About

Martin Surbeck is the Principal Investigator of the Pan Lab, which focuses on studying the behavioral ecology of our closest living relatives, bonobos, to infer insights about the evolution of human behavior. His research investigates cooperation and competition among primates by measuring hormonal correlates and comparing different primate populations. The goal of his work is to establish a bonobo model for understanding human evolution, contributing to the broader field of primatology and evolutionary biology.

Research topics

• Ecology
• Sociology
• Biology
• Psychology
• Cognitive psychology
• Genetics
• Neuroscience
• Anthropology
• Evolutionary biology
• Social psychology
• Geography

Selected publications

• Oxytocin activity is not linked to out-group prosociality in wild bonobos

  Scientific Reports · 2025-06-03 · 2 citations

  articleOpen accessSenior author

  In many group-living species, cooperative group defense is crucial to the reproduction and survival of group members. In humans and chimpanzees, this adaptive behavior is regulated by oxytocin, a highly conserved neurohormone. In humans, oxytocin can also enhance prosocial attitudes towards out-group individuals and reduces xenophobia. While the role of oxytocin in supporting cooperative group defense is likely evolutionarily ancient, it is unclear to what extent oxytocin's role in promoting out-group prosociality is conserved. Bonobos, our closest living relatives together with chimpanzees, can provide valuable insights into this question, because they are not known to engage in collective group defense but instead exhibit tolerance and prosocial behaviors across groups. Through examining variation in bonobo cooperative behavior, specifically coalition formation, we reinforce the idea that bonobo coalitions do not serve as a form of group defense. Despite increased competition, bonobos formed fewer coalitions in the presence of out-groups. Further, bonobo coalitions included both in- and out-group partners, reflecting reduced xenophobia and between-group cooperation. Physiologically, neither females nor males showed increased oxytocin activity with out-group presence. This suggests that, unlike in humans, oxytocin is not involved in regulating out-group prosociality in bonobos.

  PublisherOA PDFDOI

• Inégalités reproductives chez les bonobos et chimpanzés

  Bulletins et Mémoires de la Société d anthropologie de Paris · 2025-01-01

  articleOpen accessSenior author

  Ce document a t gnr automatiquement le 17 dcembre 2025.Le texte seul est utilisable

  PublisherOA PDFDOI

• Extensive compositionality in the vocal system of bonobos

  Science · 2025-04-04 · 33 citations

  articleOpen accessCorresponding

  Compositionality, the capacity to combine meaningful elements into larger meaningful structures, is a hallmark of human language. Compositionality can be trivial (the combination's meaning is the sum of the meaning of its parts) or nontrivial (one element modifies the meaning of the other element). Recent studies have suggested that animals lack nontrivial compositionality, representing a key discontinuity with language. In this work, using methods borrowed from distributional semantics, we investigated compositionality in wild bonobos and found that not only does each call type of their repertoire occur in at least one compositional combination, but three of these compositional combinations also exhibit nontrivial compositionality. These findings suggest that compositionality is a prominent feature of the bonobo vocal system, revealing stronger parallels with human language than previously thought.

  PublisherOA PDFDOI

• Great Ape Childhoods: Development of infant bonobos ( <i>Pan paniscus</i> ) and chimpanzees ( <i>Pan troglodytes schweinfurthii</i> ) in the wild

