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Previous work has examined how specific personality dimensions are associated with social network characteristics. However, it is unclear how the full range of personality traits relates to the quantity and quality of relationships at different network layers. This study ( N = 525) investigates how the six HEXACO personality dimensions relate to the size of support and sympathy groups, and to the level of emotional closeness to network members. Extraversion was positively related to support group size, but did not significantly relate to sympathy group size or emotional closeness. Openness to Experience and Emotionality were positively related to support group size, but not to the size of the sympathy group. Honesty–Humility, but not Agreeableness, was positively related to emotional closeness to members of the sympathy group. Findings suggest that personality effects vary across network layers and highlight the importance of considering both emotional closeness and network size. [ABSTRACT FROM AUTHOR]

In this paper we consider whether people with similar personality traits have a preference for common locations. Due to the difficulty in tracking and categorising the places that individuals choose to visit, this is largely unexplored. However, the recent popularity of location-based social networks (LBSNs) provides a means to gain new insight into this question through checkins - records that are made by LBSN users of their presence at specific street level locations. A web-based participatory survey was used to collect the personality traits and checkin behaviour of 174 anonymous users, who, through their common check-ins, formed a network with 5373 edges and an approximate edge density of 35%. We assess the degree of overlap in personality traits for users visiting common locations, as detected by user checkins. We find that people with similar high levels of conscientiousness, openness or agreeableness tended to have checked-in locations in common. The findings for extraverts were unexpected in that they did not provide evidence of individuals assorting at the same locations, contrary to predictions. Individuals high in neuroticism were in line with expectations, they did not tend to have locations in common. Unanticipated results concerning disagreeableness are of particular interest and suggest that different venue types and distinctive characteristics may act as attractors for people with particularly selective tendencies. These findings have important implications for decision-making and location. [ABSTRACT FROM AUTHOR]

Heterosexual age preferences have been extensively studied by evolutionary psychologists, social psychologists, and demographers. Much less is known about such preferences in homosexual men and women. Around two decades ago, D. T. Kenrick, R. C. Keefe, A. Bryan, A. Barr, and S. Brown (1995) examined heterosexual and homosexual mating preferences for age in men and women. Our study aimed to replicate these findings by examining age preferences in a larger UK online dating sample. Dating advertisements of 996 male and female heterosexuals and homosexuals were coded. Age preferences were assessed via generalized linear models with robust standard errors and bootstrapping. Results showed that the relation between own age and preferred age differed substantially between the groups. With increasing age, heterosexual men preferred younger partners. Older heterosexual men (>50 years) exclusively sought (much) younger women than themselves, whereas younger heterosexual men sought both older and younger women. Male and female homosexuals followed this general trend of preferring increasingly younger mates with increasing age. However, they displayed a higher upper age tolerance and greater range of acceptable ages than both heterosexual men and women. Female heterosexuals' age preferences were distinct from the other groups, in that they displayed a male older norm with no substantial interest expressed in males younger than themselves. Our findings thus largely corroborate those of Kenrick et al. with some exceptions, such as a larger tolerance of age ranges in homosexual men and women compared to heterosexual men and women. Results are discussed with reference to the current literature on similarities and differences in heterosexual and homosexual mate preferences. [ABSTRACT FROM AUTHOR]

