Conservation medicine is an emerging, interdisciplinary field that investigates the relationship between human and animal health and the environmental conditions affecting the emergence of infectious diseases. In collaboration with veterinarians, virologists, parasitologists and other experts in the bio-medical sciences, primatologists have begun to investigate the role of diseases in the natural history of primates and as a tool for the conservation of endangered wild populations. A key role of the primatologist in this multidisciplinary research is the collection of behavioral and ecological data necessary to elucidate the impact of disease on a group and to collect the relevant samples (urine, feces, hair, postmortem tissues) needed for laboratory identification and quantification of the disease in question. Many advances in the ability to identify parasite and viral infections from non-invasively collected samples has strenghtened our ability to determine and monitor disease affecting wild primate populations. Such diseases as malaria, SIV (the precursor to HIV), anthrax and ebola, all potentially life-threatening diseases to humans and animals are now readily detectable from feces and urine. Primatolgists also play a key role in long-term health monitoring of groups. This is important for understanding seasonal and individual specific processes of disease transmission and for the early detection of emergent diseases in a population that, if unchecked can propose a serious health risk to both local human and animal safety. Health monitoring is not labor intensive and can easily be incorporated into general observational protocol. Given the non-invasive nature of sample collection, it does not compromise with a policy of limited contact and proximity to study subject. This talk will introduce collection techniques and describe some recent findings from primates in the wild.

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In Japan crop-raiding by monkeys is a serious social problem now; their range expanded close to the human settlements and they often intrude into the center of big cities. After World War II it was presumed that the wild population of Japanese macaques had faced a extinction, prompting they legal protection since 1947. During these 60 years their wild populations have apparently recovered and are still increasing, especially in the area where monkey populations contact with human settlements. The population control of Japanese macaques is a controversial problem in society today. After 1998 more than 10,000 monkeys were removed every year, but crop-damages has not decreased, but instead seems to be growing more serious. The changing society in Japan including its economic structure and attitude toward wild animals as well as a loss of wildlife management measures (hunting etc) may make these problems more complicated. Meanwhile, the circumstances are quite different in Southeast Asia. The populations of wild primates are seriously threatened by large-scale habitat destruction. We surveyed the current situation of mammals in Sumatra and found that many species including arboreal primates were driven out from their original habitats. The isolated small population of primates may not be able to increase in some reserves and/or temple forests. I hope to discuss how adaptive management can help to deal with these different circumstances.

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We investigated possible differences between humans and chimpanzees underlying the perception of self-agency. Humans distinctly recognize an event which caused by the self from other events observed in an environment. Such cognitive function is called as the perception of self-agency which allows us to establish the concept of self. It is known that chimpanzees have difficulties in copying of other’s motor action but they could reproduce goal of other's action. These difference may reflect the differences in the perception of own voluntary action, however, this issue have rarely been addressed. Here we show that the chimpanzees have a difficulty in self-other distinction when goal of action was insufficient information. In experiments, two cursors were shown on the monitor and one of which was moved by the computer and the other was controlled by the participants. The participants were required to detect the cursor which they could move, and to hit either target shown on the monitor. The chimpanzees spent more time to detect the self cursor when the target which chimpanzees try to hit was accidentally correspond with the target which the distractor moved toward than when distracter moved toward different targets. However we didn’t observe such effect in human participants. These results indicate chimpanzees were more dependent on the goal of action rather than kinematic motion for the self-other distinction, and suggest chimpanzees and humans may employ different strategies for the perception of self-agency. This work adhered to the ethical guideline of our institute.

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Contrafreeloading is a phenomenon in which animals work for rewards even though they can get the same rewards for free. This phenomenon has been reported in wide taxa of animals when tested with food rewards. One explanation for the phenomenon is provided by the information primacy model, suggesting that animals are motivated to acquire not only the reward itself but also the information about the position and/or quality of the reward. This study examined if such contrafreeloading occurs when the subject monkeys are tested in a sensory reinforcement procedure with movie stimuli. Three male singly-caged Japanese macaques were studied in their home cages each of which was divided equally into two compartments. In the first condition, one compartment had a monitor presenting movies continuously ("free movies"), and the other had a monitor presenting movies only when the subject touched the color square on the screen ("earned movies"). In the second condition, the free movies were replaced by blank screen to exclude the possibility that the touch responses were reinforced by disappearance of the color square. The results from first condition revealed that the subjects continued to respond to the earned movies although identical movies were available as free movies on the other monitor. The subjects made significantly more touch responses (X² = 120.65, P < 0.001) and the earned movies were presented significantly longer (X² = 5.41, P < 0.05) in the second condition than the first condition. These results suggest that the information about movies as well as movies themselves is valuable for monkeys. This study provided the first evidence that contrafreeloading occurs even with the movie rewards. Routine care of monkeys and experiments were performed in accordance with guidelines of the Primate Research Institute, Kyoto University.

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Japanese macaques form a matrilineal, multi-male, multi-female group. In such a group, motivation to contact group members should differ among age-sex classes. Wild Japanese macaques emit coo call frequently and thereby maintain spatial cohesiveness of the group. The rate of coo calls can differ among age-sex classes reflecting their motivation of contacting group members. In this study, we examined the difference in the rate of coo call and the rate of the vocal response from the other group members among different age-sex classes, in the wild groups of Japanese macaques on Yakushima Island, Japan. Overall, adult females and juveniles of both sexes emitted coo calls more frequently than adult males. Adult females and males called more frequently when they were separated from group members. In contrast, juveniles called similarly frequently either when they were separated from group members or when they were close to them. Adult females and males were responded vocally more often than juveniles. These results suggest that adult females and juveniles are highly motivated to contact others. However, juveniles call frequently even when the group is cohesive and this may result in the lower response rate from group members. In contrast, adult males are less motivated to contact group members, probably because of their peripheral nature in the group. However, the high response rates to adults' calls suggest that the other group members are motivated to contact adult females and males.

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While most nonhuman primates live in socially-cohesive groups, some species exhibit very flexible patterns of association, also referred to a fission-fusion dynamics. Such differences among taxa in social cohesiveness can directly influence construction of social relationships. In this study, we compare the context of vocal emission at fission and fusion events in two species that differ in group cohesiveness. We conducted research on one group of wild Japanese monkeys on Kinkazan Island and one group of wild spider monkeys at Tiputini Biodiversity Station, Ecuador. These two groups have similar home range size and group size. Two or three observers conducted focal observations simultaneously on different group members, collecting a continuous record of activity and vocal behavior. At the same time, the animal locations were recorded automatically using a data-logging GPS. From these continuous location records, we calculated the distance between two individuals to identify the moment of fission and fusion events, and we then compared the frequency of short-range vocalization before and after fission-fusion events. We found that Japanese macaques emit coo calls frequently following fission events, whereas spider monkeys emit whinny vocalizations frequently before fusion events. Both coos and whinnies are exchanged among individuals affiliatively, but they likely have different functional roles. We discuss the differences in sociality (such as sense of distance and tolerance of other individuals) in relation to the spatial distribution of animals within the group

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Sexual dimorphism is one of the most focused topics in various areas of biology. The aim of this study is to investigate geographic variation in dental sexual dimorphism among Japanese macaques (Macaca fuscata). In the present study, geographic variation of sexual dimorphism in dental metrics was examined among eight populations of wild Japanese macaques. The present sample includes populations on the main islands (Honshu & Kyushu) and populations from small islands (Yakushima & Kinkazan islands) and a semi-isolated area (Boso Peninsula). These populations live under various environmental conditions, ranging from subtropical to cold temperate zone, from lowlands to high mountains. Maximum monthly snow accumulation also varies from 0 cm to over 1 m. Measurement was taken from more than three hundreds of adult monkeys. Size and shape sexual differences were compared between local populations. The present analysis has revealed: 1) Males and females have similar shape within each local population. 2) Isolated and semi-isolated populations (Yakushima, Kinkazan, Boso) have smaller dentition than non-isolated populations (Hakusan, Nagano, Nikko, Shimane, Fukui). 3) Degree of sexual dimorphism shows a weak tendency of negative correlation to size in dentition of Japanese macaques.

