Portrait of Dr Tatyana Humle

Dr Tatyana Humle

Senior Lecturer in Conservation and Primate Behaviour
Programme Convenor for MSc Conservation pathways


Dr Tatyana Humle is a zoologist by training (BSc in Zoology at the University of Edinburgh, Scotland) and completed her PhD in the Department of Psychology at the University of Stirling in 2004. Tanya was then granted a NIMH Postdoctoral Research Fellowship at the Department of Psychology based at the University of Wisconsin, Madison, USA (2004-2007) before taking on a position as an Associate Professor with the Primate Research Institute and the Wildlife Research Centre at the University of Kyoto, Japan (2007-2010). 

Dr Humle joined the School of Anthropology at the University of Kent in 2010 and DICE in 2012. She has been conducting fieldwork on wild chimpanzees (Pan troglodytes verus) in West Africa, both habituated and non-habituated individuals, since 1995, and has been working collaboratively with African Great Ape sanctuaries since 2008. 

Dr Humle's main research focuses on understanding how great apes adapt to environmental change and manage life in anthropogenic landscapes shaped by small- and large-scale development, identifying drivers of tolerance and attitudes toward wildlife, and developing and evaluating mitigation schemes aimed at improving co-existence between non-human great apes and people. Tanya is also interested in great ape rehabilitation and reintroduction with the aim to improve both welfare and conservation objectives for the species. 

Dr Humle also nourishes a keen research interest in the study of learning and culture in non-human animals, with a special focus on primates, the respective roles of the social and physical environment on learning in young, inter- and intra-community behavioural differences in chimpanzees, and behavioural ecology and cognition. 

Tanya has been an active member of the executive committee of the IUCN (The International Union for the Conservation of Nature and Natural Resources) Section on Great Ape Conservation (SGA) of the Primate Specialist Group since its inception.

Research interests

Great ape rehabilitation and reintroduction

The chimpanzee sanctuary in the Parc National du Haut Niger (PNHN) in Guinea is managed by the Chimpanzee Conservation Center (CCC), a founding member of the Pan African Sanctuary Alliance (PASA). The CCC currently holds more than 40 chimpanzees, primarily all victims of the pet trade. 

The PNHN, which extends over ca. 10,000 square kilometres, is one of the last remaining important formations of dry forest-savanna mosaic in West Africa and a site of high conservation value for both ungulates and wild chimpanzees (Pan troglodytes verus). This park also harbours leopards (Panthera pardus) and a small remnant population of lions (Panthera leo).

Based upon the IUCN reintroduction guidelines, PASA approved the release of a group of twelve chimpanzees from the CCC in the PNHN. These chimpanzees were released in June 2008, 32 km from the sanctuary. A further five chimpanzees were added to the core release group in August 2011. 

Dr Humle's role as scientific advisor and research coordinator with the CCC focuses primarily on the following three areas:

  • Evaluation of rehabilitation and release procedures 
  • Post-release monitoring employing sophisticated tracking systems 
  • Evaluation of conservation impact of the release program on the PNHN

Principle Collaborators 

Surveying and assessing oil palm use in chimpanzees in degraded landscapes

This project aims to contribute to the improving survey methodologies of wild chimpanzees in degraded landscapes harbouring oil palms and propitious to agricultural development, and to further our understanding of the reliance of chimpanzees on the oil palms in such areas. It aims to achieve this by using unmanned aerial vehicles (UAV) and camera traps. This study also seeks to test the value of using UAV technology to improve survey efficiency of chimpanzees in such landscapes. 

Funding: ARCUS Foundation 

Principle Collaborators: Tacugama Chimpanzee Sanctuary; Autonomous University of Barcelona, Spain

Patterns and drivers of wild-meat and resource utilisation in the High Niger National Park (HNNP), Guinea, West Africa

A study, led by Dr Humle and Dr Alexandre Konate in 2010-11 (in prep.) across four focal villages in the HNNP and the town of Faranah which abuts the park, indicated that, although there has been a decrease in the biomass in wild-meat off-take, there has also been an increase in the diversity of species hunted and a shift to smaller prey size and so-called ‘pest’ species. 

More primate species are being hunted and primates (with the exception of chimpanzees for now) contribute a significantly greater proportion of the wild-meat available on markets compared with the mid-nineties and early noughties. This study also identified all stakeholders involved in the wild-meat trade and market chains used to channel wild-meat to urban centres. A new survey is required to evaluate the current situation, but, most crucially, a better understanding of the key drivers of wild-meat hunting and trade is urgently needed. 

The proposed study primarily aims not only to replicate Konate and Humle’s study but also to apply the newly developed Wild-meat Toolkit developed by Josephine Head/Arcus Foundation which aims to identify drivers and factors influencing wild-meat hunting and trade across focal localities. A secondary objective of this study is to help improve the application and implementation of the Wild-meat Toolkit in francophone countries and its usage by national conservation practitioners in-country. 

Broader application of the Toolkit will favour a wider understanding of key factors and drivers across differing scales, e.g. local, national and regional, which is key to developing sound and effective strategies aimed at promoting sustainable hunting practices and protein-alternative schemes. 

Funding: ARCUS Foundation 

Principle Collaborators: Dr. Alexandre Konate; ISAV, Faranah, Republic of Guinea and the Office of Protected Areas of Guinea (OGUIPAR); the local HNNP authorities and HNNP director; and the Chimpanzee Conservation Centre (CCC).


  • DI531: Human-Wildlife Conflict and Resource Competition (convenor)
  • DI535: Tropical Ecology and Conservation
  • DI884: Research Skills for Natural Sciences (convenor)
  • DI892: Current Issues in Primate Conservation (convenor)
  • DI1001: Multidisciplinary Perspectives on Conservation
  • DI998: Dissertation - Conservation (convenor)
  • DI883: Special Topics in Conservation


Dr Humle is interested in supervising PhD students in the fields of primate conservation, rehabilitation and reintroduction, and on issues pertaining to human–wildlife interactions, especially relevant to the impact of extractive and agricultural activities on great apes.


  • Lucie Duanomou 2017-ongoing (joint supervision with Proessor Xu Jiliang, based at Beijing Forestry University, China): Patterns and Drivers Of Wild Meat and Resource Utilisation In The High Niger National Park, Guinea, West Africa
  • Thirza Loffeld 2016-ongoing (joint supervision with Dr Bob Smith, Dr Simon Black, Dr Susan Cheyne (Borneo Nature Foundation), Dr Madhu Rao (Wildlife Conservation Society)): Professional development in wildlife conservation: identifying gaps and barriers from case studies in developing countries


  • Rosa Garriga, PhD awarded 2018 (Autonomous University of Barcelona, Spain): Human-Chimpanzee Co-Existence in Non-Protected Areas in Sierra Leone, West Africa