Psychological research frequently encounters criticism regarding the representativeness of the samples under study, highlighting concerns about the external validity of the obtained results. Here, we conducted a comprehensive survey of all the quantitative samples from the journal Body Image for 2021 (n = 149 samples). Our primary objective was to examine the extent to which the sampled populations deviated from the population at large, which could potentially compromise the generalizability of findings. We identified that a substantial number of these samples came from student populations (n = 44) and the majority were from the United States, United Kingdom, and Australia. Only a small number of samples (n = 9) employed direct measurements of body mass index (BMI), while the majority relied on self-reported data (n = 93). For a subset of samples in the journal, which were drawn from the general population, we compared whether these differed from population reference values in terms of age and BMI. Using Monte Carlo simulations, we found that samples tended to be younger and score lower on BMI than reference values obtained from the broader population. Samples drawn from female university students also tended to be lower on BMI than age-matched reference samples. We discuss the implications of our findings and make recommendations on sampling and inference. We conclude that a clearer specification of the parameters or conditions under which findings are expected to generalise has the potential to enhance the overall rigor and validity of this field of research., Competing Interests: Declaration of Competing Interest No conflict of interests are known to the authors., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Previously observed negative correlations between sample size and effect size (n-ES correlation) in psychological research have been interpreted as evidence for publication bias and related undesirable biases. Here, we present two studies aimed at better understanding to what extent negative n-ES correlations reflect such biases or might be explained by unproblematic adjustments of sample size to expected effect sizes. In Study 1, we analysed n-ES correlations in 150 meta-analyses from cognitive, organizational, and social psychology and in 57 multiple replications, which are free from relevant biases. In Study 2, we used a random sample of 160 psychology papers to compare the n-ES correlation for effects that are central to these papers and effects selected at random from these papers. n-ES correlations proved inconspicuous in meta-analyses. In line with previous research, they do not suggest that publication bias and related biases have a strong impact on meta-analyses in psychology. A much higher n-ES correlation emerged for publications' focal effects. To what extent this should be attributed to publication bias and related biases remains unclear., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Linden et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Personality factors affect the properties of 'offline' social networks, but how they are associated with the structural properties of online networks is still unclear. We investigated how the six HEXACO personality factors (Honesty-Humility, Emotionality, Extraversion, Agreeableness, Conscientiousness and Openness to Experience) relate to Facebook use and three objectively measured Facebook network characteristics - network size, density, and number of clusters. Participants ( n = 107, mean age = 20.6, 66% female) extracted their Facebook networks using the GetNet app, completed the 60-item HEXACO questionnaire and the Facebook Usage Questionnaire. Users high in Openness to Experience spent less time on Facebook. Extraversion was positively associated with network size (number of Facebook Friends). These findings suggest that some personality factors are associated with Facebook use and the size of Facebook networks, and that personality is an important influence on both online and offline sociality.

To examine the relationships within and between commonly used measures of loneliness to determine the suitability of the measures in older adults. Further, to determine whether certain items in these measures are more psychometrically robust in terms of capturing different types of loneliness across this population. Data were obtained from 350 older adults via completion of an online survey. Four measures of loneliness were completed. These were the University of California Los Angeles Loneliness Scale 4 (Version 3), the de Jong Gierveld Loneliness Scale, the Social and Emotional Loneliness Scale for Adults (Short Version) and a direct measure of loneliness. Analysis via a regularized partial correlation network and via clique percolation revealed that only the SELSA-S encompassed loneliness relating to deficits in social, family and romantic relationships. The remaining measures tapped mostly into social loneliness alone. The direct measure of loneliness had the strongest connection to the UCLA item-4 and the de Jong Gierveld item-1 exhibited the strongest bridge centrality, being a member of the most clusters. The results indicate that should researchers be interested in assessing loneliness resulting from specific relationships, then the SELSA-S would be the most suitable measure. Whereas the other measures are suitable for assessing loneliness more generally. The results further suggest that the de Jong Gierveld item-1 may be a more suitable direct measure of loneliness than that currently employed as it taps into a greater number of relationships., Competing Interests: Conflicting interestsThe Authors declare that there is no conflict of interest., (© The Author(s) 2023.)

Collisson et al. (2020) found Dark Triad traits and gender role beliefs predicted "foodie calls," a phenomenon where people go on a date with others, to whom they are not attracted, for a free meal. Because gender roles and dating norms differ across cultures, we conducted a registered replication across different cultures by surveying 1838 heterosexual women from Poland, the United Kingdom (UK), and the United States (US). Relying on the structural equation modeling, as conducted in the original study, our findings revealed gender role beliefs best predicted foodie calls and their perceived acceptability, whereas the Dark Triad's general factor was nonsignificant. Analyses at the country level yielded mixed results. The original findings were replicated in the UK and Poland, but not in the US, where only narcissism predicted foodie calls. In the US, gender role beliefs predicted foodie call acceptability, but the Dark Triad general factor did not. Potential reasons for why traditional gender roles, but not the Dark Triad, predicted foodie calls in the US are discussed.

