John H. Shaver

Human preferences for sexually dimorphic faces may be evolutionarily novel

Significance It is a popular assumption that certain perceptions—for example, that highly feminine women are attractive, or that masculine men are aggressive—reflect evolutionary processes operating within ancestral human populations. However, observations of these perceptions have mostly come from modern, urban populations. This study presents data on cross-cultural perceptions of facial masculinity and femininity. In contrast to expectations, we find that in less developed environments, typical “Western” perceptions are attenuated or even reversed, suggesting that Western perceptions may be relatively novel. We speculate that novel environments, which expose individuals to large numbers of unfamiliar faces, may provide novel opportunities—and motives—to discern subtle relationships between facial appearance and other traits. A large literature proposes that preferences for exaggerated sex typicality in human faces (masculinity/femininity) reflect a long evolutionary history of sexual and social selection. This proposal implies that dimorphism was important to judgments of attractiveness and personality in ancestral environments. It is difficult to evaluate, however, because most available data come from large-scale, industrialized, urban populations. Here, we report the results for 12 populations with very diverse levels of economic development. Surprisingly, preferences for exaggerated sex-specific traits are only found in the novel, highly developed environments. Similarly, perceptions that masculine males look aggressive increase strongly with development and, specifically, urbanization. These data challenge the hypothesis that facial dimorphism was an important ancestral signal of heritable mate value. One possibility is that highly developed environments provide novel opportunities to discern relationships between facial traits and behavior by exposing individuals to large numbers of unfamiliar faces, revealing patterns too subtle to detect with smaller samples.

Effects of Anxiety on Spontaneous Ritualized Behavior

Environmental uncertainty and uncontrollability cause psycho-physiological distress to organisms, often impeding normal functioning. A common response involves ritualization, that is, the limitation of behavioral expressions to predictable stereotypic and repetitive motor patterns. In humans, such behaviors are also symptomatic of psychopathologies like obsessive-compulsive disorder (OCD) and autism spectrum disorders (ASDs). Although these reactions might be mediated by different neural pathways, they serve to regain a sense of control over an uncertain situation by engaging in behavioral patterns characterized by redundancy (superfluous actions that exceed the functional requirements of a goal), repetitiveness (recurrent behaviors or utterances), and rigidity (emphasis on fidelity and invariance). We examined whether ritualized behavior will manifest spontaneously as a dominant behavioral strategy in anxiogenic situations. Manipulating anxiety, we used motion-capture technology to quantify various characteristics of hand movements. We found that induced anxiety led to an increase in repetitiveness and rigidity, but not redundancy. However, examination of both psychological and physiological pathways revealed that repetitiveness and rigidity were predicted by an increase in heart rate, while self-perceived anxiety was a marginally significant predictor of redundancy. We suggest that these findings are in accordance with an entropy model of uncertainty, in which anxiety motivates organisms to return to familiar low-entropy states in order to regain a sense of control. Our results might inform a better understanding of ritual behavior and psychiatric disorders whose symptoms include over-ritualization.

How does male ritual behavior vary across the lifespan? An examination of Fijian kava ceremonies.

Ritual behaviors of some form exist in every society known to anthropologists. Despite this universality, we have little understanding of how ritual behavior varies within populations or across the lifespan, nor the determinants of this variation. Here we test hypotheses derived from life history theory by using behavioral observations and oral interview data concerning participant variation in Fijian kava-drinking ceremonies. We predicted that substantial variation in the frequency and duration of participation would result from (1) trade-offs with reproduction and (2) the intrinsic status differences between ritual participants. We demonstrate that when controlling for household composition, men with young offspring participated less frequently and exhibited greater variance in their time spent at ceremonies than men without young children. However, men with a larger number of total dependents in their household participated more frequently than those with fewer. Moreover, we found that men’s ascribed rank, level of education, and reliance on wage labor all significantly predict their frequency of attendance. We also found that the number of dependents a man has in his household is positively correlated with total food production, and the amount of kava he cultivates. In general, these results suggest that ritual participation is part of an important strategy employed by Fijian men for both achieving status and developing social alliances. Variation in participation in kava ceremonies by Fijian men therefore reflects the constraints of their current life history condition and their inherited rank.

