In 1966, Edward Evarts reported the neuronal activities of mortar cortex of behaving monkeys. That was the first report of the cellular level research using behaving monkeys. The Primate Research Institute (PRI) was established in Kyoto University, next year in 1967. To start a new research project in the new institute using primates, research on cellular level of brain functions, especially the functions of the frontal association cortex was selected. This topic was selected since the higher brain functions are the well-developed functions in the primates. Later, in 1970, Edward Evarts was invited to come to Japan. He stayed PRI for 4 months and brought his new techniques to PRI. Thus the cellular level of study on functions of the association corteces started using behaving monkeys in Japan. Since then, the cellular basis of the integrative brain functions, such as, perceptual decision making, emotional decision making, planning of complex behavior or complex motor control were revealed based on the analyses of the correlations of behavior and neuronal activities while monkeys are performing behavioral tasks. To investigate correlations, it was important to segregate behavioral events in the time sequence of the single task or in the multiple tasks. In addition to this, the effect of the lesion and the effect of electrical stimulation of the target brain area were helped to understand the behavioral role of the neuronal activities. Although this field of research revealed higher brain functions of monkeys in the single neuronal level, the understanding of the brain mechanisms of higher brain functions is still in the primitive phenomenal level. In future, it is necessary to reveal the role of each neuronal activity in the neural circuit of the brain.

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There are four available primate genome sequences as of 2008 A.D.; human, chimpanzee, orangutan, and rhesus macaque. Species phylogeny of representative primate lineages were already determined by former studies using much smaller scale sequence data. For example, now we know that chimpanzees are the most closest organism to human, followed by gorilla. However, species divergence times are still controversial. This is partly because molecular data can only give relative proportions of each branch of a phylogenetic tree. Yet there are still some inconsistency among various molecular data. As genomic sequences of many primate species will become available, it will become possible to estimate pattern of introgression between closely related species.

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Long-term data on population dynamics from 20 study sites including 15 species are reviewed. Data include both continuous and discrete changes, or data cover only a few group(s) or the entire population. Median of the ratio of the maximum population size to minimum population size during the entire study period was 2.12. Median of the largest annual decrease observed in each study site was 22%, and it was significantly larger than the largest annual increase, suggesting that decrease is faster than increase of population size. The frequency of events that population size decreases 10% or 20% was every 6.15 and 20 years, respectively. If data which cover the entire population are included, the frequency was 4.5 and 10.3 years, respectively. Although data on the continuous changes in population size of more than 20 years are available for only four study sites so far, this empirical evidence and the above parameters suggest that fluctuation is the normal state for primate populations, and they hardly reach equilibrium.

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More than half a century has passed since Imanishi (1952) proposed ‘culture’ to nonhuman animals. Now, although there is still some skepticism, the discussion of nonhuman cultures is widely accepted in the international academic world. It seems that the study of cultures has become one of the important topics in primatology. In this review, I introduce recent trends of cultural studies on nonhuman primates. First, I give a brief outline of the history of the studies. Then I summarize recent findings of cultural primatology by dividing them into the following three domains: 1) chimpanzee tool use; 2) chimpanzee cultures other than tool use; 3) cultures in other primate species. The most well studied domain is the foraging tool use where more and more additional information about the distributions of known tool types has been reported from new study sites in addition to several novel tool types. From long studied sites, the details of developmental process or tool selection are often well investigated. There are some reports on cultural behaviors outside of foraging tool techniques but the information is still limited compared to tool use. Finally I introduce some of the recent debates on nonhuman cultures by focusing on the distinction between culture and tradition, the distinction between social and asocial learning, and the ‘ethnographic’ method often employed by field primatologists. I argue that recent discussions of animal culture often tacitly include the idea of hierarchical advances that implies the complex and sophisticated human culture is in the highest and the best stage. This reminds us of the outdated view on human cultural hierarchism which saw the modernized western culture as the final stage. I stress the importance of writing ‘real’ ethnographies of nonhuman primates for full development of cultural primatology.

