Humans detect valid facial cues of leadership in chimpanzees

Humans detect valid facial cues of leadership in chimpanzees. Alexander Bor, Darren Schreiber, Sarah Brosnan, Susan Lambeth, Steven Schapiro, Frans de Waal, Mark Van Vugt. Human Behavior and Evolution Society, 30th Annual Meeting, July 2018. http://www.hbes.com/conference/hbes2018/

Abstract: Humans rely on facial cues to assess the leadership ability of their peers, which af fects the selection and assessment of leaders in political and business settings. Prominent theoretical explanations propose that facial cues serve as inputs into an adaptive, context-sensitive followership psychology. Here, we push this evolutionary explanation further by testing if humans are able to identify chimpanzee (pan troglodytes) leaders. Importantly, we do not claim that detecting leadership across species had adaptive benefits. Instead, we argue that it is reasonable to assume that facial cues o f leadership may be similar across humans and chimps due to convergences and/or homologies and that humans’ facial cue detecting mechanisms are triggered by encountering chimpanzee faces. We, therefore, predict that alpha chimpanzees will be perceived to b e more dominant and leader-looking than non-alpha chimpanzees. We test our hypothesis relying on a unique inventory of over 150 standardized photographs of more than 70 captive adult male chimpanzees from three colonies. Naive human raters recruited on Ama zon’s Mechanical Turk rated these photographs on six traits (dominance, age, leader ability, attractiveness, likability and competence). Subsequently, we compare the average trait ratings of alpha and non-alpha targets. Preliminary results show that interrater reliability of evaluations are very high and that alpha males are rated higher on dominance, age and leader ability.