The evolution of stratification in Fijian ritual participation

Social scientists have long sought to explain the complex relationships between religion and social inequality. Building from a recent theoretical model, I predict that social hierarchies influence the cultural evolution of ritual systems and explain substantial intracultural variation in ritual behavior. The present work investigates these predictions using historical data and an analysis of observational and ethnographic interview data collected in a contemporary Fijian village. Historical data indicate that status differences between Fijians and missionaries and those between chiefs and commoners influenced the nature of Fijian religion and the socio-ecological environment in which contemporary ritual behavior takes place. Contemporary Fijian ritual life includes participation in Christian church services, and also kava-drinking ceremonies that evolved from the indigenous religion. Observational data reveal that performance within each ritual format is significantly influenced by the age and ascribed status differences of participants, and that high-ranking men are more likely to attend church services while low-ranking men are more likely to attend kava ceremonies. Moreover, a mans ascribed status significantly predicts his achieved role in the church, with higher-ranking men more likely to be lay preachers, and low-ranking men more likely to be members of the choir. These findings point to the importance of developing multilevel approaches to the study of religion and suggest that social inequality exerts an important influence on the cultural evolution of ritual systems.

Neural correlates of mystical experience.

Mystical experiences, or subjectively believed encounters with a supernatural world, are widely reported across cultures and throughout human history. Previous theories speculate that executive brain functions underpin mystical experiences. To evaluate causal hypotheses, structural studies of brain lesion are required. Previous studies suffer from small samples or do not have valid measures of cognitive functioning prior to injury. We investigated mystical experience among participants from the Vietnam Head Injury Study and compared those who suffered penetrating traumatic brain injury (pTBI; n=116) with matched healthy controls (HC; n=32). Voxel-based lesion-symptom mapping analysis showed that lesions to frontal and temporal brain regions were linked with greater mystical experiences. Such regions included the dorsolateral prefrontal cortex (dlPFC) and middle/superior temporal cortex (TC). In a confirmatory analysis, we grouped pTBI patients by lesion location and compared mysticism experiences with the HC group. The dlPFC group presented markedly increased mysticism. Notably, longitudinal analysis of pre-injury data (correlating with general intelligence and executive performance) excludes explanations from individual differences. Our findings support previous speculation linking executive brain functions to mystical experiences, and reveal that executive functioning (dlPFC) causally contributes to the down-regulation of mystical experiences.

Anxiety and ritualization: Can attention discriminate compulsion from routine?

ABSTRACT Despite the wide occurrence of ritual behavior in humans and animals, much of its causal underpinnings, as well as evolutionary functions, remain unknown. A prominent line of research focuses on ritualization as a response to anxiogenic stimuli. By manipulating anxiety levels, and subsequently assessing their motor behavior dynamics, our recent study investigated this causal link in a controlled way. As an extension to our original argument, we here discuss 2 theoretical explanations of rituals—ritualized behavior and automated behavior—and their link to anxiety. We propose that investigating participants locus of attention can discriminate between these 2 models.

News exposure predicts anti-Muslim prejudice

News coverage of Islamic extremism is reigniting debates about the media’s role in promoting prejudice toward Muslims. Psychological theories of media-induced prejudice date to the 1950’s, and find support from controlled experiments. However, national-scale studies of media effects on Muslim prejudice are lacking. Orthogonal research investigating media-induced prejudice toward immigrants has failed to establish any link. Moreover, it has been found that people interpret the news in ways that confirm pre-existing attitudes, suggesting that media induced Muslim prejudice in liberal democracies is unlikely. Here, we test the association between news exposure and anti-Muslim prejudice in a diverse national sample from one of the world’s most tolerant societies, where media effects are least likely to hold (N = 16,584, New Zealand). In support of media-induced Islamophobia, results show that greater news exposure is associated with both increased anger and reduced warmth toward Muslims. Additionally, the relationship between media exposure and anti-Muslim prejudice does not reliably vary with political ideology, supporting claims that it is widespread representations of Muslims in the news, rather than partisan media biases, that drives anti-Muslim prejudice.

