Threat Vocalisations Are Acoustically Similar Between Humans (homo Sapiens) and Chimpanzees (pan Troglodytes)

Kamiloglu, Roza G., Cantay Çalışkan, Katie Slocombe, and Disa Sauter. 2022. “Threat Vocalisations Are Acoustically Similar Between Humans (homo Sapiens) and Chimpanzees (pan Troglodytes).” PsyArXiv. November 25. psyarxiv.com/asvwz

Abstract: In behavioural contexts like fighting, eating, and playing, acoustically distinctive vocalisations are produced across many mammalian species. Such expressions may be conserved in evolution, pointing to the possibility of acoustic regularities in the vocalisations of phylogenetically related species. Here, we test this hypothesis by examining the degree of acoustic similarity between human and chimpanzee vocalisations produced in 10 equivalent behavioural contexts. We use two complementary analysis methods: Pairwise acoustic distance measures and acoustic separability metrics based on unsupervised learning algorithms. Acoustic features of vocalisations produced when threatening another individual were distinct from other types of vocalisations and highly similar across species. Using a multimethod approach, these findings demonstrate that human vocalisations produced when threatening another person are acoustically similar to chimpanzee vocalisations in the same situation, likely reflecting a phylogenetically ancient vocal signalling system.

Inequity aversion: Bonobos respond to receiving less preferred rewards by refusing tokens and rewards, and by leaving the experimental area

Behavioral and physiological response to inequity in bonobos (Pan paniscus). Jonas Verspeek, Jeroen M. G. Stevens. American Journal of Primatology, November 23 2022. https://doi.org/10.1002/ajp.23455

Abstract: Inequity aversion (IA), the affective, cognitive, and behavioral response to inequitable outcomes, allows individuals to avoid exploitation and therefore stabilizes cooperation. The presence of IA varies across animal species, which has stimulated research to investigate factors that might explain this variation, and to investigate underlying affective responses. Among great apes, IA is most often studied in chimpanzees. Here, we investigate IA in bonobos, a reputedly tolerant and cooperative species for which few IA studies are available. We describe how bonobos respond to receiving less preferred rewards than a partner in a token exchange task. We show that bonobos respond to receiving less preferred rewards by refusing tokens and rewards, and by leaving the experimental area. Bonobos never refused a trial when receiving preferred rewards, and thus showed no advantageous IA. We also investigate the variability in the disadvantageous IA response on a dyadic level, because the level of IA is expected to vary, depending on characteristics of the dyad. Like in humans and chimpanzees, we show that the tolerance towards inequity was higher in bonobo dyads with more valuable relationships. To study the affective component of IA, we included behavioral and physiological measures of arousal: a displacement behavior (rough self-scratching) and changes in salivary cortisol levels. Both measures of arousal showed large variability, and while analyses on rough self-scratching showed no significant effects, salivary cortisol levels seemed to be lower in subjects that received less than their partner, but higher in subjects that received more than their partner, albeit that both were not significantly different from the equity condition. This suggests that although overcompensated bonobos showed no behavioral response, they might be more aroused. Our data support the cooperation hypothesis on an interspecific and intraspecific level. They show inequity aversion in bonobos, a reputedly cooperative species, and suggest that the variability in IA in bonobos can be explained by their socioecology. Most successful cooperative interactions happen between mothers and their sons and among closely bonded females. The limited need to monitor the partners' investment within these dyads can result in a higher tolerance towards inequity. We therefore suggest future studies to consider relevant socioecological characteristics of the species when designing and analyzing IA studies.

Research highlights

    Bonobos responded to inequity by refusing tokens and moving away from the experimenter
    Overcompensated subjects showed more arousal, as measured by salivary cortisol
    The level of inequity aversion decreased with increasing relationship quality

Women estimated their IQ significantly lower than men and estimated their EQ higher

Sex Difference in Estimated Intelligence and Estimated Emotional Intelligence and IQ Scores. Adrian Furnham & Charlotte Robinson. The Journal of Genetic Psychology, Nov 23 2022. https://doi.org/10.1080/00221325.2022.2140025

Abstract: In five different online studies of community samples, participants (N > 2,200) estimated their IQ and EQ on a single scale and completed three different, short, untimed intelligence tests. In all studies, women estimated their IQ significantly lower than men (effect sizes from 0.22–0.47) and estimated their EQ higher (effect size 0.04–0.32). In only one study were there actual sex differences in IQ test scores. All correlations between the two estimates were significant and positive, and ranged from .37 < r < .47. The robustness of the IQ-EQ hubris-humility effect across measures and populations is discussed. Limitations are acknowledged, particularly in the use of tests.

Keywords: EQintelligenceIQself-estimatessex differences