The Dark Tetrad in Tinder: hook-up app for high psychopathy individuals, and a diverse utilitarian tool for Machiavellians?

The Dark Tetrad in Tinder: hook-up app for high psychopathy individuals, and a diverse utilitarian tool for Machiavellians? Minna Lyons, Ashleigh Messenger, Rebecca Perry & Gayle Brewer. Current Psychology, January 6 2020. https://link.springer.com/article/10.1007/s12144-019-00589-z

Abstract: Location-based on-line dating applications are a popular tool for initiating short and long-term relationships. Besides seeking for partners, people use these applications for a myriad of other reasons. We investigated how the Dark Tetrad of personality, controlling for sex, age, and trolling tendencies, related to different motives for using Tinder. Current or former Tinder users (N = 216) completed online scales for Tinder use motivations, trolling, sadism, and the Dark Triad (Machiavellianism, narcissism, and psychopathy). Using Tinder for acquiring sexual experience was related to being male and being high in psychopathy. Psychopathy was positively correlated with using Tinder to distract oneself from other tasks (e.g., procrastination). Higher Machiavellianism and being female were related to peer pressure as a Tinder use motivation. Using Tinder for acquiring social or flirting skills had a negative relationship with narcissism, and positive relationship with Machiavellianism. Finally, Machiavellianism was also a significant, positive predictor of Tinder use for social approval and to pass the time. Results indicate that individuals high in Machiavellianism use Tinder for a number of utilitarian reasons, whereas the main motive for high psychopathy individuals is hook-up for casual sex.

Discussion

Our results suggest that darker aspects of personality are related to unique motivations for using a real-time, location-based dating application. Sadism did not predict Tinder use motivations, suggesting that Dark Triad rather than the Dark Tetrad is significant for this online behaviour. For psychopathy, we replicated the findings of Timmermans et al. (2018), showing that those high in psychopathy were more likely to use Tinder to gain sexual experience. The high sex drive and short-term mating orientation associated with psychopathy (e.g., Book et al. 2016) clearly translates into using online dating applications for sexual gratification. Other significant finding with regard to psychopathy was the use of Tinder for distracting oneself from other tasks. Previous research has found that especially the impulsive secondary psychopathy facet is related to procrastination in order to avoid completing other tasks (Lyons and Rice 2014). Perhaps high psychopathy individuals procrastinate by focussing on tasks that are more intrinsically motivating, such as finding short-term sexual partners online. The associations between psychopathy, and distraction and sexual experience motivations are interesting, and could have links with the overall impulsive, hedonistic, and procrastinating lifestyles of high psychopathy individuals.

The long-term strategic and flexible nature of Machiavellianism (Jones and Paulhus 2009) was evident in the Tinder use motivations. Machiavellianism had a positive relationship with using Tinder for social approval (i.e., to get validation from others about one’s attractiveness), when travelling, as a consequence of peer-pressure, to pass time or provide entertainment, and to practise social skills and flirting. All motivations could reflect the use of social and online environment to reach long-term objectives (Bereczkei 2018). For instance, Machiavellianism has been associated with the use of social media for self-presentation (Abell and Brewer 2014) and impression management tactics (Hart et al. 2019). Our findings extend self-presentation to the dating environment. Using Tinder for social approval and conforming to peer pressure could all be part of a façade that makes Machiavellian individuals more socially desirable partners.

The relationship between Machiavellianism and the use of Tinder to pass time or provide entertainment is consistent with a recent study that failed to find a connection between Machiavellianism and a wide range of movie and music preferences (Bowes et al. 2018). It is possible that Machiavellian individuals have a more utilitarian approach to their entertainment and use tools that also provide real-life benefits (e.g., acquisition of a partner). Additional research is required to explore Machiavellianism and this aspect of human behaviour.

Narcissism predicted the use of Tinder to improve flirting and social skills only. Those high on narcissism display a sense of superiority and entitlement (Emmons 1984), for example believing themselves to be more desirable than their romantic partners (Campbell et al. 2002). The relationship between narcissism and this motivation may, therefore, reflect the tendency of high narcissist’s to believe that they already excel in this field and do not need to develop their flirting or social skills.

This study has some limitations. For example, participants who did not conform to a binary gender identify were not represented in the sample, nor did we ascertain the sexual orientation or relationship status of participants. Sexual orientation is likely to influence the motivation of finding out information about sexual orientation of others but is unlikely to have an impact on other Tinder motives (Timmermans and De Caluwé 2017b). Around 15–20% of Tinder users report being in a committed relationship (Orosz et al. 2018; Timmermans and De Caluwé 2017b), but it is currently not clear how the motivations of individuals with different levels of Dark Tetrad may be influenced by their relationship status. This is certainly something that future research should take into consideration.

In addition, it is important to note that current findings are reliant on the honesty and accuracy of participant responses to self-report questionnaires. Socially desirable responding is positively related to narcissism and negatively related to Machiavellianism and psychopathy (Kowalski et al. 2018). In order to counteract this, future research should include objective measures of Tinder activity rather than rely only on self-reports. Also, our study included a short Dark Triad measure, which fails to capture the multidimensionality of the construct, and provides a weak differentiation between psychopathy and Machiavellianism (Miller et al. 2019). The study would benefit from replication with longer measures, which would allow investigations into how different components of the Dark Triad relate to on-line dating motivations.

Finally, it is unclear what real-life implications the Tinder use motivations have. Do high psychopathy individuals successfully acquire sexual partners on Tinder? Does Tinder use influence the status, likeability, or social influence of individuals high on Machiavellianism? The present study is hopefully a starting point for investigating whether the Dark Tetrad relates to Tinder use motivations because these motivations lead to some form of social or sexual success.

In summary, we investigated the relationship between socially malevolent personality traits, and the motivations to use a popular real-time, location-based dating application, Tinder. Beyond the identity and enjoyment in trolling, sadism may have little relationship with Tinder use motivations. Those high in psychopathy were motivated by sexual experience and distraction. As a testimony to the flexibility of Machiavellianism as a trait, we found that it correlated with a myriad of reasons not directly associated with short-term sexual hook-ups. Online dating may, therefore, provide an opportunity to develop skills that of use in future situations, something that long-term strategists (i.e., high Machiavellian individuals) may be oriented to.

From 2007... Statutory sex crime relationships between juveniles & adults: How to prevent youth from becoming involved & how to prevent adults from entering relationships

From 2007... Statutory sex crime relationships between juveniles and adults: A review of social scientific research. Denise A. Hines, David Finkelhor. Aggression and Violent Behavior, Volume 12, Issue 3, May–June 2007, Pages 300-314. https://doi.org/10.1016/j.avb.2006.10.001

Abstract: This paper reviews the social scientific literature about non-forcible, voluntary sexual relationships between adults and juveniles, what we have termed “statutory sex crime relationships” or “statutory relationships.” In the available literature, the topic is poorly defined and the research weak, but there are clearly a diverse variety of contexts and dynamics to such relationships. We detail a wide-ranging set of issues on which more research is needed to guide social policy and practice.

Keywords: Sexual abuseStatutory rapeCompliant victimJuvenile victimRape

6. Research agenda

Public policy on the topic of statutory relationships could clearly benefit from a considerably more detailed understanding of the nature of these relationships as well as from an understanding about the capacities of youth. What follows is a discussion of some of the research that might benefit some of the various policy issues that confront this topic.

6.1. Setting statutory parameters

Some may feel that the prohibitions and legal restrictions that apply to statutory relationships flow from moral principles that are not open to empirical investigation. For those open to considering an empirical perspective on the matter, the age of consent laws appear to be based on presumptions about several possibly researchable issues. These concern the developmental progression of a person's ability to consent to sex: (1) what young people of different ages know and understand about sexual behavior and sexual relationships; (2) how young people of different ages make decisions in general and particularly about sex; and (3) what the power and influence dynamics are in relationships between persons of different ages, and in particular relationships that become sexual; that is, under what conditions (age being a central one) youth are easily manipulated, or have difficulty acting as full decision-making parties in their own interest.

Knowledge. Some research exists about young people's sexual knowledge. For example, the average young adolescent has poor knowledge regarding sex: In one national survey, 13-year-olds did not know the most effective pregnancy prevention method, and only 10% of girls and 7% of boys understood the female fertility cycle and its effects on the likelihood of getting pregnant (Albert, Brown, & Flanigan, 2003). Thus, only a small minority of younger adolescents have the knowledge that is necessary to make informed decisions regarding sexual behavior, particularly sexual relationships with adults. However, to our knowledge, there are no studies that track the developmental progression of this knowledge in a detailed way. Studies also need to look not just at the average level of knowledge, but the level of knowledge among those with the least knowledge, and perhaps, as well, among some of the groups who might be most vulnerable to exploitation, such as youth who were sexually abused at an earlier age. As Guerrina (1998) has argued, some adolescent girls who are involved in adult/adolescent sex have had previous sexual experiences, which should give them the ability to make informed decisions regarding sexual activity. However, she further argues that a girl's sexual knowledge may not be a good proxy for her maturity. For example, a girl with a history of sexual abuse may have knowledge of sex that increase her capability to make an informed decision regarding sexual relations; however, her history of sexual abuse may also make her extremely vulnerable and may cause her to act in a sexually provocative manner in order to attain affection, love, and attention, a situation which makes her too immature to make such decisions (Guerrina, 1998).

