% pubman genre = article
@article{item_3646829,
title = {{Emotions mediate nonlinear phenomena production in the vocalizations of two ape species}},
author = {Fournier, Floriane and Perrier, L{\'e}o and Girard-Buttoz, C{\'e}dric and Keenan, Sumir and Bortolato, Tatiana and Wittig, Roman M. and Crockford, Catherine and Levrero, Florence},
language = {eng},
issn = {0962-8436; 1471-2970},
doi = {10.1098/rstb.2024.0013},
year = {2025},
abstract = {{Nonlinear phenomena (NLP) are widely observed in mammal{\textless}br{\textgreater}vocalizations. One prominent, albeit rarely empirically tested, theory{\textless}br{\textgreater}suggests that NLP serve to communicate individual emotional states. Here,{\textless}br{\textgreater}we test this {\textquoteleft}emotional hypothesis{\textquoteright} by assessing NLP production in the{\textless}br{\textgreater}vocalizations of chimpanzees and bonobos across various social contexts.{\textless}br{\textgreater}These two species are relevant to test this hypothesis since bonobos{\textless}br{\textgreater}are more socially opportunistic than chimpanzees. We found that both{\textless}br{\textgreater}species produced, albeit at different frequencies, the same five distinct{\textless}br{\textgreater}NLP types. Contextual valence influenced NLP production in both species{\textless}br{\textgreater}with negative valence being associated with more frequent NLP production{\textless}br{\textgreater}than positive and neutral valence. In contrast, using aggression severity{\textless}br{\textgreater}and caller role as proxies for arousal, we found that in bonobos, but not{\textless}br{\textgreater}in chimpanzees, vocalizations uttered during contact aggression or from{\textless}br{\textgreater}victims and females contained more NLP. In contrast, the type of NLP{\textless}br{\textgreater}produced was neither influenced by valence nor arousal in either species.{\textless}br{\textgreater}Our study supports the emotional hypothesis regarding the occurrence{\textless}br{\textgreater}of NLP production in mammals, particularly in opportunistics such as{\textless}br{\textgreater}bonobos. This reinforces the hypothesis of an adaptative role of NLP{\textless}br{\textgreater}in animal communication and prompts further investigations into their{\textless}br{\textgreater}communicative functions.{\textless}br{\textgreater}This article is part of the theme issue {\textquoteleft}Nonlinear phenomena in{\textless}br{\textgreater}vertebrate vocalizations: mechanisms and communicative functions{\textquoteright}.}},
journal = {{Philosophical Transactions of the Royal Society B: Biological Sciences}},
volume = {380},
number = {1923},
eid = {20240013},
}