Member of/Appointments



  • Neufuss, J. et al. (2018). Gait characteristics of vertical climbing in mountain gorillas and chimpanzees. Journal of Zoology [Online] 306:129-138. Available at: https://doi.org/10.1111/jzo.12577.
    Biomechanical analyses of arboreal locomotion in great apes in their natural
    environment are scarce and thus attempts to correlate behavioural and habitat
    differences with variations in morphology are limited. The aim of this study was to
    investigate the gait characteristics of vertical climbing in mountain gorillas (Gorilla
    beringei beringei) and chimpanzees (Pan troglodytes) in a natural environment to
    assess differences in the climbing styles that may relate to variation in body size. We
    investigated temporal variables (i.e., cycle duration, duty factors, and stride
    frequency) and footfall sequences (i.e., diagonal vs. lateral sequence gaits) during
    vertical climbing (both ascent and descent) in 11 wild mountain gorillas and
    compared these data to those of eight semi-free-ranging chimpanzees, using video
    records ad libitum. Comparisons of temporal gait parameters revealed that largebodied
    mountain gorillas exhibited a longer cycle duration, lower stride frequency
    and generally a higher duty factor than smaller-bodied chimpanzees. While both
    apes were similarly versatile in their vertical climbing performance in the natural
    environment, mountain gorillas most often engaged in diagonal sequence/diagonal
    couplet gaits and chimpanzees most often used lateral sequence/diagonal couplet
    gaits. This study revealed that mountain gorillas adapt their climbing strategy to
    accommodate their large body mass in a similar manner previously found in captive
    western lowland gorillas, and that chimpanzees are less variable in their climbing
    strategy than has been documented in captive bonobos.
  • Neufuss, J. et al. (2018). Manual skills for food processing by mountain gorillas in Bwindi Impenetrable National Park, Uganda. Biological Journal of the Linnean Society [Online] bly071. Available at: https://doi.org/10.1093/biolinnean/bly071.
    Although gorillas rarely use tools in the wild, their manipulative skills during plant processing
    may be similar to those of other tool-using great apes. Virunga mountain gorillas are known
    for the complexity in their methods of thistle and nettle plant preparation in the wild.
    However, there has been no comparable data on food processing in the population of
    mountain gorillas from the Bwindi Impenetrable National Park, Uganda. We investigated the
    manual actions and hand grips used when accessing edible parts of two hard-to-process
    plants defended by stinging hairs, epidermis or periderm (i.e., peel of Urera hypselodendron
    and pith of Mimulopsis arborescens) and one undefended plant (i.e., leaves of Momordica
    foetida) in 11 Bwindi wild mountain gorillas (Gorilla beringei beringei) using video records ad
    libitum. Similar to thistle feeding by Virunga gorillas, Bwindi gorillas used the greatest
    number of manual actions for the most hard-to-process plant (U. hypselodendron), the
    actions were ordered in several key stages and organised hierarchically. The demands of
    processing plant material elicited 19 different grips and variable thumb postures, of which
    three grips were new and 16 grips have either been previously reported or show clear
    similarities to grips used by other wild and captive African apes and humans. Moreover, our
    study only partly supports a functional link between diet and hand morphology in mountain
    gorillas and suggests that the gorilla hand is best adapted to forceful grasping that is
    required for both manipulation and arboreal locomotion.
  • Bryson-Morrison, N. et al. (2017). Activity and Habitat Use of Chimpanzees (Pan troglodytes verus) in the Anthropogenic Landscape of Bossou, Guinea, West Africa. International Journal of Primatology [Online]:1-21. Available at: http://dx.doi.org/10.1007/s10764-016-9947-4.
    Many primate populations inhabit anthropogenic landscapes. Understanding their long-term ability to persist in such environments and associated real and perceived risks for both primates and people is essential for effective conservation planning. Primates in forest–agricultural mosaics often consume cultivars to supplement their diet, leading to potentially negative encounters with farmers. When crossing roads, primates also face the risk of encounters with people and collision with vehicles. Chimpanzees (Pan troglodytes verus) in Bossou, Guinea, West Africa, face such risks regularly. In this study, we aimed to examine their activity budget across habitat types and the influence of anthropogenic risks associated with cultivated fields, roads, and paths on their foraging behavior in noncultivated habitat. We conducted 6-h morning or afternoon follows daily from April 2012 to March 2013. Chimpanzees preferentially used forest habitat types for traveling and resting and highly disturbed habitat types for socializing. Wild fruit and crop availability influenced seasonal habitat use for foraging. Overall, chimpanzees preferred mature forest for all activities. They showed a significant preference for foraging at >200 m from cultivated fields compared to 0–100 m and 101–200 m, with no effect of habitat type or season, suggesting an influence of associated risk. Nevertheless, the chimpanzees did not actively avoid foraging close to roads and paths. Our study reveals chimpanzee reliance on different habitat types and the influence of human-induced pressures on their activities. Such information is critical for the establishment of effective land use management strategies in anthropogenic landscapes.
  • Garriga, R. et al. (2017). Perceptions of challenges to subsistence agriculture, and crop foraging by wildlife and chimpanzees Pan troglodytes verus in unprotected areas in Sierra Leone. Oryx [Online]:1-14. Available at: https://dx.doi.org/10.1017/S0030605316001319.
    The 2009–2010 Sierra Leone National Chimpanzee Census Project estimated there was a population of 5,580 chimpanzees Pan troglodytes verus distributed across the country, with > 50% occurring outside protected areas. The census also highlighted the significance of competition between people and chimpanzees for resources in areas dominated by farming activities where wild chimpanzees forage on crops. We selected four study areas in two districts in Sierra Leone with high chimpanzee density in habitats dominated by agriculture, far from any protected areas. Our objectives were to assess farmers’ perceptions of the main challenges to their agricultural yields, and the wildlife involved in crop foraging, and their perceptions of chimpanzees in particular, as well as the main crop protection measures used. We conducted 257 semi-structured interviews with local farmers across the four study areas. We found that (1) farmers reported wild animals as the main challenge to their agricultural practices; (2) most complaints concerned cane rats Thryonomys swinderianus, which targeted almost all crop types, especially rice and cassava; (3) chimpanzees reportedly targeted 21 of the 23 crop types cultivated, but did so less often than cane rats, focusing particularly on oil palm, cassava and domestic fruits; (4) overall, chimpanzees were not among the top three most destructive animals reported; (5) chimpanzees were generally perceived as being more destructive than dangerous and as having declined since before the civil war; and (6) the main crop protection measure employed was fencing interspersed with traps. Our findings show the importance of investigating farmers’ perceptions to inform the development of appropriate conservation strategies aimed at promoting coexistence of people and wildlife in degraded landscapes.
  • Neufuss, J. et al. (2017). Comparison of hand use and forelimb posture during vertical climbing in mountain gorillas (Gorilla beringei beringei) and chimpanzees (Pan troglodytes). American Journal of Physical Anthropology [Online] 164:651-664. Available at: http://dx.doi.org/10.1002/ajpa.23303.
    Studies on grasping and limb posture during arboreal locomotion in great apes in their natural environment are scarce and thus, attempts to correlate behavioral and habitat differences with variation in morphology are limited. The aim of this study is to compare hand use and forelimb posture during vertical climbing in wild, habituated mountain gorillas (Gorilla beringei beringei) and semi-free-ranging chimpanzees (Pan troglodytes) to assess differences in the climbing styles that may relate to variation in hand or forelimb morphology and body size.

    Materials and methods
    We investigated hand use and forelimb posture during both ascent and descent vertical climbing in 15 wild mountain gorillas and eight semi-free-ranging chimpanzees, using video records obtained ad libitum.

    In both apes, forelimb posture was correlated with substrate size during both ascent and descent climbing. While climbing, both apes used power grips and diagonal power grips, including three different thumb postures. Mountain gorillas showed greater ulnar deviation of the wrist during vertical descent than chimpanzees, and the thumb played an important supportive role when gorillas vertically descended lianas.

