Between-group variation in production of pant-grunt vocalizations by wild bonobos (Pan paniscus) (2023)
Journal Article
Schamberg, I., Clay, Z., Townsend, S. W., & Surbeck, M. (2023). Between-group variation in production of pant-grunt vocalizations by wild bonobos (Pan paniscus). Behavioral Ecology and Sociobiology, 77(1), Article 14. https://doi.org/10.1007/s00265-022-03285-4

The potential for aggression is inherent in social interaction, and strategies to reduce the costs of aggression are ubiquitous among group-living animals. One strategy employed by lower-ranking individuals in a variety of species is the production o... Read More about Between-group variation in production of pant-grunt vocalizations by wild bonobos (Pan paniscus).

The Association Between the Bared-Teeth Display and Social Dominance in Captive Chimpanzees (Pan troglodytes) (2022)
Journal Article
Kim, Y., Vlaeyen, J., Heesen, R., Clay, Z., & Kret, M. (2022). The Association Between the Bared-Teeth Display and Social Dominance in Captive Chimpanzees (Pan troglodytes). Affective Science, 3(4), 749-760. https://doi.org/10.1007/s42761-022-00138-1

Humans use smiles — widely observed emotional expressions — in a variety of social situations, of which the meaning varies depending on social relationship and the context in which it is displayed. The homologue of the human smile in non-human primat... Read More about The Association Between the Bared-Teeth Display and Social Dominance in Captive Chimpanzees (Pan troglodytes).

Flexible signalling strategies by victims mediate post-conflict interactions in bonobos (2022)
Journal Article
Heesen, R., Austry, D., Upton, Z., & Clay, Z. (2022). Flexible signalling strategies by victims mediate post-conflict interactions in bonobos. Philosophical Transactions of the Royal Society B: Biological Sciences, 377(1860), https://doi.org/10.1098/rstb.2021.0310

Compared to other animals, humans supposedly excel at voluntarily controlling and strategically displaying emotional signals. Yet, new data shows that nonhuman great apes' emotion expressions may also be subject to voluntary control. A key context to... Read More about Flexible signalling strategies by victims mediate post-conflict interactions in bonobos.

Bared-teeth displays in bonobos (Pan paniscus): An assessment of the power asymmetry hypothesis (2022)
Journal Article
Vlaeyen, J. M., Heesen, R., Kret, M. E., Clay, Z., Bionda, T., & Kim, Y. (2022). Bared-teeth displays in bonobos (Pan paniscus): An assessment of the power asymmetry hypothesis. American Journal of Primatology, 84(9), Article e23419. https://doi.org/10.1002/ajp.23419

Facial expressions are key to navigating social group life. The Power Asymmetry Hypothesis of Motivational Emancipation predicts that the type of social organization shapes the meaning of communicative displays in relation to an individual's dominanc... Read More about Bared-teeth displays in bonobos (Pan paniscus): An assessment of the power asymmetry hypothesis.

Vocal functional flexibility: what it is and why it matters (2022)
Journal Article
Derry, T., Clay, Z., Dahl, C., Zuberbühler, J., Davila-Ross, M., & Dezecache, G. (2022). Vocal functional flexibility: what it is and why it matters. Animal Behaviour, 186, 93-100. https://doi.org/10.1016/j.anbehav.2022.01.015

Human speech is marked by a signal–function decoupling, the capacity to produce sounds that can fulfil a variety of functions, in contrast to nonverbal vocalizations such as laughter, cries and screams, which are functionally more rigid. It has been... Read More about Vocal functional flexibility: what it is and why it matters.

What makes us apes? The emotional building blocks of intersubjectivity in hominids (2022)
Journal Article
Demuru, E., Clay, Z., & Norscia, I. (2022). What makes us apes? The emotional building blocks of intersubjectivity in hominids. Ethology Ecology and Evolution, 34(3), 220-234. https://doi.org/10.1080/03949370.2022.2044390

Intersubjectivity, which refers to the capacity to create shared value or connection between individuals, is a complex and multi-faceted phenomenon involving both cognitive and affective components. Intersubjectivity has often been lauded as one of t... Read More about What makes us apes? The emotional building blocks of intersubjectivity in hominids.

