Males in many non-monogamous species have larger ranges than females do, a sex difference that has been well documented for decades and seems to be an aspect of male mating competition. Until recently, parallel data for humans have been mostly anecdotal and qualitative, but this is now changing as human behavioral ecologists turn their attention to matters of individual mobility. Sex differences in spatial cognition were among the first accepted psychological sex differences and, like differences in ranging behavior, are documented (...) for a growing set of species. This special issue is dedicated to exploring the possible adaptive links between these cognitive and ranging traits. Multiple hypotheses, at various levels of analysis, are considered. At the functional (ultimate) level, a mating-competition hypothesis suggests that range expansion may augment mating opportunities, and a fertility-and-parental-care hypothesis suggests that range contraction may facilitate offspring provisioning. At a more mechanistic (proximate) level, differences in cue availability may support or inhibit particular sex-specific navigation strategies, and spatial anxiety may usefully inhibit travel that would not justify its costs. Studies in four different cultures—Twe, Tsimane, Yucatec Maya, and Faroese—as well as an experimental study using virtual reality tools are the venue for testing these hypotheses. Our hope is to stimulate more research on the evolutionary and developmental processes responsible for this suite of linked behavioral and cognitive traits. (shrink)

In a study of the kin investment of aunts and uncles we show that the laterality effect expected as a result of paternity uncertainty is statistically reliable but somewhat smaller than the sex effect. Matrilateral aunts invest significantly more than patrilateral aunts, and the same is true for uncles. Regardless of laterality, however, aunts invest significantly more than uncles. Multivariate controls show that the matrilateral bias is fully independent of any age or distance confounds that might result from sex differences (...) in age at marriage or dispersal. We discuss our results in relation to recent findings on the kin investment of grandparents (Euler and Weitzel 1996). In addition, we propose a simple method for estimating the level of paternity uncertainty from kin investment data; application of this method to our data on aunts and uncles suggests that between 13% and 20% of children are not the offspring of their putative father. Our parallel analyses of Euler and Weitzel’s (1996) data on grandparental investment suggest a similar estimate, that paternity uncertainty lies between 9% and 17%. (shrink)

Gaulin, McBurney, and Brakeman-Wartell (1997) found that college students reported both matrilateral and sex biases in the investment of aunts and uncles (aunts invested more than uncles). They interpreted the matrilateral bias as a consequence of paternity uncertainty. We replicated that study with Orthodox Jewish college students, selected because they come from a population we presume to have higher paternity certainty than the general population. The Orthodox sample also showed matrilateral and sex biases. Comparing the two data sets, the Orthodox (...) sample reported more investment, and slightly less matrilateral and sex biases, but the differences were not statistically significant. We did find an interaction between sex of relative and group membership, resulting from greater investment by Orthodox uncles. We interpret the results as reflecting the operation of a facultative investment mechanism whose upper limit is tuned to the maximum levels of paternity certainty found in ancestral environments. Lack of a difference in matrilateral bias between groups may result from levels of paternity certainty near to, or above, that maximum in both groups. (shrink)

Low mean fundamental frequency (F 0) in men’s voices has been found to positively influence perceptions of dominance by men and attractiveness by women using standardized speech. Using natural speech obtained during an ecologically valid social interaction, we examined relationships between multiple vocal parameters and dominance and attractiveness judgments. Male voices from an unscripted dating game were judged by men for physical and social dominance and by women in fertile and non-fertile menstrual cycle phases for desirability in short-term and long-term (...) relationships. Five vocal parameters were analyzed: mean F 0 (an acoustic correlate of vocal fold size), F 0 variation, intensity (loudness), utterance duration, and formant dispersion (D f , an acoustic correlate of vocal tract length). Parallel but separate ratings of speech transcripts served as controls for content. Multiple regression analyses were used to examine the independent contributions of each of the predictors. Physical dominance was predicted by low F 0 variation and physically dominant word content. Social dominance was predicted only by socially dominant word content. Ratings of attractiveness by women were predicted by low mean F 0, low D f , high intensity, and attractive word content across cycle phase and mating context. Low D f was perceived as attractive by fertile-phase women only. We hypothesize that competitors and potential mates may attend more strongly to different components of men’s voices because of the different types of information these vocal parameters provide. (shrink)

This study aims to investigate assortative mating based on mate value from male perspective. Male participants (132 Brazilian and 106 American) evaluated hypothetical “stimulus” males described in terms of physical attractiveness, social skills, and social status (each varied in high or low levels). Participants rated each stimulus and each stimulus' preferred mating partner on nine traits. The results showed that (1) positive assortative mating was expected in romantic relationships; (2) the stimulus ratings did not vary independently, suggesting that mate value (...) is the result of the interaction of the characteristics of individuals; and (3) that participants expected physically attractive and healthier female partners to pair with high-status male stimuli. The American and Brazilian mating expectations were similar, minor differences indicate that Brazilian participants considered men with high levels of social skills to be more ambitious and intelligent; American participants expected men of high status to be healthier; Brazilians expect men of high status to have more attractive faces, while Americans expected these men to possess more attractive bodies; and Brazilian participants assigned more attractive bodies to men of lower status. These differences reflect the influence of economic and cultural factors on the local environment. The study contributes to the understanding of the construction of market value and reveals that male expectations are in line with human mating preferences. The investigation of mating expectations can be a rich approach to investigate socio-cultural aspects that are related to mating in different cultures. (shrink)

With respect to aggressiveness it is not enough to say that humans are We resemble only those species where males have higher maximum reproductive rates than females. In such species males evolve a set of hormonally mediated competitive traits via sexual selection. Because humans match the predictions of this general evolutionary model, attempts to (re)explain men's aggressiveness in sociological terms are superfluous and misleading.