemic, 50.2% of partners were geographically within 15 minutes of their partner (n = 158), whereas during the pandemic, only 28.3% of partners remained within a 15-minute travel proximity (n = 89). From these post-hoc contact explorations revealing decreased weekly contact with and increased geographical distance from partners, we believe that partner interdependence declined because of new living situations that were required as romantic partners moved from college campuses and were no longer enrolled in on-campus courses or experiencing an on-campus college life.

The within-subjects mediation model revealed parallel indirect effects for partner interdependence (both interference and facilitation) on relational turbulence, as well as a direct effect of the pandemic itself on relational turbulence. With regard to the former, increases in relational turbulence were explained in part by decreases in facilitation and interference. That is, slightly less relational turbulence was experienced to the extent that partners interfered less with daily routines during the pandemic, but at the same time, relational turbulence increased more to the extent that partners did not facilitate as much with daily routines either. These opposite indirect effects are in line with the wealth of research demonstrating that interference creates turbulence whereas facilitation diminishes it (e.g., McLaren et al., 2011, 2012; Solomon & Priem, 2016). However, a direct effect revealed that, controlling for changes in partner facilitation and interference, the pandemic itself was associated with a change in more relational turbulence above and beyond partners’ decreases in interdependence. Pandemic stressors, independent of partner interdependence, appear to disrupt the stability of romantic relationships. Although relational research on the pandemic is limited as of this writing, preliminary findings suggest that stressors from the pandemic, including social isolation, financial strain, and perceived stress, are associated with lower romantic relationship quality (Balzarini et al., 2020).

During the pandemic, college students reported an increase in negative emotions toward communicating with their romantic partners including more anger, fear, and sadness. This increase in negative emotions might be indicative of partners’ daily emotional welfare being compromised as a byproduct of the pandemic. Lades et al. (2020) found when individuals stayed home during the pandemic and did not pursue outside activities, they experienced more negative affect. However, partner interference was strongly associated with these negative emotions, which is in line with previous research in other transitional contexts (Brisini & Solomon, 2019; Knobloch et al., 2007; Knobloch & Theiss, 2010; Solomon & Brisini, 2019). From a discrete emotions perspective, such negative affect may result because partner interference behaviors are perceived as threatening, uncontrollable attempts to impede one’s goals (Nabi, 2002). Axiom 2 of RTT received support as individuals felt more anger, fear, and sadness when interacting with their partner when routines were interrupted by them during the pandemic.

The findings from this investigation extend the purview of RTT to the novel context of a global health emergency and demonstrate support for the theory’s utility in the specific context of a pandemic. This research furthers a line of relatively recent scholarship which applies and tests the mechanisms of RTT when romantic partners are experiencing situations that are out of the ordinary, further illustrating RTT’s efficacy in explaining both normative and nonnormative relational experiences (e.g., Tian & Solomon, 2020). With regard to the latter, some findings emerged here which appear to be unique to the particular context under study. For example, although transitions typically evoke increased interference and attendant negative emotions from a partner (see Solomon et al., 2010), here we found that both forms of partner interdependence decreased from before to during the pandemic. It seems clear (and others have concluded) that interference is complex and unique to the transition in question (Harvey-Knowles & Faw, 2016), as some transitions naturally lend themselves to more—or in this case, less—partner interdependence, given the stringent social distancing guidelines that have characterized the pandemic in the U.S. Although partner interference is a negatively valenced construct in RTT, and thereby the reduction of interference should lead to concomitant reductions in the experience of relational turbulence, here that effect appears to have been offset by the concurrent experience of decreased partner facilitation (again, likely due to the inherent social distancing constraints of the pandemic for the college student daters in this sample, most of whom were geographically distant). In this investigation, we observed an increase in relational turbulence, which was indirectly affected by decreased partner facilitation and directly exacerbated by the nature of the pandemic itself.

Further, the findings from this study highlight the complex role of interdependence processes within RTT, and provide some evidence for the ways in which partner interference and facilitation work together (or in this case, work against each other) to impact the experience of relational turbulence in college student dating relationships. From RTT’s perspective, the least amount of turbulence should result when partner facilitation is high while partner interference is low. Here, partner interference decreased, yet so did partner facilitation. Thus, although RTT suggests that partner facilitation may at times serve a sort of buffering function against interference or the effect of transitions, this buffering effect could not be realized (despite the decrease in partner interference) because the pandemic constrained the ability to facilitate (and to interfere with) a partner’s daily routines. Perhaps because of this, the findings from this study suggested that the pandemic itself as compared to interdependence processes had the strongest impact on the experience of relational turbulence. It is important to note that the nuances of these findings regarding interdependence processes are expected to be context-dependent, as the majority of college student daters who comprised this sample were geographically distant during the pandemic. It is likely that a different pattern of results would emerge for married or cohabitating couples with regard to interdependence processes, for whom it is unlikely that both partner facilitation and interference would decrease during this extended time of social distancing, working remotely, homeschooling children, etc. For married and cohabitating couples, interdependence processes are expected to play a stronger role in the experience of relational turbulence during a pandemic (Knoster et al., 2020).

The collective results reveal several practical implications for romantic relationships of all types, including marital relationships, during the pandemic. First, it is important to recognize that transitions are times rife with relational turbulence for couples as changes to external environments produce chaotic relational states (Solomon et al., 2010). Life, in general, has been chaotic since the pandemic began and has created stressors external to interdependent relationships that carry over into it and naturally affect its quality (Balzarini et al., 2020). It is important for partners to recognize that their romantic relationships may be strained from the pandemic, and they might expect negative affect and tumultuous sensitivities for their relationships as these are processes theorized to result from the experience of transitions (Solomon & Knobloch, 2004). Second, in order to more successfully navigate the pandemic, and to navigate extreme or nonnormative relational episodes more generally, it is important for relational partners to adapt to the “new normal” by establishing neoteric patterns of interdependence that encourage relational stability. This could include establishing new daily routines and/or maintain existing ones for psychosocial benefits (WHO, 2020). These daily routines are not all instrumental or occupational; they include hobbies as well, which have been identified as particularly important for maintaining emotional well-being during the pandemic (Lades et al., 2020).

