Staff profile

I am a comparative and developmental psychologist with expertise in primatology. I study and compare great apes and young children in order to investigate the evolutionary and developmental basis of hominid social cognition and behavior. My main interests are the development & evolution of social cognition and communication, focussing on empathy, language and social learning. 

 Research Interests 

Evolutionary & Developmental Perspectives on:

• Social cognition and communication
• Empathy & socio-emotional processes
• Language evolution
• Child gesture
• Social learning and cultural cognition
• Primate vocal communication (including referential communication & call combinations) 

I am a specialist in great ape behaviour, with particular expertise in bonobos, our closest living relatives. I have experience studying bonobos in the wild, captivity and semi-captivity, including Lola ya Bonobo Sanctuary - where I also act as a long-term Scientific Consultant. 

I conducted my doctoral work with Prof Klaus Zuberbuhler (University of St Andrews) investigating bonobo vocal communication and language evolution. I conducted post-doctoral work with Prof Frans de Waal (Emory University, USA) examining empathy development in sanctuary-living bonobos. I conducted post-doctoral research in the Dept of Comparative Cognition, University of Neuchatel (Switzerland) studying vocal communication in wild bonobos at Lui Kotale, DR Congo (MPI-EVA).

I completed a Marie Curie Research Fellowship at the University of Birmingham with Dr Claudio Tennie examining the evolution & development of imitation and language with great apes and children.

Available PhD and MRes research projects

I would welcome applications from people interested in Comparative and Developmental Psychology, more specifically on the origins of communication, empathy and social cognition. I would be happy to supervise both experimental and observational projects working with human children (UK and cross-culturally) and primates. I have a good network of contacts to arrange access to a variety of primates, including wild, sanctuary-living and captive bonobos. For those wishing to embark on a fieldwork PhD study, experience of travel and work in third world countries is a real advantage.

Please contact me if you are interested in making an application

• Comparative Affective Science
• Evolution and development of empathy
• Evolution of language and culture
• Primate Conservation
• Primate behaviour
• Science outreach - primatology
• Social cognition
• Development of communication and social learning
• Primate vocal communication
• Animal cognition
• Child gesture development
• Applications to primate conservation

Chapter in book

• 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
• 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
• 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
• 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
• Clay, Z., & Zuberbuhler, K. (2014). Vocal communication and social awareness in chimpanzees and bonobos. In D. Dor, C. Knight, & J. Lewis (Eds.), The Social Origins of Language. Oxford University Press
• Clay, Z., & Iacoboni, M. (2011). Mirroring Fictional Others. In E. Schellekens, & P. Goldie (Eds.), The Aesthetic Mind, Philosophy and Psychology. Oxford University Press