    We found that both apes generally had the same grip preferences and used similar forelimb postures on supports of a similar size, which is consistent with their overall similarity in hard and soft tissue morphology of the hand and forelimb. However, some species-specific differences in morphology appear to elicit slightly different grasping strategies during vertical climbing between mountain gorillas and chimpanzees.
  • Leendertz, S. et al. (2016). Ebola in great apes – current knowledge, possibilities for vaccination, and implications for conservation and human health. Mammal Review [Online]. Available at: http://dx.doi.org/10.1111/mam.12082.
    Ebola virus disease (EVD) is a threat to human health and to the survival of African great apes. The disease has led to major population declines in chimpanzees Pan troglodytes and gorillas Gorilla gorilla, and infected great apes play an important role as sources of human EVD outbreaks. The threat posed by EVD raises the question whether vaccination of wild apes is an effective strategy to reduce the occurrence and impact of this disease.
    We review the current knowledge about EVD in great apes and document the link between outbreaks in apes and in humans, mainly via bushmeat consumption. We discuss the need for control strategies, such as vaccination, and describe aspects of primate behaviour, virus biology, vaccine composition, and vaccination principles that need to be considered when making management decisions about great ape vaccination. Finally, we identify gaps in the understanding of Ebola ecology and highlight surveillance and research that can aid the survival of great apes and reduce human exposure to Ebola virus.
    The severe impact of EVD indicates the need for efficient monitoring and, ultimately, control of Ebola. However, the unknown reservoir and unpredictable emergence of Ebola, the elusive nature of great apes, and the lack of licensed and suitable vaccines represent major hurdles for such control. Public education about zoonotic diseases and monitoring of great ape health are both important strategies. Experts should also discuss the feasibility of developing safe vaccines that can be delivered efficiently to large populations of elusive wild apes in their natural remote habitats. This review provides a platform for further interdisciplinary discussions, so that management plans can be discussed and adjusted according to possible future changes in the development, availability and cost of vaccines, the status of EVD, knowledge about Ebola ecology, and opinion on wildlife vaccination.
  • Wilson, V. et al. (2016). Chimpanzee Personality and the Arginine Vasopressin Receptor 1A Genotype. Behavior Genetics [Online]:1-12. Available at: http://dx.doi.org/10.1007/s10519-016-9822-2.
    Polymorphisms of the arginine vasopressin receptor 1a (AVPR1a) gene have been linked to various measures related to human social behavior, including sibling conflict and agreeableness. In chimpanzees, AVPR1a polymorphisms have been associated with traits important for social interactions, including sociability, joint attention, dominance, conscientiousness, and hierarchical personality dimensions named low alpha/stability, disinhibition, and negative emotionality/low dominance. We examined associations between AVPR1a and six personality domains and hierarchical personality dimensions in 129 chimpanzees (Pan troglodytes) living in Japan or in a sanctuary in Guinea. We fit three linear and three animal models. The first model included genotype, the second included sex and genotype, and the third included genotype, sex, and sex × genotype. All personality phenotypes were heritable. Chimpanzees possessing the long form of the allele were higher in conscientiousness, but only in models that did not include the other predictors; however, additional analyses suggested that this may have been a consequence of study design. In animal models that included sex and sex × genotype, chimpanzees homozygous for the short form of the allele were higher in extraversion. Taken with the findings of previous studies of chimpanzees and humans, the findings related to conscientiousness suggest that AVPR1a may be related to lower levels of impulsive aggression. The direction of the association between AVPR1a genotype and extraversion ran counter to what one would expect if AVPR1a was related to social behaviors. These results help us further understand the genetic basis of personality in chimpanzees.
  • Humle, T. (2016). Franco-Japanese and other collaborative contributions to understanding chimpanzee culture at Bossou and the Nimba Mountains. Primates [Online] 57:339-348. Available at: http://dx.doi.org/10.1007/s10329-016-0536-0.
    The Japanese approach to science has permitted theoretical leaps in our understanding of culture in non-human animals and challenged human uniqueness, as it is not embedded in the Western traditional dualisms of human/animal and nature/culture. This paper highlights the value of an interdisciplinary approach and combining methodological approaches in exploring putative cultural variation among chimpanzees. I focus particularly on driver ants (Dorylus sp.) and oil palm (Elaeis guineensis) consumption among the Bossou and Nimba chimpanzees, in south-eastern Guinea at the border with Côte d’Ivoire and Liberia, and hand use across different tool use tasks commonly witnessed at Bossou, i.e. ant-dipping, nut-cracking, pestle-pounding, and algae-scooping. Observed variation in resource use was addressed across differing scales exploring both within- and between-community differences. Our findings have highlighted a tight interplay between ecology, social dynamics and culture, and between social and individual learning and maternal contribution to tool-use acquisition. Exploration of hand use by chimpanzees revealed no evidence for individual-level hand or community-level task specialisation. However, more complex types of tool use such as nut-cracking showed distinct lateralization, while the equivalent of a haptic manual action revealed a strong right hand bias. The data also suggest an overall population tendency for a right hand preference. As well as describing these sites’ key contributions to our understanding of chimpanzees and to challenging our perceptions of human uniqueness, this paper also highlights the critical condition and high levels of threats facing this emblematic chimpanzee population, and several questions that remain to be addressed. In the spirit of the Japanese approach to science, I recommend that an interdisciplinary and collaborative research approach can best help us to challenge perceptions of human uniqueness and to further our understanding of chimpanzee behavioural and social flexibility in the face of local social, ecological and anthropogenic changes and threats to their survival.
  • Bryson-Morrison, N., Matsuzawa, T. and Humle, T. (2016). Chimpanzees in an Anthropogenic Landscape: Examining Food Resources across Habitat Types at Bossou, Guinea, West Africa. American Journal of Primatology [Online] 78:1237-1249. Available at: http://dx.doi.org/10.1002/ajp.22578.
    Many primate populations occur outside protected areas in fragmented anthropogenic landscapes. Empirical data on the ecological characteristics that define an anthropogenic landscape are urgently required if conservation initiatives in such environments are to succeed. The main objective of our study was to determine the composition and availability of chimpanzee (Pan troglodytes verus) food resources across fine spatial scales in the anthropogenic landscape of Bossou, Guinea, West Africa. We examined food resources in all habitat types available in the chimpanzees' core area. We surveyed resource composition, structure and heterogeneity (20 m × 20 m quadrats, N = 54) and assessed temporal availability of food from phenology trails (total distance 5951 m; 1073 individual trees) over 1 year (2012-2013). Over half of Bossou consists of regenerating forest and is highly diverse in terms of chimpanzee food species; large fruit bearing trees are rare and confined to primary and riverine forest. Moraceae (mulberries and figs) was the dominant family, trees of which produce drupaceous fruits favored by chimpanzees. The oil palm occurs at high densities throughout and is the only species found in all habitat types except primary forest. Our data suggest that the high densities of oil palm and fig trees, along with abundant terrestrial herbaceous vegetation and cultivars, are able to provide the chimpanzees with widely available resources, compensating for the scarcity of large fruit trees. A significant difference was found between habitat types in stem density/ha and basal area m2 /ha of chimpanzee food species. Secondary, young secondary, and primary forest emerged as the most important habitat types for availability of food tree species. Our study emphasizes the importance of examining ecological characteristics of an anthropogenic landscape as each available habitat type is unlikely to be equally important in terms of spatial and temporal availability of resources
  • Rust, N. et al. (2016). Why Has Human–Carnivore Conflict Not Been Resolved in Namibia? Society & Natural Resources [Online] 29:1079-1094. Available at: http://dx.doi.org/10.1080/08941920.2016.1150544.
    Human–wildlife conflict has historically been portrayed as a management problem where solutions lie in technical changes or financial incentives. However, recent research shows many conflicts stem from social, economic, and political drivers. We undertook qualitative data collection on livestock farms to determine whether relationships between farmers and their workers affected frequency of reported livestock depredation in Namibia. We found that the conflict was affected by social and economic inequalities embedded in the previous apartheid regime. Macro- and microlevel socioeconomic problems created an environment where livestock depredation was exacerbated by unmotivated farm workers. Poor treatment of workers by farmers resulted in vengeful behaviors, such as livestock theft and wildlife poaching. Successfully addressing this situation therefore requires recognition and understanding of its complexity, rather than reducing it to its most simplistic parts
  • Neufuss, J. et al. (2016). Nut-cracking behaviour in wild-born, rehabilitated bonobos (Pan paniscus): a comprehensive study of hand preference, hand grips and efficiency. American Journal of Primatology [Online] 79:e22589. Available at: http://dx.doi.org/10.1002/ajp.22589.