Third, in order to more effectively manage intense relational experiences, romantic partners should put in extra efforts to facilitate their partners’ daily routines, and actively try not to interfere with them. It is possible that only so much facilitation can be reasonably and safely enacted during the pandemic (and further, some research with the RTT in the context of intense relational episodes suggests that facilitation does not always lead to positive outcomes; Tian & Solomon, 2020), so college student partners in particular—as opposed to spouses, for example—might acknowledge they have less overall influence on their partners’ daily routines since the pandemic commenced. Fourth, romantic partners should realize that their reactivity during the pandemic and other extreme relational experiences is likely to be exacerbated, and this reactivity may manifest in the form of more extreme or perhaps even volatile emotions, cognitions, and communicative behaviors (Solomon et al., 2010, 2016). Such extreme reactions have implications for a variety of relational processes, including seeking/providing social support and engaging in conflict. As such, romantic partners should be cognizant of the far-reaching impact of intense experiences such as the current global health pandemic on everyday functioning in the relationship. Being aware of the potential for such reactivity may encourage partners to pause and reassess rather than overreact and engage in communication or other behaviors that could possibly damage the relationship.

Although important insights about the pandemic’s impact on the stability of romantic relationships emerged from this investigation, the findings must be interpreted in light of the limitations that were present. The primary limitation of this research was the reliance on recollections of the romantic relationship pre-pandemic (January, 2020) with a data collection that took place during the pandemic (April, 2020). Partners reported on what their relationship was like 4 months prior and then reported on how their relationship was currently during the peak of the pandemic. This method of reporting on the relationship during a previous time and at the time of the survey has been used by previous relational turbulence scholars (Brisini et al., 2018). However, asking participants to report on “then and now” repeated measurements in the same survey presents recall limitations for modeling within-participant “change.” Yet, to design a study with two time points, we would have needed prior knowledge that a global pandemic was imminent to have collected data before it began. Thus, our repeated measurements in the same survey are a proxy for change, but cannot actually measure true changes over time, and there is a chance that recall bias was an issue (i.e., a particular fondness for “before times”). Another limitation is the college student sample which might have derived different effects due to physical separation from college campuses. As such, future researchers should examine pandemic effects in marriages and test RTT within cohabitating contexts, which might offer different conclusions from more established patterns of interdependence in shared living arrangements.

Future researchers should also continue to study major transitions as opportunities to model relational turbulence. Although transitions are not a scope condition for testing RTT because partner influence can and does occur at any point in a close relationship (Berscheid, 2002), transitions are periods of discontinuity where interdependence will change as the relational environment is affected (Solomon et al., 2016). Future researchers might also examine how the COVID-19 pandemic has created relational uncertainty, and in turn, resulted in biased cognitions as purported by RTT. To keep our survey brief with repeated measures, we only examined half of the relationship parameters in RTT. Relational uncertainty is at the core of RTT and deserves empirical attention as the pandemic continues. Finally, scholars should examine processes of relational turbulence in both dating and married samples to compare effects for generalizability (Brisini & Solomon, 2019). Although these two types of relationships have produced similar effect sizes in the relational turbulence literature (Goodboy et al., 2020), nonetheless, it remains important to continue studying both types of relationships.

This study explored changes in some of the relational processes proposed by RTT that were experienced by dating partners before the COVID-19 pandemic began to the peak of the first wave of the pandemic in the U.S. The findings revealed pandemic-related relational impacts in the form of decreased partner interdependence, increased experience of negative affect, and heightened relational turbulence (explained both by decreased partner interdependence and by the impact of the pandemic itself). These results provide continued support for RTT’s predictive and explanatory utility, and importantly, suggest practical mitigation strategies for couples who are coping with the ongoing global health crisis. This work provides support for Solomon and Brisini’s (2019) assertion that “RTT may have the greatest value when it illuminates the challenges that confront couples coping with significant life transitions, especially those that impose economic, health, or emotional burdens” (p. 2432).

COVID-19 lockdown: Women did more chores & had less satisfaction; men who were the primary caregiver or were not working fulltime had negative relationship outcomes when they did more housework & parenting

Gendered division of labor during a nationwide COVID-19 lockdown: Implications for relationship problems and satisfaction. Nina Waddell et al. Journal of Social and Personal Relationships, March 2, 2021. https://doi.org/10.1177/0265407521996476

Abstract: COVID-19 lockdowns have required many working parents to balance domestic and paid labor while confined at home. Are women and men equally sharing the workload? Are inequities in the division of labor compromising relationships? Leveraging a pre-pandemic longitudinal study of couples with young children, we examine gender differences in the division and impact of domestic and paid labor during a nationwide COVID-19 lockdown (N = 157 dyads). Women did more of the parenting and housework, whereas men engaged in more paid work and personal time, during the lockdown. Couple members agreed that women’s share of parenting, housework and personal time was unfair, but this did not protect women from the detrimental relationship outcomes associated with an inequitable share of domestic labor. A greater, and more unfair, share of parenting, housework and personal time predicted residual increases in relationship problems and decreases in relationship satisfaction for women. Exploratory analyses indicated that men who were the primary caregiver or were not working fulltime also experienced negative relationship outcomes when they did more housework and parenting. These results substantiate concerns that the COVID-19 pandemic may undermine advances toward gender equality by reinforcing inequitable divisions of labor, thereby damaging women’s relationship wellbeing.