Decision-making ability. There is some literature concerning the ability of youth to make decisions at different stages of development. For example, some research has established that there is a delayed development of the prefrontal cortex, a seat of decision-making, in adolescents (Segalowitz & Davies, 2004). In other research, adolescents who have sex often do not perceive it as a decision that they made, merely something that “just happened” (BrooksGunn & Furstenberg Jr., 1989; Chilman, 1983), suggesting perhaps difficulties in projecting sequences of activity into the future (Brooks-Gunn & Furstenberg Jr., 1989; Coley & Chase-Lansdale, 1998).

Drawing policy conclusions from such findings is not easy, however. The potential vulnerability to prejudgment on the basis of other values are illustrated by the contrasting conclusions of those concerned about consent to sex with those concerned about consent to abortion (American Psychological Association, 2000) or youth culpability for criminal behavior (Donovan, 1997; Lanning, 2002). Some of the same evidence marshaled to support youth capacity to decide to have an abortion might equivalently be cited in support of youth capacity to consent to sex with an adult. It may indeed be the case that decision-making capacity does vary from context to context. For example, the interpersonal pressures or likelihood of manipulation may be greater in the sexual relationship than in the abortion decision.  However, this illustrates how research about general decision making capacities may be inadequate to the problem, and research may need to look at how adolescents reason and decide about very specific domains of behavior.

Relationship dynamics, power, and influence. Some researchers and those who deal with statutory rape cases have described a seduction and grooming process to which adolescents presumably are subjected (e.g., Lanning, 2002).  They argue that the seducers treat the adolescents better than other adults in their lives have. For example, the adults listen to the adolescents' problems and concerns and fulfill their emotional, physical, and sexual needs. As testimony to the adults' skillfulness, the adolescents often willingly return for sex. According to accounts of other dynamics, adolescents (particularly boys) are typically sexually curious, rebellious, inexperienced, and easily sexually aroused.  This makes them targets for adults who wish to sexually seduce them, and once seduced, easily convinced to return.  Eventually, the adolescents may initiate sexual contact themselves, which may create the impression that they consented to this process. In addition, some adolescents are willing to trade sex for attention, gifts, and affection, and will deny that they are victims (Lanning, 2002).

Grover (2003) uses dissonance theory to explain why an adolescent who has gone through this seduction process nevertheless would argue that s/he freely consented to the relationship. She argues that adolescents perceive that they were compliant in the sexual acts because they were given cues by the adult to imply that they had a choice (i.e., no force was used). The adult gradually convinces the adolescent through steps over the course of time to “consent” to the sexual relationship. Because they falsely perceive that they have chosen the situation, they assert that they consented to the relationship.

Although many adolescents may be subjected to such a grooming process, there is evidence that not all are. In fact, some adolescents have sex with the adults during their first meeting (e.g., Sandfort, 1984), and a minority of adolescent girls who are involved with adults state that they sought out adults because they wanted to learn about sex from an older, experienced, more knowledgeable partner (Higginson, 1999); they believed that their first sexual experiences would be much more pleasurable this way, and many of these girls admitted to seducing reluctant older men to reach these goals. Other girls have reported that they and their female peers seek out older men because their male peers are not considered an acceptable dating pool; they feel that they are too mature to be dating someone their own age, and that older men would be able to provide for their sexual and other needs much better (Higginson, 1999). Additional research is needed to describe the full range of dynamics in the variety of statutory relationships.

Another issue that needs to be resolved empirically is the nature of the power differential in these relationships.  Some argue that the adults hold all power, which precludes the adolescent from making a free choice (Grover, 2003; Guerrina, 1998; Watkins & Bentovim, 2000); others argue that even if the adult does have the power, that does not mean that s/he will misuse the power (Sandfort, 1984), and still others argue that sometimes the adolescent has power over the adult (Money & Weinrich, 1983). No empirical studies have been done to our knowledge to resolve this argument concerning power perceptions and realities in these relationships and how the power differentials affect the ability of the adolescent to make decisions. Because these relationships tend to be furtive and stigmatized, their uncontaminated dynamics may be hard to study. Other things that need to be looked at concern how these dynamics differ depending on the age difference between the partners, itself an important matter that can be regulated in sexual consent statutes.

Conclusion. Even with considerably more information about the developmental progression of knowledge, decision-making ability and relationship dynamics, it might still be very difficult to apply this information to the practical problem of establishing age of consent limits. An example of the difficulty is posed by the problem of gender equity. Suppose it were to be found that younger boys were considerably less subject to manipulation in statutory relationships than younger girls. It seems unlikely and may be even constitutionally impossible that policymakers would craft laws that would then set different standards according to gender. Nonetheless, the policy obstacles should not inhibit the pursuit of more information on these topics.

7. Prevention/intervention research

7.1. How to prevent youth from becoming involved
Advocates have argued for a variety of programs and policies that would discourage young people from becoming involved in relationships with adults (Elstein & Davis, 1997). Two lines of research might be very useful to help build and enhance such initiatives. One would focus on understanding the main risk factors for and reasons why youth become involved in such relationships with a specific eye to trying to target vulnerable youth and meet their needs and deficits in an alternative way.

A variety of suggested risk factors and reasons need to be fully explored:
• Youth involved in conflict with their families who may be looking for alliances with adults to help them gain independence more completely than they could through relationships with other youth.
• Youth who are isolated from peers or have other barriers to peer involvement that may orient them more toward adult relationships.
• Youth who have extremely limited career or employment opportunities, for whom relationships with adults may provide a quicker route to motherhood or family formation.
• Youth who are sexually precocious, who may gravitate to adults for sexual opportunities not available among their peers.
• Youth who are gay, confused about sexual orientation or have other sexual concerns that may make them vulnerable to offers from adults to help mentor them around these concerns by engaging with them sexually.

A second line of research would try to discover what kinds of information or messages are most persuasive in discouraging positive attitudes about or openness to cross-generational relationships. For example, would it be useful to emphasize to young people that such relationships are illegal and may result in prosecution and incarceration for the adults? Or, does such a message fail to persuade because it seems authoritarian, reminds youth of their immaturity and even adds to the allure of such relationships? By contrast, would it be useful to emphasize that such relationships generally do not work out or may involve deceptions by the adult? Focus groups, surveys and evaluation studies of prevention efforts should all be directed at identifying the components of an effective prevention message.

7.2. How to prevent adults from entering relationships
The adults who become involved with youth in statutory relationships may well be a diverse group, if the research reviewed here and experience in regard to other sexual offenders is any guide (Lanning, 2002). Although there may be some statutory offenders who bear resemblance to child molesters, who have compulsive or predatory sexual patterns, and who use deception, there may likewise be others who are dissimilar to other categories of more conventional sex offenders. Nonetheless, there have been few, if any, studies of these adults to catalog their diversity and explore the question of whether there are important differentiable subtypes. Such studies would be useful to aid prevention efforts. As has been tried with other sex offenders against children, it may even be useful to talk with statutory sex offenders explicitly about factors that might have inhibited their behaviors (Conte, Wolfe, & Smith, 1989).

An issue of considerable potential for prevention concerns offenders who were frankly ignorant of the laws criminalizing adult–youth sexual behavior, that is, individuals for whom reinforcement or knowledge about laws and norms might have been a deterrent. Social surveys may also be useful to ascertain whether there are some groups in society among whom the norms are supportive of such behavior. As with prevention messages for youth themselves, it may be useful to test a variety of messages with adults in focus groups, surveys and evaluation studies, to investigate which may be most effective in discouraging a proclivity toward sexual involvement with youth. Such studies should look at different subcultural groups and adults of different ages. In addition, it is probably important to look at these issues with gay adults, who may have a different set of rationales and concerns, although such research obviously needs a great deal of sensitivity to avoid reinforcing the unsubstantiated stereotype that in comparison to heterosexual adults, gay adults are more predatory toward youth.

