Body height is a life-history component. It involves important costs for its expression and maintenance, which may originate trade-offs on other costly components such as reproduction or immunity. Although previous evidence has supported the idea that human height could be a sexually selected trait, the explanatory mechanisms that underlie this selection are poorly understood. Despite extensive studies on the association between height and attractiveness, the role of immunity in linking this relation is scarcely studied, particularly in non-Western populations. Here, we tested whether human height is related to health measured by self-perception, and relevant nutritional and health anthropometric indicators in three Latin-American populations that widely differ in socioeconomic and ecological conditions: two urbanised populations from Bogota (Colombia) and Mexico City (Mexico), and one isolated indigenous population (Me’Phaa, Mexico). Results showed that self-reported health is best predicted by an interaction between height and waist circumference: the presumed benefits of being taller are waist-dependent, and affect taller people more than shorter individuals. If health and genetic quality cues play an important role in human mate-choice, and height and waist interact to signal health, its evolutionary consequences, including cognitive and behavioural effects, should be addressed in future research.

Non-verbal behaviours, including voice characteristics during speech, are an important way to communicate social status. Research suggests that individuals can obtain high social status through dominance (using force and intimidation) or through prestige (by being knowledgeable and skillful). However, little is known regarding differences in the vocal behaviour of men and women in response to dominant and prestigious individuals. Here, we tested within-subject differences in vocal parameters of interviewees during simulated job inter-views with dominant, prestigious, and neutral employers (targets), while responding to questions which were classified as introductory, personal, and interpersonal. We found that vocal modulations were apparent between responses to the neutral and high-status targets, with participants, especially those who perceived themselves as low in dominance, increasing fundamental frequency (F0) in response to the dominant and prestigious targets relative to the neutral target. Self-perceived prestige, however, was less related to contextual vocal modulations than self-perceived dominance. Finally, we found that differences in the context of the interview questions participants were asked to respond to (introductory, personal, interpersonal), also affected their vocal parameters, being more prominent in responses to personal and interpersonal questions. Overall, our results suggest that people adjust their vocal parameters according to the perceived social status of the listener as well as their own self-perceived social status.

Speakers modulate their voice when talking to infants but we know little about subtle variation in acoustic parameters during normal adult speech, and investigation is impeded by listeners’ understanding of semantic content. Here we circumvent this problem by analysing speech in simulated courtship scenarios and testing responses in naïve listeners, across both a Germanic (English) and a Slavic (Czech) language. Acoustic analysis revealed striking similarity across the two languages in patterns of social context-dependent variability in fundamental frequency (F0) but not in other parameters. Both sexes varied F0 most when responding to attractive individuals. We then show that speech directed towards these attractive individuals increased proceptivity in naïve listeners of either language, even when voices were stripped of all acoustic properties except F0 by low-pass filtering, which renders speech unintelligible. Our results demonstrate that modulating F0 is a critical parameter in human courtship, independently of semantic content.