Keywords: COVID-19 lockdown, division of labor, housework, parenting, relationship problems

Discussion

The COVID-19 pandemic poses considerable challenges to couples, including lockdowns forcing working parents to coordinate an increase in domestic and paid labor. We leveraged an existing study of mixed-gender couples with young children assessed prior to the pandemic and conducted pre-registered tests of gender differences in the division and impact of domestic and paid labor as families endured a nationwide COVID-19 lockdown. Although lockdowns offer opportunities for couples to more equally share the domestic load, women did more of the parenting and housework, whereas men generally engaged in more paid work and personal time. Couple members agreed that the balance of labor was unfair on women, but this did not protect women from the detrimental outcomes of a greater domestic burden. Women who were unfairly doing a greater share of housework and parenting, and having less personal time, experienced residual increases in relationship problems and residual decreases in satisfaction.

The inequities in domestic labor and detrimental effects on women’s relationship outcomes occurred irrespective of caregiver or employment status. These results substantiate concerns that the COVID-19 pandemic may have greater risks for women, including quarantine efforts reinforcing gender inequality and placing greater strains on women’s health and wellbeing. Interestingly, exploratory analyses provided tentative evidence that men who were the primary caregiver or not working fulltime also experienced poorer relationship outcomes when they did more of the domestic labor. Thus, generating an equitable division of labor is an important target to protect the health and wellbeing of women (and men) who are shouldering more of the home demands exacerbated by the COVID-19 pandemic and lockdowns.

Couples agree: Women are doing more labor and this division is perceived as unfair

Both women and men reported that women did more housework and parenting, whereas men engaged in more paid work and personal time. The overall pattern of division of housework and parenting is consistent with established gender differences (Bianchi et al., 2000; Kamp Dush et al., 2018; Newkirk et al., 2017) and those reported during the pandemic (Carlson et al., 2020; Craig & Churchill, 2020). Gathering reports from couples, however, clarified that the gender differences typically shown by between-group comparisons of individual reports are evident when comparing women’s and men’s reports within the same relationship. The overall pattern illustrated that, despite home confinement potentially reducing structural barriers to men sharing housework and parenting, both women and men agree that women are shouldering the increased burden of domestic labor arising from COVID-19 lockdowns.

Yet, despite agreeing that gender differences existed, women and men disagreed about the extent of the inequity. Although men reported that women were doing more housework and having less personal time, women reported doing more housework and having less personal time than men’s reports acknowledged. These discrepancies could emerge because housework is less valued than other domains and thus not as visible or fully appreciated. Men may also tend to underestimate the time and energy housework involves due to their lower contribution to this domain, and consequently overestimate the personal time women are afforded or perhaps misinterpret some activities as personal time (e.g., planning, playing with children). It is also possible that women’s greater share of housework and men’s greater share of personal time result in women viewing these inequities as even greater than they are. Importantly, regardless of why disagreement across couples emerged, such disagreement may contribute to the persistence of gender discrepancies in domestic labor. For example, if women’s share of the housework or lack of personal time is not fully appreciated by partners then there is likely less chance that couples will work together to rectify these inequities.

Despite disagreeing about how much more housework and how much less personal time women were engaging compared to men, women and men equally perceived that the relative labor in these domains was unfair. Couples may have more insights into each other’s perceived fairness, perhaps because people are more likely to directly or indirectly communicate their discontent with unfairness. Couples also may consider relative fairness, rather than amount of time and energy spent, when considering each other’s contributions. The prominence of perceived fairness in the evaluation and effects of equity is why perceived fairness tends to have relatively stronger effects on relationship outcomes (Greenstein, 1996). Nonetheless, men’s recognition that the division of domestic labor was more unfair on women did not protect women from the detrimental relationship outcomes associated with a greater domestic burden.

Perceiving inequities as unfair create relationship problems and dissatisfaction for women

Leveraging an existing dyadic study enabled us to uniquely assess how couples’ division of labor predicted residual changes in relationship problems and satisfaction. The pattern of results confirmed that women are more at risk of the negative relationship outcomes associated with perceiving an unfair share of housework, parenting and personal time. With regard to housework, women who reported a more inequitable and unfair division experienced greater problems and lower satisfaction. Applying an equity perspective, tests of the interaction between the relative division and perceived fairness of housework revealed that women who did more housework than their partner and perceived their larger share as unfair experienced the greatest residual increases in relationship problems and reductions in satisfaction.

Perceived unfairness of parenting was also central to how couples’ division of parenting shaped women’s relationship outcomes. Prior cross-sectional studies indicate that inequity and unfairness in the division of parenting is associated with greater conflict and lower satisfaction (Newkirk et al., 2017; Schieman et al., 2018). In the current study, only perceived unfairness in parenting predicted residual changes in problem and satisfaction. A significant interaction also revealed that women who did more parenting than their partner only experienced greater relationship problems when they perceived their share of parenting to be unfair on them. Compared to the onerous necessity of housework, parenting may often be personally fulfilling (Tully et al., 1999) in ways that compensate for a greater burden of the parenting workload. Any compensation of personal fulfilment, however, may not be enough to counter dissatisfaction and problems in the marital relationship when mothers feel their greater contribution is unfair.

Our investigation also extended insight into the relative impact of an unfair division in both domestic and personal activities. First, the impact of gender inequities in domestic labor were not balanced by counter inequities in other domains. Although men on average did more paid work, neither women or men experienced poorer relationship outcomes as a function of a greater or more unfair share of paid work. Instead, women experienced greater problems when their partner perceived their work was unfair, perhaps due to men’s feelings of unfairness creating more relationship difficulties managing expectations around housework, parenting and personal domains. Second, couples agreed that men (on average) had more personal time than women, and men who had relatively more personal time reported lower problems and greater satisfaction. However, couples agreed that women’s lower share of personal time was unfair, and women (but not men) who had less personal time relative to their partner and perceived the share of personal time to be unfair experienced greater relationship problems and lower satisfaction.