7.3. How to minimize iatrogenic impacts on youth
A policy issue of considerable interest is how to make sure that criminal justice interventions do not cause additional harm to victims. Some of the potential for iatrogenic harm that is widely acknowledged in the sexual assault area (Jones, Cross, Walsh, & Simone, 2005) would certainly be expected in regard to statutory victims. Because some of these youth may have considerable allegiance to the offenders, they may not see themselves as victims, may see the criminal justice system as agents for their parents and as limiting their own autonomy, and may experience interventions as highly coercive and hostile. Intervention may also create considerable stigma for the youth, including such humiliations as outing their sexual orientation, and may cause them to feel guilt and self-blame for actions taken against the offender. Observers have noted that adolescents who are brought into the judicial system as part of these investigations may embellish or change their stories to please the legal authorities (Berliner, 2002), to adhere to societal expectations and/or to avoid embarrassment (Lanning, 2002). Thus, “they inaccurately claim they were afraid, ignorant, or indoctrinated” (Lanning, 2002, p. 6). However, no systematic research has been conducted to verify whether and how often adolescents behave this way.

Research could fruitfully be directed to identifying the most alienating and stressful components of criminal justice intervention for youth involved in statutory relationships. Such research could be the basis for designing interventions that mitigate such harms. Given that these youth frequently have additional problems, the research might suggest adjuncts to criminal justice interventions that may help the youth and improve cooperation with authorities.

There seems to be a genetic predisposition to following a vegetarian diet; & a link between vegetarianism and political ideology may exist because of a shared genetic predisposition

Where the Rubber Meats the Road: Relationships between Vegetarianism and Socio-political Attitudes and Voting Behavior. John B. Nezlek & Catherine A. Forestell. Jul 15 2019. Ecology of Food and Nutrition, Volume 58, 2019 - Issue 6, pp 548.559. https://doi.org/10.1080/03670244.2019.1641801

ABSTRACT: Previous research has found that omnivores are more hierarchical and more authoritarian than vegetarians. To examine if such differences extend to political behavior a sample of American undergraduates (N = 1211) described their diets, endorsement of social policies, political orientation, and voting behavior. Consistent with previous research, we found that compared to vegetarians and semi-vegetarians, omnivores favored conservative policies more strongly and liberal polices less strongly, identified more closely with the Republican party and less closely with the Democratic party, were less liberal, approved of Donald Trump’s performance more, and were more likely to have voted for Trump.

KEYWORDS: Vegetarianism, voting behavior, conservatism, liberalism, Trump

Discussion As expected, vegetarians and semi-vegetarians were more politically liberal than omnivores, differences that are consistent with previous research. Moreover, our results suggest that consumption of red meat is associated with these differences. Vegetarians and semi-vegetarians did not differ on any of the measures we analyzed. The power of this comparison was .67 for a medium (d = .5) effect size (Faul et al. 2009). Why was the consumption of (red) meat associated with more politically conservative attitudes and behaviors? We believe that the differences between omnivores and vegetarians reflect the operation of the processes described by Dhont and Hodson (2014): “Rightwing adherents do not simply consume more animals because they enjoy the taste of meat, but because doing so supports dominance ideologies and resistance to cultural change” (p. 12). For example, research has shown that relationships between speciesism and conservative attitudes are driven by dominance orientation (e.g., Costello and Hodson 2010; Dhont, Hodson, and Leite 2016). The differences we found between omnivores and vegetarians in the endorsement of various social policies were clearly consistent with omnivores being more resistant to change and more supportive of hierarchies than vegetarians. Such differences are also consistent with the possibility that vegetarians restrict their meat intake not because they dislike the taste of meat but because of there are concerned about animal welfare. Such concerns can go beyond issue of hygiene and methods of slaughter and can include beliefs that as sentient beings, animals should not be killed for food. The present results extend previous research in two ways. They expand the domain of attitudes and behaviors that are associated with the consumption of red meat. Compared to vegetarians and semi-vegetarians, omnivores both endorsed more conservative policies more strongly and endorsed more liberal policies less strongly, indicating that diet is associated with attitudes across the political spectrum. Perhaps more important, because voting is where the “rubber meets the road” in terms of politics, demonstrating that the voting behavior of omnivores is different than the voting behavior of vegetarians and semivegetarians extends existing research into a critical domain. Consistent with our results, Wrenn (2017) found that vegans were much less likely to vote for Trump than the norm (4% vs. 46% overall), but Wrenn did not study semi-vegetarians, a group whose intake has been shown to be motivated more by weight control or health reasons rather than ethical reasons compared to strict vegetarians (Forestell, Spaeth, and Kane 2012). This difference may explain why a lower (though not significantly lower) proportion of semi-vegetarians than vegetarians endorsed liberal attitudes. Whether vegetarians’ political attitudes and behaviors are associated with the degree to which their motivations are health- or ethically-based is a topic for future research. The present results also increase the diversity of the database describing relationships between vegetarianism and political beliefs. Much of the research on this topic has been done in Europe or Australasia. Although culturally the US has much in common with these countries, there are differences among them, and finding that relationships between diet and political orientation in an American sample are similar to the relationships found in other countries supports the validity of these relationships. Nevertheless, the sample examined in the present study may limit the generalizability of the results. As discussed by Henrich, Heine, and Norenzayan (2010), the present sample came from a WEIRD culture (Western, Educated, Industrialized, Rich, and Democratic). Also, similar to previous research on this topic, the study was conducted in a society in which people are “vegetarians of choice” rather than “vegetarians of necessity” (Leahy, Lyons, and Tol 2010). The majority of the world’s vegetarians do not have the resources to buy meat, and so it is possible that the type of relationships we found are limited to individuals who choose to be vegetarian. Finally, a smaller percent of the present sample voted for Trump (17%) than the percent of college-educated voters in the general US population (36%, Pew Research Center 2018), and the sample consisted of young adults. Nevertheless, the present results comport with the results of previous research suggesting that the selective nature of the sample did not skew the results in a specific direction. Such questions can be resolved only by examining the same processes in larger, more representative samples. There is also the issue of the extent to which the results found in our sample of collegians can be generalized to people of other ages. Following Erik Erikson many believe that adolescence (and to some extent early adulthood) is a time when people search for their identities, at least in Western cultures. In terms of political ideology and voting behavior this is often referred to as the “impressionable years hypothesis,” which is accompanied by the “aging-stability hypothesis” (stability increases with age) (e.g., Alwin and Krosnick 1991). Support for these complementary mechanisms is mixed (e.g., Alwin and Krosnick 1991). For example, Markus (1986) found that the political attitudes of a sample of young adults was no more or no less stable over 17 years than the attitudes of their parents were. Perhaps the most intriguing perspective on this issue is the work of Verhulst and colleagues (e.g., Verhulst, Eaves, and Hatemi 2012). They suggest that political ideology reflects genetic predispositions (at least in part), and to the extent this is true, political ideology may be as stable in early adulthood as it is at any other stage of life assuming that genetic predispositions are stable. There is the issue of how well a distinction based upon dietary habit predicts the types of socio-political attitudes we examined. Although the differences in means for some measures were meaningful in terms of scale points (e.g., over a half point difference between omnivores and vegetarians for strength of identification with the Democratic party), for most measures, the ANOVAs that compared the three groups accounted for about 4–5% of the variance, certainly not large effects. This was due to the variance in these outcome measures within the groups. For example, although vegetarians identified more closely with the Democratic party than omnivores, 46% of omnivores identified with the Democratic party either closely or very closely. On the other hand, omnivores were approximately three times more likely than vegetarians to have voted for Trump. Although this ratio needs to be understood within the context of the number of participants who voted for Trump (77 of 468), it is possible that the individual differences that are associated with an omnivorous diet when considered collectively may have had a stronger influence on how people voted. This is perhaps because voting is a decision that is based on the collective influence of a set of individual factors that may vary in strength. The present study was intended primarily as an empirically focused extension of research on the socio-political correlates of following a vegetarian diet. We believe that we accomplished this goal, albeit with the limitations imposed by our sample. As noted previously, the available data suggest that vegetarians have a more pro-social orientation than omnivores (Ruby 2012). Such a pro-social orientation is probably the driving force behind the political ideologies and behaviors of vegetarians. Even so, such an explanation still begs the question of why vegetarians are more prosocial than omnivores.

Recent research suggests that there may be a genetic predisposition to following a vegetarian diet (e.g., Ye et al. 2017). If this is the case, then relationships between vegetarianism and political ideology may exist because of a shared genetic predisposition. This is similar to the argument Verhulst and colleagues have made regarding relationships between personality and political beliefs. Clearly, answering such questions requires research that is designed to address them specifically.



