LOL!The evolutionary roots of human laughter - Finanziamento dell’Unione Europea – NextGenerationEU – missione 4, componente 2, investimento 1.1.

Laughter is an essential tool to create and maintain social relationships in hominids and, for this reason, it is reasonable to suppose that it contains salient information that has to be adequately perceived and decoded by the listener. Laughter is not exclusively related to the expression of humor and, according to the naturalistic and social account, it should be studied considering the message it conveys and the response it elicits in the recipient. This naturalistic approach allows making hypotheses on the evolutionary adaptive significance of the phenomenon and expanding the study of laughter beyond Homo sapiens. However, new evidence remains fragile if not integrated within a coherent theoretical and experimental framework able to capture the interdisciplinary and cross-species nature of the phenomenon. LOL's overarching goal is to understand the biological scaffolds and universal features of laughter as a multimodal signal shared between human and non-human primates by tracing back its evolutionary pathways. The project is organized into two complementary work packages (WPs) toward which each research unit contributes interactively. Since humans live in a social world and communicate with others through multisensory modalities, in the WP1, we aim at exploring the form and function of laughter in humans and great apes, focusing on the multimodal nature of this phenomenon. Through sophisticated analytical techniques, we will examine whether the flexibility in the laughter multimodality can convey different social messages in great apes and children during their spontaneous activities. Moreover, after ascertaining the persistence of laughing as a non-conscious evolutionary social phenomenon in human adults, we will investigate the role of multimodality in boosting perceptual awareness of laughter. In WP2, we will explore behavioral and neural correlates of recognizing familiar and unfamiliar laughter. Through a validated approach for recognition systems, we will evaluate if great apes can perceive as different the laughter emitted by two unfamiliar subjects (never heard before) and if they can recognize the performer based on their previous experience (familiarity). Furthermore, we will verify whether humans have a neural fingerprint of familiar and unfamiliar laughter through fMRI techniques. The similarity in brain anatomy, reward system and behavioral responses to laughter, among great apes and humans, should permit us to look at the neural substrate and at the evolutionary relevance of laughter as a social trait. In conclusion, by departing from the current mainstream, LOL! proposes to focus on new questions, brings our understanding of laughter to the next level, and inspires a new wave of translational studies in neuroethology.