Detrimental effects of inequities in domestic labor occur for women regardless of family role, but men who occupy domestic roles may experience similar outcomes as women

More women (50.3%) than men (16.6%) were the primary caregiver, and more men (64.3%) than women (29.9%) worked fulltime. Nonetheless, the gender differences in the division and perceived fairness of parenting, housework and personal time, and the effects of the relative division and fairness of parenting, housework and personal time on women’s relationship outcomes, did not vary across women and men’s caregiver and employment status. Thus, the gendered pattern of the division of labor, and the detrimental effects of the division and perceived fairness of housework and parenting on women’s relationship outcomes, occurred for women in traditional and non-traditional family roles.

Interestingly, however, additional analyses provided some tentative evidence that men may experience poorer relationship outcomes when their family role or situation forces them to pick up more domestic labor. In general, men did not report greater relationship problems or lower relationship satisfaction when they reported doing more housework or parenting or perceived their contributions in these domains were unfair. However, when exploring the moderating role of caregiver and employment status, a small number of consistent effects emerged. Men who were primary caregivers and reported an inequitable division of parenting, and men who were not working fulltime and reported that the division of housework was inequitable or unfair, experienced greater problems and lower satisfaction. This pattern of results indicates that men who take on more of the domestic work and perceive their contribution as unfair experience the same negative relationship outcomes as women.

These novel findings indicate a promising direction for future research by highlighting that the constraints of social roles, in addition to gender, are important for understanding the division and impact of domestic labor (Eagly & Wood, 2016). In particular, the pattern of expected and unexpected effects indicates that prescriptive pressures regarding women’s and men’s social roles result in women experiencing poor outcomes from carrying the burden of domestic labor across social contexts as well as men experiencing negative outcomes when men occupy women’s traditional social role. However, given these unexpected findings for men involved 4 out of 16 interaction effects tested, and the sample composition (16.6% men primary caregivers, 35.7% men not working fulltime) did not provide optimal conditions for these comparisons, future research is needed to more reliably test this intriguing pattern by gathering samples that more evenly represent different family role configurations. Such efforts may also emphasize the primary findings from the current study. Specifically, although these additional findings indicate that poor outcomes may emerge for both women and men who are shouldering more of the domestic labor, women experience more relationship difficulties arising from an unfair division of labor across contexts regardless of family roles.

Caveats and conclusions

Compared to typical large cross-sectional surveys of individuals, our dyadic and longitudinal design provides stronger evidence that an unequal and unfair division labor is likely to increase relationship problems and reduce relationship satisfaction when couples need to be working together to manage the challenges of COVID-19 lockdowns. Dyadic longitudinal designs, however, necessarily restrict sample size and thus statistical power to test for gender differences and interactions. The majority of the effects shown for women were significantly different from the null effects for men, supporting our general conclusions. We also focused on sets of theoretically relevant interactions, but some interaction patterns for relationship problems were relatively weak, likely because problems involve difficulties arising from both individuals’ and partners’ discontent. Finally, our sample involved relatively satisfied couples who agreed that the division was unfair on women. The detrimental outcomes shown here are likely to be magnified in couples who are facing more challenges, report greater discrepancies in the relative division and perceived fairness of labor, and who enter the pandemic and lockdowns with greater relationship difficulties.

Despite these caveats, the results indicate that key challenges of the COVID-19 pandemic are more likely to have detrimental effects on women. Women were more unfairly burdened with domestic labor, and as a consequence were more likely to experience increased relationship problems and dissatisfaction. Accounting for caregiver and employment status revealed that women experienced these poor outcomes across family roles and contexts. The detrimental impact of these inequities is unlikely to be fleeting and may grow as the pandemic and related economic and family disruptions continue across time. Couples who learn to share the load more equitably, however, may protect women from relationship difficulties at a time when satisfying, supportive relationships are crucial for health and wellbeing.

We provide strong evidence for greater male variability in preferences; men are more likely to have extreme time, risk, and social preferences, while women are more likely to have moderate preferences

Converging evidence for greater male variability in time, risk, and social preferences. Christian Thöni and Stefan Volk. Proceedings of the National Academy of Sciences, June 8, 2021 118 (23) e2026112118; https://doi.org/10.1073/pnas.2026112118

Significance: There is continuing interest in the study of gender differences in economic and social outcomes. An important factor underlying gender differences in outcomes are gender differences in fundamental economic preferences, which are at the core of many differential choices of women and men. We provide strong evidence for greater male variability in preferences. We find that men are more likely to have extreme time, risk, and social preferences, while women are more likely to have moderate preferences. With the focus on mean differences, the current literature underestimates the importance of gender differences and their effects on differential choices and outcomes between women and men.

Abstract: Gender differences in time, risk, and social preferences are important determinants of differential choices of men and women, with broad implications for gender-specific social and economic outcomes. To better understand the shape and form of gender differences in preferences, researchers have traditionally examined the mean differences between the two genders. We present an alternative perspective of greater male variability in preferences. In a meta-analysis of experimental economics studies with more than 50,000 individuals in 97 samples, we find converging evidence for greater male variability in time, risk, and social preferences. In some cases, we find greater male variability in addition to mean differences; in some cases, we only find greater male variability. Our findings suggest that theories of gender differences are incomplete if they fail to consider how the complex interaction of between-gender differences and within-gender variability determines differential choices and outcomes between women and men.