Studies have indicated that people are attracted to partners who resemble themselves or their parents, in terms of physical traits including eye color. We might anticipate this inclination to be relatively stable, giving rise to a sequential selection of similar partners who then represent an individual's "type". We tested this idea by examining whether people's sequential partners resembled each other at the level of eye color. We gathered details of the eye colors of the partners of participants (N = 579) across their adult romantic history (N = 3250 relationships), in three samples, comprising two samples which made use of self-reports from predominantly UK-based participants, and one which made use of publicly available information about celebrity relationship histories. Recorded partner eye colors comprised black (N = 39 partners), dark brown (N = 884), light brown (N = 393), hazel (N = 224), blue (N = 936), blue green (N = 245), grey (N = 34), and green (N = 229). We calculated the proportion of identical eye colors within each participant's relationship history, and compared that to 100,000 random permutations of our dataset, using t-tests to investigate if the eye color of partners across an individual's relationship history was biased relative to chance (i.e., if there was greater consistency, represented by higher calculated proportions of identical eye colors, in the original dataset than in the permutations). To account for possible eye color reporting errors and ethnic group matching, we ran the analyses restricted to White participants and to high-confidence eye color data; we then ran the analyses again in relation to the complete dataset. We found some limited evidence for some consistency of eye color across people's relationship histories in some of the samples only when using the complete dataset. We discuss the issues of small effect sizes, partner-report bias, and ethnic group matching in investigating partner consistency across time., (© 2022. The Author(s).)

Background: High levels of loneliness are associated with negative health outcomes and there are several different types of interventions targeted at reducing feelings of loneliness. It is therefore important to accurately measure loneliness. A key unresolved debate in the conceptualisation and measurement of loneliness is whether it has a unidimensional or multidimensional structure. The aim of this study was to examine the dimensional structure of the widely used UCLA Loneliness Scale and establish whether this factorial structure is equivalent in men and women., Methods and Sample: Two online UK-based samples were recruited using Prolific. The participants in Study 1 were 492 adults, selected to be nationally representative by age and gender, whilst the participants in Study 2 were 290 older adults aged over 64. In both studies, participants completed the UCLA Loneliness Scale (Version 3) as part of a larger project., Results: In both studies, the best fitting model was one with three factors corresponding to 'Isolation,' 'Relational Connectedness,' and 'Collective Connectedness.' A unidimensional single factor model was a substantially worse fit in both studies. In both studies, there were no meaningful differences between men and women in any of the three factors, suggesting measurement invariance across genders., Conclusion: These results are consistent with previous research in supporting a multidimensional, three factor structure to the UCLA scale, rather than a unidimensional structure. Further, the measurement invariance across genders suggests that the UCLA scale can be used to compare levels of loneliness across men and women. Overall the results suggest that loneliness has different facets and thus future research should consider treating the UCLA loneliness scale as a multidimensional scale, or using other scales which are designed to measure the different aspects of loneliness., Competing Interests: We have read the journal’s policy and the authors of this manuscript have the following competing interests: TVP/SGBR have been supported by Facebook Research via an Instagram Research Award. This does not alter our adherence to PLOS ONE policies on sharing data and materials., (Copyright: © 2022 Pollet et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Psychological concerns are frequently indexed by psychometric questionnaires but the mental representations that they seek to quantify are difficult to visualise. We used a set of questionnaires designed to measure men's concept of their bodies including: the Drive for Muscularity Scale (DMS; McCreary & Sasse, 2000), the Perceived Sociocultural Pressures Scale (PSPS; Stice, Nemeroff, & Shaw, 1996a), the Body Appreciation Scale (BAS-2; Tylka & Wood-Barcalow, 2015), and the Sociocultural Attitudes Towards Appearance Questionnaire-3 (SATAQ-3; Thompson, van den Berg, Roehrig, Guarda, & Heinberg, 2004). We combined their use with an interactive 3D modelling programme to allow men to create computer-generated representations of their ideal bodies. We used a principal component analysis to extract those shape components of our participants' CGI ideal bodies that were predicted by the questionnaires and reconstructed the body shapes that these questionnaires were capturing. Moving from the lowest to the highest score on both the DMS and SATAQ corresponded with changes in muscularity, particularly muscle mass and definition. This approach allows us to demonstrate the actual body features that are being captured by a particular questionnaire., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Verbal denigration of personal body size and shape ("fat talk") is correlated with, and can have a causal influence on body dissatisfaction and disordered eating. What is less clear is who is most likely to fat talk. To address this, Corning and Gondoli (2012) conducted a study confirming that a woman's body dissatisfaction directly predicted their fat talk. But this effect was scaled so that the likelihood of engaging in fat talk intensified if she had a stronger tendency to socially compare: the relationship was multiplicative. Here, we carried out two replications of Corning and Gondoli's (2012) study, the first with 189 UK participants and the second with 371 US participants. We found that multiple regression models predicting fat talk showed additive, but not multiplicative relationships. A robust Bayesian meta-analysis combining the results of our two studies with the results of the original study confirmed this. In conclusion, these studies show an additive relationship between fat talk and social comparison on fat talk., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Purpose: Stress is associated with subjective and objective sleep disturbances; however, it is not known whether stress disrupts sleep and relevant physiological markers of stress immediately after it is experienced. The present study examined whether demand, in the form of cognitive tasks, disrupted sleep and the cortisol awakening response (CAR), depending on whether it was experienced or just anticipated., Participants and Methods: Subjective and objective sleep was measured in 22 healthy adults on three nights (Nights 0-2) in a sleep laboratory using sleep diaries and polysomnography. Saliva samples were obtained at awakening, +15, +30, +45 and +60 minutes on each subsequent day (Day 1-3) and CAR measurement indices were derived: awakening cortisol levels, the mean increase in cortisol levels (MnInc) and total cortisol secretion (AUC G ). On Night 1, participants were informed that they were required to complete a series of demanding cognitive tasks within the sleep laboratory during the following day. Participants completed the tasks as expected or unexpectedly performed sedentary activities., Results: Compared to the no-demand group, the demand group displayed significantly higher levels of state anxiety immediately completing the first task. There were no subsequent differences between the demand and no-demand groups in Night 2 subjective sleep continuity, objective sleep continuity or architecture, or on any Day 3 CAR measure., Conclusion: These results indicate that sleep and the CAR are not differentially affected depending on whether or not an anticipated stressor is then experienced. This provides further evidence to indicate that the CAR is a marker of anticipation and not recovery. In order to disrupt sleep, a stressor may need to be personally relevant or of a prolonged duration or intensity., Competing Interests: The authors declare that they have no financial or non-financial competing interests., (© 2020 Elder et al.)