Journal Article

• Brooker, J. S., Webb, C. E., van Leeuwen, E. J. C., Kordon, S., de Waal, F. B. M., & Clay, Z. (2025). Bonobos and chimpanzees overlap in sexual behaviour patterns during social tension. Royal Society Open Science, 12(3), Article 242031. https://doi.org/10.1098/rsos.242031
• Lahiff, N. J., Clay, Z., Epping, A. J., Taglialatela, J. P., Townsend, S. W., & Slocombe, K. E. (2025). Conspecific alarm calls, but not food-associated calls, elicit affect-based and object-based mental representations in a bonobo (Pan paniscus). Royal Society Open Science, 12(3), Article 241901. https://doi.org/10.1098/rsos.241901
• Vreden, C., Renner, E., Ainamani, H. E., Crowther, R., Forward, B., Mazari, S., Tuohy, G., Ndyareeba, E., & Clay, Z. (2025). Contagious Crying Revisited: A Cross‐Cultural Investigation Into Infant Emotion Contagion Using Infrared Thermal Imaging. Developmental Science, 28(2), Article e13608. https://doi.org/10.1111/desc.13608
• Kordon, S., Webb, C. E., Brooker, J. S., de Waal, F. B., & Clay, Z. (2024). Factors shaping socio-emotional trajectories in sanctuary-living bonobos: a longitudinal approach. Royal Society Open Science, 11(12), Article 240435. https://doi.org/10.1098/rsos.240435
• Sandars, G., Brooker, J. S., & Clay, Z. (2024). ChimpanSEE, ChimpanDO: Grooming and play contagion in chimpanzees. PLoS ONE, 19(11), Article e0312467. https://doi.org/10.1371/journal.pone.0312467
• Heesen, R., Szenteczki, M. A., Kim, Y., Kret, M. E., Atkinson, A. P., Upton, Z., & Clay, Z. (2024). Impact of social context on human facial and gestural emotion expressions. iScience, 27(11), Article 110663. https://doi.org/10.1016/j.isci.2024.110663
• Brooker, J. S., Webb, C. E., de Waal, F. B. M., & Clay, Z. (2024). The expression of empathy in human's closest relatives, bonobos and chimpanzees: current and future directions. Biological Reviews, 99(4), 1556-1575. https://doi.org/10.1111/brv.13080
• Clay, Z. (2024). Frans de Waal - A pioneer who shone a light on the primate mind. Neuroscience & Biobehavioral Reviews, 162, Article 105725. https://doi.org/10.1016/j.neubiorev.2024.105725
• Heesen, R., Kim, Y., Kret, M. E., & Clay, Z. (2024). Perceptual integration of bodily and facial emotion cues in chimpanzees and humans. PNAS Nexus, 3(2), Article pgae012. https://doi.org/10.1093/pnasnexus/pgae012
• Brooks, J., van Heijst, K., Epping, A., Lee, S. H., Niksarli, A., Pope, A., Clay, Z., Kret, M. E., Taglialatela, J., & Yamamoto, S. (2024). Increased alertness and moderate ingroup cohesion in bonobos’ response to outgroup cues. PLoS ONE, 19(8), Article e0307975. https://doi.org/10.1371/journal.pone.0307975
• van Leeuwen, E. J., Staes, N., Brooker, J. S., Kordon, S., Nolte, S., Clay, Z., Eens, M., & Stevens, J. M. (2023). Group-specific expressions of co-feeding tolerance in bonobos and chimpanzees preclude dichotomous species generalizations. iScience, 26(12), Article 108528. https://doi.org/10.1016/j.isci.2023.108528
• Doherty, E., Davila-Ross, M., & Clay, Z. (2023). Multimodal communication development in semiwild chimpanzees. Animal Behaviour, 201(July), 175-190. https://doi.org/10.1016/j.anbehav.2023.03.020
• 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
• Debracque, C., Slocombe, K. E., Grandjean, D., Clay, Z., & Gruber, T. (2023). Humans recognize affective cues in primate vocalizations: acoustic and phylogenetic perspectives. Scientific Reports, 13(1), Article 10900. https://doi.org/10.1038/s41598-023-37558-3
• 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
• 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
• 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
• 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
• 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
• Kavanagh, E., Street, S. E., Angwela, F. O., Bergman, T. J., Blaszczyk, M. B., Bolt, L. M., Briseño-Jaramillo, M., Brown, M., Chen-Kraus, C., Clay, Z., Coye, C., Thompson, M. E., Estrada, A., Fichtel, C., Fruth, B., Gamba, M., Giacoma, C., Graham, K. E., Green, S., Grueter, C. C., …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
• 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
• 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
• 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
• 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
• 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
• 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
• 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
• 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
• 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
• Clay, Z., de Waal, F. B., & Furuichi, T. (2016). Obstacles and catalysts to peaceful coexistence in chimpanzees and bonobos. Behaviour, 153(9-11), 1293-1330. https://doi.org/10.1163/1568539x-00003335
• Clay, Z., Archbold, J., & Zuberbühler, K. (2015). Functional flexibility in wild bonobo vocal behaviour. PeerJ – the Journal of Life & Environmental Sciences, 3, Article e1124. https://doi.org/10.7717/peerj.1124
• Scarantino, A., & Clay, Z. (2015). Contextually variable signals can be functionally referential. Animal Behaviour, 100, e1-e8. https://doi.org/10.1016/j.anbehav.2014.08.017
• Clay, Z., & de Waal, F. B. (2015). Sex and strife: post-conflict sexual contacts in bonobos. Behaviour, 152(3-4), 313-334. https://doi.org/10.1163/1568539x-00003155
• Clay, Z., Pople, S., Hood, B., & Kita, S. (2014). Young Children Make Their Gestural Communication Systems More Language-Like: Segmentation and Linearization of Semantic Elements in Motion Events. Psychological Science, 25(8), 1518-1525. https://doi.org/10.1177/0956797614533967
• Genty, E., Clay, Z., Hobaiter, C., & Zuberbühler, K. (2014). Multi-Modal Use of a Socially Directed Call in Bonobos. PLoS ONE, 9(1), Article e84738. https://doi.org/10.1371/journal.pone.0084738
• Clay, Z., & de Waal, F. (2013). Development of socio-emotional competence in bonobos. Proceedings of the National Academy of Sciences, 110(45), 18121-18126. https://doi.org/10.1073/pnas.1316449110
• Clay, Z., & de Waal, F. B. (2013). Bonobos Respond to Distress in Others: Consolation across the Age Spectrum. PLoS ONE, 8(1), Article e55206. https://doi.org/10.1371/journal.pone.0055206
• Clay, Z., & Zuberbühler, K. (2012). Communication during sex among female bonobos: effects of dominance, solicitation and audience. Scientific Reports, 2, Article 291. https://doi.org/10.1038/srep00291
• Clay, Z., Smith, C. L., & Blumstein, D. T. (2012). Food-associated vocalizations in mammals and birds: what do these calls really mean?. Animal Behaviour, 83(2), 323-330. https://doi.org/10.1016/j.anbehav.2011.12.008
• Clay, Z., & Zuberbühler, K. (2011). The Structure of Bonobo Copulation Calls During Reproductive and Non-Reproductive Sex. Ethology: international journal of behavioural biology, 117(12), 1158-1169. https://doi.org/10.1111/j.1439-0310.2011.01975.x
• Clay, Z., Pika, S., Gruber, T., & Zuberbuhler, K. (2011). Female bonobos use copulation calls as social signals. Biology Letters, 7(4), https://doi.org/10.1098/rsbl.2010.1227
• Clay, Z., & Zuberbühler, K. (2011). Bonobos Extract Meaning from Call Sequences. PLoS ONE, 6(4), Article e18786. https://doi.org/10.1371/journal.pone.0018786
• Gruber, T., Clay, Z., & Zuberbühler, K. (2010). A comparison of bonobo and chimpanzee tool use: evidence for a female bias in the Pan lineage. Animal Behaviour, 80(6), 1023-1033. https://doi.org/10.1016/j.anbehav.2010.09.005
• Clay, Z., & Zuberbühler, K. (2009). Food-associated calling sequences in bonobos. Animal Behaviour, 77(6), 1387-1396. https://doi.org/10.1016/j.anbehav.2009.02.016