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-03-15

  preprintOpen access

  Abstract Human development is marked by extended immaturity, necessitating extended care throughout infancy and childhood, facilitating advanced cognitive, social, and cultural skill acquisition. Parallels of extended development are also present in our closest living relatives, bonobos ( Pan paniscus ) and chimpanzees ( Pan troglodytes ). The Self-Domestication Hypothesis (SDH) suggests that human uniqueness stems from selection against aggression. Bonobos are also considered self-domesticated, exhibiting lower aggression and greater social tolerance, which are linked to delayed development and prolonged maternal dependence compared to chimpanzees. However, systematic, quantitative comparisons of the two species’ developmental patterns are limited and conflicting. This study addressed this gap by examining behavioural development in bonobo and chimpanzee infants aged 0-5.5 years living in two populations (Kokolopori community, Kokolopori Bonobo Reserve, DRC, N=21; Ngogo community, Kibale National Park, Uganda, N=22) in their natural environments. We specifically focused on (i) general behaviours (travel, feeding, grooming), and (ii) spatial independence. By systematically comparing developmental data and using consistent methods, we tested whether bonobo development aligns with SDH predictions. Our results showed similar developmental trajectories, with no species differences concerning ventral riding, nipple contact, or grooming. However, we found species differences regarding travel and proximity patterns, with chimpanzees exhibiting prolonged dorsal riding, bonobos travelling independently more often and maintaining greater distances from their mothers. Age, sibling presence, and maternal parity influenced behavioural patterns, but no sex differences were observed. These findings challenge assumptions of slower bonobo maturation, and highlight the importance of systematic, collaborative research on primate behavioural diversity in natural environments.

  PublisherOA PDFDOI

• Great Ape Childhoods: Social and Spatial Pathways to Independence in Bonobo and Chimpanzee Infants

  Developmental Science · 2025-12-15

  articleOpen access

  Human development is marked by extended immaturity, necessitating extended care throughout infancy and childhood, facilitating advanced cognitive, social, and cultural skill acquisition. Parallels of extended development are also present in our closest living relatives, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes), which differ markedly in their social systems. Bonobos live in more tolerant, female-bonded societies, while societies of chimpanzees are more hierarchical, and male-dominated. These differences in social ecology may thus also shape the pace and nature of early behavioural development. However, systematic, quantitative comparisons of developmental patterns of bonobos and chimpanzees are very limited, and results are conflicting. Hence, this study addressed this crucial gap by systematically examining behavioural development in bonobo and chimpanzee infants living in two populations (Kokolopori community, Kokolopori Bonobo Reserve, DRC, N = 21; Ngogo community, Kibale National Park, Uganda, N = 22) in their natural environments. We specifically focused on infants aged 0-5.5 years and investigated behavioural markers of independence (travel, feeding, grooming) and spatial independence. Our results showed similar developmental trajectories but marked species differences concerning specific social and spatial patterns. While chimpanzee infants exhibited prolonged dorsal riding, bonobo infants travelled independently more often and maintained greater distances from their mothers. In addition, age, sibling presence and maternal parity, but not sex, influenced behavioural patterns. These findings highlight the importance of systematic comparative developmental research across great ape populations for understanding both species-specific adaptations and the broader evolutionary foundations of extended development in the human lineage.

  PublisherOA PDFDOI

• Adapting the facial action coding system for chimpanzees (<i>Pan troglodytes</i>) to bonobos (<i>Pan paniscus</i>): the ChimpFACS extension for bonobos

  PeerJ · 2025-06-13 · 3 citations

  articleOpen access

  The Facial Action Coding System (FACS) is a widely recognised coding scheme for analysing human facial behaviour, providing an objective method to quantify discrete movements associated with facial muscles, known as Action Units (AUs), and reducing subjective bias. FACS has been adapted for nine other taxa, including apes, macaques, and domestic animals, but not yet bonobos. To carry out cross species studies of facial behaviours within and beyond apes, it is essential to include bonobos. Hence, we aimed at adapting FACS for bonobos. We followed a similar methodology as in previous FACS adaptations: first, we examined the facial muscular plan of bonobos from previously published dissections. Given the similarity between bonobo and chimpanzee musculature, we tested if ChimpFACS for chimpanzees could be applied to bonobos. Second, we used ChimpFACS to analyse spontaneous facial behaviour in bonobos through videos recorded in various contexts. Third, we noted any differences in appearance changes between the AUs included in ChimpFACS and the AUs observed in bonobos. Our findings showed that bonobos exhibit all the facial movements observed in chimpanzees, and thus ChimpFACS can reliably be applied to bonobos. Bonobos presented a diverse repertoire of 28 facial movements (22 AUs, three Action Descriptors, and three Ear Action Descriptors). Although the range of facial movement is lower than in humans, bonobo's potential for facial movement is comparable to that of chimpanzees, underscoring the significance of this behaviour modality during social interactions for both species. The ChimpFACS Extension for bonobos is an objective coding scheme for measuring facial movements in bonobos, designed to be used in conjunction with ChimpFACS. This coding scheme extension will allow us to better understand bonobos' behaviour and communication, with practical applications for assessing their welfare, particularly in human care. It also provides a framework for comparing primate species, contributing to insights into the origin and evolution of facial emotion and communication.