Middleborns have been argued to be the neglected birth order. The present study aimed to test whether the emotional closeness to parents, siblings or friends differed between middleborns and otherborns, across two different datasets. Using a between family design this study accounted for gender, nationality, educational attainment, age and sibship size via matching. We found no evidence to suggest that middleborns differ from otherborns in familial sentiment. The sign of closeness to friends was in the opposite direction than predicted, with middleborns being less close than other birth orders. The findings are discussed with reference to current literature on birth order and familial sentiment., (© 2020 The Authors.)

Background: Male height is positively associated with social dominance, and more agonistic/competitive behaviours. However, the 'Napoleon complex' or 'small man syndrome' suggests that smaller males are more assertive and punitive to compensate for lack of height and social dominance. Here, we assess possible relationships between height and punitive behaviours in a real-world setting., Methods: Using a non-experimental correlational design, we analysed data on 61 male association football referees from four professional leagues in England, and explored relationships between their height and punitive behaviours in the form of yellow cards, red cards and penalties given during an entire season., Results: Overall there was no effect of referee height on fouls awarded. However, there was a main effect of height on yellow cards awarded, with shorter referees issuing more yellow cards. The same effect was found for red cards and penalties, though this was moderated by league. In the lower leagues, more red cards and penalties were awarded by relatively shorter referees, but in the higher leagues more red cards and penalties were awarded by relatively taller referees., Conclusions: These findings from real-life public dominance encounters show that height is associated with punitive behaviours, but is sensitive to context.