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Enamel thickness and distribution of the molar crown has been evaluated 3-dimensionally for the four extant great ape species (Pan troglodytes, Pan paniscus, Gorilla gorilla, and Pongo pygmaeus) and modern humans (Homo sapiens). The 3-dimensional distribution pattern of enamel within the molar crown has recently been recognized to have significant functional, developmental, and phylogenetic information. A total of 100 molar teeth of five species were micro-CT scanned and segmented so as to digitally extract the shape of the enamel cap. The combined evaluation of enamel thickness patterns and 3-dimensionally based morphometric comparison of occlusal basin size and shape among extant great ape species revealed the contrasting patterns of enamel distribution and occlusal topography between Pan and Pongo molars. Molars of Pan troglodytes and Pan paniscus are characterized by relatively thin enamel on the capacious occlusal basins, which can be interpreted as a morphological adaptation to relatively soft-fruit frugivory. On the other hand, Pongo molars combine relatively thick enamel and less salient cuspal/occlusal basin topography. This may be an adaptation to withstanding greater occlusal forces and/or the efficient breakdown of hard but brittle foodstuff. Gorilla molars are characterized by the most salient cuspal topography and relatively thin enamel both occlusally and laterally. These can be explained as an adaptation to a more folivorous/herbivorous diet. The possible links between morphological characteristics and dietary dependencies shown above in the extant ape species provide important clues in elucidating the diet of extinct species such as fossil hominoids including early hominids.

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When experimental data from animal experiments are being evaluated, the background diseases occurring in the experimental animal species used should be considered. Nonhuman primates include some species that are important in the field of biomedical science. However, spontaneous diseases are often found during experiments because complete microbiological and genetic controls have not been performed in nonhuman primates, unlike in rodents. On the other hand, number of nonhuman primates used in medical science is lesser than that of rodents. Therefore the incidence and tendency of diseases are not well understood in the different primate species, and this must be a cause of concern with respect to the understanding of experimental data. In this article, we describe some well-defined spontaneous diseases that occur in a nonhuman primate facility, based on our experiences. This information will contribute to better understanding of biomedical data obtained in studies, using nonhuman primates and their veterinary care.

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One of the important things for macaques to keep healthy is how to control infectious diseases, especially zoonoses. Recently Hepatitis E virus (HEV) infection was revealed among macaque colonies kept in outdoor enclosures at the Primate Research Institute, Kyoto University. We will discuss the way to control zoonoses for macaque outdoor colonies with focus on this infection. An acute hepatitis caused by HEV is found among many developing countries in Asia, the Middle East and North Africa in humans. Serum antibodies to HEV were detected in many kinds of animals including pigs, deers, wild boars, wild rats, dogs, cats, cows, and monkeys as well. Among these seropositive animal species, HEVs genetically similar to human HEVs have been isolated from pigs, deers and wild boars. A total of 100 macaques belonging to nine colonies kept in outdoor enclosures were serologically examined for the HEV infection from 2004 to 2008 as a part of annual health inspections. Antibodies to HEV were not detected among the macaques in 2004. Whereas, in 2005 seropositive individuals were found in the two colonies. Furthermore, anti-HEV seropositive individuals were identified in 7 out of 9 colonies in 2006. Molecular analyses identified the presence of HEV genome in the plasma of a seropositive Japanese macaque by RT-PCR and direct sequencing. Reservoirs and transmission routes of HEV from outside are still unclear. However, care staffs and/or researchers could have carried HEV among those colonies until we took measures against HEV.

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Understanding the functional anatomy of the hands in humans and African apes is essential for estimating manipulative ability of fossil hominoids and clarifying the evolution of morphofunctional basis for the human precision grip capabilities. We therefore constructed three-dimensional anatomical models of the human and chimpanzee hand musculoskeletal systems. The hand skeleton was described as a chain of 20 links connected by revolute joints, joint centers and rotation axes of which were determined based on quadric surface approximation of joint surfaces. Muscle paths were defined as a series of points connected by line segments. Such anatomically realistic model of the complex hand musculoskeletal system allows us to investigate how the morphology of the hands facilitates or restricts manipulative capabilities. Using the constructed hand models, we simulated pincer grasp and estimated the direction and magnitude of maximum possible grip force vectors. We also conducted a virtual knockout experiment of muscles to predict functional significance of each of the muscles on grasping capabilities. Comparisons of the simulated results suggested that human morphological features especially that in the first dorsal interosseous muscle may facilitate pincer grasp. The present computer simulation technique based on the anatomical musculoskeletal models presents potentials for elucidating morphofunctional relationships of the hand musculoskeletal systems and hopefully predicting manipulative dexterity in extinct hominoids from fossil hand bones.

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Non-human primates are important biological resources that facilitate studies of pharmacology, infectious diseases, behaviors, and physiology. Many of these research projects have assumed that non-human primates are the evolutionary closest animals to humans and thus their physiology is a reasonable reflection of a human physiology. In other words, these animals are used for studying to know human beings. However, humans and non-human primates still have a lot of dissimilarity in many biological aspects.
In this symposium, we discuss similarities and dissimilarities between humans and non-human primates at various biological levels. In the genomic era, many of the differences can be measured at a molecular level. Some phenotypes may be more differentiated than expected from their genetic distance. We could investigate whether observed differences in physiology between humans and non-human primates are related to the genetic difference between them, and wish to understand the genetic basis of the differences. We would like to present a lot of examples, such as difference in genome structure, transcriptome, protein structure, drug metabolisms, and genetic diversity, and discuss the potential of biomedical applications of non-human primates.

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Comparative genomic analyses using reference sequences in various vertebrates revealed that the evolution of T2R genes, bitter taste receptor genes, is likely to reflect their dietary changes. In humans, analyses of DNA polymorphisms in the entire repertoire of 25 putatively functional T2R genes showed that nucleotide diversity in the T2R genes is relatively high, and results in a large number of amino acid substitutions, suggesting that multiple and functionally divergent alleles are likely found at T2R loci due to relaxation of functional constraints on these genes. These raise the question of whether the large number of amino acid substitutions reflect a low level of selective constraint on bitter taste receptors in general, or if they reflect dietary changes during human evolution. Here, we report the analysis of polymorphisms in the entire repertoire of T2R genes in chimpanzees, the closest extant relatives of humans. The numbers of functional genes were different among individuals, but most chimpanzees had 2 or 3 more functional genes than those of humans. Evolutionary analysis of the chimpanzee T2R genes revealed that nucleotide diversity is also high, along with a high rate of amino acid substitutions, suggesting that a selective constraint on these genes was weak as seen earlier in human T2R genes. The weak functional constraint in both species has resulted in the occurrence of various functionally divergent alleles within the populations, and in heterozygous individuals who might have the ability to taste a broader range of substances.