Check also Vegetarianism as a Social Identity. John B Nezlek, Catherine A Forestell. Current Opinion in Food Science, December 20 2019. https://www.bipartisanalliance.com/2019/12/vegetarians-are-more-pro-social-than.html

And Gender Differences in Vegetarian Identity: How Men and Women Construe Meatless Dieting. Daniel L.Rosenfeld. Food Quality and Preference, November 28 2019, 103859. https://www.bipartisanalliance.com/2019/11/could-they-be-lying-vegetarian-women.html

And Taste and health concerns trump anticipated stigma as barriers to vegetarianism. Daniel L.Rosenfeld, A. JanetTomiyama. Appetite, Volume 144, January 1 2020, 104469. https://www.bipartisanalliance.com/2019/09/vegetarian-diets-may-be-perceived-as.html

And Relationships between Vegetarian Dietary Habits and Daily Well-Being. John B. Nezlek, Catherine A. Forestell & David B. Newman. Ecology of Food and Nutrition, https://www.bipartisanalliance.com/2018/10/vegetarians-reported-lower-self-esteem.html

And Psychology of Men & Masculinity: Eating meat makes you sexy / Conformity to dietary gender norms and attractiveness. Timeo, S., & Suitner, C. (2018). Eating meat makes you sexy: Conformity to dietary gender norms and attractiveness. Psychology of Men & Masculinity, 19(3), 418-429. https://www.bipartisanalliance.com/2018/06/psychology-of-men-masculinity-eating.html

And Baby Animals Less Appetizing? Tenderness toward Baby Animals and Appetite for Meat. Jared Piazza, Neil McLatchie & Cecilie Olesen. Anthrozoös, Volume 31, 2018 - Issue 3, Pages 319-335. https://www.bipartisanalliance.com/2018/05/presenting-images-of-baby-animals.html

Infection and Ideology: Perceived Vulnerability to Disease Predicts Political Conservatism

Jacob Appleby, Christopher M. Federico, Joseph A. Vitriol, Allison L. Williams. 2020. “Infection and Ideology- Perceived Vulnerability to Disease Predicts Political Conservatism.” PsyArXiv. January 4. doi:10.31234/osf.io/6ag92

Abstract: Recent research on the behavioral immune system suggests that perceived vulnerability to disease is associated with greater ingroup preference, conformity, and support for established cultural practices. However, little of this research has looked at the implications of perceived vulnerability to disease for an orientation linked to many of the above outcomes: ideology. In two studies, we test the hypothesis that perceived vulnerability to disease should be associated with greater political conservatism. In Study 1, we find a relationship between perceived vulnerability to disease and increases in conservatism over time. In Study 2, we use data from the World Values Survey to demonstrate that perceived vulnerability to disease predicts a stronger preference for the political right in a large sample of respondents from a wide variety of nations. Together, these results suggest that the consequences of the behavioral immune system may extend to abstract identifications like ideology.

General Discussion

In these studies, we extend prior work on the social implications of the behavioral immune system by examining the relation between subjective perceptions of disease vulnerability and ideological self-placement. Consistent with the expectation that the perceived prevalence of pathogens activates motivational goals and values congruent with conservatism, Study 1 found that perceived vulnerability to disease was associated with increases political conservatism over time and a stronger tendency to evaluate conservatives more positively than liberals net of baseline political beliefs. Extending this finding, Study 2 found that PVD was also related to a greater preference for the political right in a large representative survey of respondents from a wide variety of nations. In both cases, our results were robust to controls for relevant demographic characteristics and competing psychological determinants of ideology. Together, our findings address a major gap in our understanding of the behavioral immune system’s social implications. Although PVD has been shown to predict conformity (Murray & Schaller, 2012; Wu & Chang, 2012) and exclusionary outgroup attitudes (Faulkner et al., 2004), the current studies are the first to provide direct evidence for a relationship between PVD and ideological conservatism. Given the relatively abstract nature of ideology as an identification (Jost et al., 2009), they suggest that the operation of the behavioral immune system may also have consequences for outcomes less concrete and socially immediate than ingroup bias or conformity. Methodologically, they provide a more precise look at the relationship between the behavioral immune system and ideology than studies that rely solely on disgust sensitivity as an indicator of pathogen avoidance, which have yielded inconsistent findings (Tybur et al., 2009). By relying on a more direct indicator of pathogen avoidance that accounts for both the subjective perceptions of susceptibility to infection and related affective responses, our results help clarify the connection between the functioning of the behavioral immune system and ideology. Despite the strength of our evidence, our studies are not without their limitations. First, our correlational data cannot provide decisive evidence for a causal link between PVD and ideology. That said, our inclusion of a lagged indicator for our dependent variable does allows us to model change in conservatism across time as a function of PVD and overcome some of the bias potentially introduced by feedback effects (Finkel, 1995). Second, in Study 2, we were only able to use a simple proxy measure of PVD from the World Values Survey, rather than the validated scale employed in Study 1(Duncan et al., 2009). Nevertheless, the WVS items measure perceptions closely related to those included in the PVD scale, leaving us with confidence in their face validity; the similarity of our results across the two studies (and two very different samples) also testifies to the correspondence between the two measures. The evidence we present for a relationship between PVD and conservatism also has a number of broader implications, both for society as a whole and for future research. Like other threats (e.g., Jost et al., 2003, 2009), increased attention to public health concerns associated with infectious disease—both in communications from political elites and in media coverage—may have the potential to produce a conservative shift in public opinion and ideological sympathies. Such changes in the salience of disease threat may have both a main effect on conservatism, as well as a moderating effect in which they activate individual differences in PVD and produce especially large ideological shifts among those who feel chronically susceptible to infection. Given the tendency for pathogen prevalence to produce especially strong reactions against cultural outgroups and those who fail to conform to dominant social norms (e.g., Schaller et al. 2003; Thornhill & Fincher, 2012), we might also expect these effects to be especially strong when disease threats are associated with “foreign” groups (e.g., West Africans in the case of Ebola) or “non-normative” groups (e.g., gay men in the case of HIV). These questions await future research.

Increased Support for Same-sex Marriage in the US: Americans of all ages modified their beliefs about same-sex marriage over time

Increased Support for Same-sex Marriage in the US: Disentangling Age, Period, and Cohort Effects. Jean M. Twenge &Andrew B. Blake. Journal of Homosexuality, Jan 4 2020. https://doi.org/10.1080/00918369.2019.1705672

ABSTRACT: Previous research established a substantial increase in support for same-sex marriage in the US, but it is unclear if this increase is due to cohort (a change that affects only the younger generation) or time period (a change that affects those of all ages). In a nationally representative sample of American adults (n = 13,483) in 1988 and 2004–2018, increased support for same-sex marriage was primarily due to time period (from 11.1% in 1988 to 66.7% in 2018). There was a smaller cohort effect, with a fairly linear increase between cohorts born in the 1960s and those born in the 1990s. Time period increases in support for same-sex marriage appeared among across gender, race, education levels, regions, and levels of religious service attendance, though differences in support still remain. The results suggest Americans of all ages modified their beliefs about same-sex marriage over time.

KEYWORDS: Same-sex marriage, cultural change, time period, cohort, lgbt rights, gender differences, regional differences

Discussion

Increased support for same-sex marriage between 1988 and 2018 appears to
be primarily a time period effect, with those of all ages increasing in support,
rather than a generational phenomenon. Thus, increased support for samesex marriage is not primarily due to generational shifts. Instead, Americans
of all ages changed their beliefs about same-sex marriage. The trends also
appeared across all demographic groups. Differences based on gender, race,
education, region, and religion remain, but all groups are now substantially
more likely to support same-sex marriage. Thus, the increased support for
same-sex marriage was pervasive, appearing across ages and generations as
well as across demographic groups.
The results suggest that some attitudes may be malleable after young
adulthood under the right historical and political conditions. The extraordinary cultural shift toward embracing LGBT rights, including the right to
marry, apparently impacted older people as well as younger ones. Future
research should explore whether other attitudes may be changed later in life,
or if LGBT attitudes are the exception.
This analysis is limited to the data available. First, support for same-sex
marriage was measured only once before 2004 (in 1988), and it is possible
this year had unique cultural influences that could skew the results. However,
the numbers are consistent with other measures of LGBT attitudes in the GSS
in the late 1980s and early 1990s (Twenge, Sherman, & Wells, 2015). Data from
Gallup asking about same-sex marriage suggest that support continued to
increase between 1996 (27%) and 2004 (42%; McCarthy, 2019), suggesting
that there was a fairly linear trend during the 16 years when the GSS did not
field the same-sex marriage question. Second, the GSS does not include data on
all cohorts at all ages, which limits our ability to discern (for example) the
young adulthood responses of the earlier cohorts and the midlife responses of
the later cohorts. Third, the analysis is based on a self-report survey question
that may be subject to social desirability bias; perhaps people express support
for same-sex marriage because they believe this is what they should say.
However, one study found that support for same-sex marriage was similar
even when respondents were afforded more anonymity, suggesting social
desirability bias does not have much effect on survey questions about support
for same-sex marriage (Lax, Phillips, & Stollwerk, 2016).
In summary, the extraordinary increase in support for same-sex marriage
appears to have occurred for an extraordinary reason: Those past young
adulthood altering their views as the culture shifted to embrace LGBT rights.
The fight for same-sex marriage not only won the hearts of the younger
generations but the hearts of many in older generations as well in a pervasive
wave of cultural change.

