Men display faster in male-biased mating contexts.

Across diverse species with sexual reproduction, typically the more male-biased the adult sex ratio (ASR), the greater the investments by the more populous males in the rarer females who hold greater bargaining power in a mating context. Relatively few studies have examined this effect in humans however, and almost none involve observations of actual male investment in a potential mating context. Here, we present one of the first studies to observe investments of men in a potential mating context under differing ASRs. Across 163 mixed-sex groups from three taverns on 7 days of observation, we measured both a group's ASR and each group's leading man's latency to position himself at the tavern's bar to order and pay for beverages. The higher the proportion of men in a group (ASR) and the fewer the absolute number of women in a group, the faster the leading man in the group travelled to reach the bar to order and pay for beverages. Results are consistent with the hypothesis that similar to males in many species, men tactically regulate their investments to adapt to the fluctuation in the ASR in order to maximize their probabilities of attracting a mate.