Keywords: gendergreater male variabilitypreferencesmeta-analysis

From 2019... Urban spatial order: street network orientation, configuration, and entropy

From 2019... Urban spatial order: street network orientation, configuration, and entropy. Geoff Boeing. Applied Network Science volume 4, Article number: 67. Aug 23 2019. https://appliednetsci.springeropen.com/articles/10.1007/s41109-019-0189-1

Abstract: Street networks may be planned according to clear organizing principles or they may evolve organically through accretion, but their configurations and orientations help define a city’s spatial logic and order. Measures of entropy reveal a city’s streets’ order and disorder. Past studies have explored individual cases of orientation and entropy, but little is known about broader patterns and trends worldwide. This study examines street network orientation, configuration, and entropy in 100 cities around the world using OpenStreetMap data and OSMnx. It measures the entropy of street bearings in weighted and unweighted network models, along with each city’s typical street segment length, average circuity, average node degree, and the network’s proportions of four-way intersections and dead-ends. It also develops a new indicator of orientation-order that quantifies how a city’s street network follows the geometric ordering logic of a single grid. A cluster analysis is performed to explore similarities and differences among these study sites in multiple dimensions. Significant statistical relationships exist between city orientation-order and other indicators of spatial order, including street circuity and measures of connectedness. On average, US/Canadian study sites are far more grid-like than those elsewhere, exhibiting less entropy and circuity. These indicators, taken in concert, help reveal the extent and nuance of the grid. These methods demonstrate automatic, scalable, reproducible tools to empirically measure and visualize city spatial order, illustrating complex urban transportation system patterns and configurations around the world.

Discussion

The urban design historian Spiro Kostof once said: “We ‘read’ form correctly only to the extent that we are familiar with the precise cultural conditions that generated it… The more we know about cultures, about the structure of society in various periods of history in different parts of the world, the better we are able to read their built environment” (Kostof 1991, p. 10). This study does not identify whether or how a city is planned or not. Specific spatial logics cannot be conflated with planning itself, which takes diverse forms and embodies innumerable patterns and complex structures, as do informal settlements and organic urban fabrics. In many cities, centrally planned and self-organized spatial patterns coexist, as the urban form evolves over time or as a city expands to accrete new heterogeneous urban forms through synoecism.

Yet these findings do, in concert, illustrate different urban spatial ordering principles and help explain some nuances of griddedness. For example, gridded Buenos Aires has a φ value suggesting it only follows a single grid to a 15% extent. However, its low circuity and high average node degree values demonstrate how it actually comprises multiple competing grids—which can indeed be seen in Figs. 4 and 5—and it clusters accordingly in Figs. 6 and 7 with gridded American cities. Jointly considered, the φ indicator, average circuity, average node degree, and median street segment length tell us about the extent of griddedness and its character (curvilinear, straight-line, monolithic, heterogeneous, coarse-grained, etc.). Charlotte further illustrates the importance of taking these indicators together. Although its φ and orientation entropy are more similar to European cities’ than American cities’, it is of course an oversimplification to claim that Charlotte is therefore the US city with the most “European” street network—in fact, its median street segment length is about 50% longer than that of the average European city, and among European cities, Charlotte clusters primarily with those of the Communist Bloc. Pittsburgh, on the other hand, sits alone in a small sub-cluster with Munich and Vienna.

We find that cities with higher φ values also tend to have higher node degrees, more four-way intersections, fewer dead-ends, and less-winding street patterns. That is, cities that are more consistently organized according to a grid tend to exhibit greater connectedness and less circuity. Interestingly, the Ηo and Ηw orientation entropies are extremely similar and strongly correlated: the weighted curvatures (versus straight-line orientation) of individual street segments have little impact on citywide orientation entropy, but the average circuity of the city network as a whole positively correlates with orientation entropy. This finding deserves further exploration.

These results also demonstrate substantial regional differences around the world. Across these study sites, US/Canadian cities have an average φ value nearly thirteen-times greater than that of European cities, alongside nearly double the average proportion of four-way intersections. Meanwhile, these European cities’ streets on average are 42% more circuitous than those of the US/Canadian cities. These findings illustrate the differences between North American and European urban patterns. However, likely due to such regional heterogeneity, this study finds statistical relationships somewhat weaker (though still significant) than prior findings examining cities in the UK exclusively.

Accordingly, given the heterogeneity of these world regions, future research can estimate separate statistical models for individual regions or countries—or even the neighborhoods of a single city to draw these findings closer to the scale of planning/design practice. The methods and indicators developed here offer planners and designers a toolbox to quantify urban form patterns and compare their own cities to those elsewhere in the world. Our preliminary results suggest trends and patterns, but future work should introduce additional controls to clarify relationships and make these findings more actionable for researchers and practitioners. For instance, topography likely constrains griddedness and influences circuity and orientation entropy: a study of urban elevation change and hilliness in conjunction with entropy and circuity would help clarify these relationships. Additionally, further research can unpack the relationship between development era, design paradigm, city size, transportation planning objectives, and street network entropy to explore how network growth and evolution affect spatial order. Finally, given the importance of taking multiple indicators in concert, future work can develop a grid-index to unify them and eventually include streetscape and width attributes as further enrichment to explore walkability and travel behavior.

We present the results of a pilot study conducted in Bangladesh which suggests that heightened mortality arising from mother-in-law/daughter-in-law conflict may be a two-way street

In-Law Relationships in Evolutionary Perspective: The Good, the Bad, and the Ugly. Martin Daly, Gretchen Perry. Front. Sociol., June 4 2021. https://doi.org/10.3389/fsoc.2021.683501

Abstract: In-laws (relatives by marriage) are true kin because the descendants that they have in common make them “vehicles” of one another’s inclusive fitness. From this shared interest flows cooperation and mutual valuation: the good side of in-law relationships. But there is also a bad side. Recent theoretical models err when they equate the inclusive fitness value of corresponding pairs of genetic and affinal (marital) relatives-brother and brother-in-law, daughter and daughter-in-law-partly because a genetic relative’s reproduction always replicates ego’s genes whereas reproduction by an affine may not, and partly because of distinct avenues for nepotism. Close genetic relatives compete, often fiercely, over familial property, but the main issues in conflict among marital relatives are different and diverse: fidelity and paternity, divorce and autonomy, and inclinations to invest in distinct natal kindreds. These conflicts can get ugly, even lethal. We present the results of a pilot study conducted in Bangladesh which suggests that heightened mortality arising from mother-in-law/daughter-in-law conflict may be a two-way street, and we urge others to replicate and extend these analyses.