Low-probability events were viewed as more random than similar events that were judged (rightly or wrongly) to be more likely; only extremely deviant outcomes made some people reject the randomness account

Are random events perceived as rare? On the relationship between perceived randomness and outcome probability. Karl Halvor Teigen & Gideon Keren. Memory & Cognition, January 2020.  https://link.springer.com/article/10.3758/s13421-019-01011-6

Abstract: Many daily life events, from lotteries to coincidental encounters, occur partly or entirely randomly or “by chance.” Six experiments, in two different languages, explored how perceptions of randomness are related to the perceived probability of the same events—specifically, whether low-probability events were viewed as more random than similar events that were judged (rightly or wrongly) to be more likely. The experiments suggest that low-probability outcomes of stochastic events are indeed considered as being more random than medium and highly likely outcomes, even when all are produced by a “blind” (hence random) process. Degree of randomness involved in catching a bus was inversely related to the subjective probability estimates of the same event, both for correct and incorrect estimates. Unlikely coincidences were perceived to be more random than the same events presented in a more likely frame. The outcome of a match between two soccer teams was  deemed to be more random when the weaker team wins than when the stronger team wins. Only extremely deviant outcomes—for instance, a top student who fails on two successive exams—made some people reject the randomness account, presumably believing that such extreme events must have a causal explanation. We conclude that people generally associate randomness with low-probability events, indicating outcomes that “cannot be predicted.”

Check also Are random events expected to be small? Karl Halvor Teigen, Alf Børre Kanten. Psychological Research, September 30 2019. https://www.bipartisanalliance.com/2019/09/randomness-and-related-concepts-events.html

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General discussion

The present set of studies constitutes the first attempt to examine empirically how perceived randomness of singular events
is related to their judged probability. We reviewed arguments
for different, seemingly plausible accounts for such a relationship, but subsequent experiments offered most consistent support for the low-probability account: Low-probability events
will be perceived as more random than comparable outcomes
that are estimated (rightly or wrongly) to have a higher probability of occurrence. This supports the more informal observations by Shanahan and Porfeli (2006) and Jolfaee et al. (2014),
and is congruent with the fact that real-life stories about random happenings, particularly coincidences, are typically illustrated by descriptions of low-probability events (Bandura,
1982; Johansen & Osman, 2015).
The results of the first four experiments all supported the
low-probability hypothesis rather than a process account, endorsed by scientists who think that randomness “objectively”
depends upon the generating mechanism (Fitelson &
Osherson, 2015; Lecoutre et al., 2006; Nickerson, 2002).
Experiment 5, which compared probability estimates and perceived randomness of selected soccer results, indicated a potential boundary condition for this rule. Results that were considered highly likely were again perceived as being less random than those that were not considered so likely, whereas
exceptionally extreme unlikely results turned out to be ambiguous, as participants were split into those who thought that
such results indicated a very high degree of randomness and
those who thought that such results could not be due to
chance. This split was replicated in Experiment 6, where very
deviant exam grades were viewed as being either more random (because they were unusual) or less random (because
there had to be a reason). However, for low-probability events
to appear nonrandom a nonrandom explanation has to be
available. Thus, unexpected grades (Experiment 6a) are easier
Table 4 Mean probability estimates and randomness scores (with mean
absolute deviations [MAD]) for poor exam grades and lottery wins,
Experiments 6a and 6b
Scenario Probability (1–7) Randomness (1–7)
Mean score Mean score MAD
Exam scenario (6a)
Two poorer grades (Ann) 3.34 a 3.16 a 1.36 a
Two failed grades (Carol) 1.93 b 3.24 a 2.02 b
Lottery scenario (6b) Objective probability
One win 1/20 6.29 b 0.88 c
Two wins 1/400 6.11 b 1.06 d
Note. Numbers with different subscripts in each column are significantly
different from each other (p < .001 for Experiment 6a and p < .05 for
Experiment 6b)
perceived as nonrandom than unexpected lottery results
(Experiment 6b).

Comparing our results with randomness judgments performed within the binary sequence paradigm, a striking contrast can be observed. In these studies patterns were judged
less random when they were perceived as unlikely outputs
from a series of tosses by a coin. In Falk and Konold’s
(1997) studies, ratings of “apparent randomness” were in fact
obtained by asking participants about the likelihood of achieving particular sequences randomly, and then concluding that
unlikely outcomes meant not random. Our studies indicate the
opposite—namely, that for singular events in daily life,
unlikely indicates more random. These differences suggest
that studies of binary sequences have limitations as a universal
model of the perception of randomness (see also Matthews,
2013, on the evaluation of streaks of different kinds).
These evaluations are not as incompatible as they may
seem. Judgments of randomness in sequences assume the existence of a random generator producing inchoate strings,
where order is “surprising” (Feldman, 2004) and anomalous.
Participants in these tasks make judgments based on an assumption of disorder, where observations of irregularity are
expected and, in a way, considered as default. Outside of this
rather artificial universe, however, people will look for, and
expect, some degree of predictability and order. They will find
irregular events to be the exception rather than the rule, and
only draw conclusions about randomness in the “unlikely”
case of aberrant events that cannot be predicted. By this epistemic attitude they manage to preserve a model of the world
as basically orderly and explainable.
In the present studies, we have compared participants’ solutions to a task of predicting outcomes (probability estimates)
with a task of postdicting hypotheses (randomness ratings). In
terms of conditional probabilities, this changed their task from
considering p(data | H) to expressing their opinions about the
inverse relationship p(H | Data). To do so in a meaningful way,
one needs to have an idea not only about p(data | H), but also
about the prior probability of potential alternative hypotheses,
and how compatible the actual outcomes are with both alternative hypotheses, as required by Bayes’s theorem. It is reasonable to assume that a search for alternative hypotheses will
emerge when p(data | H) is quite low, unless the process is so
well described that the role of other contributing causes can be
controlled for. To illustrate, the winner of the lottery in
Experiment 1a had only 10% chance, yet the fact that he
won could not rule out randomness, as the process of a blind
draw did not allow the winning to be explained in any other
way. This was replicated in Experiments 1b and 6b with even
lower probabilities. In contrast, the factors responsible for the
outcome of a soccer match include situational determinants
and skills, making it easier to produce a narrative that highlights factors different from randomness. So, when an extraordinary and unlikely 5-0 outcome happens, some participants
decided to look for potential reasons that made this result
appear more plausible, and hence less random than before.
These apparently divergent judgments do not invalidate the
link between low probability and high perceived randomness,
as they may simply stem from an attempt to think that extraordinary outcomes must be due to an overriding cause, making
them more likely (and less random) than originally assumed.
A similar process can be observed when exceptional coincidences are “explained” by recourse to magical or supernatural
forces. They then become more likely (and not random) by
means of an unlikely (magical) theory of coincidences
(Griffiths & Tenenbaum, 2007).
We do not claim that all low-probability events will be
regarded as random, and certainly not that probability is the
only determinant for attributing an outcome to randomness, or
chance. Other potential determinants of randomness could be
examined by manipulating other variables—for instance,
causal factors, skill, intentionality, and effort. Our results indicate that low probabilities constitute one (supposedly important) facet in the perception of randomness, though we do not
claim that it is the only one.
Why should low p events be regarded as more random? Low
p events need not be uncaused or unintentional, and even quite
infrequent happenings (like Halley’s comet appearing once in
75 years) can form a pattern. We propose that the answer may
reside in two related characteristics of subjective randomness.
People consider an event as random if it appears as
disconnected from the general flow of events, like an unmotivated cough in the middle of a sentence or an unexpected computer crash before the document is saved. In these cases, the
“random” events cannot be conceived as causally related to the
main story line. It is also in the nature of such events to be
unforeseeable. They are deviant and form exceptions to the rule.
By this logic, it was less foreseeable (and more random) that
Karl in Experiment 1 drew a winning marble from his 10% urn
than John did, as John’s urn contained 90% winning marbles.
Indeed, unpredictability has been suggested as an optional
definition of randomness—for instance, as independence (zero autocorrelations) between the parts of a random sequence,
where one part cannot be predicted from preceding parts
(Neuringer, 1986; Nickerson, 2002). Also, in the case of blind
draws from an urn with unequal frequency of different colors,
all marbles (but not all colors) have the same probability of
being chosen, implying unpredictability on the level of individual marbles (but not on the level of colors). Our participants appear to go one step further and reason that degree of
randomness depends on outcome features: a drawing of the
dominant color is less random, by being more expected than
other colors.
The present studies did not instruct participants as to what
should be meant by a random or a nonrandom outcome. This
was done deliberately, in order to avoid directing our respondents towards a specific interpretation of the term. Like
probability, randomness is a polysemous concept (Hertwig &
Gigerenzer, 1999), having multiple, related meanings.
Accordingly, we do not claim that this term was used by all
participants in exactly the same way. Notwithstanding, the
results showed a remarkable consistency of low-probability
events being rated as being more random across a wide range
of situations with speakers of two different languages.
The idea that random events are rare can have several important implications. One is exaggerated beliefs in foreseeability and control, as indicated by research on the hindsight bias
(Roese & Vohs, 2012). It might reinforce a preference for
intentional rather than accidental explanations of behaviour
as demonstrated by studies of the “intentionality bias”
(Reich, Kupor & Smith, 2018; Rosset, 2008). It may lead
historians, social scientists, and psychologists to underestimate the role of randomness in shaping individual and collective history (Krantz, 1998; Sunstein, 2015), and make them
look for patterns, plans, and explanations behind phenomena
that cannot be adequately attributed to single causes or to a
purposeful design.
An association between randomness and low probability
may suggest that random events are in themselves
insignificant and do not, as a rule, give rise to important
changes. As John Stuart Mill (1856) observed, people tend to
think that effects share important characteristics with their
causes; large effects are supposed to have large causes, and evil
effects are supposed to flow from evil forces (Nisbett & Ross,
1980). By a similar logic, one may believe that random and
unlikely events can be taken lightly, if they have only in their
power to produce slight and insignificant consequences. What
people think about the “magnitude” of random events and their
potential causal power has been recently been examined by
Teigen and Kanten (2019). Their perceived low probability
suggests that they can be easily ignored or discounted as “exceptions.” Correspondingly, one rarely stops to consider whether frequent or more noteworthy events could be due to chance.