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Capuchin monkeys are one of the most important primate subjects in understanding the evolution of kokoro (mind and heart), because of their outstanding intelligence and gentleness despite their phylogenetic distance from humans and apes. Here we report a series of experimental studies on various aspects of the kokoro of tufted capuchin monkeys (Cebus apella) conducted at the comparative cognition laboratory, Graduate School of Letters, Kyoto University. Briefly, for the physical intelligence, the monkeys amodally completed partly occluded figures basically like humans do. They also perceived never-presented contours by spatially and temporally integrating a sequence of fragmentary information just like humans do. They understood physical causality in a type of tool-use task involving tool, goal, and environment. In the social intelligence domain, they spontaneously took actions interpretable as tactically deceiving the conspecific opponent in an experimental food-competition contest. They also cooperated by dividing a sequence of actions leading to rewards. This cooperation continued when only one of the participants obtained a reward at a time. They were sensitive to attentional states of humans shown by eyes, though they might not try to control human attentional focus. They inferred a conspecific's behavior that they never directly observed and adaptively modified their next behavior based on the predicted consequence. They were also able to correct their actions by observing unsuccessful actions of their conspecific partner. One monkey of this species showed evidence that she recognized the knowledge status of humans suggested by their preceding actions toward the items in question. In the affective domain, this species was shown to utilize affective reactions of a conspecific against a hidden object to regulate their own actions toward it. Finally, the monkeys were sensitive to the benefit of their conspecific partner. They sometimes took thoughtful actions toward a low-ranking individual and in other times spiteful actions against a high-ranking individual. All of these results show that this New World species shares many characteristics of kokoro observed in humans.

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Experimental studies to understand prefrontal functions started after Jacobsen (1936) first reported that bilateral prefrontal lesions produced a permanent deficit of delayed-response performance in monkeys. However, neurophysiological experiments to understand neural mechanisms of prefrontal functions began in the early 1970s using awake behaving monkeys first by Kubota's group in Japan and Fuster's group in USA. These groups reported many important and basic findings, including the finding of delay-period activity and its characteristics. Although spatial tasks, such as a delayed-response task or a delayed alternation task, were initially used to examine neural mechanisms of prefrontal functions, non-spatial tasks, such as a delayed matching-to-sample task, were also used for these experiments in the 1980s and the importance of delay-period activity was gradually recognized as a key activity to understand prefrontal functions. In the late 1980s, Goldman-Rakic proposed "working memory" as a key concept to combine findings of behavioral and neurophysiological experiments using animals with findings of clinical studies using human frontal patients and to interpret all these findings using one common concept. Her proposal was supported by a series of neurophysiological and behavioral studies conducted by her group. The term working memory became a key word in prefrontal studies in the 1990s, especially in non-invasive brain imaging studies. Although working memory may not be an appropriate concept to interpret functions of whole prefrontal cortex, working memory is a useful concept to understand functions of the lateral prefrontal cortex. Only a small number of groups in the world started neurophysiological studies in the primate prefrontal cortex in the 1970s. Studies of prefrontal functions have now become one of the major fields in neuroscience. The prefrontal cortex is the most important cortical area to understand the human mind. Although a huge volume of new findings regarding prefrontal functions have been accumulated since the 1970s, the prefrontal cortex is still a not-well-understood cortical area. We need further experiments to solve the secrets of prefrontal functions.

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Recent discoveries of new hominoid species from the Late Miocene of Africa provide us various insights for the study of hominoid evolution and human origins. One of them, Nakalipithecus is a large-bodied hominoid from 9.8 my-old Nakali, Kenya. It has a close relationship with the slightly younger Ouranopithecus known from Greece and Turkey and is very likely the sister taxon to the extant African apes and humans among the currently known hominoids. More importantly, Nakalipithecus is accompanied with several other catarrhine taxa, including another large-bodied hominoid, small-bodied non-cercopithecoid catarrhines, and cercopithecid and victoriapithecid monkeys. In this article, we review the phylogeny of Late Miocene hominoids, morphological evidences to connect Nakalipithecus with Ouranopithecus, and paleoenvironments of Nakali and biogeography of Late Miocene hominoids. Also, we propose a scenario of competition in cercopithecoids and non-cercopithecoid catarrhines in the Late Miocene of Africa and its influence on hominoid evolution.

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This article summarizes recent findings on the evolution and adaptation of primate locomotor behavior, and discusses the current status and future prospects of this field of study. Japan once led the world in this field of study, but currently the Japanese research community is not very active, partly because of the limited availability of facilities where experimental studies can be conducted. In addition, it has become more difficult to keep and breed primate species in the laboratory, especially in the last five years. By contrast, in the US and Europe, the numbers of researchers and papers in this field are increasing rapidly. This is partly because there are more facilities for experimental studies, but more importantly because they are developing various new approaches. These include sophisticated analyses of limb joint function using computer simulations based on computed tomography images and the statistical shape atlas. Collaboration with researchers in other fields of study, such as physiology, has also begun. In addition, some researchers have taken advanced kinematic apparatus to zoos to collect motion data, since zoos have many species and are now enriching the habitats of their animals. Although it is now more difficult to undertake experiments in the laboratory using living animals, there is still much that we can do. Locomotion is one of the most basic animal behaviors, and reflects both body structure and natural habitat. To discuss primate and human adaptation and evolution, information on locomotor behavior is essential. The various techniques introduced in the studies in this article will make the coming decades exciting and fruitful, and I really hope that this wave of activity spreads to Japan and reverses the recent decline of primate locomotion research.