  PublisherDOI

• Drivers of female power in bonobos

  Communications Biology · 2025-04-24 · 17 citations

  articleOpen access1st authorCorresponding

  In mammals, female dominance over males is a rare phenomenon. However, recent findings indicate that even in species with sexual dimorphism biased towards males, females sometimes occupy high status. Here we test three main hypotheses explaining intersexual power relationships, namely the self-reinforcing effects of winning and losing conflicts, the strength of mate competition, and female coalition formation. We test these for bonobos (Pan paniscus), one of our closest living relatives, where females have high status relative to males despite male-biased size dimorphism. We compiled demographic and behavioral data of 30 years and 6 wild living communities. Our results only support predictions of the female coalition hypothesis. We found that females target males in 85% of their coalitions and that females occupy higher ranks compared to males when they form more frequent coalitions. This result indicates that female coalition formation is a behavioral tool for females to gain power over males.

  PublisherOA PDFDOI

• Group-mindedness as evolved solution to deal with group-living

  Behavioral and Brain Sciences · 2025-01-01

  articleOpen access

  Challenges of group-living include foundational problems of cooperation and coordination that extend beyond anthropoid primates and may potentially be managed through evolved group-mindedness rather than expanded neocortical size and enhanced capacities for executive functions.

  PublisherOA PDFDOI

• An updated vocal repertoire of wild adult bonobos ( <i>Pan paniscus</i> )

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-01-23 · 2 citations

  preprintOpen access

  Abstract While research over the last 20 years has shed important light on the vocal behaviour of our closest living relatives, bonobos and chimpanzees, a quantitative description of their full vocal repertoire is absent. Such data are critical for a holistic understanding of a species’ communication system and unpacking how these systems compare more broadly with other primate and non-primate species. Here we make key progress by providing the first quantitative Pan vocal repertoire, specifically for wild bonobos. Using data comprising over 1500 calls from 53 adult individuals collected over 33 months, we employ machine-learning-based random forest analyses and describe 11 acoustically distinguishable call types. We discuss issues associated with resolving vocal repertoires from wild data in great apes and highlight potential future approaches to further capture the complexity of the bonobo vocal system.

  PublisherOA PDFDOI

• The evolution of infant-directed communication: Comparing vocal input across all great apes

  Science Advances · 2025-06-25 · 3 citations

  articleOpen access

  Human language is unique among communication systems since many elements are learned and transmitted across generations. Previous research suggests that this process is best predicted by infant-directed communication, i.e., a mode of communication directed by caregivers to children. Despite its importance for language, whether infant-directed communication is unique to humans or rooted more deeply in the primate lineage remains unclear. To assess this, we investigated directed and surrounding vocal communication in human infants and infants of wild nonhuman great apes. Our findings reveal that human infants receive dramatically more infant-directed communication than nonhuman great ape infants. These data suggest that the earliest hominins likely relied more on surrounding communication to become communicatively competent, while infant-directed vocal communication became considerably more prominent with human language.

  PublisherDOI

Frequent coauthors

• Liran Samuni

  German Primate Center

  74 shared

• Gottfried Hohmann

  70 shared

• Roman M. Wittig

  61 shared

• Barbara Fruth

  Max Planck Institute of Animal Behavior

  52 shared

• Cédric Girard‐Buttoz

  Max Planck Institute for Human Cognitive and Brain Sciences

  35 shared

• Catherine Crockford

  Institut des Sciences Cognitives

  33 shared

• Christophe Boesch

  32 shared

• Tobias Deschner

  Osnabrück University

  32 shared

Education

• Ph.D., Human Evolutionary Biology

  Harvard University

  2010

• M.A., Human Evolutionary Biology

  Harvard University

  2005

• B.A., Human Evolutionary Biology

  Harvard University

  2003