A critique of life history approaches to human trait covariation

Covariation of life history traits across species may be organised on a ‘fast-slow’ continuum. A burgeoning literature in psychology and social science argues that trait covariation should be similarly organised across individuals within human populations. Here we describe why extrapolating from inter-species to inter-individual trait covariation is not generally appropriate. The process that genetically tailors species to their environments (i.e. Darwinian evolution) is fundamentally different from processes that tailor individuals to their environments (e.g. developmental plasticity), so their outcomes in terms of trait covariation need not be parallel or even related. We discuss why correlational selection, physical linkage, pleiotropy, and non-random mating do not substantively affect this claim in the context of complex human traits. We also discuss life history trade-offs and their relation to inter-individual trait covariation. We conclude that researchers should avoid hypotheses and explanations that assume trait covariation will correspond across and within species, unless they can mount a theoretically coherent argument to support this claim in the context of their research question

Women's pathogen disgust predicting preference for facial masculinity may be specific to age and study design

Facial masculinity in men is thought to be an indicator of good health. Consistent with this idea, previous research has found a positive association between pathogen avoidance (disgust sensitivity) and preference for facial masculinity. However, previous studies are mostly based on young adult participants and targets, using forced-choice preference measures; this begs the question whether the findings generalise to other adult age groups or other preference measures. We address this by conducting three studies assessing facial masculinity preferences of a wider age range of women for a wider age range of male faces. In studies 1 and 2, 447 and 433 women respectively made forced choices between two identical faces that were manipulated on masculinity/femininity. In study 1, face stimuli were manipulated on sexual dimorphism using age-matched templates, while in study 2 young face stimuli were manipulated with older templates and older face stimuli were manipulated using young templates. In the full sample for study 1, no association was found between women's pathogen disgust and masculinity preference, but when limiting the sample to younger women rating younger faces we replicated previous findings of significant association between pathogen disgust and preference for facial masculinity. Results for study 2 found no effect of pathogen disgust sensitivity on facial masculinity preferences regardless of participant and stimuli age. In study 3, the facial masculinity preferences of 386 women were revealed through their attractiveness ratings of natural (unmanipulated) faces. Here, we did not find a significant association of pathogen disgust on facial masculinity preferences, regardless of participant and stimuli age. These results call into question the robustness of the link between women's pathogen avoidance and facial masculinity preference, and raise questions as to why the effect is specific to younger adults and the forced-choice preference measure

Pathogen disgust sensitivity and resource scarcity are associated with mate preference for different waist-to-hip ratios, shoulder-to-hip ratios, and body mass index

Environmental factors, such as pathogen prevalence and resource scarcity, are thought to influence mate preferences for traits related to health and resource provisioning potential. Specific body dimensions, such as women's waist-to-hip-ratio (WHR), men’s shoulder-to-hip ratio (SHR), and body mass index (BMI) have also been theorised to be associated with health benefits, or ability to deal with resource scarcity. Here, we test across two studies using different study designs whether the effects of pathogen disgust sensitivity and socioeconomic status (SES; a negative proxy for resource scarcity) on mate preferences extend to men’s WHR preferences, women’s SHR preferences, and both sex’s BMI preferences. Study 1 found that pathogen disgust significantly negatively influenced men’s WHR preference in female bodies, while SES was significantly negatively associated with women’s SHR and BMI preferences in male bodies. Study 2 found that pathogen disgust negatively predicted men’s WHR preference, and positively predicted women’s SHR preference, while SES negatively predicted men’s WHR preference. Our findings support the notion that body shapes are used as cues to health and likelihood of resource provision, and may help explain inconsistencies in the literature regarding variation in body shapes preferences

Facial Trustworthiness is Associated with Heritable Aspects of Face Shape

Facial trustworthiness is thought to underlie social judgements in face perception, though it is unclear whether trustworthiness judgements are based on stable facial attributes. If this were the case, we could expect a genetic component of facial trustworthiness. From facial photographs of a large sample of identical and nonidentical twins and siblings (1320 individuals), we tested for genetic variation in facial trustworthiness and genetic covariation with several stable facial attributes, including facial attractiveness, two measures of masculinity, and facial width-to-height ratio. We found a significant genetic component of facial trustworthiness in men (but not women), and significant genetic correlations with the stable morphological facial traits of attractiveness (positive), perceived masculinity (negative), and facial width-to-height ratio (negative). However, there was no significant genetic or shared environmental correlation between facial trustworthiness and an objective masculinity score based on facial landmark coordinates, despite there being a significant phenotypic correlation. Our results suggest that heritable facial traits influence trustworthiness judgements

Sex differences in misperceptions of sexual interest can be explained by sociosexual orientation and men projecting their own interest onto women

