Mean target response latencies for Study 1 are depicted in this figure.

<p><b>A</b> shows mean reaction times to the target probe when it follows own - and other - race faces and is presented in the attended and unattended locations (with SE bars) for the Face-at-unattended-locus trials. <b>B</b> shows mean reaction times to the target probe when it follows own – and other – race faces and is presented in the attended and unattended locations (with SE bars) for the Face-at-attended-locus trials. * p<0.05.</p

Participants' mean target probe response latencies (ms) for each condition (with standard deviations).

<p>Participants' mean target probe response latencies (ms) for each condition (with standard deviations).</p

Chronological Age, Cognitive Ability, SCQ, ADOS-G and CFMT-C scores for children with autism and typically developing children.

<p>Notes. <b>^a</b>Non-verbal and Verbal IQ were each measured with two subtests of the WISC-IV (Wechsler, 2003); Non-verbal IQ = Matrix Reasoning and Picture Completion, Verbal IQ = Similarities and Vocabulary. ^bHigher scores on both the parent-report Social Communication Questionnaire (SCQ); Rutter et al., 2003) and the ADOS-G (Autism Diagnostic Observation Schedule – Generic, Lord et al., 2000) indicate a greater degree of autistic symptomatology. Score reported = Communication+Social Interaction algorithm total (cutoffs: autism = 10, autism spectrum = 7). ^cn = 15 for the autism sample, n = 18 for the typical sample. ^dAccuracy (total correct) scores on the Cambridge Face Memory Test – for Children (maximum = 60).</p

Foo et al. beta-carotene supplementation study dataset

Foo et al. beta-carotene supplementation study datase

This figure depicts the experimental sequence for Study 1.

<p><b>A</b> shows the two sequences of displays for the Face-at-unattended-locus trials: target probe in the attended location (top) and target probe in the unattended location (bottom). <b>B</b> shows the two sequences of displays for the Face-at-attended locus: target probe in the attended location (top) and target probe in the unattended location (bottom).</p

Relationship between mate guarding frequency and the unstandardized residuals of PC3 (after accounting for the influence of lifestyle and collection variables), which describes ejaculates with a high concentration of sperm and sperm that do not move erratically.

<p>Relationship between mate guarding frequency and the unstandardized residuals of PC3 (after accounting for the influence of lifestyle and collection variables), which describes ejaculates with a high concentration of sperm and sperm that do not move erratically.</p

Sperm Competition in Humans: Mate Guarding Behavior Negatively Correlates with Ejaculate Quality

<div><p>In species where females mate with multiple males, the sperm from these males must compete to fertilise available ova. Sexual selection from sperm competition is expected to favor opposing adaptations in males that function either in the avoidance of sperm competition (by guarding females from rival males) or in the engagement in sperm competition (by increased expenditure on the ejaculate). The extent to which males may adjust the relative use of these opposing tactics has been relatively neglected. Where males can successfully avoid sperm competition from rivals, one might expect a decrease in their expenditure on tactics for the engagement in sperm competition and vice versa. In this study, we examine the relationship between mate guarding and ejaculate quality using humans as an empirical model. We found that men who performed fewer mate guarding behaviors produced higher quality ejaculates, having a greater concentration of sperm, a higher percentage of motile sperm and sperm that swam faster and less erratically. These effects were found independent of lifestyle factors or factors related to male quality. Our findings suggest that male expenditure on mate guarding and on the ejaculate may represent alternative routes to paternity assurance in humans.</p></div

Mean d′ for own-race and other-race faces. Error bars show standard errors of the mean.

<p>Mean d′ for own-race and other-race faces. Error bars show standard errors of the mean.</p

Contour plot showing the correlations between voice pitch, rated masculinity and attractiveness (colour "heat" corresponds to increasing voice pitch, which ranged from 85.3–134.2 Hz, blue being low pitch and red being high pitch).

<p>Contour plot showing the correlations between voice pitch, rated masculinity and attractiveness (colour "heat" corresponds to increasing voice pitch, which ranged from 85.3–134.2 Hz, blue being low pitch and red being high pitch).</p

Means (±SE) of the sperm parameters, and the principal components analysis of their variation.

<p>VAP, average path velocity; VSL, straight line velocity; VCL, curvilinear velocity; ALH, lateral amplitude of sperm head; BCF, cross beat frequency; STR, straightness; LIN, linearity.</p