Religion and the Unmaking of Prejudice toward Muslims: Evidence from a Large National Sample

In the West, anti-Muslim sentiments are widespread. It has been theorized that inter-religious tensions fuel anti-Muslim prejudice, yet previous attempts to isolate sectarian motives have been inconclusive. Factors contributing to ambiguous results are: (1) failures to assess and adjust for multi-level denomination effects; (2) inattention to demographic covariates; (3) inadequate methods for comparing anti-Muslim prejudice relative to other minority group prejudices; and (4) ad hoc theories for the mechanisms that underpin prejudice and tolerance. Here we investigate anti-Muslim prejudice using a large national sample of non-Muslim New Zealanders (N = 13,955) who responded to the 2013 New Zealand Attitudes and Values Study. We address previous shortcomings by: (1) building Bayesian multivariate, multi-level regression models with denominations modeled as random effects; (2) including high-resolution demographic information that adjusts for factors known to influence prejudice; (3) simultaneously evaluating the relative strength of anti-Muslim prejudice by comparing it to anti-Arab prejudice and anti-immigrant prejudice within the same statistical model; and (4) testing predictions derived from the Evolutionary Lag Theory of religious prejudice and tolerance. This theory predicts that in countries such as New Zealand, with historically low levels of conflict, religion will tend to increase tolerance generally, and extend to minority religious groups. Results show that anti-Muslim and anti-Arab sentiments are confounded, widespread, and substantially higher than anti-immigrant sentiments. In support of the theory, the intensity of religious commitments was associated with a general increase in tolerance toward minority groups, including a poorly tolerated religious minority group: Muslims. Results clarify religion’s power to enhance tolerance in peaceful societies that are nevertheless afflicted by prejudice.

Sync to link: Endorphin-mediated synchrony effects on cooperation

Behavioural synchronization has been shown to facilitate social bonding and cooperation but the mechanisms through which such effects are attained are poorly understood. In the current study, participants interacted with a pre-recorded confederate who exhibited different rates of synchrony, and we investigated three mechanisms for the effects of synchrony on likeability and trusting behaviour: self-other overlap, perceived cooperation, and opioid system activation measured via pain threshold. We show that engaging in highly synchronous behaviour activates all three mechanisms, and that these mechanisms mediate the effects of synchrony on liking and investment in a Trust Game. Specifically, self-other overlap and perceived cooperation mediated the effects of synchrony on interpersonal liking, while behavioural trust was mediated only by change in pain threshold. These results suggest that there are multiple compatible pathways through which synchrony influences social attitudes, but endogenous opioid system activation, such as β-endorphin release, might be important in facilitating economic cooperation.

Selective reading and selectionist thinking: Why violence has been, and should be, important to the cognitive science of religion

We agree with Martin and Wiebe that CSR researchers would benefit from the insights of ethnographers and historians and we commend them for drawing attention to both the prosocial and violent aspects of religion, as we think both are crucial for understanding religion’s role in human sociality. Here we stress this point by drawing attention to the socioecological conditions under which we expect violence associated with religion to occur between, as well as within, groups. We begin, however, by noting that Martin and Wiebe’s reading of the CSR literature is selective; despite their protestations, violence has been a topic of considerable interest to CSR researchers for some time. In fact, major contributors to CSR including Scott Atran, Dominic Johnson, and Harvey Whitehouse have all written books and numerous articles focusing on the violent side of religion (e.g. Atran 2003, 2010; Johnson 2008; Johnson and Reeve 2013; Johnson and Toft 2014; Whitehouse 1995, 1996; Whitehouse and McGuinn 2013). The second author of this commentary has also written various pieces that aim to explain religious violence (e.g. Alcorta and Sosis 2013; Sosis 2011; Sosis and Alcorta 2008; Sosis et al. 2007; Sosis et al. 2012). And most notably, Norenzayan, who takes the brunt of Martin and Wiebe’s criticism concerning CSR’s alleged prosociality bias, has published several important papers on religious violence (e.g. Hansen and Norenzayan 2006; Ginges et al. 2009). All of this literature was curiously ignored in the target article. In light of Martin and Wiebe’s concern that Templeton is leading CSR’s supposed “Kumbayah” festivities, we should also point out that Templeton has funded all of these researchers. Ultimately, to assess Martin and Wiebe’s contention, we recommend a systematic meta-analysis to determine whether a prosociality bias genuinely exists in the