Sex differences in misperceptions of sexual interest have been well documented; however, it is unclear whether this cognitive bias could be explained by other factors. In the current study, 1226 participants (578 men, 630 women) participated in a speed-dating study, where participants rated their sexual interest in each other as well as the sexual interest they perceived from their partners. Consistent with previous findings, we found that men tended to overperceive sexual interest from their partners, while women tended to underperceive sexual interest. However, this sex difference becomes negligible when considering potential mediators, such as the raters’ sociosexual orientation, and raters projecting their own levels of sexual interest onto their partners. These findings challenge the popular notion that sex differences in misperceptions in sexual interest have evolved as a specialised adaptation due to different selection pressures in men and women

A multivariate approach to human mate preferences

Human mate choice is complicated, with various individual differences and contextual factors influencing preferences for numerous traits. However, focused studies on human mate choice often do not capture this multivariate complexity. Here, we consider multiple factors simultaneously to demonstrate the advantages of a multivariate approach to human mate preferences. Participants (N = 689) rated the attractiveness of opposite-sex online dating profiles that were independently manipulated on facial attractiveness, perceived facial masculinity/femininity, and intelligence. Participants were also randomly instructed to either consider short- or long-term relationships. Using fitness surfaces analyses, we assess the linear and nonlinear effects and interactions of the profiles' facial attractiveness, perceived facial masculinity/femininity, and perceived intelligence on participants' attractiveness ratings. Using hierarchical linear modeling, we were also able to consider the independent contribution of participants' individual differences on their revealed preferences for the manipulated traits. These individual differences included participants' age, socioeconomic status, education, disgust (moral, sexual, and pathogen), sociosexual orientation, personality variables, masculinity, and mate value. Together, our results illuminate various previously undetectable phenomena, including nonlinear preference functions and interactions with individual differences. More broadly, the study illustrates the value of considering both individual variation and population-level measures when addressing questions of sexual selection, and demonstrates the utility of multivariate approaches to complement focused studies

Assessing the accuracy of perceptions of intelligence based on heritable facial features

Perceptions of intelligence based on facial features can have a profound impact on many social situations, but findings have been mixed as to whether these judgements are accurate. Even if such perceptions were accurate, the underlying mechanism is unclear. Several possibilities have been proposed, including evolutionary explanations where certain morphological facial features are associated with fitness-related traits (including cognitive development), or that intelligence judgements are over-generalisation of cues of transitory states that can influence cognition (e.g., tiredness). Here, we attempt to identify the morphological signals that individuals use to make intelligence judgements from facial photographs. In a genetically informative sample of 1660 twins and their siblings, we measured IQ and also perceptions of intelligence based on facial photographs. We found that intelligence judgements were associated with both stable morphological facial traits (face height, interpupillary distance, and nose size) and more transitory facial cues (eyelid openness, and mouth curvature). There was a significant association between perceived intelligence and measured IQ, but of the specific facial attributes only interpupillary distance (i.e., wide-set eyes) significantly mediated this relationship. We also found evidence that perceived intelligence and measured IQ share a familial component, though we could not distinguish between genetic and shared environmental sources

No relationship between intelligence and facial attractiveness in a large, genetically informative sample

Theories in both evolutionary and social psychology suggest that a positive correlation should exist between facial attractiveness and general intelligence, and several empirical observations appear to corroborate this expectation. Using highly reliable measures of facial attractiveness and IQ in a large sample of identical and fraternal twins and their siblings, we found no evidence for a phenotypic correlation between these traits. Likewise, neither the genetic nor the environmental latent factor correlations were statistically significant. We supplemented our analyses of new data with a simple meta-analysis that found evidence of publication bias among past studies of the relationship between facial attractiveness and intelligence. In view of these results, we suggest that previously published reports may have overestimated the strength of the relationship and that the theoretical bases for the predicted attractiveness–intelligence correlation may need to be reconsidered

The association of genetic predisposition to depressive symptoms with non-suicidal and suicidal self-Injuries

Non-suicidal and suicidal self-injury are very destructive, yet surprisingly common behaviours. Depressed mood is a major risk factor for non-suicidal self-injury (NSSI), suicidal ideation and suicide attempts. We conducted a genetic risk prediction study to examine the polygenic overlap of depressive symptoms with lifetime NSSI, suicidal ideation, and suicide attempts in a sample of 6237 Australian adult twins and their family members (3740 females, mean age\ua0=\ua042.4\ua0years). Polygenic risk scores for depressive symptoms significantly predicted suicidal ideation, and some predictive ability was found for suicide attempts; the polygenic risk scores explained a significant amount of variance in suicidal ideation (lowest p\ua0=\ua00.008, explained variance ranging from 0.10 to 0.16\ua0%) and, less consistently, in suicide attempts (lowest p\ua0=\ua00.04, explained variance ranging from 0.12 to 0.23\ua0%). Polygenic risk scores did not significantly predict NSSI. Results highlight that individuals genetically predisposed to depression are also more likely to experience suicidal ideation/behaviour, whereas we found no evidence that this is also the case for NSSI