Conclusion

Dow (1984) and Hughes (1988) proposed that affinal “kinship” is no mere metaphor. The commonality of interest among persons related by marriage derives from the same ultimate source as the commonality of interest among persons related by blood. In both cases, the protagonists are “related” by virtue of the fact that they can expect to derive fitness from the same particular reproductive events.

We show, however, that recent theoretical arguments that treat daughters and daughters-in-law (for example) as equivalent contributors to ego’s fitness go too far. “Parallel” pairs of genetic and affinal relationships such as these are importantly different, both quantitatively and qualitatively. Any child of my daughter will be my grandchild, but that is not necessarily true of my daughter-in-law, and even if the latter were to reproduce only with my son, she would retain an interest in natal relatives who are of no relevance to me. The “brute fact” of genetic relatedness (Haig, 2011) favors forgiveness and reconciliation among blood kin, even after betrayals, but a daughter-in-law, unlike a daughter, is replaceable (Voland and Beise, 2005; Mace, 2013). Bride-burnings are committed by mothers-in-law, not by mothers. The oppressive mistreatment of young women by their mothers-in-law, especially in the Indian subcontinent, has been much remarked upon, but we show, in addition, that the destructive effects of this relationship can be a two-way street.

According to Leonetti et al. (2007) “We can speak of “in-law conflict” as an extension of sexual conflict, with parents on both sides joining the fray. Cooperation may also be part of these relationships when the interests of both sides are enhanced. This game, of course, becomes vastly more complicated than the simple struggle between the sexes but is likely to be ancient and of critical importance to human reproductive success.” We concur.

Awareness of lateral posing asymmetries: Although people do not have an acute awareness of their lateral posing preference, they reliably show one side of their faces to express or hide emotions

Do you know your best side? Awareness of lateral posing asymmetries. Matia Okubo & Takato Oyama. Asymmetries of Brain, Behaviour, and Cognition, Jun 4 2021. https://doi.org/10.1080/1357650X.2021.1938105

Abstract: People tend to show the left cheek to broadly express emotions while they tend to show the right cheek to hide emotions because emotions were expressed more on the left than on the right side of the face. The present study investigated the level of awareness on the left- and right-cheek poses using the method of structural knowledge attributions. When asked to broadly express emotions for a family portrait, right-handed participants were more likely to show the left cheek than the right. On the other hand, when asked to conceal emotions to show a calm and reassuring attitude as a scientist, they were more likely to show the right cheek. After the posing session, participants selected the conscious level of their knowledge about posing from five categories: Random, intuition, familiarity, recollection, and rules. Most participants rated their knowledge as unconscious (i.e., either as random, intuition, or familiarity). The choice of the conscious level did not differ across posing orientations and posing instructions. These results suggest that although people do not have an acute awareness of their lateral posing preference, they reliably show one side of their faces to express or hide emotions.

KEYWORDS: Lateral posing asymmetryemotional expressionsawareness

Among liberal countries, inequality was negatively related to subjective well-being for men & women; there was some evidence that the relation was stronger for women; in conservative countries, the relation was not significant

Culture Moderates the Relation Between Gender Inequality and Well-Being. Chen Li, Miron Zuckerman, Ed Diener. Psychological Science, June 1, 2021. https://doi.org/10.1177/0956797620972492

Abstract: Research on the relation of gender inequality and subjective well-being (SWB) has produced inconsistent results. We suggest that culture moderates this relation such that inequality has a greater adverse effect in liberal than in conservative societies. The present studies, using aggregate data from 86 countries (Study 1) and 145,975 individuals’ data from 69 countries (Study 2), support this notion. Among liberal countries, inequality was negatively related to SWB for both men and women; there was some evidence that this relation was stronger for women. In conservative countries, the relation was not significant. Previously, the same liberal–conservative continuum moderated the relation between income inequality and SWB for groups with both high and low socioeconomic status (SES) but particularly for the low-SES group. The similarity in results across two different studies strongly supports the notion that the relation between inequality and SWB is contingent on where specific cultures are located on the liberal–conservative continuum.

Keywords: culture, gender inequality, subjective well-being

Breeding season length (bsl) & mating system are the strongest predictors of testosterone concentrations; bsl, environmental temperature, & variability in precipitation are the strongest predictors of within-population variation in test.

Life history and environment predict variation in testosterone across vertebrates. Jerry F. Husak et al. Evolution, March 23 2021. https://doi.org/10.1111/evo.14216

Abstract: Endocrine systems act as key intermediaries between organisms and their environments. This interaction leads to high variability in hormone levels, but we know little about the ecological factors that influence this variation within and across major vertebrate groups. We study this topic by assessing how various social and environmental dynamics influence testosterone levels across the entire vertebrate tree of life. Our analyses show that breeding season length and mating system are the strongest predictors of average testosterone concentrations, whereas breeding season length, environmental temperature, and variability in precipitation are the strongest predictors of within-population variation in testosterone. Principles from small-scale comparative studies that stress the importance of mating opportunity and competition on the evolution of species differences in testosterone levels, therefore, likely apply to the entire vertebrate lineage. Meanwhile, climatic factors associated with rainfall and ambient temperature appear to influence variability in plasma testosterone, within a given species. These results, therefore, reveal how unique suites of ecological factors differentially explain scales of variation in circulating testosterone across mammals, birds, reptiles, amphibians, and fishes.

Breeding season length (bsl) & mating system are the strongest predictors of testosterone concentrations; bsl, environmental temperature, & variability in precipitation are the strongest predictors of within-population variation in test.