Comparative Perspectives of Empathy Development: Insights from chimpanzees and bonobos (2022)
Book Chapter
Clay, Z., Webb, C., Romero, T., & de Waal, F. (2022). Comparative Perspectives of Empathy Development: Insights from chimpanzees and bonobos. In D. Dukes, E. Walle, & A. Samson (Eds.), The Oxford Handbook of Emotional Development (277-290). Oxford University Press. https://doi.org/10.1093/oxfordhb/9780198855903.013.30

Empathy - the sharing and understanding of others’ emotions and thoughts - is considered a defining feature of what it means to be human. Although empathy underpins many of our social interactions and is thought to be evolutionarily ancient, its orig... Read More about Comparative Perspectives of Empathy Development: Insights from chimpanzees and bonobos.

Dominance style is a key predictor of vocal use and evolution across nonhuman primates (2021)
Journal Article
Kavanagh, E., Street, S. E., Angwela, F. O., Bergman, T. J., Blaszczyk, M. B., Bolt, L. M., …Slocombe, K. (2021). Dominance style is a key predictor of vocal use and evolution across nonhuman primates. Royal Society Open Science, 8(7), Article 210873. https://doi.org/10.1098/rsos.210873

Animal communication has long been thought to be subject to pressures and constraints associated with social relationships. However, our understanding of how the nature and quality of social relationships relates to the use and evolution of communica... Read More about Dominance style is a key predictor of vocal use and evolution across nonhuman primates.

Anthropomorphism in comparative affective science: Advocating a mindful approach (2020)
Journal Article
Williams, L. A., Brosnan, S. F., & Clay, Z. (2020). Anthropomorphism in comparative affective science: Advocating a mindful approach. Neuroscience & Biobehavioral Reviews, 115, 299-307. https://doi.org/10.1016/j.neubiorev.2020.05.014

Anthropomorphism is the attribution of human-like capacities and traits to non-human entities. Anthropomorphism is ubiquitous in everyday life and in scientific domains, operating both implicitly and explicitly as a function of the human lens through... Read More about Anthropomorphism in comparative affective science: Advocating a mindful approach.

Emotional expressions in human and non-human great apes (2020)
Journal Article
Kret, M., Prochazkova, E., Sterc, E. M., & Clay, Z. (2020). Emotional expressions in human and non-human great apes. Neuroscience & Biobehavioral Reviews, 115, 378-395. https://doi.org/10.1016/j.neubiorev.2020.01.027

Humans and great apes are highly social species, and encounter conspecifics throughout their daily lives. During social interactions, they exchange information about their emotional states via expressions through different modalities including the fa... Read More about Emotional expressions in human and non-human great apes.

Ethological Approaches to Empathy in Primates (2018)
Book Chapter
Clay, Z., Palagi, E., & de Waal, F. B. (2018). Ethological Approaches to Empathy in Primates. In K. Meyza, & E. Knapska (Eds.), Neuronal Correlates of Empathy: From Rodent to Man (53-66). Academic Press

Ethological Approaches to Empathy in Primates (2018)
Book Chapter
Clay, Z., Palagi, E., & de Waal, F. B. (2018). Ethological Approaches to Empathy in Primates. In K. Meyza, & E. Knapska (Eds.), Neuronal correlates of empathy – from rodent to man. Elsevier

Higher fundamental frequency in bonobos is explained by larynx morphology (2018)
Journal Article
Grawunder, S., Crockford, C., Clay, Z., Kalan, A., Stevens, J., Stoessel, A., & Hohmann, G. (2018). Higher fundamental frequency in bonobos is explained by larynx morphology. Current Biology, 28(20), R1188-R1189. https://doi.org/10.1016/j.cub.2018.09.030

Acoustic signals, shaped by natural and sexual selection, reveal ecological and social selection pressures [1]. Examining acoustic signals together with morphology can be particularly revealing. But this approach has rarely been applied to primates,... Read More about Higher fundamental frequency in bonobos is explained by larynx morphology.