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Tsukuba Primate Research Center (TPRC) in Japan has a large scale breeding colony of experimental cynomolgus monkeys (approximately 1500 monkeys), which play a significant role in the development of pharmaceutical products and medical technologies. The breeding colony is comprised of 600 cynomolgus macaques and produces 250 monkeys for biomedical research every year. The cynomolgus monkeys in TPRC were obtained from Indonesia, Malaysia and Philippines. The monkeys have been bred as pure-blood of each origin without interbreed crossing. These pure-blood monkeys should be important for comparison of various genetic effects in biological studies such as vaccine development. By this genetic management, the monkeys in our colony enable a researcher to analysis for discovering differences between lineages. Since several information, i.e. health condition, breeding condition, clinical treatment, and experimental procedures are recorded on a computer, these data can readily be used to analysis. In genetic studies, a prerequisite for mapping genes is development of a genome-wide set of microsatellite markers in target organisms. A microsatellite marker set is a versatile tool that would assist in colony management, conservation work, and paternity testing of nonhuman primates. Now, we developed about 600 microsatellite markers for cynomolgus monkeys in TPRC. The development of microsatellite marker set in this species is a first step toward exploring the genes responsible for genetic disorders in captive macaques.

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Non-human primates have been used to model diseases in humans for several decades. The success of these paradigms has issued from comparable physiology and endocrinology, cognitive skills, brain morphology, and social complexity in adult monkeys and humans. In most preclinical studies in non-human primates the species-of-choice is the macaque monkey. However, there is an increasing trend to investigate the marmoset monkey in biomedical research programs. Therefore, this symposium is focused on research in these two species. In the first presentation E. Sasaki will report on the successful creation of transgenic marmoset monkeys providing a new animal model for human diseases that has the great advantage of a close genetic relationship with humans. In the second presentation, M. Takada will discuss the potential of viral vector application in macaque monkeys as a therapeutical approach in the treatment of Parkinson’s disease. The wide immunological gap between humans and laboratory rodents makes many disease models in these species invalid. B. t’ Hart will report on a model of chronic multiple sclerosis -experimental autoimmune encephalitis in the marmoset monkey - that can help to bridge this gap. Using a comparative endocrine approach to the diversity of adrenal androgen biosynthesis and its developmental timing in female macaques and marmosets, D. Abbott will provide a unique insight into mechanisms underlying adrenal androgen regulation and its patho-physiology in humans (e.g. polycystic ovary syndrome; PCOS). Finally E. Fuchs explores aspects of programming obesity in marmoset monkeys to study chronic aspects of obesity and its long-lasting effects.

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Since publication of the draft human genome in 2001, genome sequencing has been achieved in chimpanzees (2005), rhesus macaques (2007), orangutans and marmosets (2008), baboons and lemurs (2009), and it is ongoing in many other primates, such as gorillas, and galagos. New insights are thus required to think about how we ought to use the vast information of genome sequences for post-genome investigations. Now is the best time to establish goals for post-genomic primatology in these early days in several areas of genomic research. In this symposium, we consider the sensory functions and inter-/intra-species genomic diversity of primates as a first important clue for understanding the pathway of hominization. Cellular and molecular properties of gene products, such as receptors and enzymes, and individual behaviors will help to correlate genomes with environmental conditions in which primates are living. We introduce approaches which can be used to investigate primates with the aim of understanding what makes us human. This is a review of the basis for projects on the post-genome biology in primates.

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In mammals, bitter taste is mediated by T2R gene family members, which belong to the large family of seven transmembrane G protein-coupled receptors. Since T2Rs are directly involved in the interaction between mammals and their dietary sources, it is likely that these genes evolved to reflect regionally specific diets during mammalian evolution. Human T2R genes (hT2Rs) have been observed to be polymorphic, however, polymorphisms in other wild animals has not been investigated so far. In order to elucidate the evolutional process of bitter taste recognition, we started genotyping of bitter taste receptors of individual primates living in the Primate Research Institute, Kyoto University. As a result, it has been revealed that there are lots of Single Nucleotide Polymorphisms (SNPs) in T2Rs compared to visual photoreceptors, opsins. In addition to furthering analysis of molecular properties and behavioral impacts, in cooperation with the global COE program, we are constructing the genetic database of the individual captive primates in the institute.

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By increasing the number of genes, gene duplication allows gain of new functions and properties, and is one of the most important mechanisms for genome evolution. The alcohol dehydrogenase (ADH) gene family exists widely in the genomes of many organisms, and provides a fine model for evolution of gene families. The seven human ADH genes are classified into five classes based on nucleotide/amino acid sequence similarity. Mice have six ADH genes in the same order as humans. One of the most interesting differences between humans and mice is that mice have only one Class I gene. The three Class I genes (ADH1A, ADH1B, ADH1C) in humans show very high nucleotide similarity both in exons (> 90%) and introns (> 70%), suggesting duplication events occurred probably after primates diverged from rodents. We have proposed a hypothesis that the primates’ frugivorous behavior has maintained the duplicated genes because of the necessity of digesting ethanol generated by fermentation of fruit sugar. To test the hypothesis, we are screening the BAC clone libraries of 11 primates, and sequencing the ADH cluster clones in order to obtain nucleotide sequence information for the whole region of the gene cluster in the primates. Initial analyses of the three Class I genes suggest that the Class I genes have evolved without concerted evolution. Here we present the progress of the sequencing on the ADH gene cluster evolution in primate lineage.

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Transcriptome can be defined as the total set of transcripts in a given cell or a population of cells (e.g., tissue). Using mRNA-sequencing (mRNA-seq) technology, which sequences the transcripts with massively parallel DNA sequencing (new generation sequencer: NGS), we can see the dynamics of transcripts among different type of cells (e.g., cancer cells vs. normal cells) or different organisms (e.g., human brain vs. chimpanzee brain). Here we used this mRNA-seq for transcriptome analysis of leukocyte in a chimpanzee trio (father-mother-child). We obtained 3∼ 5 Gb from each individual by Illumina-GAII sequencer and found about a hundred thousand SNPs against a reference chimpanzee genome sequence (panTro2). Moreover we found ten thousands and several thousands of expression SNPs (expSNPs) and several thousands of expression INDEL (insertions and deletions) on average among trio, and revealed that expSNPs are more enriched on 3’-UTR than CDS or 5’-UTR, suggesting a major role of expSNPs as a gene expression regulator. Besides that, NGS enables us to quantify a level of gene expression in an allele-specific way, and it is thus possible to estimate relative contribution of cis and trans mutations for gene expression divergence, and more importantly, to detect candidate imprinting genes straightforwardly. At present, we have thousands of such expSNPs in the data. Further analysis as well as conjunction with human trio data could help us to get a comprehensive understanding for precise dynamics of transcriptome both intra- (trio) and inter- (humans and chimpanzees) specific levels.

