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Bonobos and people at Wamba: 50 years of research By Takeshi Furuichi, Gen'ichi Idani, Daiji Kimura, Hiroshi Ihobe, Chie Hashimoto, Singapore: Springer Nature, 2023. pp. 1–589. ISBN: 978‐981‐99‐4787‐4

2024; Wiley; Volume: 86; Issue: 9 Linguagem: Inglês

10.1002/ajp.23663

1098-2345

Roman M. Wittig,

Primate Behavior and Ecology

Who is eliya? Since 50 years researchers at Wamba are trying to answer this question. There is no other study site where researchers investigate the behavior and the ecology of the bonobo (Pan paniscus), or eliya, as this ape is called by the local people, for longer. When Takayoshi Kano searched in 1973 for the bonobos, this last discovered great ape was vastly unknown. Living only on the left banks of the Congo-river, scientist had never studied them in their natural habitat. Surveying for many months the Congo basin, he finally arrived in December of 1973 on a bicycle in the village of Wamba. Before he entered the village, he found himself in between a single party of bonobos. The bonobos called on either side of him while he observed them for 20 min. Kano was surprised how relaxed the bonobos were in his presence. This unexpected experience kick started 50 years of research. The book tells the story of these 50 years of research. Divided in six parts, researchers write about the big questions of bonobo research. Recognized latest amongst the great apes as its own species, part 1 includes chapters that describe the historical search and perception of bonobos. Section 2 provides overview of genetic and physiological research at Wamba, while section 3 and 4 focus on the different behaviors and their development and social relationships respectively. Naturally, the authors of the chapters in parts 2–4 take a comparative approach with the chimpanzee literature. Part 5 takes us on an anthropological discourse on the coexistence of eliya (or elia) and local human population. In the last part the chapters formulate the different hypothesis of how the bonobo evolved and which selection pressures account for the species specification. For an additional historic account many researchers that have visited Wamba for shorter periods of time have contributed a short communication chapter of 2–3 pages, showing that research at Wamba has attracted many people. In part 1, besides the first chapter by Kano, Suehisa Kuroda provides an interesting historical account of the first half of research at Wamba before the Congo War. He tells the story of how the female–female relationships, the long-lasting mother–son relationships and the peaceful between-group meetings in bonobos caught the interest of anthropologists. Kuroda points out that bonobo infants develop slower than chimpanzees', potentially increasing a desire to share interest with the mother, however for him the bonobo-ness relates to understanding or obedience, potentially avoiding aggression and stressful situations. In a third chapter Frans de Waal argues that the last common ancestor of humans and Pan must take the behavior of both Pan species into account, thinking about their behavioral differences. In part 2 there are three chapters investigating sexual behaviors and hormones by Chie Hashimoto, personality and polymorphic genes by Cintia Garai, and kin structure by Shintaro Ishizuka. Hashimoto compares the maximum swelling phase with several sexual hormones. She concludes that bonobos females show an early resumption of sexual receptivity, but that this does not lead to much shorter interbirth intervals compared to chimpanzees. This prolonged sexual receptivity in bonobo females is linked to a reduced operational sex ratio and a enhanced affiliative relationship among females. Garai provides a study on bonobo personality with a set of personality related genes. Four loci of these three genes, related to aggressiveness in humans, showed polymorphisms with a high diversity. Finally, Ishizuka investigated within- and between-group kin structure and conforms what is expected from a male philopatric species with female migration into neighboring groups and concludes that irrespective of the lower aggression rate bonobos show higher mating skew than chimpanzees. Part 3 is one of the largest sections in the book and extremely rich for people that are into comparisons. The part starts with two chapters that are rather unexpected in a book on bonobo research: a chapter on hunting and meat eating by Hiroshi Ihobe and Tetsuya Sakamaki and a chapter on tool use by Kathelijne Koops. Both subjects are traditionally not topics in bonobo research because they seem rare, however they are of great interest in relation to human evolution. Although hunting and meat eating is rare in Wamba, in other bonobo sites it is more frequent. Ihobe and Sakamaki conclude that bonobos typically hunt alone and opportunistically, while chimpanzees often hunt in groups and sometimes even actively come together to pursue a hunt. Koops reaches a similar conclusion in the tool use chapter. She summarizes the tool use observed in wild bonobos and concludes that there is almost an absence in using tools for extracting food in bonobos, which seems neither explained by social nor ecological factors. Since bonobos do manipulate less objects than chimpanzees, an intrinsic cause could be the reason. Further in part 3 there are four more chapters. Morgane Allanic investigates the grooming patterns amongst the Wamba bonobos, finding a preference for dyadic, with little polyadic, grooming. Allanic makes the point that it will be important to look at side preferences or body orientation to properly describe population or species differences. Kirsty Graham provides the repertoire of bonobo gestures at Wamba. In the end Graham advocates to move away from only looking at intentionality, but to consider more the perspective of the bonobo. The last two chapters in this part investigate the migration of female bonobos into new groups, one of the features where bonobo and chimpanzees are the same. One chapter is from the perspective of the bonobos' life history, by Kazuya Toda, Nahoko Tokuyama and Tetsuya Sakamaki, and one is looking into the social behavior of newly immigrated females, by Gen'ichi Idani. Toda and colleagues describe an average difference between first dispersal and final settlement in the new community of 2 years, with a younger migration age than chimpanzees. Idani describes the immigration process of immigrant females building slowly relationships with older resident females in the new community using different strategies, from grooming to genital rubbing. Part 4 has a highly relevant collection of chapters on social relationships within and between communities. Nahoko Tokuyama investigated bonobos' aggression and dominance structure. Tokuyama points out that although aggression can be fierce the risk of aggression in bonobos is lower than in chimpanzees. Competition in the female—male co-dominance