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

• Comparative Perspectives of Empathy Development: Insights from chimpanzees and bonobos
  
  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 (pp. 277-290). Oxford University Press. https://doi.org/10.1093/oxfordhb/9780198855903.013.30
• Ethological Approaches to Empathy in Primates
  
  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 (pp. 53-66). Academic Press.
• Ethological Approaches to Empathy in Primates
  
  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.
• Natural communication in bonobos: Insights into social awareness and the evolution of language
  
  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
• Vocal communication and social awareness in chimpanzees and bonobos
  
  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.
• Mirroring Fictional Others
  
  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

• Social contagion in primates: Moderating factors and significance for individuals and the group
  
  Sandars, G., & Clay, Z. (2025). Social contagion in primates: Moderating factors and significance for individuals and the group. Neuroscience and Biobehavioral Reviews, 173, Article 106156. https://doi.org/10.1016/j.neubiorev.2025.106156
• Early empathy development: Concern and comforting in 9- and 18-month-old infants from Uganda and the UK
  
  Vreden, C., Buryn-Weitzel, J. C., Atim, S., Donnellan, E., Hoffman, M., Holden, E., Jurua, M., Knapper, C. V., Lahiff, N. J., Marshall, S., Paricia, J., Tuncgenc, B., Tusiime, F., Wilke, C., Slocombe, K. E., & Clay, Z. (2025). Early empathy development: Concern and comforting in 9- and 18-month-old infants from Uganda and the UK. PLOS One, 20(5), Article e0320371. https://doi.org/10.1371/journal.pone.0320371
• Within-species variation eclipses between-species differences in Pan consolation
  
  Brooker, J. S., Webb, C. E., Kordon, S., de Waal, F. B., & Clay, Z. (2025). Within-species variation eclipses between-species differences in Pan consolation. Evolution and Human Behavior, 46(3), Article 106682. https://doi.org/10.1016/j.evolhumbehav.2025.106682
• Bonobos and chimpanzees overlap in sexual behaviour patterns during social tension
  
  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
• Conspecific alarm calls, but not food-associated calls, elicit affect-based and object-based mental representations in a bonobo (Pan paniscus)
  
  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
• Contagious Crying Revisited: A Cross‐Cultural Investigation Into Infant Emotion Contagion Using Infrared Thermal Imaging
  
  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
• Factors shaping socio-emotional trajectories in sanctuary-living bonobos: a longitudinal approach
  
  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
• ChimpanSEE, ChimpanDO: Grooming and play contagion in chimpanzees
  
  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
• Impact of social context on human facial and gestural emotion expressions
  
  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
• The expression of empathy in human's closest relatives, bonobos and chimpanzees: current and future directions
  
  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
• Frans de Waal - A pioneer who shone a light on the primate mind.
  
  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
• Perceptual integration of bodily and facial emotion cues in chimpanzees and humans
  
  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
• Increased alertness and moderate ingroup cohesion in bonobos’ response to outgroup cues
  
  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
• Group-specific expressions of co-feeding tolerance in bonobos and chimpanzees preclude dichotomous species generalizations
  
  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
• Multimodal communication development in semiwild chimpanzees
  
  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
• Between-group variation in production of pant-grunt vocalizations by wild bonobos (Pan paniscus)
  
  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
• Humans recognize affective cues in primate vocalizations: acoustic and phylogenetic perspectives
  
  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
• The Association Between the Bared-Teeth Display and Social Dominance in Captive Chimpanzees (Pan troglodytes)
  
  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
• Flexible signalling strategies by victims mediate post-conflict interactions in bonobos
  
  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
• Bared-teeth displays in bonobos (Pan paniscus): An assessment of the power asymmetry hypothesis
  
  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
• Vocal functional flexibility: what it is and why it matters
  
  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
• What makes us apes? The emotional building blocks of intersubjectivity in hominids
  
  Demuru, E., Clay, Z., & Norscia, I. (2022). What makes us apes? The emotional building blocks of intersubjectivity in hominids. Ethology Ecology & Evolution, 34(3), 220-234. https://doi.org/10.1080/03949370.2022.2044390
• Dominance style is a key predictor of vocal use and evolution across nonhuman primates
  
  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., … 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
• Anthropomorphism in comparative affective science: Advocating a mindful approach
  
  Williams, L. A., Brosnan, S. F., & Clay, Z. (2020). Anthropomorphism in comparative affective science: Advocating a mindful approach. Neuroscience and Biobehavioral Reviews, 115, 299-307. https://doi.org/10.1016/j.neubiorev.2020.05.014
• Emotional expressions in human and non-human great apes
  
  Kret, M., Prochazkova, E., Sterc, E. M., & Clay, Z. (2020). Emotional expressions in human and non-human great apes. Neuroscience and Biobehavioral Reviews, 115, 378-395. https://doi.org/10.1016/j.neubiorev.2020.01.027
• Higher fundamental frequency in bonobos is explained by larynx morphology
  
  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
• Is Overimitation a Uniquely Human Phenomenon? Insights From Human Children as Compared to Bonobos
  
  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
• What drives young children to over-imitate? Investigating the effects of age, context, action type, and transitivity
  
  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
• Bonobos use call combinations to facilitate inter-party travel recruitment
  
  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
• Call combinations, vocal exchanges and interparty movement in wild bonobos
  
  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
• A Comparison Between Bonobos and Chimpanzees: A Review and Update
  
  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
• Bonobos (Pan paniscus) vocally protest against violations of social expectations
  
  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
• Obstacles and catalysts to peaceful coexistence in chimpanzees and bonobos.
  
  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
• Functional flexibility in wild bonobo vocal behaviour
  
  Clay, Z., Archbold, J., & Zuberbühler, K. (2015). Functional flexibility in wild bonobo vocal behaviour. PeerJ, 3, Article e1124. https://doi.org/10.7717/peerj.1124
• Sex and strife: post-conflict sexual contacts in bonobos.
  
  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
• Contextually variable signals can be functionally referential
  
  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
• Young Children Make Their Gestural Communication Systems More Language-Like: Segmentation and Linearization of Semantic Elements in Motion Events
  
  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
• Multi-Modal Use of a Socially Directed Call in Bonobos
  
  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
• Development of socio-emotional competence in bonobos
  
  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
• Bonobos Respond to Distress in Others: Consolation across the Age Spectrum
  
  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
• Communication during sex among female bonobos: effects of dominance, solicitation and audience
  
  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
• Food-associated vocalizations in mammals and birds: what do these calls really mean?
  
  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
• The Structure of Bonobo Copulation Calls During Reproductive and Non-Reproductive Sex.
  
  Clay, Z., & Zuberbühler, K. (2011). The Structure of Bonobo Copulation Calls During Reproductive and Non-Reproductive Sex. Ethology, 117(12), 1158-1169. https://doi.org/10.1111/j.1439-0310.2011.01975.x
• Female bonobos use copulation calls as social signals.
  
  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
• Bonobos Extract Meaning from Call Sequences
  
  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
• A comparison of bonobo and chimpanzee tool use: evidence for a female bias in the Pan lineage.
  
  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
• Food-associated calling sequences in bonobos.
  
  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