Fisher's lost model of runaway sexual selection: Sexy sons theory survives math modeling better than good genes theory

Fisher's lost model of runaway sexual selection. Jonathan M. Henshaw  Adam G. Jones. Evolution, December 30 2019. https://doi.org/10.1111/evo.13910

Abstract: The bizarre elaboration of sexually selected traits like the peacock's tail was a puzzle to Charles Darwin and his 19th century followers. Ronald A. Fisher crafted an ingenious solution in the 1930s, positing that female preferences would become genetically correlated with preferred traits due to non‐random mating. These genetic correlations would translate selection for preferred traits into selection for stronger preferences, leading to a self‐reinforcing process of ever‐elaborating traits and preferences. It is widely believed that Fisher provided only a verbal model of this ‘runaway’ process. However, in correspondence with Charles Galton Darwin, Fisher also laid out a simple mathematical model, which purportedly confirms his verbal prediction of runaway sexual selection. Unfortunately, Fisher's model contains inconsistencies that render his quantitative conclusions inaccurate. Here we correct Fisher's model and show that it contains all the ingredients of a working runaway process. We derive quantitative predictions of his model using numerical techniques that were unavailable in Fisher's time. Depending on parameter values, mean traits and preferences may increase until genetic variance is depleted by selection, exaggerate exponentially while their variances remain stable, or both means and variances may increase super‐exponentially. We thus present the earliest mathematical model of runaway sexual selection.

Check also Meta-Analysis Suggests Choosy Females Get Sexy Sons More Than 'Good Genes'. Zofia M. Prokop, Łukasz Michalczyk, Szymon M. Drobniak, Magdalena Herdegen, Jacek Radwan. Evolution, https://www.bipartisanalliance.com/2018/05/meta-analysis-suggests-choosy-females.html

Menopause may be the result of the accumulation of infertility mutations in older women due to men’s preference for younger mates;it can de-evolve, be delayed and even disappear, in theory

Is menopause still evolving? Evidence from a longitudinal study of multiethnic populations and its relevance to women's health. Rama Shankar Singh, Shirley Chan, Alyssa Gomes. BMC Women's Health, Dec 26 2019 (under review). DOI:10.21203/rs.2.19623/v1

Abstract: To reflect on the impact of changing patterns of delayed marriage and reproduction and to seek evidence as to whether menopause is still evolving, characteristics of the menopause transition were investigated within and between ethnic populations in this study. A cross-sectional analysis was conducted using data on 747 middle-aged women obtained from the Study of Women’s Health Across the Nation (SWAN) from 1996 to 2008. The ethnic groups included: Afro-American, Chinese, Japanese, Caucasian, and Hispanic. Perimenopause age and duration, menopause age, and hormonal indicators of menopause were examined across five ethnicities. We found a similar window of menopause age within populations, but no significant difference in perimenopause and menopause age between populations. The rate of increase of follicle-stimulating hormone and testosterone differed significantly in Hispanics and African-Americans during the menopause transition period. The broad window of variation in age at menopause within the population (45-60 years) and the absence of significant differences between populations, in combination with population variation in menopause symptoms, suggest that menopause is a relatively recently evolved and still evolving trait. Under the mate choice theory of menopause, menopause is the result of the accumulation of infertility mutations in older women due to men’s preference for younger mates. We propose a shifting mate choice-shifting menopause model which posits that, as the age of mate choice/marriage shifts to older age, so will the age at menopause, and that menopause is a transient phase of female fertility; it can de-evolve, be delayed and even disappear, in theory.

KEYWORDS: Mate choice, menopause, perimenopause, sex-hormones, menstruation

Discussion

Insight into the association between ethnic diversity and the characteristics of a woman’s menopause transition may provide evidence for the timing of the appearance of menopause in human evolution. In this study, we evaluated perimenopause and menopause age, perimenopause duration, and the associated reproductive hormonal changes in a longitudinal, multi-ethnic sample from the cross-sectional study SWAN⁹. While the results of this study revealed lack of a consistent ethnicity-specific difference in the timing of the menopause transition, there were significant changes in the associated hormones which, together with variations within populations in the menopause “window” and population-specific variation in menopausal symptoms, are suggestive of menopause as a recently evolved and still evolving trait in human evolution.

Before discussing the significance of these results, it is important to state the rationale for this study. From the women’s health point of view, it is important to know if menopause is still evolving and, if so, can it de-evolve, i.e. can it be delayed or even eliminated. To be able answer this question, we need to know the nature of variation in menopause. The SWAN study (and many others reviewed by Gold et al.⁹) looked into the effect of lifestyle factors on menopause. Controlling for sociodemographic, lifestyle, and health factors affecting the final menstrual period (FMP), Gold et al.⁹ found that “racial/ethnic groups did not differ in age at the FMP. Higher educational level, prior oral contraceptive use, and higher weight at baseline, as well as being employed, not smoking, consuming alcohol, having less physical activity, and having better self-rated health over follow-up, were significantly associated with later age at the FMP”. These results suggest that menopause is a complex trait, but it is interesting to note that, in spite of the effect of socioeconomic factors, the onset-age “window” of menopause remains more or less stable from population to population (Fig. 2). Our reduced data set was designed to increase the chances of discovering ethnic differences in the onset age of menopause; we found it to vary significantly in Hispanic population only. In the following, we review our findings and use them to propose a model of “shifting mate choice-shifting menopause” and predict that there is population variation in the onset age of perimenopause and that the shifting patterns of mate choice and marriage will lead to a shift, a delay in the onset age of menopause.

Ethnic variation in perimenopause age

At present, this is the first assessment of the age of perimenopause onset in a multi-ethnic sample. This study has identified a significantly earlier perimenopause onset in women of Hispanic descent compared to women of Caucasian, African-American, Chinese, and Japanese descent. Hispanics experience perimenopause approximately two years earlier, which suggests that changes in the reproductive systems are still taking place and that menopause has not stopped evolving separately in each population. While this result may be suspect because of small sample size and heterogeneity among samples originating from different Central American countries, as we show below, other studies have reported similar results.