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We followed physical growth and aging in the cynomolgus monkeys (Macaca fascicularis) bred and reared in the laboratory frorm gestation to old age, for those individuals whose gestational age and/ or exact age were known. Growth patterns of body mass were compared between sexes by a cross sectional study. Although higher rates of growth for infants and early juveniles were observed in both sexes, the pre-pubertal spurt with sexual maturity was observed only in males. The significant sex difference in body mass growth patterns was demonstrated in cynomolgus monkeys, which has not been observed in humans. The characteristics of physical growth from birth to 12 weeks of age in both sexes were examined morphometrically and discussed from the point of view of allometry. The postnatal growth of facial and extremity parts of the body were relatively greater than other body parts, particularly the trunk. Furthermore, physical growth during the first 6 years of life was analyzed. All measurement items in females showed monophasic allometry against the growth of the anterior trunk length. However, several items in males including body mass showed biphasic allometry with the inflection point occurring at about 2.5 years of age. The process producing sexual dimorphism in the cynomolgus monkey was demonstrated.
Then age at menarche and menopause and post-menopausal lifespan in female cynomolgus monkeys are presented.

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Since non-human primates are closely related to human and share many physical similarities, they are important for use in translational research from basic research. The study of non-human primates has contributed to our understanding of basic biological phenomena such as reproduction; diseases and the development of drugs, treatment and vaccines for the promotion of better health for human and non-human primate alike. A lot of researches are obtained basic data from rodents such as mouse. However, even if the results are directly applied to human clinical situations, new generation therapeutics in reproduction are often so specific and cannot be predicted by testing in rodents. Often these important side effects can only be detected in specific primate models. The close genetic, immunological and virological relation with human makes non-human primates an excellent model of diseases. Therefore, primate research for medical science is conducted and the formation of the breeding colonies for this purpose is recognized to be great importance. It is necessary to pay attention to developmental study on reproduction field for the reproductive medicine and regenerative medicine. In this paper, I describe the current state of this research and the problems of developmental reproductive technology in the non-human primate.

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Noninvasive methods for the measurement of estrone conjugates (E₁C), pregnanediol-3-glucronide (PdG), testosterone (T), follicle stimulating hormone (FSH), monkey chorionic gonadotropin (mCG) and cortisol in excreta of non-human primates were described. In the series of studies, results suggest that 1) urinary and fecal steroid metabolites accurately reflected the same ovarian or testicular events as observed in plasma steroid profiles in captive Japanese macaques, time lags associated with fecal measurements were one day after appearance in urine; 2) these noninvasive methods were applicable to wild and free-ranging animals for determining reproductive status; 3) hormonal changes during menstrual cycles and pregnancy could be analyzed by measurement of FSH, CG and steroid metabolites in the excreta in captive great apes and macaques; and 4) hormone-behavior relationships of macaques in their natural habitats and social setting could be analyzed. In these studies, we confirmed an association between maternal rejection and excreted estrogen, but not excreted progesterone, for Japanese macaques. We also reported that significantly higher levels of fecal cortisol were observed in high-ranking male Japanese macaques. 5) A reliable non- instrumented enzyme-linked immunosorbent assay for detection of early pregnancy in macaques was established.
These results suggest that the noninvasive methods for monitoring characteristics of excreted hormones provide a stress-free approach to the accurate evaluation of reproductive status in primates. These methods provide the opportunities for the study of hormone-behavior interactions in not only captive but also wild and free-ranging animal species.

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Animal welfare is an essential idea for researchers using captive animals. Primates are often like to be treated as targets for animal welfare. Non-human primates are genetically closed and similar to human being. However, this is not necessarily a reason to be considered deeply the welfare of primates. Primates have a specific property as they have complex requirements and/or suffering; social, intellectual, 3D space using requirements, and suffering of mental and physical stress. We have to focus on this in order to precede adequately discussion of animal welfare on primates. One of actual procedures to improve the animal welfare is environmental enrichment. In order to evaluate improvement of QOL of captive animals, behavioral criterion is mainly used, but physiological criterion should also be considered. Practicing environmental enrichment emphasizes on the importance of social environment for captive primates. A group-living condition in large individuals requires tackling physical and cognitive tasks, at the same time, through their complex social interaction. Complex social relationships associate captive animals with additional enrichment for adjusting feeding, inanimate, and physical environment. Such an approach of welfare entailing an animal's entire resources possibly satisfies the complex demands in daily life of captive primates in direct and indirect manners.

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