The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Drawing on evolutionary, criminological, developmental, and personality theories, we predicted that sex differences would be most pronounced in risky activities with men demonstrating greater sensation seeking, greater reward sensitivity and lower punishment sensitivity. We predicted a small female advantage in effortful control.We analyzed 741 effect sizes from 277 studies, including psychometric and Shepherd, 1990). Men are more physically and verbally aggressive than women across data sources and nations (Archer, 2004(Archer, , 2009 Bettencourt & Miller, 1996; Eagly & Steffen, 1986; Hyde, 1986; Knight, Fabes & Higgins, 1996 Frank, 2000; Gershon & Gershon, 2002; Kessler et al., 2006; Moffitt, Caspi & Rutter, 2001).In all of these domains, impulsivity has been invoked as an explanatory variable. Sometimes impulsivity is embedded in a theory or model, but more often it Sex differences in impulsivity 4 appears as an independent variable in regression analyses along with other plausible explanatory candidates. It is surprisingly rare, however, that sex differences in social and psychological pathologies have been considered in relation to sex differences in impulsivity in society at large. The present study uses meta-analysis to examine whether there are average sex differences in unselected community samples across a range of psychometric and behavioral measures of impulsivity. We also examine whether, in these samples, variance in men's impulsivity scores is greater than women's. Such a finding could explain men's over-representation in extreme and problematic impulsive behaviors. (Though men would also be overrepresented at the left as well as the right tail of the distribution, low levels of impulsivity are unlikely to attract attention from educational, medical or judicial systems.) Impulsivity: Models, measures, and sex differences.

Hominin reliance on Oldowan stone tools – which appear from 2.5mya and are believed to have been socially transmitted – has been hypothesised to have led to the evolution of teaching and language. Here we present an experiment investigating the efficacy of transmission of Oldowan tool-making skills along chains of adult human participants (N=184) using 5 different transmission mechanisms. Across six measures, transmission improves with teaching, and particularly with language, but not with imitation or emulation. Our results support the hypothesis that hominin reliance on stone tool-making generated selection for teaching and language and imply that (i) low-fidelity social transmission, such as imitation/emulation, may have contributed to the ~700,000 year stasis of the Oldowan technocomplex, and (ii) teaching or proto-language may have been pre-requisites for the appearance of Acheulean technology. This work supports a gradual evolution of language, with simple symbolic communication preceding behavioural modernity by hundreds of thousands of years.

Men score higher than women on measures of sensation-seeking, defined as a willingness to engage in novel or intense activities. This sex difference has been explained in terms of evolved psychological mechanisms or culturally transmitted social norms. We investigated whether sex differences in sensation-seeking have changed over recent years by conducting a meta-analysis of studies using Zuckerman's Sensation Seeking Scale, version V (SSS-V). We found that sex differences in total SSS-V scores have remained stable across years, as have sex differences in Disinhibition and Boredom Susceptibility. In contrast, the sex difference in Thrill and Adventure Seeking has declined, possibly due to changes in social norms or out-dated questions on this sub-scale. Our results support the view that men and women differ in their propensity to report sensation-seeking characteristics, while behavioural manifestations of sensation-seeking vary over time. Sex differences in sensation-seeking could reflect genetically influenced predispositions interacting with socially transmitted information.

AcknowledgementsWe are grateful to Alex Mesoudi, Volker Franz and two anonymous reviewers for comments on the manuscript. The research was supported in part by an ERC Advanced Grant (EVOCULTURE, Ref. 232823) awarded to KNL.Sex differences in confidence and conformity 2 AbstractLack of confidence in one's own ability can increase the likelihood of relying on social information.Sex differences in confidence have been extensively investigated in cognitive tasks, but implications for conformity have not been directly tested. Here, we tested the hypothesis that, in a task that shows sex differences in confidence, an indirect effect of sex on social information use will also be evident. Participants (N=168) were administered a mental rotation (MR) task or a letter transformation (LT) task. After providing an answer, participants reported their confidence before seeing the responses of demonstrators and being allowed to change their initial answer. In the MR, but not the LT, task, women showed lower levels of confidence than men, and confidence mediated an indirect effect of sex on the likelihood of switching answers. These results provide novel, experimental evidence that confidence is a general explanatory mechanism underpinning susceptibility to social influences. Our results have implications for the interpretation of the wider literature on sex differences in conformity.Sex differences in confidence and conformity 3

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Men's greater use of direct aggression is not evident in studies of intimate partner aggression. In previous research, the effects of target sex and relationship intimacy have frequently been confounded. This study sought to examine these effects separately. One hundred and seventy-four participants (59 male and 115 female) read vignette scenarios in which they were provoked by a same-sex best friend, an opposite-sex best friend, and a partner. For each target, participants estimated their likely use of direct physical and verbal aggression as well as noninjurious forms of anger expression. Results showed that men lower their aggression in the context of an intimate partnership and that this is an effect of the target's sex. In contrast, women raise their aggression in the context of an intimate partnership and this is an effect of intimacy with the target. The use of noninjurious angry behavior did not vary between targets for either sex of the participant, which suggests that the effects of target are confined to behaviors which carry an intention to harm. Possible effects of social norms and oxytocin-mediated emotional disinhibition on intimate partner aggression are discussed.

Humans are sexually dimorphic: men and women differ in body build and composition, craniofacial structure, and voice pitch, likely mediated in part by developmental testosterone. Sexual selection hypotheses posit that, ancestrally, more 'masculine' men may have acquired more mates and/or sired more viable offspring. Thus far, however, evidence for either association is unclear. Here, we meta-analyze the relationships between six masculine traits and mating/reproductive outcomes (96 studies, 474 effects, N = 177,044). Voice pitch, height, and testosterone all predicted mating; however, strength/muscularity was the strongest and only consistent predictor of both mating and reproduction. Facial masculinity and digit ratios did not significantly predict either. There was no clear evidence for any effects of masculinity on offspring viability. Our findings support arguments that strength/muscularity may be sexually selected in humans, but cast doubt regarding selection for other forms of masculinity and highlight the need to increase tests of evolutionary hypotheses outside of industrialized populations.

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