Luca Pedruzzi, Veronica Maglieri, Paolo Oliveri, Martina Francesconi, Rea Riccobono, Filippo Bigozzi, Alban Lemasson, Elisabetta Palagi
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引用次数: 0
Abstract
Complex communication systems appear to evolve alongside social complexity. Comparing closely related species with similar social structures but distinct sociobiology offers valuable insights into the evolution of communicative variability. Here, we explore yawning (morphology, sensory modalities, contexts, contagious effect), a highly conserved behavioral trait, in two zoo-housed groups of geladas (Theropithecus gelada, nsubjects = 67, nyawns = 1422) and hamadryas baboons (Papio hamadryas, nsubjects = 28, nyawns = 602). The species are optimal candidates as they both form multilevel groups but differ in intra-group dynamics, cohesion, and cross-sex bonding. Although both species displayed distinct yawn morphologies, hamadryas yawned less frequently than geladas, mainly in non-social contexts and without vocalization. In contrast, geladas yawned more often during affiliative interactions, highlighting a more social dimension to their yawns. When focusing on silent yawns, hamadryas showed a male-biased yawning frequency, whereas geladas exhibited similar rates between sexes, suggesting a more prominent female role in their yawning patterns. We found that yawning is contagious not only in geladas, as previously known, but also in hamadryas baboons. However, geladas were more responsive to others' yawns, possibly due to their greater communicative complexity or to the need to maintain cohesion in larger groups. In geladas, both sexes exhibited similar levels of yawn contagion, whereas in hamadryas it was predominantly male-driven, reflecting the central role of males in hamadryas social dynamics. Our study suggests both evolutionary inertia and divergence in Papionine yawning evolution. The findings confirm the derived nature of gelada yawn vocalizations and highlight the link between multimodal communication and social complexity. Moreover, geladas exhibit more nuanced, context-dependent yawning, likely shaped by their intricate sociobiology. In contrast, hamadryas display a more male-dominated yawning pattern, reflecting their distinct social dynamics. To fully understand the ecological significance of this ancient behavior, further cross-species research on yawning and its contagious effect in wild populations is essential.
期刊介绍:
The objective of the American Journal of Primatology is to provide a forum for the exchange of ideas and findings among primatologists and to convey our increasing understanding of this order of animals to specialists and interested readers alike.
Primatology is an unusual science in that its practitioners work in a wide variety of departments and institutions, live in countries throughout the world, and carry out a vast range of research procedures. Whether we are anthropologists, psychologists, biologists, or medical researchers, whether we live in Japan, Kenya, Brazil, or the United States, whether we conduct naturalistic observations in the field or experiments in the lab, we are united in our goal of better understanding primates. Our studies of nonhuman primates are of interest to scientists in many other disciplines ranging from entomology to sociology.