Previous perimenopause literature is highly limited. Mentions of perimenopause age in other literature are either not quantified or they refer to the mean age of women in the perimenopause cohort, rather than onset age. Of the feasible literature, McKinlay et al.²⁷ has reported the inception of perimenopause to be 47.5 years, earlier than determined in our study (51.8 years). It should be noted that McKinlay et al.’s²⁷ perimenopause age was not specific to any ethnicity and was limited to women in Massachusetts. Sammel et al.²⁸ also examined the menopause transition across ethnicities, albeit limited to Caucasians and African-Americans. The specific age was not listed, but it was found that African-American women entered perimenopause earlier than Caucasians, a finding that was not observed in this study²⁸. Differences in the reported age in McKinlay et al.’s²⁷ study and the variation in African-American and Caucasian women perimenopause age of onset in Sammel et al.’s²⁸ study can be attributed to definition bias introduced in our study. Other studies define perimenopause onset using early perimenopause (menstrual irregularity). In contrast, we used late perimenopause (3 to 11 months of amenorrhea) due to a change in the questionnaire following the 1997–1999 follow-up (SWAN), which led to overestimation of perimenopause onset age. It is likely that a change in perimenopause definition will yield results similar to other studies, as our results are consistent with Sammel et al.’s²⁸ finding that entry into late perimenopause did not differ significantly between African-American and Caucasian women. Although it is probable that the definition of perimenopause influenced observed trends, it is likely that an ethnic variation in perimenopausal age exists. Perimenopause age in Indian women was reported to be 44.69 years, which is prominently earlier than any reported perimenopause age for US women as a whole and thus suggestive of differential biological timing of perimenopause present among populations²⁹. More studies with diverse population samples are needed.

Ethnic variation in menopause age

In agreement with wide variation in menopause age across women worldwide, heterogeneity in menopausal age among ethnicities was found only in Hispanics in our study. Hispanic women experienced menopause two years earlier than women of other ethnicities, which mimics the results found for perimenopause age. Again, this result may due to small sample size, but several studies have reported a two year difference in menopausal age between Hispanic and Caucasian women^{30 − 32}. Age of menopause in Hispanic populations has been reported at 48.5 years for 15 countries across Latin America and 47.9 years in Mexican women, whereas Caucasian populations experience menopause at 50 years^{33, 34}. Despite the higher menopausal age recorded in this study (51 vs. 53 years; Fig. 2), which was attributed to differences in methodology, our findings support previous literature. Furthermore, we suggest this difference is unlikely to be the result of lifestyle factors such as smoking prevalence, which accelerates menopause by 1–2 years^{27, 32, 35}. Previous analysis of SWAN participants have shown that smoking frequency was lower among Hispanics than Caucasians and African Americans, which was consistent with other studies^{36, 37}. Hence, the earlier onset in Hispanic women may be due to a different biological clock for the timing of menopause onset compared to other ethnicities.

Studies of candidate gene polymorphisms affecting menopausal age have found that the rs16991615 SNP in MCM8 locus, a gene involved in the repair of double-stranded DNA breaks reduces age at menopause by 2.3 years for Hispanic women³⁸. The samers16991615 SNP exerts the opposite result in Caucasian women, increasing menopausal age by 0.82 years³⁹. The effect of an SNP may vary according to ethnicity, which suggests that menopause may have co-opted different genes in ancestral Hispanic populations.

Whether a difference in menopausal age between African-Americans and Caucasians exists is unclear. Bromberger et al.³⁵ proposed that African-American women experience menopause six months to a year earlier than Caucasian women. This seems plausible given that studies of African women, specifically from Ghana and Nigeria, determined that menopause occurred at 48–49 years, which is earlier than Caucasian women^30,32,34. In contrast, several studies did not report differences in menopausal age between Caucasians and African-Americans^28,30,31. Our findings support the latter, as both the mean and median menopausal age in both ethnicities was similar. It is possible that the small African American sample size (n = 19) and high percentage of smokers could have contributed to Bromberger et al.’s³⁵ observations.

The similarity in menopausal age observed in both African-American and Caucasian women led us to expect similar evolution of menopause in their ancestral populations. Interestingly, however, many of the Caucasian associated SNPs studied in candidate gene polymorphisms associated with menopause age were poorly replicated or not replicable in African-Americans in GWAS studies, which suggest that African-Americans are not as similar to Caucasians as initially believed^39,41. Given the high linkage disequilibrium, African-Americans were suggested to have a variant of the SNP at the associated loci, although it was not identified^{39, 41}. If variants exist in African-Americans, it is possible that the effect of the variant would be similar to the Caucasian SNP to result in the similar phenotype (i.e. menopause age) observed between these two ethnicities. This seems plausible since the SNP findings were able to be replicated in African Americans, such as the rs365132 SNP at the UIMC1 locus, with effects similar to Caucasians (i.e. increased menopausal age by ~ 0.4 years)⁴¹. Further research is required to determine the variation between Caucasians and African-Americans, as SNPs associated with menopause onset in African-Americans have not been well-studied.

Menopausal age for Chinese women from China and Singapore and Japanese women from Japan was roughly 50 years in both populations, which resembles the Caucasian menopausal age^34,41,44. Concurrent with our results, similarity in menopausal age between Caucasian, Chinese, and Japanese women have been reported in the literature^42,45−47. Several SNPs associated with menopausal age in Caucasians were replicated to the same effect and direction in Chinese women from Shanghai, suggesting that there are some shared menopausal evolutionary traits between these two ethnicities⁴⁸.

Recent studies have suggested that Japanese women entered menopause at later ages than Caucasian women^28,30,31,37. While the mean menopausal age did not differ significantly between Caucasian and Japanese women in our study, we did observe a higher percentage of Japanese women entering perimenopause and menopause later than other ethnicities, which supports past findings^28,30,31,37. If differences in menopause age exist between the two ethnicities, this may indicate differences in menopause affecting loci. One study reported several SNPs associated with menopause age in Caucasians could not be replicated in Japanese women in GWAS studies; however this was a very small study³⁹. Further research is needed to determine whether or not Caucasian SNPs can actually be replicated in Japanese women or whether other variants exist.

Ethnic variation in the duration length of perimenopause

This is also the first study reporting the duration of perimenopause among different ethnic groups. In spite of the heterogeneity in the timing of the menopause transition, our findings show that the length of perimenopause was consistent across all ethnicities (Fig. 4). The duration of perimenopause appears negatively correlated with the age of menopause. This result presents the possibility that the intrinsic mechanisms underlying the progressive loss in ovarian function from the perimenopause to menopause stage is shared among individuals. Combined with the data for timing of the menopause transition, it is hypothesized that the timing of onset is what separates the menopause phenotype between ethnicities, as opposed to the duration. Future research can be directed to understanding why and how the timing of menopause has been shifted in different populations over the course of human evolution to result in the current ethnic variation in the onset of the menopause transition. One evolutionary theory explores the idea that women of ancestral populations with lower female biased dispersal would experience earlier menopause, although the required information about ancestral ecologies in these populations is lacking⁴⁹.

McKinlay et al.²⁷ determined the length of perimenopause to be 3.7 years, which was markedly higher than the 1.3 years reported in this study. Again, this can be partly attributed to the definition bias of perimenopause, which would have led to an underestimation of the perimenopause duration in this study (Fig. 4). Alternatively, the methodological differences used to determine the duration was also a factor. For example, McKinlay et al.²⁷ determined duration by subtracting the mean age of menopause from perimenopause onset. This could lead to under/overestimation of the duration since it was not representative of the duration in individuals. There is individual variation in duration of perimenopause; hence, the duration should be determined by averaging the duration in each individual, which was done in this study. Future studies in perimenopause length are encouraged to average individual duration for greater accuracy of the duration. Additionally, further research is needed to determine if the similarity in duration in ethnic groups still exists when early perimenopause is used to define perimenopause onset, as opposed to late perimenopause.

Ethnic variation in hormone concentrations

Across all ethnicities, E2 concentrations declined over the menopause transition, as expected. As the menopause transition progresses, there is progressive loss of ovarian follicles, which produces E2, leading to overall reduced E2 levels³². Consistent with studies conducted by Randolph et al. [50] and Kim et al.⁵¹, mean E2 levels did not differ significantly across ethnicities. Similarities between E2 levels across ethnicities may be linked to earlier observations of the perimenopause duration. Klaiber et al.⁵² noted that women with lower E2 levels had shorter menopause transition duration. Since all ethnicities were similar in E2 levels, the duration was not expected to differ between ethnicities, which are consistent with our results.

Since changes in E2 are correlated to changes in FSH, we did not expect differences in serum FSH across ethnicities either. However, we found a significantly lower FSH increase in Hispanics and African-Americans compared to other ethnicities during the menopause transition. These ethnic differences in FSH levels were thought to be linked to ethnic variation in pituitary-ovarian feedback during the menopause transition, such as variation in estrogen sensitivity^{53 − 55}. Greater sensitivity to estrogen decline is associated with higher FSH levels, as estrogen is a negative regulator of FSH. Examination of polymorphisms in ESR1, which codes for an estrogen receptor, has shown that the rs2234693 polymorphism was significantly associated with Caucasian women menopause onset, although further research is needed for other ethnicities⁵⁶. In contrast, other studies have reported higher FSH levels in Hispanics and African-Americans, regardless of menopausal status^50,53. This was attributed to the lack of adjusted BMI hormonal values in our study and different hormonal collection times. Fundamentally, both our results and Randolph et al.’s^50,53 have consistently noted an ethnic difference in FSH levels.