    There has been an enduring interest in primate tool-use and manipulative abilities, most often with the goal of providing insight into the evolution of human manual dexterity, right-hand preference, and what behaviours make humans unique. Chimpanzees (Pan troglodytes) are arguably the most well-studied tool-users amongst non-human primates, and are particularly well-known for their complex nut-cracking behaviour, which has been documented in several West African populations. However, their sister-taxon, the bonobos (Pan paniscus), rarely engage in even simple tool-use and are not known to nut-crack in the wild. Only a few studies have reported tool-use in captive bonobos, including their ability to crack nuts, but details of this complex tool-use behaviour have not been documented before. Here, we fill this gap with the first comprehensive analysis of bonobo nut-cracking in a natural environment at the Lola ya Bonobo sanctuary, Democratic Republic of the Congo. Eighteen bonobos were studied as they cracked oil palm nuts using stone hammers. Individual bonobos showed exclusive laterality for using the hammerstone and there was a significant group-level right-hand bias. The study revealed 15 hand grips for holding differently sized and weighted hammerstones, 10 of which had not been previously described in the literature. Our findings also demonstrated that bonobos select the most effective hammerstones when nut-cracking. Bonobos are efficient nut-crackers and not that different from the renowned nut-cracking chimpanzees of Bossou, Guinea, which also crack oil palm nuts using stones.
  • Hockings, K. et al. (2015). Tools to tipple: ethanol ingestion by wild chimpanzees using leaf-sponges. Royal Society open science [Online] 2:150150-150150. Available at: http://dx.doi.org/10.1098/rsos.150150.
    African apes and humans share a genetic mutation that enables them to effectively metabolize ethanol. However, voluntary ethanol consumption in this evolutionary radiation is documented only in modern humans. Here, we report evidence of the long-term and recurrent ingestion of ethanol from the raffia palm (Raphia hookeri, Arecaceae) by wild chimpanzees (Pan troglodytes verus) at Bossou in Guinea, West Africa, from 1995 to 2012. Chimpanzees at Bossou ingest this alcoholic beverage, often in large quantities, despite an average presence of ethanol of 3.1% alcohol by volume (ABV) and up to 6.9% ABV. Local people tap raffia palms and the sap collects in plastic containers, and chimpanzees use elementary technology—a leafy tool—to obtain this fermenting sap. These data show that ethanol does not act as a deterrent to feeding in this community of wild apes, supporting the idea that the last common ancestor of living African apes and modern humans was not averse to ingesting foods containing ethanol.
  • Wich, S. et al. (2014). Will Oil Palm’s Homecoming Spell Doom for Africa’s Great Apes? Current Biology [Online] 24:1659-1663. Available at: http://dx.doi.org/10.1016/j.cub.2014.05.077.
    Expansion of oil palm plantations has led to extensive wildlife habitat conversion in Southeast Asia [ 1 ]. This expansion is driven by a global demand for palm oil for products ranging from foods to detergents [ 2 ], and more recently for biofuels [ 3 ]. The negative impacts of oil palm development on biodiversity [ 1, 4, 5 ], and on orangutans (Pongo spp.) in particular, have been well documented [ 6, 7 ] and publicized [ 8, 9 ]. Although the oil palm is of African origin, Africa’s production historically lags behind that of Southeast Asia. Recently, significant investments have been made that will likely drive the expansion of Africa’s oil palm industry [ 10 ]. There is concern that this will lead to biodiversity losses similar to those in Southeast Asia. Here, we analyze the potential impact of oil palm development on Africa’s great apes. Current great ape distribution in Africa substantially overlaps with current oil palm concessions (by 58.7%) and areas suitable for oil palm production (by 42.3%). More importantly, 39.9% of the distribution of great ape species on unprotected lands overlaps with suitable oil palm areas. There is an urgent need to develop guidelines for the expansion of oil palm in Africa to minimize the negative effects on apes and other wildlife. There is also a need for research to support land use decisions to reconcile economic development, great ape conservation, and avoiding carbon emissions.
  • Humle, T. et al. (2014). Biology's drones: undermined by fear. Science [Online] 344:1351-1351. Available at: http://dx.doi.org/10.1126/science.344.6190.1351-a.
  • Kormos, R. et al. (2014). Great Apes and Biodiversity Offset Projects in Africa: The Case for National Offset Strategies. PLoS ONE [Online] 9:e111671. Available at: http://dx.doi.org/10.1371/journal.pone.0111671.
    The development and private sectors are increasingly considering “biodiversity offsets” as a strategy to compensate for their negative impacts on biodiversity, including impacts on great apes and their habitats in Africa. In the absence of national offset policies in sub-Saharan Africa, offset design and implementation are guided by company internal standards, lending bank standards or international best practice principles. We examine four projects in Africa that are seeking to compensate for their negative impacts on great ape populations. Our assessment of these projects reveals that not all apply or implement best practices, and that there is little standardization in the methods used to measure losses and gains in species numbers. Even if they were to follow currently accepted best-practice principles, we find that these actions may still fail to contribute to conservation objectives over the long term. We advocate for an alternative approach in which biodiversity offset and compensation projects are designed and implemented as part of a National Offset Strategy that (1) takes into account the cumulative impacts of development in individual countries, (2) identifies priority offset sites, (3) promotes aggregated offsets, and (4) integrates biodiversity offset and compensation projects with national biodiversity conservation objectives. We also propose supplementary principles necessary for biodiversity offsets to contribute to great ape conservation in Africa. Caution should still be exercised, however, with regard to offsets until further field-based evidence of their effectiveness is available.
  • Yamamoto, S., Humle, T. and Tanaka, M. (2013). Basis for Cumulative Cultural Evolution in Chimpanzees: Social Learning of a More Efficient Tool-Use Technique. PLoS ONE [Online] 8:e55768. Available at: http://dx.doi.org/10.1371/journal.pone.0055768.
    Background: The evidence for culture in non-human animals has been growing incrementally over the past two decades. However, the ability for cumulative cultural evolution, with successive generations building on earlier achievements, in non-human animals remains debated. Faithful social learning of incremental improvements in technique is considered to be a defining feature of human culture, differentiating human from non-human cultures. This study presents the first experimental evidence for chimpanzees' social transmission of a more efficient tool-use technique invented by a conspecific group member. Methodology/Principal Findings: The chimpanzees were provided with a straw-tube, and spontaneously demonstrated two different techniques in obtaining juice through a small hole: "dipping" and "straw-sucking". Both the "dipping" and "straw-sucking" techniques depended on the use of the same tool (straw-tube) for the same target (juice) accessible from exactly the same location (small hole 1 cm in diameter). Therefore the difference between "dipping" and "straw-sucking" was only in "technique". Although the two techniques differed significantly in their efficiency, their cognitive and perceptuo-motor complexity were comparable. All five chimpanzees who initially performed the "dipping" technique switched to using the more efficient "straw-sucking" technique upon observing a conspecific or human demonstrate the more proficient alternate "straw-sucking" technique. Conclusions/Significance: The social learning mechanism involved here was clearly not local or stimulus enhancement, but imitation or emulation of a tool-use technique. When there is no biologically relevant difference in cognitive or perceptuo-motor complexity between two techniques, and when chimpanzees are dissatisfied with their own technique, chimpanzees may socially learn an improved technique upon close observation of a proficient demonstrator. This study provides important insights into the cognitive basis for cumulative culture in chimpanzees, and also suggests possible conditions in which cumulative cultural evolution could arise even in non-human animals.
  • Ongman, L. et al. (2013). The "Super Chimpanzee": The ecological dimensions of rehabilitation of orphan chimpanzees in Guinea, West Africa. Animals [Online] 3:109-126. Available at: http://dx.doi.org/10.3390/ani3010109.
    To date few studies, especially among non-human primates, have evaluated or monitored rehabilitation effectiveness and identified key species-specific behavioral indicators for release success. This four-months study aimed to identify behavioral indicators of rehabilitation success among ten infant and juvenile orphaned chimpanzees cared for in peer groups at the Centre for Conservation of Chimpanzees (CCC), Guinea, West Africa. Behavioral data focused on foraging skills and activity budget. During bush-outings, rehabilitants spent on average nearly a quarter of their activity budget foraging, resting or traveling, respectively. Neither age, sex, the level of abnormal behaviors demonstrated upon arrival nor human contact during bush-outings predicted individual dietary knowledge. However, individuals who spent more time arboreal demonstrated a greater dietary breadth than conspecifics who dwelled more terrestrially. Although our data failed to demonstrate a role of conspecific observation in dietary acquisition, we propose that the mingling of individuals from different geographical origins may act as a catalyst for acquiring new dietary knowledge, promoted by ecological opportunities offered during bush-outings. This "Super Chimpanzee" theory opens up new questions about cultural transmission and socially-biased learning among our closest living relatives and provides a novel outlook on rehabilitation in chimpanzees.
  • Fragaszy, D. et al. (2013). The fourth dimension of tool use: temporally enduring artefacts aid primates learning to use tools. Philosophical Transactions of the Royal Society B: Biological Sciences [Online] 368. Available at: http://dx.doi.org/10.1098/rstb.2012.0410.
    All investigated cases of habitual tool use in wild chimpanzees and capuchin monkeys include youngsters encountering durable artefacts, most often in a supportive social context. We propose that enduring artefacts associated with tool use, such as previously used tools, partly processed food items and residual material from previous activity, aid non-human primates to learn to use tools, and to develop expertise in their use, thus contributing to traditional technologies in non-humans. Therefore, social contributions to tool use can be considered as situated in the three dimensions of Euclidean space, and in the fourth dimension of time. This notion expands the contribution of social context to learning a skill beyond the immediate presence of a model nearby. We provide examples supporting this hypothesis from wild bearded capuchin monkeys and chimpanzees, and suggest avenues for future research.