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IPS23’s host country, Japan, is in a unique position among “first-world” nations: it has its own indigenous species of primate, Macaca fuscata, the Japanese snow monkey. The late Kinji Imanishi and his colleagues began fieldwork in Kohshima in 1948, with the aim of elucidating the evolutionary origins of human society. After accumulating knowledge on Japanese macaques, they travelled to Africa to study gorillas - and later chimpanzees - in the wild. At almost the same time, Western scholars were also embarking on long-term field observation projects in Africa. The Gombe chimpanzee project, led by Jane Goodall, is perhaps the best known such pioneering endeavor. Thanks to the continuing efforts of many dedicated fieldworkers, the past five decades have brought forth a wealth of information on the lives of chimpanzees, bonobos, and gorillas, our evolutionary neighbors. However, coexistence among African hominoids is not without problems; humans in particular are often in conflict with the other Great Apes. The number of gorillas, bonobos, and chimpanzees is decreasing steadily, due to deforestation, poaching, bush-meat trade, and contagious diseases. This symposium invites Jane Goodall as the principal speaker. She will provide a summary of her 50-year history in research and conservation, while the other participants will outline efforts at their respective research sites in Africa. This session, as a whole, aims to illuminate collective efforts among primatologists towards conservation and sustainable coexistence with nonhuman primates.

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SAGA was founded on November 19, 1998 by Japanese primatologists in collaboration with Western colleagues, including Jane Goodall and Jan van Hooff. The aim of the organization is to offer support to our evolutionary neighbors, the great apes. SAGA is a spiritual descendant of CCCC (Committee for Conservation and Care of Chimpanzees), established in Chicago in November 1986. SAGA extended CCCC's principles by including all of the great apes as targets, as well as consolidating support, not only from researchers, but also from zoo professionals, the media, and the general public. SAGA aims to facilitate the conservation of the great apes and their natural habitats, to promote animal welfare in captive populations, and to put an end to invasive research. In this talk, I will describe the collective efforts of SAGA over the past decade, resulting in the first chimpanzee sanctuary in Japan (CSU, established in 2007), and the founding, in 2008, of the Wildlife Research Center (WRC) of Kyoto University, which promotes collaboration between research institutes and zoos. I will also describe my endeavors towards a more holistic understanding of the chimpanzee through parallel efforts in laboratory studies in Japan and fieldwork in West Africa. In the course of synthesizing the two different approaches, understanding and utilizing environmental enrichment has become an integral part of my laboratory work, while my fieldwork is continuously accompanied by efforts toward the conservation of the chimpanzees’ natural habitat through, for example, the “Green Corridor” reforestation program.

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Japanese primatology is characterized by a unique history among mammalian studies in Japan. After World War II, Kinji Imanishi started his field studies to consider the evolution of human society through comparisons with other animal societies. He conducted field studies on non-human primates by identifying each individual and naming it, which were essential for illustrating social interactions among individual animals. The first generation of Japanese primatologists thought that social structure was not a mere reflection of individual survival or reproductive strategies but reflected a norm of species-specific sociality. In the late 1950s, they started a survey of wild gorillas to elucidate the origin of the human family. To date, Japanese scientists have conducted long-term field studies of gorillas in various study sites across Equatorial Africa. The accumulated data on their social ecology provides a remarkable contrast with those of chimpanzees living allopatrically and sympatrically with gorillas. Gorillas also show a high degree of ecology and social flexibility in response to habitat alterations caused by human disturbances. I will try to reconsider the social ecology of gorillas along with the scope of Japanese primatology and discuss ways how we can support their survival with us.

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Dr. Takayoshi Kano initiated in earnest the first field study of wild bonobos. He cycled around the Congo (former Zaire) and arrived in Wamba in 1973. He managed to keep the site operative for more than two decades, despite primitive conditions and political instability. Without his pioneering work, our knowledge of bonobos in their natural habitat would be extremely limited. Since then, many Japanese researchers conducted research seasonally until 1991, and developed much knowledge of the area. I joined those researches in 1984. However, the studies were interrupted by repeated political instability. We had to discontinue our research due to rioting in 1991. The research resumed in 1994, but we were forced to leave again due to two civil wars between1996 and 2002. Although the situation has remained unpredictable since those wars, we resumed research intermittently just after the end of the war in 2002. The Wamba Forest significantly deteriorated between 1991 and 2002, and the number of groups and group sizes of bonobos in Wamba also dramatically decreased. I also began in parallel the ecological study on woodland-dwelling chimpanzees in the Ugalla area, Western Tanzania. Population density of chimpanzees at Ugalla is very low, and various human activities are threatening the survival of the chimpanzees in this area. We must push forward conservation activities for the co-existence of bonobos/chimpanzees and human beings. This talk introduces the history of bonobo research at Wamba and the fieldwork on woodland-dwelling chimpanzees in Ugalla.

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Within groups of females, menses or oestrus can occur synchronously, asynchronously, or randomly. Whether oestrus is synchronous or asynchronous raises an important question on the evolution of female strategy: do females compete with each other for desirable males or do they share a “good male”? Examining the discrepancies in the first day of menses or oestrus, previous studies have reported that menses or estrous are synchronized (humans, some primates, rodents, lions and marsupials) and not is synchronized (ring-tailed lemurs and chimpanzees). However, the factors affecting synchrony and its relationship with evolution are not understood. It is an important point to clarify synchrony (or asynchrony) as a population characteristic to think about a general mate strategy in animals.
In this study, we employed an oestrus synchrony index and a randomization procedure to analyze long-term observations of female baboons (Papio anubis) oestrus cycles at the Gombe Stream National Park, Tanzania. Our results revealed that three of four groups of female baboons avoided synchronizing their oestrus periods. Moreover, our study by meta-analyses showed that asynchrony of oestrus was an inherent characteristic of Gombe baboons.

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The Arashiyama group of Japanese macaques (Macaca fuscata fuscata), a free-ranging provisioned troop living in the mountains on the northwest outskirts of city of Kyoto, Japan, is one of the longest studied non-human primate populations in the world, and has been the focus of numerous international collaborative research efforts for decades. This symposium aims to 1) emphasize the unique value of the longitudinal data sets that have been collected on the Arashiyama macaques for more than half a century, 2) review some historical and ongoing research contributions that are indicative of the range of investigations conducted on this group, and 3) encourage future studies of this primate population. First, we will show how fifty years of continuous demographic data represent unique resources for behavioral studies that are contingent on individual identification and known genealogical relationships. Then, we will present some of the major findings that have been derived from these longitudinal records, covering topics such as group fission, male transfer, reproductive and non-reproductive sexual behaviors, social interactions, and behavioral traditions. Finally, we will discuss the scope and magnitude of research and management efforts that have been conducted on the Arashiyama macaques, as well as, its overall significance for wider issues in the area of evolutionary studies.

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Female Japanese macaques have a long 20-year lifespan in the wild, which extends beyond 30 years in provisioning. They have been observed in a variety of environments (e.g., monkey parks, subtropical, temperate, coniferous, and alpine forests), presenting valuable data for evaluating the socio-ecological hypotheses concerning the evolution of primate societies. “Arashiyama East/West” have been ones of the most intensively studied field sites of Japanese macaques. Koyama (1967, 1970) confirmed Kawamura’s principles among adult female members of Arashiyama troop, and found that group fissions progressed along the female matrilines, which is common to other macaca species. Norikoshi and Koyama (1975) discovered that matured males left their natal groups and transferred to non-natal groups, but adult females remained in natal groups (female philopatry). Here, I summarize long-term field data of female life history accumulated in Arashiyama troops. For example, as Fedigan (1991) pointed out, a trade-off between the onset of reproduction and lifespan of females may have existed in Arashiyama West, whereas the age of first births had no correlation with the number of lifetime births. Consistently, there was no significant difference in reproductive parameters (birth rate, infant mortality, birth sex ratio etc.) among female rank-groups. I compare these results with the data of wild populations to examine socio-ecological hypotheses concerning the female life history.