is regulated by mother–son support and female–female coalitions. Female relationships were the focus in the chapter by Heungjin Ryu. Ryu concluded that age and the presence of a son were the two most important factors to explain the variation in female–female grooming and sexual relationships. Shohei Shibata and Takeshi Furuichi find that adult males in bonobos as in chimpanzee stay with their mothers as much as possible, and when excluding the mother–son relationship, the most frequent grooming partners of male bonobos are other males. During intergroup-encounters, males show the most aggression against males of the neighboring group. Taking all together, Shibata and Furuichi conclude that there are many similarities in the behaviors of male bonobos and chimpanzees, potentially due to the same philopatry. In the final chapter of Part 4 Sakamaki and Tokuyama discuss intergroup relationships in bonobos and their relationships. Part 5 combines six chapters in anthropology, development and conservation pointing out the co-existence of local people and bonobos in the area. Daiji Kimura provides the history of anthropological studies around Wamba. Kimura concludes that for the conservation of the bonobos it is imperative to investigate the cultural, economic, social, and political conditions in the area. The next chapter by Ryota Yamaguchi describes the subsistence activities before and after the Congo War in the forest and its impact on fauna and flora. Due to decline of mammals, the local people shifted from meat to fish as main source of animal protein. Cash crops changed from coffee to cassava and maize for distillation of spirits. This commodity economy requires a distribution network, which is described by Shingo Takamura and Daiji Kimura. The production of spirits and dried fish/meat have affected the local fauna and flora. In the next chapter Naoki Matsuura and Ryota Yamaguchi point out how empowering local associations helps sustainable local development. Long-term investment in sustainable development is one reason why this has also positive effects on conservation. The last two chapters in part 5 investigate directly the effect of human activity on bonobo conservation. Aya Yokotsuka looks at the degradation of the taboo on eating bonobo by the local people. While the taboo had developed due to the bonobo's obvious similarity with humans, it started to decline within the younger generation after the Congo War, potentially due to the abundance of guns, however with less hunting in protected areas. Furthermore, Janet Nackoney and Saeko Terada investigate the structure of bonobo habitat and why it is important to monitor forests for conservation plans. They conclude that monitoring the Congo basin habitats using satellite images and comparing it with continuous bonobo behavior observations and tracking and bonobo habitat surveys is the key to create effective conservation management plans. In part 6 the book has one chapter on the evolution of empathy by Zanna Clay and three chapters investigating different hypothesis of how bonobos have evolved after the split off from a common ancestor with chimpanzees. Clay presents several areas that are of interest in studying empathy and concludes that there is much evidence that bonobos besides chimpanzees and some other species possess the capacity for empathy. In relation to species evolution, Hiroyuki Takemoto is discussing the importance of the Congo-river in the separation of the last common ancestor of the two pan species. Takemoto concludes that a small group of the bonobo ancestor has reached the left bank of the river during a severe drought, which explains the low genetic diversity in bonobos. The gene-flow barrier of the river is one main reason for the evolution of a new species. Richard Wrangham combines the mechanisms of self-domestication with ecological adaptation. He concludes that the lack of gorillas on the left banks of the Congo-river allowed the bonobo ancestors to feed on gorilla food, which is present everywhere, without competition. This selected for more female sociality, less male aggression and generated therefore a self-domestication syndrome. Finally, Takeshi Furuichi states prolonged sexual receptivity of females as the cause of evolution. He argues that the founding population for bonobos was very small and a few genetic mutations could have changed the females' receptivity and therefore could have impacted on the social structure and adaptation in this extraordinary great ape. In general, this book nicely puts together the research conducted at Wamba within its historic context. This, by itself already, provides enough merit for a book even of this size (almost 600 pages). Wamba is the most iconic bonobo research site as it was the first of those running continuously. What the Japanese research teams around Kano and Furuichi have accomplished over the last 50 years is remarkable. Despite wars, poaching, and many other obstacles, researchers have never given up and continued against all odds to provide science with an account of the nature of bonobos. Two chapters, however, I missed in the book. One is a study on vocal communication in bonobos, which to my understanding is crucial for the evolution of language and therefore our understanding of human evolution. And the other is a study on postconflict behavior in wild bonobos. Since the peacefulness and postconflict behavior was so prominently perceived in captive bonobos, the lack of data on postconflict behavior in wild bonobos is really puzzling. Good that this was pointed out by Tokuyama in the chapter on aggressive behavior. Additionally, the book provides a comparison on a population level that will become more and more important. There are now several study sites observing different populations of bonobos. There will be behavioral variability between the different populations, which is extremely important to document, since only with this variability we can answer the question "Who is eliya?". Once the between population comparison data set will become stronger the question of bonobo cultures will emerge naturally. Third the book provides the species comparison with the chimpanzee, the closest living relative of the bonobo. Only if we understand the similarities and differences between these two ape species, we will understand how our behavior has evolved. In this book several of these similarities and differences are pointed out. As such long-term research at Wamba holds a key for our understanding of human evolution. Finally, this book with all its rich information and scientific knowledge is a strong testimony that long-term research is becoming exponentially more valuable the longer a field site is running. Long-term field research needs to stay a pillar of ecology and evolution research. At Wamba, researchers have shown that one can run a field site for 50 years, and I wish everybody responsible the necessary perseverance for the next 50 years.