We used a high-level adaptation paradigm to distinguish between two hypotheses: (1) perceptual and attitudinal body image measurements reflect conceptually different mechanisms which are statistically independent of each other; (2) attitudinal (e.g., questionnaire) and perceptual (e.g., visual yes-no) body image tasks represent two different ways of measuring exactly the same construct. Forty women, with no history of eating disorders, carried out the experiment. Each participant carried out five adaptation blocks, with adapting stimuli representing female bodies at: extreme-low body mass index (BMI), mid-low BMI, actual BMI of the observer, mid-high BMI, and extreme-high BMI. Block order was randomized across participants. The main outcome variable was percentage error in participants' self-estimates of body size, measured post-adaption. In regressions of this percentage error on the strength of the adapting stimuli together with observers' attitudinal body image as a covariate, we found positive regression slopes and no evidence for any interaction between the fixed effects. Therefore, we conclude that perceptual and attitudinal body image mechanisms are indeed independent of each other. In the light of this evidence, we discuss how people with eating disorders, like anorexia nervosa, may come to over-estimate their body size., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A modified version of the bubbles masking paradigm was used in three experiments to determine the key areas of the body that are used in self-estimates of body size. In this paradigm, parts of the stimuli are revealed by several randomly allocated Gaussian "windows" forcing judgements to be made based on this partial information. Over multiple trials, all potential cues are sampled, and the effectiveness of each window at predicting the judgement is determined. The modified bubbles strategy emphasises the distinction between central versus edge cues and localises the visual features used in judging one's own body size. In addition, eye-movements were measured in conjunction with the bubbles paradigm and the results mapped onto a common reference space. This shows that although observers fixate centrally on the torso, they are actually directing their visual attention to the edges of the torso to gauge body width as an index of body size. The central fixations are simply the most efficient way of positioning the eye to make this estimation. Inaccurate observers are less precise in their central fixations and do not evenly allocate their attention to both sides of the torso's edge, illustrating the importance of efficiently sampling the key information., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Research on group cohesion often relies on individual perceptions, which may not reflect the actual social structure of groups. This study draws on social network theory to examine the relationship between observable structural group characteristics and individual perceptions of group cohesion. Leveraging Facebook data, we extracted and partitioned the social networks of 109 participants into groups using a modularity algorithm. We then surveyed perceptions of cohesion, and computed group density and size using social network analysis. Out of six linear mixed effects models specified, a random intercept and fixed slope model with group size as a predictor of perceived group cohesion emerged as best fitting. Whereas group density was not linked to perceived cohesion, size had a small negative effect on perceived cohesion, suggesting that people perceive smaller groups as more cohesive. We discuss the potential of social network analysis, visualization tools, and Facebook data for advancing research on groups., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Human adult sex ratios have been studied extensively across the biological and social sciences. While several studies have examined adult sex ratio effects in a multilevel perspective, many studies have focused on effects at an aggregated level only. In this paper, we review some key issues relating to such analyses. We address not only nation-level analyses, but also aggregation at lower levels, to investigate whether these issues extend to lower levels of aggregation. We illustrate these issues with novel databases covering a broad range of variables. Specifically, we discuss distributional issues with aggregated measures of adult sex ratio, significance testing, and statistical non-independence when using aggregate data. Firstly, we show that there are severe distributional issues with national adult sex ratio, such as extreme cases. Secondly, we demonstrate that many 'meaningless' variables are significantly correlated with adult sex ratio (e.g. the max. elevation level correlates with sex ratio at US state level). Finally, we re-examine associations between adult sex ratios and teenage fertility and find no robust evidence for an association at the aggregate level. Our review highlights the potential issues of using aggregate data on adult sex ratios to test hypotheses from an evolutionary perspective in humans.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'., (© 2017 The Author(s).)

Many recent evolutionary psychology and human behavioral ecology studies have tested hypotheses by examining correlations between variables measured at a group level (e.g., state, country, continent). In such analyses, variables collected for each aggregation are often taken to be representative of the individuals present within them, and relationships between such variables are presumed to reflect individual-level processes. There are multiple reasons to exercise caution when doing so, including: (1) the ecological fallacy, whereby relationships observed at the aggregate level do not accurately represent individual-level processes; (2) non-independence of data points, which violates assumptions of the inferential techniques used in null hypothesis testing; and (3) cross-cultural non-equivalence of measurement (differences in construct validity between groups). We provide examples of how each of these gives rise to problems in the context of testing evolutionary hypotheses about human behavior, and we offer some suggestions for future research.

Variation in testosterone (T) is thought to affect the allocation of effort between reproductive and parenting strategies. Here, using a large sample of elderly American men (n = 754) and women (n = 669) we examined the relationship between T and self-reported parenthood, as well as the relationship between T and number of reported children. Results supported previous findings from the literature, showing that fathers had lower T levels than men who report no children. Furthermore, we found that among fathers T levels were positively associated with the number of children a man reports close to the end of his lifespan. Results were maintained when controlling for a number of relevant factors such as time of T sampling, participant age, educational attainment, BMI, marital status and reported number of sex partners. In contrast, T was not associated with either motherhood or the number of children women had, suggesting that, at least in this sample, T does not influence the allocation of effort between reproductive and parenting strategies among women. Findings from this study contribute to the growing body of literature suggesting that, among men, pair bonding and paternal care are associated with lower T levels, while searching and acquiring sex partners is associated with higher T levels.