  • Yamamoto, S., Humle, T. and Tanaka, M. (2012). Chimpanzees' flexible targeted helping based on an understanding of conspecifics' goals. Proceedings of the National Academy of Sciences of the United States of America [Online] 109:3588-3592. Available at: http://dx.doi.org/10.1073/pnas.1108517109.
    Humans extensively help others altruistically, which plays an important role in maintaining cooperative societies. Although some nonhuman animals are also capable of helping others altruistically, humans are considered unique in our voluntary helping and our variety of helping behaviors. Many still believe that this is because only humans can understand others' goals due to our unique "theory of mind" abilities, especially shared intentionality. However, we know little of the cognitive mechanisms underlying helping in nonhuman animals, especially if and how they understand others' goals. The present study provides the empirical evidence for flexible targeted helping depending on conspecifics' needs in chimpanzees. The subjects of this study selected an appropriate tool from a random set of seven objects to transfer to a conspecific partner confronted with differing tooluse situations, indicating that they understood what their partner needed. This targeted helping, (i.e., selecting the appropriate tool to transfer), was observed only when the helpers could visually assess their partner's situation. If visual access was obstructed, the chimpanzees still tried to help their partner upon request, but failed to select and donate the appropriate tool needed by their partner. These results suggest that the limitation in chimpanzees' voluntary helping is not necessarily due to failure in understanding others' goals. Chimpanzees can understand conspecifics' goals and demonstrate cognitively advanced targeted helping as long as they are able to visually evaluate their conspecifics' predicament. However, they will seldom help others without direct request for help.
  • Unwin, S. et al. (2012). Does Confirmed Pathogen Transfer between Sanctuary Workers and Great Apes Mean that Reintroduction Should not Occur?: Commentary on "Drug-resistant human Staphylococcus aureus findings in sanctuary apes and its threat to wild ape populations". American Journal of Primatology [Online] 74:1076-1083. Available at: http://dx.doi.org/10.1002/ajp.22069.
    This commentary discusses the findings and conclusions of the paper "Drug resistant human Staphylococcus aureus findings in sanctuary apes and its threat to wild ape populations." This paper confirms the zoonotic transfer of Staphylococcus aureus in a sanctuary setting. The assertion that this in itself is enough to reconsider the conservation potential of ape reintroduction provides an opportunity to discuss risk analysis of pathogen transmission, following IUCN guidelines, using S. aureus as an example. It is concluded that ape reintroduction projects must have disease risk mitigation strategies that include effective biosecurity protocols and pathogen surveillance. These strategies will assist with creating a well planned and executed reintroduction. This provides one way to enforce habitat protection, to minimise human encroachment and the risks from the illegal wildlife trade. Thus reintroduction must remain a useful tool in the conservation toolbox.
  • Hockings, K. et al. (2012). Chimpanzee interactions with nonhuman species in an anthropogenic habitat. Behaviour [Online] 149:299-324. Available at: http://dx.doi.org/10.1163/156853912X636735.
    Interactions between wildlife species are numerous and diverse, ranging from commensalism to predation. Information on cross-species interactions in anthropogenic habitats are rare but can serve to improve our understanding of animal behavioural and ecological flexibility in response to human-induced changes. Here we report direct observations of interactions between chimpanzees (Pan troglodytes verus) and wild and domesticated species in a forest-farm mosaic at Bossou, Guinea, recorded between 1997 and 2009. The low diversity and abundance of wildlife, in particular typical chimpanzee prey species, are reflected in both the low interaction rates (one interaction per 400 observation hours) and the low number of species with which chimpanzees interacted (nine species, mostly mammals, but also birds and reptiles). Chimpanzees generally chose either to make direct physical contact with a species or not; interactions that involved direct contact lasted longer than noncontacts. Interactions with mammals showed the greatest diversity in nature and duration. Adults most often consumed a captured animal, while immatures most often engaged in playful behaviours with other species. Immatures also exhibited distinctive accompanying behaviours whereas adults rarely did so. Species-specific behaviours that depend on the age-class of the interactant are consistent with the idea that chimpanzees categorise different animals. We anticipate that chimpanzee interactions with sympatric species inhabiting humanised habitats will change over time to include more domesticated species. Conservation management strategies should anticipate behavioural flexibility in response to changing landscapes.
  • Sugiyama, Y. and Humle, T. (2011). A wild chimpanzee uses a stick to disable a snare at Bossou, Guinea. Pan Africa News [Online] 18:3-4. Available at: http://mahale.main.jp/PAN/18_1/18(1)_03.html.
  • Humle, T. et al. (2011). Group Release of Sanctuary Chimpanzees (Pan troglodytes) in the Haut Niger National Park, Guinea, West Africa: Ranging Patterns and Lessons So Far. International Journal of Primatology [Online] 32:456-473. Available at: http://dx.doi.org/10.1007/s10764-010-9482-7.
    The release of wild or captive-bred mammals within their historical ranges typically aims to reestablish populations in areas where they have become extinct or extirpated, to reinforce natural populations, or to resolve human-wildlife conflicts. Such programs, which also typically in parallel help foster the protection of the release site, concern a wide range of endangered mammalian species, including our closest living relatives: chimpanzees. In June 2008, the Chimpanzee Conservation Center (CCC), which is located in the High Niger National Park (HNNP) in Guinea, released a group of 12 chimpanzees (Pan troglodytes verus) comprised of 6 females and 6 males (8-20 yr old). The selected release site lies 32 km from the sanctuary in the Mafou, a core area of HNNP where wild chimpanzees are also known to occur. The purpose of this release was therefore to reinforce the natural chimpanzee population within the Mafou core area and to promote the protection of the HNNP. Nearly 2 yr postrelease, 9 chimpanzees still remain free-living. Two thirds of the release chimpanzees were equipped with VHF-GPS store-on-board tracking collars. We used data from retrieved collars to explore the release chimpanzees' habitat use, individual day range, and core area use (50% and 80%) during the first year of the release. Males traveled significantly further than females. Although minimum day range did not differ between the sexes or vary seasonally, some release males were active for longer during the day than the females. Males also ranged over larger areas and used a wider network of core areas than the females. Habitat use was similar to that recorded in wild chimpanzees in the HNNP. As of September 2010, 2 males and 3 females form a group at the release site. Two of these females gave birth to healthy offspring respectively 16 and 20 mo postrelease. Another female successfully immigrated into a wild chimpanzee community. We suggest that the success of this chimpanzee release can be attributed to the CCC's lengthy rehabilitation process and the savanna-mosaic habitat of the HNNP. This release demonstrates that under special socioecological circumstances, the release of wild-born adult chimpanzees of both sexes is a viable strategy, which can also function as an effective conservation tool.
  • Hong, K. et al. (2011). Polymorphism of the tryptophan hydroxylase 2 (TPH2) gene is associated with chimpanzee neuroticism. PLoS ONE [Online] 6:e22144. Available at: http://dx.doi.org/10.1371/journal.pone.0022144.
    In the brain, serotonin production is controlled by tryptophan hydroxylase 2 (TPH2), a genotype. Previous studies found that mutations on the TPH2 locus in humans were associated with depression and studies of mice and studies of rhesus macaques have shown that the TPH2 locus was involved with aggressive behavior. We previously reported a functional single nucleotide polymorphism (SNP) in the form of an amino acid substitution, Q468R, in the chimpanzee TPH2 gene coding region. In the present study we tested whether this SNP was associated with neuroticism in captive and wild-born chimpanzees living in Japan and Guinea, respectively. Even after correcting for multiple tests (Bonferroni p = 0.05/6 = 0.008), Q468R was significantly related to higher neuroticism (β = 0.372, p = 0.005). This study is the first to identify a genotype linked to a personality trait in chimpanzees. In light of the prior studies on humans, mice, and rhesus macaques, these findings suggest that the relationship between neuroticism and TPH2 has deep phylogenetic roots.
  • Dillis, C., Humle, T. and Snowdon, C. (2010). Socially biased learning among adult cottontop tamarins (Saguinus oedipus). American Journal of Primatology [Online] 72:287-295. Available at: http://dx.doi.org/10.1002/ajp.20778.
    We presented adult cottontop tamarins (Saguinus oedipus) with a novel foraging task that had been used previously to examine socially biased learning of juvenile observers [Humle & Snowdon, Animal Behaviour 75:267-277, 2008]. The task could be solved in one of two ways, and thus allowed for an analysis of behavioral matching between an observer and a skilled demonstrator (trained to use one of the two methods exclusively). Because the demonstrator was an adult in both this study and the juvenile study, the influence of the observer's age could be isolated and examined, as well as the behavior of demonstrators toward observers of different ages. Our main goals were to (1) compare adults and juveniles acquiring the same task to identify how the age of the observer affects socially biased learning and (2) examine the relationship between socially biased learning and behavioral matching in adults. Although adults spent less time observing the trained demonstrators than did juveniles, the adults were more proficient at solving the task. Furthermore, even though observers did not overtly match the behavior of the demonstrator, observation remained an important factor in the success of these individuals. The findings suggested that adult observers could extract information needed to solve a novel foraging task without explicitly matching the behavior of the demonstrator. Adult observers begged much less than juveniles and demonstrators did not respond to begging from adult. Skill acquisition and the process of socially biased learning are, therefore, age-dependent and are influenced by the behavioral interactions between observer and demonstrator. To what extent this holds true for other primates or animal species still needs to be more fully investigated and considered when designing experiments and interpreting results.