Rolf Degen summarizing... The sources of information by which people were most often exposed to politically dissimilar news were search engines and social media, once again giving the lie to the condescending notion of "echo chambers"

Avenues to News and Diverse News Exposure Online: Comparing Direct Navigation, Social Media, News Aggregators, Search Queries, and Article Hyperlinks. Magdalena Wojcieszak. The International Journal of Press/Politics, May 31, 2021. https://doi.org/10.1177/19401612211009160

Abstract: The online environment dramatically expands the number of ways people can encounter news but there remain questions of whether these abundant opportunities facilitate news exposure diversity. This project examines key questions regarding how internet users arrive at news and what kinds of news they encounter. We account for a multiplicity of avenues to news online, some of which have never been analyzed: (1) direct access to news websites, (2) social networks, (3) news aggregators, (4) search engines, (5) webmail, and (6) hyperlinks in news. We examine the extent to which each avenue promotes news exposure and also exposes users to news sources that are left leaning, right leaning, and centrist. When combined with information on individual political leanings, we show the extent of dissimilar, centrist, or congenial exposure resulting from each avenue. We rely on web browsing history records from 636 social media users in the US paired with survey self-reports, a unique data set that allows us to examine both aggregate and individual-level exposure. Visits to news websites account for about 2 percent of the total number of visits to URLs and are unevenly distributed among users. The most widespread ways of accessing news are search engines and social media platforms (and hyperlinks within news sites once people arrive at news). The two former avenues also increase dissimilar news exposure, compared to accessing news directly, yet direct news access drives the highest proportion of centrist exposure.

Keywords: news exposure, avenues for news, social networks, search engines, cross-cutting exposure, echo chambers

Insufficiently Complimentary?: Underestimating the Positive Impact of Compliments Creates a Barrier to Expressing Them

Zhao, Xuan, and Nicholas Epley. 2021. “Insufficiently Complimentary?: Underestimating the Positive Impact of Compliments Creates a Barrier to Expressing Them.” PsyArXiv. June 4. doi:10.1037/pspa0000277

Abstract: Compliments increase the well-being of both expressers and recipients, yet people report in a series of surveys giving fewer compliments than they should give, or would like to give. Nine experiments suggest that a reluctance to express genuine compliments partly stems from underestimating the positive impact that compliments will have on recipients. Participants wrote genuine compliments and then predicted how happy and awkward those compliments would make recipients feel. Expressers consistently underestimated how positive the recipients would feel but overestimated how awkward recipients would feel (Experiments 1-3, S4). These miscalibrated expectations are driven partly by perspective gaps in which expressers underestimate how competent—and to a lesser extent how warm—their compliments will be perceived by recipients (Experiments 1-3). Because people’s interest in expressing a compliment is partly driven by their expectations of the recipient’s reaction, undervaluing a compliment creates a barrier to expressing them (Supplemental Experiments S2, S3, S4). As a result, directing people to focus on the warmth conveyed by their compliment (Experiment 4) increased interest in expressing it. We believe these findings may reflect a more general tendency for people to underestimate the positive impact of prosocial actions on others, leading people to be less prosocial than would be optimal for both their own and others’ well-being.

The share of participants willing to be vaccinated increased with the payment amount; a significant change required large rewards of €3,250 or more

Sprengholz, Philipp, Luca Henkel, and Cornelia Betsch. 2021. “Payments and Freedoms: Effects of Monetary and Legal Incentives on COVID-19 Vaccination Intentions in Germany.” PsyArXiv. June 4. doi:10.31234/osf.io/hfm43

Abstract: Monetary and legal incentives have been proposed to promote COVID-19 vaccination uptake. To evaluate the suitability of incentives, an experiment with German participants examined the effects of payments (varied within subjects: 0 to 10,000 EUR) and freedoms (varied between subjects: vaccination leading vs. not leading to the same benefits as a negative test result) on the vaccination intentions of previously unvaccinated individuals (n = 782). While no effect could be found for freedoms, the share of participants willing to be vaccinated increased with the payment amount. However, a significant change required large rewards of 3,250 EUR or more. While monetary incentives could increase vaccination uptake by a few percentage points, the high costs of implementation challenge the efficiency of the measure and call for alternatives. As experimental data suggest that considering vaccination as safe, necessary, and prosocial increases an individual’s likelihood of wanting to get vaccinated without payment, educational campaigns should emphasize these features when promoting vaccination against COVID-19.

Romantic Partners Are Similar in Their Well-Being and Sociopolitical Attitudes but Change Independently Over Time

Romantic Partners Are Similar in Their Well-Being and Sociopolitical Attitudes but Change Independently Over Time. Matthew D. Hammond, Chris G. Sibley. Social Psychological and Personality Science, June 3, 2021. https://doi.org/10.1177/19485506211019843

Abstract: Similarity within romantic couples forms one component of the formation and maintenance of relationships, meaning that, romantic partners’ views about themselves and the world are theorized to converge over time. We advance prior research on romantic couple similarities using cross-sectional or time-lagged designs, testing convergence with dyadic trajectories of change—how changes in one person relate to changes in their partner. Dyadic growth curve models assessed initial similarities, and longitudinal convergence, for 35 measures of well-being and individual differences in 171 mixed-gender couples from a national longitudinal study (the New Zealand Attitudes and Values Survey). Results indicated consistent average-level similarities between romantic partners, a few instances of short-term convergence in sociopolitical views, and the consistent pattern that changes in people occurred independently to their partners. Findings advance theory on romantic interdependence by emphasizing the perspective that romantic partners’ convergence occurs as subjective experience rather than externally measured unification.