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Animal populations primarily have been kept within the limits of food supplies and habitats. However, under certain circumstances, uncontrolled increases in population occurs in some species throughout the world, and have caused social problems. Though various measures for population control have been taken, these methods have only transient effects. Moreover, these methods are not always socially acceptable from a standpoint of animal welfare. Synthetic progesterone is commonly used in contraception and hormone replacement therapy in women. In this study, we investigated the effects of administration of synthetic progesterone for contraception in female Japanese macaques. In Experiment 1, the effects of synthetic progesterone on suppressive of menstrual cycles and ovulation were studied in female Japanese macaques at the Primate Research Institute, Kyoto University. After treatments, their menstrual cycles completely disappeared and anovulation persisted. In Experiment 2, multiparae female Japanese macaques living in Arashiyama Monkey Park, Kyoto, Japan were used for behavioral and contraceptive studies. They received a single injection of synthetic progesterone in early autumn. They did not exhibit copulatory behaviors during the following breeding season, and did not deliver during the subsequent birth season. In Experiment 3, we treated synthetic progesterone orally to multiparae female Japanese macaques of the same troop. Most of these monkeys did not show delivery during the subsequent birth season. This study indicates that treatment of synthetic progesterone is one of the effective strategies for fertility control in Japanese macaques. This hormone-induced sterility is reversible; the females eventually returned to normal cycles and experienced normal pregnancy

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Male reproductive success is not always correlated with male dominance rank when dominant males cannot monopolize the copulation. I observed sexual behavior and analyzed paternity in Arashiyama E troop, in which the number of females simultaneously in estrus is large and dominant males cannot monopolize the estrous females. Central adult (high-ranking) males did not attain high reproductive success and peripheral adult (low-ranking) males attained higher reproductive success. Although central males copulated with females, almost the copulation was observed when fertilization was unlikely. I also analyzed male masturbation which is suggested to be a reproductive strategy for flushing low-quality sperm. I observed 149 cases of male masturbation behavior, and 47 cases were accompanied by ejaculation. Eleven of 12 males performed masturbation behavior and 10 males ejaculated by masturbation. Three of these males used only the right hand, while one used only the left hand. Masturbation frequency was high at the beginning and the end of the mating seasons, when copulation frequency was low. The frequency of ejaculation by masturbation was not correlated with male dominance rank, but was negatively correlated with the frequency of ejaculation by copulation. Ejaculation frequency by masturbation was not correlated with the number of infants. These data suggest that female mate choice affected male reproductive success and ejaculation by male masturbation may be a startegy for flushing low-quality sperm.

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Social grooming is one of the most important social behaviors in Japanese macaques (Macaca fuscata), a primate species characterized by a marked seasonality in its reproductive cycles. During the non-estrus period, females do not copulate with males; moreover, even during the mating season, females are not always in estrus. Social grooming in Japanese macaques has been intensively studied during the non-mating season. Females generally tend to choose high-ranking individuals as grooming partners to expect their support in the future. Because of estrus periodicity, the number and identity of available females differ between the mating and non-mating seasons. The aim of this study is to compare social grooming partners and interactions between the mating and non-mating seasons. Observations were conducted from October 2002 to September 2003 at the Arashiyama monkey park, Kyoto, Japan. Observation time was 222 hours during the mating season and 151 hours during the non-mating season. I sampled 10 adult female focal subjects of various social ranks. During the mating season, I observed the females in their non-estrus days. The observation revealed 2 remarkable findings. First, the frequency of social grooming with kin and non-kin females differed between the 2 seasons. Unlike in the non-mating season, the females tended to choose non-kin females during the mating season. Second, during the mating season, the frequency of grooming from dominants to subordinates was higher than that from subordinates to dominants, and dominant females groomed subordinates one-sidedly. Social grooming behavior might differ during the mating and non-mating seasons.

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Many ethologists have pointed out the multiple difficulties to study animal play behavior. Among them, two substantial hurdles lie in the various and sometimes contrasting definitions of play, as well as the possible functional aspects of play. Thus, to cope with these inherent difficulties, it seems important to find possible detours. Here, I discuss resent studies on regional variations in animal behavior, sometimes referred to as cultural behaviors, as an example of methodological approach to studying animal play behavior. In order to systematically compare the play patterns observed across regions, it is necessary to construct a comprehensive list of play patterns characteristic of a particular species (a play ethogram). I video-recorded play patterns of juvenile Japanese macaques from Arashiyama, and several other field sites in Japan. I present a part of the ongoing collection of video data. I discuss how the study of regional variation in play may provide new insights into research of animal play behavior. The result suggests that play pattern such as “play chasing with a target object” would be fixed only among juveniles in particular study sites, while play pattern such as “play fighting” would be universal among juveniles in all study sites.

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Japanese macaques are known for their cultural behaviors, among which is stone handling (SH), a form of solitary object play involving the non-instrumental manipulation of stones through the performance of various stone-directed patterns. SH by the Arashiyama macaques is one of the most thoroughly documented behavioral traditions in nonhuman primates. At Arashiyama, a combination of longitudinal, comparative, and experimental approaches has provided sound evidence for long-term maintenance, inter-troop variability, and social transmission of a single cultural behavior. Since SH appeared in 1979, its diffusion within the group and across generations has been recorded at several points in time over a 30-year period. Between 1991 and 2004, the size of the SH repertoire almost doubled. We found an expansion of the contexts in which SH is performed, including the integration of SH with food-related activities and the gradual emergence of food-directed SH patterns. Compared to other troops of Japanese macaques, the Arashiyama troop presented a unique profile in terms of frequencies of SH patterns, i.e. its own SH tradition. Recent field experiments showed a stimulating effect of SH artefacts (such as piles of stones left on the ground by previous stone handlers) on the subsequent performance of SH. The transformation of the SH tradition, associated with a generational ‘ratchet effect’ could ultimately result in future stone-tool use, as stone-related behaviors become more deeply ingrained into the behavioral landscape of these macaques at the group level.

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Evolutionary shift from pronograde quadrupedalism to habitual orthogrady is an intriguing event of the hominoid lineage. To understand how this shift of the body plan had occurred in the past, knowledge of the morphological variation in the thoracic cage of various pronograde/orthograde living species is useful. Here we report comparisons of cranial (transversal) views of partially-mounted thoracic cage skeletons. Samples of Homo, Gorilla and prosimians are incorporated into the previous analysis of non-human anthropoids (Kagaya et al. 2008). Some non-cursorial carnivores (lesser pandas and bears) and marsupials (wallabies and kangaroos) are also analyzed preliminarily. The hominoid samples are unique, while the rest of primates and carnivores are similar in general; the thoracic cages of hominoids are characterized by the deep dorsal depth behind the thoracic column and by the strongly medially oriented sternal end of ribs (dorso-ventrally flattened thorax). Both these characters are extreme in Homo. Gorilla samples show similarity to pronograde monkeys and brown bears in the 7^th to 9^th rib levels in a slight ventral elongation of the thoracic cage, which may be related to terrestrial habit of Gorilla. The orthograde leapers Indri and Propithecus have slight expression of the hominoid-like features in the middle to lower rib cage. Kangaroos (especially the heavier species) show a ventrally elongated thoracic cage in spite of the prominent dorsal depth. Therefore, the powerful forelimbs and shoulder girdles of hominoids likely explain the marked dorso-ventral flatness of the hominoids’ upper thoracic cage.

