Facial width-to-height ratio (fWHR) has been proposed as a sexually dimorphic signal in humans that develops under the influence of pubertal testosterone (T); however, no studies have examined the association between fWHR and T during the phase in which facial growth is canalized—adolescence. In a sample of adolescent Tsimane males, we evaluate the relationship between T, known T-derived traits (i.e. strength and voice pitch), and craniofacial measurements. If fWHR variation derives from T’s effect on craniofacial growth during adolescence, several predictions should be supported: 1) fWHR should increase with age as T increases, 2) fWHR should reflect adolescent T (rather than adult T per se), 3) fWHR should exhibit velocity changes during adolescence in parallel with the pubertal spurt in T, 4) fWHR should correlate with T after controlling for age and other potential confounds, and 5) fWHR should show strong associations with other T-derived traits. Only prediction 4 was observed. Additionally, we examined three alternative facial masculinity ratios: facial width/lower face height, cheekbone prominence, and facial width/full face height. In contrast to fWHR, all three alternative measures show a strong age-related trend and are associated with both T and T-dependent traits. Overall, our results question the status of fWHR as a sexually-selected signal of pubertal T and T-linked traits.

Social liberals tend to be less pathogen-avoidant than social conservatives, a pattern consistent with a model wherein ideological differences stem from differences in threat reactivity. Here we investigate if and how individual responses to a shared threat reflect those patterns of ideological difference. In seeming contradiction to the general association between social conservatism and pathogen avoidance, the more socially conservative political party in the United States has more consistently downplayed the dangers of COVID-19 during the ongoing pandemic. This puzzle offers an opportunity to examine the contributions of multiple factors to disease avoidance. We investigated the relationship between social conservatism and COVID-19 precautionary behavior in light of the partisan landscape of the United States. We explored whether consumption of, and attitudes toward, different sources of information, as well as differential evaluation of various threats caused by the pandemic—such as direct health costs versus indirect harms to the economy and individual liberties—shape partisan differences in responses to the pandemic in ways that overwhelm the contributions of social conservatism. In two pre-registered studies, socially conservative attitudes correlate with self-reported COVID-19 prophylactic behaviors, but only among Democrats. Reflecting larger societal divisions, among Republicans and Independents, the absence of a positive relationship between social conservatism and COVID-19 precautions appears driven by lower trust in scientists, lower trust in liberal and moderate sources, lesser consumption of liberal news media, and greater economic conservatism.

Consistent with a threat-bias model of ideological differences, social liberals have been shown to be less pathogen-avoidant than tradition-valuing social conservatives. However, particularly when pathogen threat occurs at a societal level, additional factors may influence individual responses. In the current pandemic, the more socially conservative U.S. political party has consistently downplayed the dangers of COVID-19. This creates a natural experiment, allowing examination of the contributions of multiple factors to disease avoidance. We investigated the relationship between social conservatism and COVID-19 precautionary behavior in light of the partisan landscape, exploring whether consumption of, and attitudes toward, different sources of information, as well as differential evaluation of various threats caused by the pandemic—such as direct health costs versus indirect harms to the economy and individual liberties—shape political differences in responses to the pandemic in ways that mask the contributions of social conservatism. In two studies, socially conservative attitudes correlate with self-reported COVID-19 prophylactic behaviors, but only among Democrats. Reflecting larger societal divisions, among Republicans and Independents, the positive relationship between social conservatism and COVID-19 precautions is jointly suppressed by lower trust in scientists, lower trust in liberal and moderate sources, lesser consumption of liberal news media, and greater economic conservatism.

Disgust has long been viewed as a primary motivator of defensive responses to threats posed by both microscopic pathogens and macroscopic ectoparasites. Although disgust can defend effectively against pathogens encountered through ingestion or incidental contact, it offers limited protection against ectoparasites, which actively pursue a host and attach to its surface. Humans might, therefore, possess a distinct ectoparasite defence system—including cutaneous sensory mechanisms and grooming behaviours—functionally suited to guard the body's surface. In two US studies and one in China, participants ( N = 1079) viewed a range of ectoparasite- and pathogen-relevant video stimuli and reported their feelings, physiological sensations, and behavioural motivations. Participants reported more surface-guarding responses towards ectoparasite stimuli than towards pathogen stimuli, and more ingestion/contamination-reduction responses towards pathogen stimuli than towards ectoparasite stimuli. Like other species, humans appear to possess evolved psychobehavioural ectoparasite defence mechanisms that are distinct from pathogen defence mechanisms.

Abstract

Conservatives and liberals have previously been shown to differ in the propensity to view socially-transmitted information about hazards as more plausible than that concerning benefits. Given differences between conservatives and liberals in threat sensitivity and dangerous-world beliefs, correlations between political orientation and negatively-biased credulity may thus reflect endogenous mindsets. Alternatively, such results may owe to the political hierarchy at the time of previous research, as the tendency to see dark forces at work is thought to be greater among those who are out of political power. Adjudicating between these accounts can inform how societies respond to the challenge of alarmist disinformation campaigns. We exploit the consequences of the 2016 U.S. elections to test these competing explanations of differences in negatively-biased credulity and conspiracism as a function of political orientation. Two studies of Americans reveal continued positive associations between conservatism, negatively-biased credulity, and conspiracism despite changes to the power structure in conservatives’ favor.

No abstract

People vary in the extent to which they embrace their society’s traditions, impacting a range of social and political phenomena. People also vary in the degree to which they perceive disparate dangers as salient and necessitating a response. Over evolutionary time, traditions likely regularly offered direct and indirect avenues for addressing hazards; consequently, via multiple possible pathways, orientations toward tradition and toward danger may have become associated. Emerging research documents connections between individual differences in traditionalism and variation in threat responsivity in general, and pathogen-avoidance motivations in particular. Importantly, because threat-mitigating behaviors can conflict with competing priorities, the precise associations between traditionalism and pathogen avoidance likely depend on contextually contingent costs and benefits. The COVID-19 pandemic requires individuals to make decisions about consequential and costly pathogen-avoidance behaviors that can clash with other priorities. The pandemic therefore provides a real-world setting in which to test the posited relationship between traditionalism and pathogen avoidance across socio-political contexts. Across 27 societies (N = 7,844), we find that costly COVID-19-avoidance behaviors positively correlate with greater endorsement of traditional norms and values in a majority of countries. Accounting for the conflict that arises in some societies between public health precautions and competing priorities, such as the exercise of personal liberties, reveals a consistent relationship between traditionalism and COVID-19 precautions across an even wider range of social and cultural contexts. These findings support the thesis that traditionalism is associated with an enhanced tendency to attend to hazards.