Book section

  • Humle, T. and Hill, C. (2016). People–primate interactions: implications for primate conservation. in: Wich, S. A. and Marshall, A. J. eds. Introduction to Primate Conservation. Oxford University Press, pp. 219-240. Available at: http://dx.doi.org/10.1093/acprof:oso/9780198703389.003.0014.
    In this chapter, patterns of interactions are reviewed, from benign to mutually harmful, that characterize people–primate relationships, and the main social and ecological factors shaping people–primate coexistence are summarized. The reasons why certain primate species are better able to share landscapes with their human neighbours are examined, along with factors that influence people’s perceptions of, and attitudes, towards them. The chapter stresses how, at a local level, variations in socio-economic and cultural norms and values often underlie negative interactions between humans and primates. Lessons learned from studies to reduce negative interactions between people and primates are discussed, and broader scale landscape approaches that could facilitate effective primate conservation and human livelihood objectives examined. Finally, it is emphasized that understanding people–primate interactions requires a multifaceted approach, combining detailed understanding of the context, and needs of the different stakeholders, human and animal, and drivers of changing patterns of coexistence.
  • Ancrenaz, M. et al. (2015). Impacts of Industrial Agriculture on Ape Ecology. in: Lanjouw, A., Rainer, H. and White, A. eds. Industrial Agriculture and Ape Conservation. Cambridge University Press, pp. 165-192. Available at: https://doi.org/10.1017/CBO9781316488959.
  • Williamson, E. et al. (2013). Family Hominidae (Great Apes). in: Mittermeier, R. A., Rylands, A. B. and Wilson, D. E. eds. Handbook of the Mammals of the World: Primates. Lynx Edicions in association with Conservation International and IUCN. Available at: http://www.lynxeds.com/hmw/handbook-mammals-world-volume-3.
  • Humle, T. and Newton-Fisher, N. (2013). Culture in Non-human Primates: Definitions and Evidence. in: Ellen, R. F., Lycett, S. J. and Johns, S. E. eds. Understanding Cultural Transmission in Anthropology: A Critical Synthesis. Berghahn Books.
    The attribution of culture to non-human animals has been controversial and continues to fuel much heated debate, much of which hinges on how culture is defined. We illustrate how definitions have become less human-centric as observations from wild primates have led to a new discipline – cultural primatology – and challenged the idea of culture as uniquely human. Although cultural primatology has it roots in field studies of wild primates, the weight of captive studies across a variety of species has resulted in a comparative view of culture which emphasises the mechanism of transmission. We argue that, while this has broadened the species and behaviours that have been considered ‘cultural’, it weakens the usefulness of comparative studies in understanding the evolutionary origins of human culture. We prefer a definition that centres on the concept of culture as an array of behaviour patterns across multiple domains that vary between groups or populations due to differing histories of social transmission. We argue for the necessity of field studies of wild primates in the comparative study of culture, providing examples of how such studies allow both the identification of cultures across non-human primate social groups and the mechanisms by which behaviours are transmitted both within and between groups. Such studies are essential for an ecologically valid understanding of culture, and to investigate how social dynamics, ecology and demographics shape culture and the diffusion and dissemination of socially learned behaviours.
  • Humle, T. et al. (2013). Release of the western subspecies of chimpanzee, Guinea, West Africa. in: Soorae, P. S. ed. Global Reintroduction Perspectives: Additional Case Studies from Around the Globe. Gland, Switzerland: IUCN/ SSC Re-introduction Specialist Group and Abu Dhabi, UAE: Environment Agency-Abu Dhabi, pp. 222-228. Available at: http://cmsdata.iucn.org/downloads/rsg_book_2013.pdf.
  • Humle, T. and Kormos, R. (2011). Chimpanzees in Guinea and in West Africa. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 393-401. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_41.
    The Western subspecies of chimpanzees (Pan troglodytes verus) is the second most endangered subspecies among the four recognized subspecies in Africa today. P. t. verus is patchily distributed and numbers between 21,300 and 55,600 individuals. P. t. verus is very rare or close to extinction in four West Africa countries, including Burkina Faso, Ghana, Guinea-Bissau, and Senegal. It has already disappeared from the wild in Togo and the Gambia. The subspecies is also possibly now extinct in Benin. P. t. verus, therefore, survives mainly in Côte d’Ivoire, Guinea, Liberia, Sierra Leone, and Mali. Guinea is probably the country with the greatest number of chimpanzees in West Africa, with approximately 17,582 (8,113–29,011) chimpanzees nationwide. It is acknowledged today that the majority (more than 90%) of chimpanzees in Guinea are living outside protected areas. A large proportion of the chimpanzee population is believed to be living in the Fouta Djallon Region of Guinea, while it is estimated that a significant proportion also inhabits the forest region of Guinea. Hunting, poaching, the bush-meat and pet trade, and habitat loss variably threaten chimpanzee populations across different regions of Guinea. As human encroachment into chimpanzee habitat intensifies, the risk of disease transmission is also of increasing concern. This chapter aims to summarize the current status of P. t. verus across West Africa, as well as in Guinea, with a special focus on current and future threats.
  • Humle, T. (2011). The Chimpanzees of Yeale, Nimba. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 267-275. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_28.
    The Kyoto University Primate Research Institute (KUPRI) international team of researchers and students has been studying chimpanzees (Pan troglodytes verus) in Yealé, Côte d’Ivoire, in the Nimba Mountains intermittently since 1993. These efforts were interrupted in 2002 for reasons of political unrest in the country and have only resumed more recently in 2008. Nevertheless, local assistants continued progressive habituation of chimpanzees in the region, rendering this site promising for future research. The Yealé site is located approximately 10 km southeast of Bossou and south of the Seringbara site, a more recently established field site on the Guinean side of the Nimba massif. Compared to the Guinean portion of the massif, the region of Yealé presents a unique topography. In addition, chimpanzees at this site are beginning to reveal a unique behavioral repertoire quite different from that of their neighbors. This chapter aims to compile our current understanding of the behavior and ecology of chimpanzees of Yealé and to highlight how this site may in the future valuably further our understanding of chimpanzees.
  • Yamamoto, S. et al. (2011). Ant Fishing in Trees: Invention and Modification of a New Tool-Use Behavior. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 123-130. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_13.
    Wild chimpanzees are known to have a different repertoire of tool-use unique to each community. For example, “ant-dipping” is a tool-use behavior known in several chimpanzee communities across Africa targeted at army ants (Dorylus spp.) on the ground, whereas “ant-fishing,” which is aimed at carpenter ants (Camponotus spp.) in trees, has primarily been observed among the chimpanzees of Mahale in Tanzania. Although the evidence for differences between field sites is accumulating, we have little knowledge on how such “cultural” tool-use behaviors appear at each site and on how these are modified over time. In this chapter, we report “ant-fishing” by a young male chimpanzee at Bossou, Guinea, a behavior never before observed in this community during the past 27 years. This chimpanzee went on to modify this novel tool technology over the course of the following 2 years. At the age of 5, he employed wands of similar length to those used in ant-dipping on the ground, which is a customary tool-use behavior of this community. However, 2 years later, at the age of 7, his ant-fishing tools were shorter and the efficiency in obtaining carpenter ants was improved. This observation is a rare example of innovation in the wild and does provide some insights into the emergence and the learning process of a cultural behavior in chimpanzees.
  • Humle, T. (2011). Ant-Dipping: How Ants Have Shed Light on Culture. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 97-105. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_10.
    Ant-dipping is a tool-use behavior targeted at biting and gregarious army ants (Dorylus spp.). Although several wild chimpanzee communities exhibit this behavior, some do not, although army ants are ubiquitous across Africa. This tool-use behavior is often cited as one of the best examples of culture in chimpanzees. Nevertheless, recent data emerging from Bossou in southeastern Guinea and detailed entomological analysis of the army ant species available at different chimpanzee study sites, as well as direct observations of this behavior, indicate that the aggressiveness and the density of the ant species influence tool length and the technique employed to consume the ants off the tool. Behavioral differences persist, however, between the communities of Taï, Côte d’Ivoire, and Bossou, where the same species of army ants are consumed by the chimpanzees. A comparative study indicates that these variations in ant-dipping between these two long-term field sites cannot solely be explained on the basis of prey behavior, characteristics, and availability and must therefore be cultural. A longitudinal study of the acquisition of ant-dipping among the chimpanzees of Bossou supports this assertion by revealing the importance of social influences and the role of the mother in the learning process of young chimpanzees. Finally, studies of ant-dipping, especially at Bossou, have demonstrated a narrow interrelationship between ecology, social learning, and culture.
  • Humle, T. (2011). The 2003 Epidemic of a Flu-Like Respiratory Disease at Bossou. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 325-333. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_33.