Natural communication in bonobos: Insights into social awareness and the evolution of language (2017)
Book Chapter
Clay, Z., & Genty, E. (2017). Natural communication in bonobos: Insights into social awareness and the evolution of language. In B. Hare, & S. Yamamoto (Eds.), Bonobos: Unique in Mind Brain and Behavior. Oxford University Press. https://doi.org/10.1093/oso/9780198728511.003.0008

What drives young children to over-imitate? Investigating the effects of age, context, action type, and transitivity (2017)
Journal Article
Clay, Z., Over, H., & Tennie, C. (2018). What drives young children to over-imitate? Investigating the effects of age, context, action type, and transitivity. Journal of Experimental Child Psychology, 166, 520-534. https://doi.org/10.1016/j.jecp.2017.09.008

Imitation underlies many traits thought to characterize our species, which includes the transmission and acquisition of language, material culture, norms, rituals, and conventions. From early childhood, humans show an intriguing willingness to imitat... Read More about What drives young children to over-imitate? Investigating the effects of age, context, action type, and transitivity.

Is Overimitation a Uniquely Human Phenomenon? Insights From Human Children as Compared to Bonobos (2017)
Journal Article
Clay, Z., & Tennie, C. (2018). Is Overimitation a Uniquely Human Phenomenon? Insights From Human Children as Compared to Bonobos. Child Development, 89(5), 1535-1544. https://doi.org/10.1111/cdev.12857

Imitation is a key mechanism of human culture and underlies many of the intricacies of human social life, including rituals and social norms. Compared to other animals, humans appear to be special in their readiness to copy novel actions as well as t... Read More about Is Overimitation a Uniquely Human Phenomenon? Insights From Human Children as Compared to Bonobos.

Bonobos use call combinations to facilitate inter-party travel recruitment (2017)
Journal Article
Schamberg, I., Cheney, D. L., Clay, Z., Hohmann, G., & Seyfarth, R. M. (2017). Bonobos use call combinations to facilitate inter-party travel recruitment. Behavioral Ecology and Sociobiology, 71(4), Article 75. https://doi.org/10.1007/s00265-017-2301-9

Many primates produce vocalizations when initiating travel. These “travel calls” are often acoustically similar to vocalizations unrelated to travel, and listeners appear to rely on a shared context with callers to correctly interpret the calls. When... Read More about Bonobos use call combinations to facilitate inter-party travel recruitment.

Call combinations, vocal exchanges and interparty movement in wild bonobos (2016)
Journal Article
Schamberg, I., Cheney, D. L., Clay, Z., Hohmann, G., & Seyfarth, R. M. (2016). Call combinations, vocal exchanges and interparty movement in wild bonobos. Animal Behaviour, 122, 109-116. https://doi.org/10.1016/j.anbehav.2016.10.003

The vocal repertoire of nonhuman primates is largely fixed. Individuals produce their species-specific vocalizations from a young age, and do not acquire new call types over their lifetime. Despite these limitations, however, monkeys and apes are abl... Read More about Call combinations, vocal exchanges and interparty movement in wild bonobos.

A Comparison Between Bonobos and Chimpanzees: A Review and Update (2016)
Journal Article
Gruber, T., & Clay, Z. (2016). A Comparison Between Bonobos and Chimpanzees: A Review and Update. Evolutionary Anthropology, 25(5), 239-252. https://doi.org/10.1002/evan.21501

Chimpanzees (Pan troglodytes) and bonobos (P. paniscus) are our closest living relatives, with the human lineage diverging from the Pan lineage only around five to seven Mya, but possibly as early as eight Mya.1–2 Chimpanzees and bonobos even share g... Read More about A Comparison Between Bonobos and Chimpanzees: A Review and Update.

Bonobos (Pan paniscus) vocally protest against violations of social expectations (2016)
Journal Article
Clay, Z., Ravaux, L., de Waal, F. B., & Zuberbühler, K. (2016). Bonobos (Pan paniscus) vocally protest against violations of social expectations. Journal of Comparative Psychology, 130(1), 44-54. https://doi.org/10.1037/a0040088

Research has shown that great apes possess certain expectations about social regularities and both perceive and act according to social rules within their group. During natural and experimentally induced contexts, such as the inequitable distribution... Read More about Bonobos (Pan paniscus) vocally protest against violations of social expectations.