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Miocene Hominoid, Nacholapithecus kerioi was discovered in Nachola, northern Kenya. The stratigraphic horizon of these fossils was dated to 15 Ma, early middle Miocene. The set of the specimens included various parts of the body. In this presentation, we discuss about the reconstruction of the locomotion from the pelvic morphology. The size of the large specimen was close to living anubis baboons and smaller than a specimen of Proconsul nyanzae. The shape of the iliac blade was rectangular not like as living hominoids but living cercopithecoids. The ischial tuberosity was not remarkable as living cercopithecoids. We compared the specimens with twenty living primate species including great apes. However, all of the fossil specimens were fragments and it was difficult to compare by the metrical data except for the ratio of a minimum iliac width to the minimum ischial width. The value plotted in the range of cercopitecoids. We also used non-metrical data, as the development of ischial spine or the shape of the superior articular facet of the sacrum, for the comparison. In the results, the following morphological and locomotor characters of Nacholapithecus were discussed: the hipbone remaining the features of quadruped primates, less sitting posture on the trees, no long tail, no pronogarde posture as living cercopithecids, no jumping or leaping on the ground and trees, relatively slow walking. Nacholapithecus should have the transitional locomotion to recent Hominoid.

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This study aims to provide new information on the catarrhine fauna of the African early Late Miocene. In the present primate fossil record of Africa, there is a great gap during the late Middle to early Late Miocene, despite that this is a critical period to understand the divergence of extant African great apes and humans as well as the early evolution of the modern-typed Old World monkeys (cercopithecines and colobines). Nakali is one of the few early Late Miocene fossil localities known in East Africa. We have carried out a new field survey in Nakali for recent several years. Our geological studies have determined the age of Nakali more precisely than before, to be 9.9-9.8 Ma. Hundreds of new fossils have been recovered through surface collection and excavations. Especially, the number of catarrhine fossils from Nakali has been greatly increased. At present, they include two species of large-bodied hominoids, at least three species of non-cercopithecoid small catarrhines, and Old World monkeys including colobines. These discoveries have largely expanded the known diversity of fossil catarrhines during the above-mentioned great gap in the African primate fossil record. The newly discovered catarrhine fossils from Nakali indicate that non-cercopithecoid catarrhines were still fairly diverse at the early Late Miocene. After 7-6 Ma, the African primate fossil record is dominated with Old World monkeys. The circumstantial evidence suggests that the decline of non-cercopithecoid catarrhines would have occurred around 9-8 Ma.

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One of the most interesting issues for research on the fossils is to shed light on ecological reconstruction of these fossil species. Dental remains can be a very good indicator for dietal adaptation of the species. The topographical analysis for molars can tell us general diet pattern, and the microwear indicates the diet of which the animal ate just few days before its death. Nakali, a Late Miocene fossil site in Kenya, had a great diversity of primates. Two species of large hominoids, at least three species of small non-cercopithecoid catarrhine, and several old world monkeys include colobines have been recovered from Nakali. There would be food segregations among Nakali primate species. The purpose of this study was to investigate dietal adaptation of Nakali fossil primates using the topographical analysis for outer morphology of molars and the microwear analysis for the second molar. Colobine monkey from Nakali had scratch dominant microwear, whereas others had pit dominant microwear. Colobine monkey from Nakali had higher occlusal relief and longer shearing crests than other species. This early colobus already had more folivorous diet. Other species from Nakali had similar diet pattern.

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The mesowear method is a new approach of reconstructing ungulate diets and their paleoenvironments. We analyzed mesowear of Hipparion and bovid upper and lower cheek teeth (P4-M3) from the Late Miocene Nakali (10-9.8 Ma) and Namurungule (9.6-9.3 Ma) Formations, Samburu Hills from Northern Kenya for reconstraction of paleoenvironments of both sites. The distance between both sites and geologic age of both formations is very close. Both sites have yielded the important Late Miocene hominoid fossils. Samburupithecus kiptalami was found from the Namurungule Formation, and Nakalipithecus nakayamai and several catarrhine taxa were discovered from the Nakali Formation.For tooth mesowear analysis, occlusal relief of buccul side is scored as high or low. Cusp shape is classified as "sharp", "round" or "blunt". For occlusal relief, many Hipparion teeth from Nakali show high, but many Hipparion teeth from Namurungule show low. Almost all bovid teeth from Nakali show high, but many bovid teeth from Namurungule show low. For cusp shape, many Hipparion teeth from Nakali show sharp, but many Hipparion teeth from Namurungule show blunt. No bovid teeth from Nakali show blunt. This leads conclusions that the paleoenvironment of the Nakali Formation may have been a woodland environment, while the Namurungule Formation may have been more open environment. This environmental difference between Namurungule and Nakali probably indicates the environmental change through geological age and/or the topographic difference between highland and lowland at the similar age. This result is supported by stable isotope analysis of ungulates tooth enamel and pollen analysis from both formations.

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Although tests of primate cognitive abilities have traditionally been conducted in particular testing rooms, several merits seems to be provided if a test can be done in the subject monkeys’ home cages. Home-cage tests don’t require habituation of the subject monkeys to novel laboratory environment, and the monkeys can perform the tasks simultaneously only if the experimenter prepares multiple sets of apparatus. On the other hand, several difficulties accompanies to such a home-cage test mainly because of the severe environment of cage rooms (e.g., high humidity after cleaning, destruction by the subject and other monkeys). To overcome the difficulty, a new automated apparatus for home-cage tests was developed. The apparatus consisted of a touch-sensitive display, an automatic pellet dispenser, and an embedded PC (controller). These components were installed in a water-proof box which was attached to individual cages of Japanese macaques. The apparatus worked well: the subject monkeys acquired the task quickly, continued to perform the task for several hours, and usually performed more than 1000 trials a day. The test was discussed in terms of efficient data collection and potential contributions to environmental enrichment. This study complied with the guidelines approved by the ethics committee for primate research in National Center of Neurology and Psychiatry.

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The extremely high reproductive power of common marmosets (Callithrix jacchus) can realize the development of genetically modified primate models for human disease, including nervous and mental disease. However, In spite of the high potential of marmosets as experimental animals for human disease, no simple and convenient method to test cognitive functions of marmosets has been available. Considering its nervous character and susceptibility to environmental change, the best approach is testing their cognitive functions in their home cages. To this end, we developed a PC-based automated apparatus consist of a small sized PC with touch screen and a special designed reward delivery machine. The total weight of this apparatus is about 3 kilograms and therefore, we could easily hang the apparatus on the front panel of their home cages. Because the apparatus could run with a battery of the PC, we don’t have to care about any power cables. We applied this apparatus for training marmosets to perform a pattern discrimination task. In the pattern discrimination task, the marmosets were required to correctly choose one (S+) of two patterns to get a reward. The marmosets usually perform 150 trials a day, and learnt each discrimination in one or two days. All experiments were conducted in accordance with Guide for the Care and Use of Laboratory Primate (Primate Research Institute, Kyoto University) and Japanese regulations on animal experiments. Our newly developed apparatus allows us to measure cognitive functions of common marmosets in their home cages.