    Disease is one of the major threats facing great apes today. Chimpanzees across Africa are fatally susceptible to a variety of diseases, including Ebola and a range of typically human-borne diseases ranging from pneumonia to polio. In November 2003, all members of the Bossou community suffered from an outbreak of respiratory disease that resulted in the confirmed death of four individuals (two infants, one adolescent male, and one old adult female) and the presumed death of one old adult female. This chapter aims to present the sequence of events that escalated in the loss of these five chimpanzees. The only other confirmed respiratory disease outbreak at Bossou since 1976 occurred in 1992 and resulted in the death of an infant. Finally, the 2003 epidemic strongly reminds us of the vulnerability of chimpanzees to human-borne diseases, especially respiratory diseases, and the urgent need to put in place practical measures aimed at preventing the occurrence of similar outbreaks in the future.
  • Matsuzawa, T. et al. (2011). Green Corridor Project: Planting Trees in the Savanna Between Bossou and Nimba. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 361-370. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_38.
    The present chapter aims to report on a reforestation program known as the “Green Corridor Project,” which was initiated in January 1997. This project aims to connect the chimpanzee habitat of Bossou to that of the Nimba Mountains. This project began with a pilot study known as the “Petit Jardin Botanique.” This study aimed to evaluate the plant species that would best thrive in a savanna environment. Over the years, the Green Corridor Project has involved the creation of tree nurseries, the introduction of hexatubes to protect the young trees, and the planting of cuttings of Spondias cythera trees. The Green Corridor Project has promoted environmental awareness in the locality.
  • Humle, T. (2011). The Tool Repertoire of Bossou Chimpanzees. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 61-71. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_7.
    Chimpanzees in the wild make and use a diverse and rich kit of tools and, with the exception of humans, they are the only living primates to habitually or customarily use and make tools during their daily activities. Tool-use behavior in chimpanzees (Pan troglodytes) has been observed at all field sites where chimpanzees have been studied. The Bossou chimpanzees (P. t. verus) display a large repertoire of tool-using behaviors, some of which are unique to this community. This chapter aims to present globally the diversity of tool-use behaviors of the Bossou chimpanzees, highlighting their age-class, sex, and temporal distribution, the diversity of domains in which they are observed, and patterns of hand use during tool manipulation. We also briefly discuss the relevance of tool use among Bossou chimpanzees to understanding innovation and cultural evolution in chimpanzees. Because each community of chimpanzees has a unique material cultural repertoire within the feeding, social, and hygiene domains, we also describe how the tool-use repertoire of the Bossou community differs from that recorded in other communities.
  • Humle, T. (2011). Environmental Education and Community Development in and Around Bossou. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 371-380. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_39.
    Researchers at Bossou and Nimba have undertaken several initiatives promoting chimpanzee conservation and environmental education. The local community education sessions have involved video screenings and the distribution of pamphlets, badges, and T-shirts, as well as informal discussions tackling issues such as human–chimpanzee resource competition. In July 2003, we conducted three campaigns across nine local villages. A questionnaire was used during the first and the third campaign sessions, aimed at evaluating the local peoples’ understanding of national and traditional laws (e.g., hunting laws and bushfire regulation), as well as about how best to react when confronted with a chimpanzee on a path or in a field. Since 2003, environmental education has become an integral aspect of the secondary school curriculum in Guinea. To contribute to this program, a bilingual book was produced for distribution in schools locally and nationally. This book provides children with a fictional but factual story about a young female chimpanzee. It touches on aspects of chimpanzee behavior, and addresses threats to fauna and flora in the region and the close interconnection between humans and nature. Our school outreach program has also involved classroom interventions and material aid, as well as the construction or maintenance of school buildings in several villages in and around Bossou. In addition, to sensitize the villagers to the threats of disease transmission, we have helped villagers construct latrines in the schools and in some districts of the village.
  • Humle, T. (2011). Location and Ecology. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 13-21. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_3.
    The village of Bossou is a sub-prefecture in the prefecture of Lola, located in the forest region of southeastern Guinea, West Africa, about 1,050 km from the capital city, Conakry. Bossou provides a rare example of a site where historically wild chimpanzees (Pan troglodytes verus) and the local people have been living harmoniously, sharing the resources of the same forest. Bossou is surrounded by small hills 70–150 m high that are covered in primary and secondary forest. This habitat constitutes the core area of the Bossou community. At the foot of those hills, cultivated or abandoned fields and secondary, riverine, and scrub forests form a patchy mosaic for about 6 km in all directions. The Bossou chimpanzees mostly confine their daily activity within this core area of about 6 km2, although they sometimes travel to adjacent forests using the few remaining gallery forest corridors, thus extending their home range to about 15–20 km2. The nearest currently known chimpanzee populations have their ranges in the Nimba Mountains, about 6 km west of Bossou. The feeding behavior of chimpanzees is extremely diversified. It also varies seasonally and is greatly influenced by fruit availability and habitat type. Several fallback foods are important for the Bossou chimpanzees. These resources include plant species that show little interannual variation, either in the amount of resources they produce or in their seasonal timing of availability.
  • Matsuzawa, T. and Humle, T. (2011). Bossou: 33 Years. in: Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 3-10. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_2.
    A small group of chimpanzees inhabits the forested hills surrounding the village of Bossou in southeastern Guinea, West Africa. Over the years, cultural primatology has driven much of the research on this unique group of wild chimpanzees.
  • Humle, T., Yamakoshi, G. and Matsuzawa, T. (2011). Algae Scooping Remains a Puzzle. in: Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. Chimpanzees of Bossou and Nimba. Springer Verlag, pp. 117-122. Available at: http://dx.doi.org/10.1007/978-4-431-53921-6_12.
    Algae scooping is a tool-use signature marker of the Bossou chimpanzee community, as it is unique to this community and has never been observed at any other chimpanzee field site in Africa. Bossou chimpanzees use different techniques to feed on free-floating species of filamentous algae of the genus Spyrogyra available at the surface of ponds. However, the chimpanzees mainly rely on stick or stalk tools to gather the algae. This tool-use behavior is seasonal and occurs predominantly during rainy season months. A majority of tools were made from only two plant species. The availability of these plants beside ponds needs to be evaluated in the future to test whether the chimpanzees are purposely selecting those species over others. Differences in algae-feeding techniques recorded at Bossou may reveal interesting intracommunity patterns of social transmission. In addition, it is hypothesized that the chimpanzees select tools depending on algae abundance at the ponds’ surface to maximize proficiency as well as efficiency. Future perspectives are also discussed with regard to sex differences in algae scooping, with males performing algae scooping significantly more often than females, and the nutritional content of Spirogyra.
  • Humle, T. and Fragaszy, D. (2010). Tool use and cognition in primates. in: Campbell, C. et al. eds. Primates in Perspective. Oxford University Press, pp. 637-651. Available at: http://global.oup.com/academic/product/primates-in-perspective-9780195390438;jsessionid=89AAED1FB4B854BD85BCAD211564EBA5?cc=gb&lang=en&#.
  • Humle, T. (2010). Primate Material Culture. in: Hicks, D. and Beaudry, M. C. eds. Oxford Handbook of Material Culture Studies. Oxford University Press, pp. 406-424. Available at: http://dx.doi.org/10.1093/oxfordhb/9780199218714.013.0017.
    This article focuses on the idea of material culture in primates. The ascription of culture to non-human animals has been controversial and a source of much debate. Much of this debate hinges on the definition of culture. This article cites the classic definition by Tylor which says that culture as ‘that complex whole which includes knowledge, belief, art, morals, custom, and any other capabilities and habits acquired by man as a member of society’. The term ‘culture’ was first used in relation to non-human primates by Kummer. This article explains elementary technology among primates which concerns predominantly subsistence behaviours, expressed in, often complex, foraging techniques. Elementary technology among wild primates is typically based on natural materials, whether vegetation or non-organic matter. The various processes involved in the transmission of material culture are explained in detail. An in-depth analysis of the conditions of material culture followed by a study of culture among primates concludes this article.
  • Humle, T. (2010). How are army ants shedding new light on culture in chimpanzees? in: Lonsdorf, E., Ross, S. and Matsuzawa, T. eds. The Mind of the Chimpanzee: Ecological and Experimental Perspectives. Chicago University Press, pp. 116-126. Available at: http://www.press.uchicago.edu/ucp/books/book/chicago/M/bo8331037.html.