We predicted that the perceived likelihood of acquiring a hoped-for thin self would mediate perfectionistic strivings on dietary restraint, and that the perceived likelihood of acquiring a feared fat self would mediate perfectionistic concerns on dietary restraint. We also predicted that the mediation pathway from perfectionistic concerns to dietary restraint would have a greater impact than that from perfectionistic strivings. Participants were 222 female college students who reported their height and weight and completed measures of perfectionism, the likelihood of acquiring the feared fat and hoped-for thin selves, and dietary restraint. Statistical analyses revealed that the perceived likelihood of acquiring the feared fat self mediated both perfectionistic concerns and perfectionistic strivings on dietary restraint, and that the mediating pathway from perfectionistic concerns to dietary restraint was greater than that from perfectionistic strivings. Implications for future research and eating pathology interventions are discussed., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The present research examined how a preference for influencing the mate choice of one's offspring is associated with opposition to out-group mating among parents from three ethnic groups in the Mexican state of Oaxaca: mestizos (people of mixed descent, n = 103), indigenous Mixtecs (n = 65), and blacks (n = 35). Nearly all of the men in this study were farmworkers or fishermen. Overall, the level of preferred parental influence on mate choice was higher than in Western populations, but lower than in Asian populations. Only among the Mixtecs were fathers more in favor of parental influence on the mate choice of children than mothers were. As predicted, opposition to out-group mating was an important predictor of preferred parental influence on mate choice, more so among fathers than among mothers, especially in the mestizo group-the group with the highest status. In addition, women, and especially mestizo women, expressed more opposition to out-group mating than men did.

Human male height is associated with mate choice and intra-sexual competition, and therefore potentially with reproductive success. A literature review (n = 18) on the relationship between male height and reproductive success revealed a variety of relationships ranging from negative to curvilinear to positive. Some of the variation in results may stem from methodological issues, such as low power, including men in the sample who have not yet ended their reproductive career, or not controlling for important potential confounders (e.g. education and income). We investigated the associations between height, education, income and the number of surviving children in a large longitudinal sample of men (n = 3,578; Wisconsin Longitudinal Study), who likely had ended their reproductive careers (e.g. > 64 years). There was a curvilinear association between height and number of children, with men of average height attaining the highest reproductive success. This curvilinear relationship remained after controlling for education and income, which were associated with both reproductive success and height. Average height men also married at a younger age than shorter and taller men, and the effect of height diminished after controlling for this association. Thus, average height men partly achieved higher reproductive success by marrying at a younger age. On the basis of our literature review and our data, we conclude that men of average height most likely have higher reproductive success than either short or tall men. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00265-011-1283-2) contains supplementary material, which is available to authorized users.

Testosterone (T) has been argued to modulate mating and parenting behavior in many species, including humans. The role of T for these behaviors has been framed as the challenge hypothesis. Following this hypothesis, T should be positively associated with the number of opposite sex partners a male has. Indeed research in humans has shown that T is positively related to the number of opposite sex partners a young man has had. Here we test, in both men and women, whether this relationship extends to the lifetime number of sex partners. We also explored whether or not T was associated with current marital status, partnership status and whether or not the participant remarried. Using a large sample of elderly men and women (each sample n>700), we show that T is positively and sizably associated with the number of opposite sex partners in men. When controlling for potential confounding variables such as educational attainment, age, BMI, ethnicity, specific use of a medication and time of sampling this effect remained. For women, the relationship between T and number of opposite sex partners was positive but did not prove to be robust. In both men and women there was no evidence for an association between T and current marital status and partnership status (being in a relationship or not). However, remarriage was positively associated with T, but only in males. Results are discussed with reference to the literature on T and sex partners, remarriage and more broadly the challenge hypothesis., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The 'helpers at the nest' hypothesis suggests that individuals who are not currently reproducing often help kin by caretaking and thereby increase their inclusive fitness. Using a large scale historical dataset (Integrated Public Use Microdata Series sample of 1910; n=13,935), the hypothesis is tested that childless couples are more likely to fulfil such a role by taking care of a niece or nephew, but not a parent, than couples with children. Childless couples were significantly more likely to take care of a niece or nephew than couples with children. In contrast, couples with children and childless couples did not differ in caretaking of parents. Childless couples were also more likely to have more and younger nieces/nephews in their home than couples with children.