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Several studies have shown associations between behavioral traits and genetic polymorphisms of neurotransmitter-related proteins in humans. To better understand the evolutionary bases of these genetic polymorphisms, we analyzed homologous genes in nonhuman primates. Nine neurotransmitter/hormone-related genes were surveyed polymorphism in chimpanzees, gorillas, orangutans, siamangs, and Japanese macaques. Comparisons of species revealed that the repeat numbers of variable number of tandem repeats in neurotransmitter-related genes such as dopamine receptor and serotonin transporter increased or decreased from nonhuman primates to humans, respectively. Functional differences of human alleles estimated by cellular expression of different alleles indicate that such differences might have been a factor in human evolution. We also found differences in the allelic distribution between and within species in aggression/affiliation-related candidate genes such as the monoamine oxidase and vasopressin receptor genes. We are presently studying the relationship between personality and genotypes in chimpanzees and gorillas. The findings from these studies will be a useful tool for estimating the susceptibility of nonhuman primates to stress, and thus improving animal welfare in laboratories and zoos.

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The availability of positron emission tomography (PET) for human and nonhuman primates has enabled examination of the in vivo functions of specific neurotransmitter systems underlying behavior. We established a PET imaging method for conscious common marmosets (Callithrix jacchus), a small primate species noted for its high social tolerance and cooperative sociality. We used this method to examine the dopaminergic and serotonergic systems in the brain using [¹¹C]DASB and [¹¹C]PE2I, which are highly selective to serotonin transporter (SERT) and dopamine transporter (DAT), respectively. Furthermore, we have identified personality dimensions, labeled ‘sociability’, ‘aggressiveness’, and ‘social anxiety’, in common marmosets by examining behavioral responses in encounter trials. Parametric images of [¹¹]DASB and [¹¹C]PE2I binding potential (BP) values have been generated and processed on the statistical mapping to identify brain areas of which BP values of SERT and DAT are tightly associated with behavioral factor scores. SERT BP values were positively correlated with ‘sociability’ and negatively correlated with ‘social anxiety’ in the hippocampus, caudate nucleus, and some other brain regions. DAT BP value in the substantia nigra was negatively correlated with ‘social anxiety’. These results demonstrate that molecular imaging of the brain combined with quantitative behavioral analysis can provide valuable information for understanding the neural bases of personality in nonhuman primates. This type of studies will also be useful in highlighting how genes and the environment influence personality. All procedures of this study were approved by the Animal Care and Use Committee of Kobe Institute in Riken (MAH18-03-6).

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Block manipulation in chimpanzees and humans was examined as an index of cognitive development. The object-manipulation tasks can be a non-verbal scale of comparison among primates including humans. The tasks were conducted in a face-to-face situation and the pattern of manipulation was analyzed. The first task focused on physical understanding involved in stacking blocks of different shapes. The subjects were required to stack up variously shaped blocks by selectively using an appropriate orientation for stacking. The result showed that chimpanzees are capable of learning the efficient strategy of stacking variously shaped blocks as well as human children of 2-3 years of age. The second task examined imitative ability in the context of stacking blocks. The subjects were required to stack colored blocks in an order that was identical to a model made by human tester. Although human children of 2-3 years old succeeded to make a copy of model stack, chimpanzees showed greater difficulty in learning the rule of copying the arbitral order of colored blocks. These results were discussed in terms of their tendency in learning rules of different domains. In order to investigate the rules spontaneously used by chimpanzees and humans, a new task was introduced to test sorting behavior with blocks of different shapes and colors. The result showed that chimpanzees share a rudimental form of sorting behavior with human children. In sum, a series of block-manipulation task illuminated the similarities and differences in cognitive development in chimpanzees and humans.

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We directly compared the drawing behavior of chimpanzees with those in different ages of human children. Although chimpanzees have the ability of manipulating tools to draw, there is no clear evidence of representational drawing. Thus, two tasks were designed to explain the lack of representational drawing. The subjects were 6 chimpanzees and human children of 1-3 years of age. The first task investigated the motor skills by requiring subjects to draw simple shapes after showing the model drawing. While human children started to succeed in imitating the simplest figures at the age of 2 years onward, none of the chimpanzees imitated the figures. However, chimpanzees spontaneously moved their scribbles to mark on the models and sometimes traced them. Thus chimpanzees have the ability to finely control their manual movement in drawing. The second task investigated the underlying cognitive mechanism by requiring subjects to draw freely on face stimuli. We prepared an illustration of a chimpanzee face and deleted some facial parts to test whether the chimpanzees fill in the missing parts to complete. Most humans over 2.5 years started to fill in the missing parts for completion and some of them traced the facial outlines. Although chimpanzees sometimes marked on the existent parts and traced the outlines, they never completed the face by drawing the missing parts. Hence, the basic cognition and motor control required for drawing was well in chimpanzees’ capability. There may be difference in the higher level cognition, such as imagining something on incomplete figures.

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Ecotourism is widely conducted in the habitat countries of great apes in Africa. Ecotourism can promote conservation since it is one of the means to provide positive economic effects to the local people and encourages them to understand the importance of both animals and their habitats. Meanwhile, frequent and intensive contact between human and great apes in such human activities can have a negative impact on great ape health: Travelers potentially bring infectious pathogens of which humans are hosts to habitats of great apes; also habituation can impose stress to the naive animals. Practically, there have been many reports on outbreaks of diseases, which are sometimes fatal, in the habituated populations of African great apes. Therefore, in the wild populations of great apes under the influence of human activities, it is necessary to monitor their health status and develop methods for managing their health risks. In this symposium, I will provide some topics in our field sites, in which monitoring for health status and stress levels in the great apes has been conducted. Applying these methods, we may devise appropriate measure to minimize human impact on great ape health in ecotourism. This study was financed by Global Environment Research Fund (F-061) from Ministry of the Environment, Japan, and the fund for Science and Technology Research Partnership for Sustainable Development from Japan Science and Technology Agency / Japan International Cooperation Agency.