Similar to FSH levels, there was an ethnic difference in the increase of T levels across the menopause transition. Premenopausal T concentrations did not vary among ethnicities, but in menopausal women, T was significantly higher in Hispanic and African-American women compared to other ethnicities, suggestive of ethnic differences in T metabolism over the menopause transition. Literature to support this observation is scarce because T assays have difficulties reporting the low T concentrations in women, making it challenging to study in menopausal women⁵⁷. A study by Luckey et al.’s⁵⁸ provides a possible indicator of ethnic differences in T metabolism by examining rates of bone loss during the menopause transition, as lower T levels are suggested to contribute to greater bone loss. In Luckey et al.’s⁵⁸ study, African-American women were found to have lower rates of bone loss than white women, suggestive of higher T levels in African-Americans, which is consistent with our findings in this study. Other studies have found lower T levels for African-Americans and Hispanics compared to other ethnicities, which was attributed to BMI adjusted values^50,51. Overall, we can affirm that ethnic variation for T levels exists.

Several studies have correlated changes in SHBG to changes in T, which may suggest that ethnic differences in T could be attributed to ethnic differences in SHBG during the menopause transition^59,60. This was unlikely given that ethnic differences in SHBG in menopausal women and SHBG rate of increase over the menopause transition were not observed, which was consistent with findings from Burger et al.⁵⁹. Alternatively, studies have found associations between DHAS and T, which may also suggest ethnic differences in DHAS as a factor for ethnic differences in T^60,61. While ethnic differences were noted in DHAS levels in both premenopausal women and menopausal women, no ethnic differences were found in the rate of DHAS increase. Similar findings have also been reported in other studies⁵⁹. It thus seems that ethnic differences in DHAS changes are not specifically associated with the menopause transition, and is unlikely to be the cause of ethnic differences in T during the menopause transition, so other factors are likely responsible for the ethnic differences in T changes. One possibility involves androstenediol, which is secreted similarly to DHAS during the menopause transition⁶². Its concentrations are thought to affect the balance of androgens over the menopause transition, hence research determining if ethnic differences exist for androstenediol, along with other possibilities for the ethnic differences in T, would be beneficial⁶².

As mentioned before, there are several limitations to this study. The first is regarding the participants. The age of participants was limited to 42–55 years, which may have biased the perimenopause and menopause age to older ages. This may not be a significant limitation, given that, in a study done by Luborsky et al.³⁷, they reported ethnic variation in premature menopause (menopause age < 40 years) consistent with our study. The exclusion of women with inconsistent bleeding patterns in this study could also have biased the results. Although not shown, we retested our findings with these exceptions added, but overall the findings remained the same. Secondly, late perimenopause was used to define perimenopause onset, leading to an overestimation of perimenopause age, underestimation of menopause duration, and irregularity in premenopausal hormone values. Additionally, use of BMI adjusted hormonal values could have altered our findings, as BMI has been shown to affect hormonal values significantly, positively for T and negatively for all other tested hormonal values⁵³. It is also possible that hormone therapy could have interfered with our findings; however, as explored by Kim et al.⁵¹, hormone therapy does not deviate from the results comparing ethnicities; rather, it only reduces the differences between groups.

A “shifting mate choice-shifting menopause” model of female fertility

The main results regarding variation in age of menopause, from this study as well as others, can be summarized as follows. Firstly, all human populations, regardless of socioeconomic status, show a roughly 15-year window of menopause^{45 − 60}, which means that there is plenty of variation within populations. Secondly, many lifestyle factors are known to affect the age of menopause, but with the exception of premature menopause, the menopause window persists in all populations. Thirdly, there are no significant ethnic differences in the onset age of perimenopause, presumably because there has not been sufficient time since the origin of menopause to produce such differences. Furthermore, as we show below, the absence of variation among populations may indicate the role of similar mate choice mechanisms (i.e. male preference for younger mates) operating in all human populations. Fourth, there are significant changes in the levels of associated hormones within as well as between populations. Finally, different populations show ethnicity/race-specific menopause symptoms; for example, vasomotor symptoms were more common in Afro-American and Hispanic women than in other ethnicities⁶³. This suggests a role of both biological and cultural factors. We take these results to mean that menopause is a relatively recent trait, and most variation in the trait is present within populations with relatively little variation between populations. This is not surprising in view of what is known about human genetic variation in general¹⁹.

We use these results to extend the mate choice theory of menopause¹⁰, which holds that menopause is the result of men’s preference for younger mates, leading to the accumulation of deleterious mutations affecting fertility in women deprived of reproduction. We propose (1) that the present menopause window (roughly 45–60 years) is directly related to the “mate choice window” in the present-day human population (roughly 15–30 years); (2) that the lack of between-variation in perimenopause is the result of a similar mate choice system operating in all human populations; and (3) that changing patterns of mate choice/marriage will ultimately lead to a shift in the onset age of menopause. This shift will not occur immediately as the pressure from the shifting mate choice will only have its effect if women of premenopausal age will choose to engage in reproduction. Under the mate choice theory, menopause is a transient phase of male-imposed female fertility and it will be delayed with changing patterns of delayed mate choice/marriage and reproduction.

Older Brothers and Male Homosexuality: Antibodies as an Explanation

Older Brothers and Male Homosexuality: Antibodies as an Explanation. T.S. Sathyanarayana Rao, Chittaranjan Andrade. Journal of Psychosexual Health, August 9, 2019. https://doi.org/10.1177/2631831819855199

The familial nature of homosexuality in men has been known for decades.1 The finding is gender-specific; homosexual men have a higher proportion of homosexual brothers than heterosexual men, but not a higher proportion of homosexual sisters.2

It has also been known for decades that homosexual men have a lower birth order, on average, than heterosexual men.3, 4 More specifically, homosexual men have a greater number of older brothers but not older sisters, younger brothers, or younger sisters.5

The evidence for the fraternal birth order effect is strong. There is a very large number of studies on the subject, and these studies have been subjected to meta-analysis. In this meta-analysis,6 the strength of the effect in persons from small versus large families and in homosexual males with masculine gender identities versus those with feminine gender identities were compared.

The meta-analysis included 30 homosexual and 30 heterosexual groups from 26 studies. The pooled sample included 7140 homosexual and 12,837 heterosexual males. The outcome variable of interest, the older brothers odds ratio (OR), was calculated as follows:

First, an older brothers ratio was calculated for homosexuals and heterosexuals separately. This value was the number of older brothers divided by the number of all other siblings.

Next, the older brothers OR was calculated as the older brothers ratio in homosexuals divided by that in heterosexuals. This OR is interpreted in the conventional way; a value of 1 indicates no fraternal birth order effect and values >1 indicate support for the fraternal birth order hypothesis.

Important findings from the meta-analysis are presented in Box 1. In summary, the meta-analysis found that having a larger number of older brothers was associated with a significantly increased risk of homosexual orientation, especially feminine or transgender homosexual orientation. This fraternal birth order effect was unrelated to family size. Of interest, the meta-analysis also found that only about 15% to 29% of men in any given homosexual group could attribute their sexual orientation to the fraternal birth order effect.

Why should having (more) older brothers increase the risk of homosexuality in men? A superficially plausible explanation is that fraternal sexual exposure or experimentation in childhood may behaviorally prime individuals towards a homosexual orientation. This explanation fails because it does not explain why having younger brothers does not predispose to male homosexuality or why the same-sex sibling effect does not exist for women.

The fraternal birth order effect has therefore led to a search for biological explanations, and an in utero maternal immune response has been suggested.7, 8 In this context, Bogaert et al.9 examined plasma from mothers of male offspring about half of whom had a gay son, and controls, comprising men as well as women with no sons. They used immune assays to study whether mothers develop antibodies against two Y-linked proteins that are important in male brain development in utero, and whether this effect strengthens with succeeding male gestations. The proteins that they studied were protocadherin 11 Y-linked (PCDH11Y) and neuroligin 4 Y-linked (NLGN4Y; isoforms 1 and 2).

Important findings from the study of Bogaert et al.9 are presented in Box 2. In summary, the findings suggested that the maternal immune response against a Y-linked protein (that is important in male brain development in utero) is associated with homosexual orientation in sons. This protein, the NLGN4Y protein, is a cell-adhesion protein that plays a vital role in cell-cell interactions, specifically in the process of synapse formation, during in utero neurodevelopment.7

At the risk of stating the obvious, it must be noted that the development of sexual orientation is multifactorial and depends on biological and social influences from the womb through early life. Nevertheless, if an antibody response can be confirmed as an etiological factor, might primary prevention interventions be possible?