Keywords: romantic relationships, interdependence, matching, alignment, shared reality

Those with simple number systems (an upper limit not much higher than ‘four’) often had few material possessions, such as weapons, tools or jewellery; those with elaborate systems always had a richer array of possessions

How did Neanderthals and other ancient humans learn to count? Colin Barras. Nature 594, 22-25, Jun 2 2021. https://www.nature.com/articles/d41586-021-01429-6

Archaeological finds suggest that people developed numbers tens of thousands of years ago. Scholars are now exploring the first detailed hypotheses about this life-changing invention.

Counting on possessions

In a 2013 study11, Overmann analysed anthropological data relating to 33 contemporary hunter-gatherer societies across the world. She discovered that those with simple number systems (an upper limit not much higher than ‘four’) often had few material possessions, such as weapons, tools or jewellery. Those with elaborate systems (an upper numeral limit much higher than ‘four’) always had a richer array of possessions. The evidence suggested to Overmann that societies might need a variety of material possessions if they are to develop such number systems.

In societies with complex number systems, there were clues to how those systems developed. Significantly, Overmann noted that it was common for these societies to use quinary (base 5), decimal or vigesimal (base 20) systems. This suggested to her that many number systems began with a finger-counting stage.

This finger-counting stage is important, according to Overmann. She is an advocate of material engagement theory (MET), a framework devised about a decade ago by cognitive archaeologist Lambros Malafouris at the University of Oxford, UK12. MET maintains that the mind extends beyond the brain and into objects, such as tools or even a person’s fingers. This extension allows ideas to be realized in physical form; so, in the case of counting, MET suggests that the mental conceptualization of numbers can include the fingers. That makes numbers more tangible and easier to add or subtract.

The societies that moved beyond finger-counting did so, argues Overmann, because they developed a clearer social need for numbers. Perhaps most obviously, a society with more material possessions has a greater need to count (and to count much higher than ‘four’) to keep track of objects.

Overmann thinks MET implies that there is another way in which material possessions are necessary for the elaboration of number systems. An artefact such as a tally stick also becomes an extension of the mind, and the act of marking tally notches on the stick helps to anchor and stabilize numbers as someone counts. These aids could have been crucial to the process through which humans first began counting up to large numbers13.

Eventually, says Overmann, some societies moved beyond tally sticks. This first happened in Mesopotamia around the time when cities emerged there, creating an even greater need for numbers to keep track of resources and people. Archaeological evidence suggests that by 5,500 years ago, some Mesopotamians had begun using small clay tokens as counting aids.

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According to Overmann, MET suggests that these tokens were also extensions of the mind, and that they fostered the emergence of new numerical properties. In particular, the shapes of tokens came to represent different values: 10 small cone tokens were equivalent to a sphere token, and 6 spheres were equivalent to a large cone token. The existence of large cones, each equivalent to 60 small cones, allowed the Mesopotamians to count into the thousands using relatively few tokens.

Andrea Bender, a psychologist at the University of Bergen in Norway and another leader of the QUANTA project, says that the team members plan to gather and analyse large amounts of data relating to the world’s numeral systems. That should allow them to test Overmann’s hypothesis that body parts and artefacts might have helped societies to develop number systems that ultimately count into the thousands and higher. But Bender says she and her colleagues are not presupposing that Overmann’s MET-based ideas are correct.

Others are more enthusiastic. Karim Zahidi, a philosopher at the University of Antwerp in Belgium, says that although Overmann’s scenario is still incomplete, it has real potential to explain the development of the elaborate number systems in use today.

Linguistic leads

Overmann acknowledges that her hypothesis is silent on one issue: when in prehistory human societies began developing number systems. Linguistics might offer some help here. One line of evidence suggests that number words could have a history stretching back at least tens of thousands of years.

Evolutionary biologist Mark Pagel at the University of Reading, UK, and his colleagues have spent many years exploring the history of words in extant language families, with the aid of computational tools that they initially developed to study biological evolution. Essentially, words are treated as entities that either remain stable or are outcompeted and replaced as languages spread and diversify. For instance, English ‘water’ and German ‘wasser’ are clearly related, making them cognates that derive from the same ancient word — an example of stability. But English ‘hand’ is distinct from Spanish ‘mano’ — evidence of word replacement at some time in the past. By assessing how frequently such replacement events occur over long periods, it is possible to estimate rates of change and to infer how old words are.

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Using this approach, Pagel and Andrew Meade at Reading showed that low-value number words (‘one’ to ‘five’) are among the most stable features of spoken languages14. Indeed, they change so infrequently across language families — such as the Indo-European family, which includes many modern European and southern Asian languages — that they seem to have been stable for anywhere between 10,000 and 100,000 years.

This doesn’t prove that the numbers from ‘one’ to ‘five’ derive from ancient cognates that were first spoken tens of thousands of years ago, but Pagel says it’s at least “conceivable” that a modern and a Palaeolithic Eurasian could have understood one another when it came to such number words.

Pagel’s work has its fans, including Gray, another of QUANTA’s leaders, but his claims are challenged by some scholars of ancient languages. Don Ringe, a historical linguist at the University of Pennsylvania in Philadelphia, says it isn’t clear that the stability of lower-number words can just be projected far back into prehistory, regardless of how stable they seem to be in recent millennia.

That all adds up to a slew of open questions about when and how humans first started using numbers. But despite the debate swirling around these questions, researchers agree it’s a topic that deserves a lot more attention. “Numbers are just so fundamental to everything we do,” says Gray. “It’s hard to conceive of human life without them.”

Numbers might even have gained this importance deep in prehistory. The notched baboon bone from Border Cave is worn smooth in a way that indicates that ancient humans used it over many years. “It was clearly an important item for the individual who produced it,” says D’Errico.

Not so for the Les Pradelles specimen, which lacks this smooth surface. If it does record numerical information, that might not have been quite as important at the time. In fact, although D’Errico and his colleagues have spent innumerable hours analysing the bone, he says it’s possible that the Neanderthal who chipped away at that hyena femur some 60,000 years ago spent very little time using it before tossing the bone aside.