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The ∼4.5 Ma Ardipithecus ramidus is represented by well over 100 specimens from more than 30 to 60 individuals recovered from the Middle Awash and Gona research areas, Ethiopia. These fossils include a partial skeleton of Ar. ramidus from Aramis, as well as other informative postcranial and dentognathic remains, such as over 20 canines almost certainly from different individuals. Recent analyses of the Ar. ramidus fossils, published in October 2009, indicate that Ar. ramidus was phylogenetically ancestral to, or the immediate outgroup of, the Australopithecus anamensis/afarensis lineage, and combined substantial arboreal capabilities with an Australopithecus-like upper pelvic balance mechanism for bipedal locomotion. The generalized forelimb and foot morphologies of Ar. ramidus suggest that it did not share a suspensory, advanced vertical climbing, and/or knuckle walking heritage with modern African apes. The Ar. ramidus dentition indicates loss of functional male canine honing by 6 to 4.4 Ma. Its incisal/postcanine morphology, wear and enamel isotopics suggest a predominantly woodland-based frugivorous/omnivorous diet, lacking specializations seen in Gorilla, Pan or Australopithecus. The Ar. ramidus cranium shares with that of Sahelanthropus a short basicranium and a lack of morphologies associated with heavy chewing. The Ar. ramidus skull was absolutely and relatively small, in keeping with its reduced male canine size, and inferred weak sexual dimorphism in cranial and body size. Comparisons suggest enhanced canine size and facial prognathism in Pan troglodytes, a general facial and dental size reduction in Pan paniscus, and exaggerated sexual dimorphism and allometric and/or dietary effects in the Gorilla cranium. Considerable specializations involving dietary, locomotor, and social behaviors are inferred in each of the modern African ape species. Both the Ar. ramidus and Miocene ape evidence supports the hypothesis of extensive parallel evolution of modern-ape like suspensory adaptations, suggesting a Pongo-African ape divergence deep in the early Miocene. This in turn conforms to Pan and Gorilla divergences of ∼8 and ∼11 Ma, respectively, from the human lineage.

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Early learning about edible food is a critical survival task for infant and juvenile non-human primates. Indi-vidual and social learning processes seem to be related to the slow growth of young primates and extended juvenile period that offers ample opportunities for seeking food information. Plant selection seems also to be correlated with the close observation displayed by the young and directed toward the elders whereas mothers rarely interfere with infant’s plant selection. Concerning nutritional values, only a few studies have been car-ried out with captive monkeys. Ontogeny of plant selection according to their medicinal properties is a very new theme of research and little documented for adult primates. The current symposium aims at discussing new results on plant selection by young non-human primates of different taxa related to their nutritional values and medicinal properties from captive and field studies. Results confirm that synchronized consumption with adults and observational learning is responsible for the food transmission preferences and information in the different species studied. In Japanese macaques, young selected their food according to crude protein con-tent, and the ease of processing food could play a more important role than previously expected. Concerning plants with medicinal properties, it appeared that neophobia is variable among apes species. The conse-quence of a strong conservative and neophobic feeding behavior acquired through social learning would be an important issue to consider for conservation of species threatened by habitat disturbance.

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I studied dietary differences between mothers and infants, and its influence on infant behaviors in a wild group of Japanese macaques (Macaca fuscata) inhabiting the northern temperate region of Japan. This study was conducted during the winter (from November 2008 to April 2009) in Shimokita Peninsula, Aomori Prefecture. I observed 4 mother-infant pairs and simultaneously followed the infant and the mother within each of them. Their activities, food items, and the distance between the infant and its mother were recorded by scan sampling at 3 min intervals. I found significant differences between mothers and infants in the proportion of each food item in about one-fourth of all the food items. Thus, I categorized the food items into the following three categories: 1) “mother foods”: the food items with the higher proportion in mother diet; 2) “infant foods”: the food items with the higher proportion in infant diet; 3) “common foods”: the food items which no significant difference was found between them. When mothers ate “common food” (e.g. seed, grass), infants often ate the same food items as their mothers within 2m. In contrast, when mothers ate “mother food” (e.g. bark), infants often ate “infant food” (e.g. dormant bud) apart from their mothers. Infants probably change their feeding behavior to meet their food requirement according to their mother’s food items.

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Primates must learn what, when and where to eat. The present study concerns the foraging ontogeny of 10 young Japanese macaques (Macaca fuscata yakui) less than one year of age, inhabiting a natural environment. To determine how youngsters select edible solid foods, feeding occurrences by the mother and her offspring, and their synchronization, were systematically recorded. In each context (independent or synchronized foraging), the quantity of food ingested by the infants was estimated. Because youngsters seek additional nutritional resources, the protein and lipid content of the main food items was analyzed in addition to their fiber content (ADF). The mother-offspring feeding events for solid foods were generally synchronized. Food items eaten by the youngsters were generally similar to those synchronously selected by their mother, and the quantity of the food ingested during co-feeding was higher than when eating alone. But a substantial divergence in foods selected by the mother and their offspring emerged after weaning (over 20% of feeding occurrences). This divergence was not explained because youngsters were selecting a food similar to this selected by the closest elder. Youngsters also preferentially selected solid foods rich in protein but low in fiber. Thus, young Japanese macaques were socially influenced to select solid foods mainly during co-feeding. This social influence appeared comparable to social facilitation. However, youngsters also displayed independent foraging, suggesting that they seek dietary information by themselves to meet their protein requirements.

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One goal of captive management is to make the activity budget of captive animals closer to wild counterparts. However, few studies have directly compared the activity budget between wild and captivity. In addition, behavioural consequence of achieving the activity budget in captivity similar to wild remains unknown. We focused on the cognitive experiments conducted on chimpanzees at Primate Research Institute (Kyoto University) since the experiments might serve as a good opportunity for feeding enrichment. We compared the activity budget among three groups of chimpanzees; wild chimpanzees in Bossou (Guinea), captive chimpanzees who participate in the experiments (participant chimpanzees) and who don’t participate in the experiments (non-participant chimpanzees). The data from captivity were obtained both in the experimental days (weekdays) and non-experimental days (weekends). In the both field sites, the first author followed the chimpanzees by using focal animal sampling method and recorded the behaviours every one minute. The results showed that on weekdays, feeding time and resting time of participant chimpanzees were almost the same with wild chimpanzees, whereas those of non-participant chimpanzees were significantly different. In contrast, activity budget of the both groups of captive chimpanzees were not different on weekends. These results suggested that the cognitive experiments work as an efficient tool for increasing feeding opportunity. However, we still observed individual variation in the rate of abnormal behaviours and stress related behaviours during and outside of the experiments. Based on the results, we will discuss the applicability and limitation of the cognitive experiments for environmental enrichment.

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In human cognitive developmental studies, use of unrestrained eye-tracking techniques promoted the great amount of advances in this area. This technique has also been introduced in nonhuman primate species who could not be physically restrained such as chimpanzees and infant primates. In this symposium, we intend to overview the recent advances in the study of gaze behavior on the basis of those methodological breakthroughs. We try to integrate findings from the traditional and new methodologies in nonhuman primates, those from human and nonhuman primates, and also those from gaze behavior per se and gaze recording techniques. From the outcome of this symposium, new directions of comparative primate cognition will be clearly proposed.

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We introduce a novel approach to comparative cognition studies - a comparative eye-tracking study in chimpanzees and humans. Eye-tracking methodology enables us to compare the eye movements of two species directly (i.e. both qualitatively and quantitatively). First, we will show the striking similarities in eye movements between chimpanzees and humans when viewing photographs. Both species viewed the same sets of photographs depicting bodies and faces freely under the same experimental conditions. The similarities between the species were pronounced in terms of how they view faces. Second, we will focus on the differences in eye movements between chimpanzees and humans when viewing various scenes including both social and non-social ones. Fixation duration (defined as the time during which the gaze is still) is known to play an important role in semantic processing. Compared to chimpanzees, humans exhibited longer durations of fixation on average and spent more time viewing objects/faces in peripheral vision. We interpret these results in terms of species-specific strategies in eye movements/information processing.

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