  • Humle, T. (2015). The dimensions of ape-human interactions in industrial agricultural landscapes. Cambridge University Press. Available at: http://www.stateoftheapes.com/reports/.

Conference or workshop item

  • Humle, T. and Konate, A. (2015). Primates and Bushmeat Hunting Around the High Niger National Park, Guinea, West Africa: Drivers and Patterns of Change. in: 6th European Federation for Primatology Meeting, XXII Italian Association of Primatology Congress. pp. 298-298. Available at: http://www.dx.doi.org/ 10.1159/000435825.
    Bushmeat hunting contributes to the decline of primate species across Africa; however, few
    studies have explored how such practises change over time in specific localities and how changes
    in land-use patterns and economic drivers may enhance threats to primates in Muslim dominated
    areas where, traditionally, primates are spared from such trade. The Haut Niger National
    Park (HNNP) is one of only two national parks in the Republic of Guinea. The park is one of the
    last remaining important formations of dry forest-savannah mosaics in West Africa and is a site
    of high conservation priority for ungulates and the western subspecies of chimpanzee. This study
    aimed to: (1) estimate the diversity and abundance of animal species sold for consumption across
    several markets in and around the HNNP, (2) analyse the evolution of the bushmeat trade since
    the mid-1990s, and (3) identify the players and drivers of the commercial bushmeat trade in the
    area. Local market assessments were conducted across four village markets and in Faranah, one
    of the closest urban areas abutting the HNNP. We successfully identified 5,807 wildlife carcasses
    of 46 species and 22 families on markets surveyed over a 7 month period spanning both the dry
    and wet seasons. In addition, semi-structured interviews with hunters, farmers and people involved
    in the bushmeat trade helped identify more recent drivers of the bushmeat trade in the
    HNNP. Our results indicated an increase in diversity of species targeted and the influence of
    crop-foraging and local microcredit systems in exacerbating the presence of primate species sold
    at bushmeat stalls in urban areas. Finally, whilst identifying key recommendations and gaps for
    future research, this study emphasises the growing risks facing primates as targets for bushmeat
    where people depend on agriculture and natural resource extraction for subsistence. This study
    complied with the International Primatological Society (IPS) Guidelines for the Use of Nonhuman
    Primates in Research.
  • Neufuss, J. et al. (2015). Diversity of Hand Grips and Laterality in Wild African Apes. in: 6th European Federation for Primatology Meeting, XXII Italian Association of Primatology Congress. KARGER, pp. 329-329. Available at: http://dx.doi.org/10.1159/000435825.
    Comparative studies of primate grasping and manipulative behaviours in captivity have
    highlighted, among others, two human abilities that are generally considered unique compared
    with other primates: (1) the use of forceful precision and power squeeze grips involving the use
    of the thumb, and (2) a species-wide dominant use of one hand (usually the right hand), known
    as laterality. However, recent research has highlighted a diversity of precision and power grips in
    general among many non-human primates, and there is much debate around the potential for
    population-level or species-wide laterality in non-human primates. The majority of this research
    to date has been done on captive primates performing specific manipulative tasks, which may
    bias or confound these species comparisons. Comparatively little research has been done on hand
    use in wild primates, especially during natural, non-manipulative activities, including locomotion.
    Here, we investigate hand use during locomotor and non-locomotor behaviours in wild
    mountain gorillas ( Gorilla beringei beringei , Bwindi Impenetrable National Park, Uganda), wild
    chimpanzees ( Pan troglodytes verus , Taï National Park, Cote d’Ivoire) and chimpanzees kept under
    semi-natural conditions ( Pan troglodytes ssp., Chimfunshi Wildlife Trust, Zambia). Preliminary
    results propose that hand grips are similar between gorillas and chimpanzees during the
    manipulation of common object types. Bwindi gorillas show various hand use strategies during
    the processing of several plant foods. Chimfunshi chimpanzees also use forceful precision grips
    during daily manipulative tasks, suggesting that this is not a uniquely human ability.
  • Vanlangendonck, N., Guttierrez-Espeleta, G. and Humle, T. (2013). Assessment of the Consequences of Anthropogenic Pressures on Alouatta palliata and Ateles geoffroyi Physiology in Northern Costa Rica. in: 5th Congress of the European Federation of Primatology: Primates in our Hands. pp. 340-340. Available at: http://dx.doi.org/10.1159/000354129.
    Previous studies have shown a positive relationship between proximity to humans or habitat fragmentation and parasitic levels in non-human primates (NHPs). However, to date few have explicitly explored links between parasite load and stress conditions. To better understand the links between parasite prevalence and NHP immune system efficiency and stress levels, faecal samples of Alouatta palliata and the critically endangered Ateles geoffroyi geoffroyi were non-invasively collected in northern Costa Rica. We investigated whether the presence of gastrointestinal parasites was related to the abundance of hormones (cortisol and testosterone). Samples were gathered across three areas differing in the frequency and diversity of human presence, i.e. around the Caño Palma Biological Station, near villages and at ecotourism sites. Two grams of each faecal sample were stored in a sugar saturated solution with 10% formalin to conserve the parasites; the remaining matter was dried to preserve DNA and steroid hormones. The samples enabled the quantification of parasites as well as testosterone and cortisol levels using ELISA as proxies of general health status and stress levels. Data on parasite abundance and hormone levels were contrasted across the two species and the three different sampling areas. Furthermore, we assessed the genetic exchange among the different groups of primates sampled. We genetically analysed the samples using 12 microsatellites previously validated by the University of Costa Rica. We verified whether transmission of parasites among the groups could be possible concomitant to the genetic exchange. This study aimed to better understand and assess the impact of human factors on NHP health and across NHPs with different socio-ecological characteristics.
  • Humle, T., von Cramon-Taubadel, N. and Lycett, S. (2013). The Bootstrapping Dimensions of Culture in Chimpanzees. in: 5th Congress of the European Federation for Primatology. pp. 289-289. Available at: http://dx.doi.org/10.1159/000354129.

Edited book

  • Matsuzawa, T., Humle, T. and Sugiyama, Y. eds. (2011). The Chimpanzees of Bossou and Nimba. [Online]. Springer Verlag. Available at: http://link.springer.com/book/10.1007/978-4-431-53921-6.