We investigated the possibility of detecting wild Japanese macaque troop locations based on their vocalizations on Yakushima Island, a typical habitat of this species, in order to design adequate census methods and observe wild monkeys more efficiently. For each category of vocalizations we determined the maximum distance between the observers and the vocalizing monkeys. Trackers and fixed-point observers determined the actual real-time location of the vocalizing monkeys. ”Loud calls” and ”loud screams” could travel the farthest distance and were most suitable for obtaining precise directional estimation on the position of the troop. The maximum distance from which ”loud calls” were heard was 580m, and that for the ”loud screams” was 420m. However, it was concluded that when conducting censuses by using vocal cues in steep terrain like on Yakushima Island, the frequencies of these two vocalizations might sometimes be too low to conduct a census efficiently. Thus, we recommend that a more effective detection distance should be less than 200m, which is close enough to hear the next long-distance transmittable vocalizations such as ”loud aggressive vocalization” and ”loud alarm calls.” Although loud alarm calls were less precise when determining the direction from which the voice came, they were more practical for large-scale census methods.

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We quantify structural strength of primate scapula (baboon, chimpanzee, and spider monkey) under different loading conditions using finite element (FE) analysis, in order to biomechanically evaluate the relationship between scapular form and locomotor habits. Three-dimensional FE models of their scapulae are generated using consecutive cross-sectional images retrieved from CT. Material property of the bone is assumed to be isotropic, uniform, and constant for all three. The coordinate system of each bone is locally defined by using morphological landmarks, so that equivalent loading conditions can be set for all. In order to approximate actual loading of the bones, the models are fixed at their vertebral boarder and forces are applied at the glenoid and acromion regions. Stress and strain distributions in the bones are then calculated while changing the direction of the force.
The results show that the chimpanzee gross scapular shape is relatively more rigid than that of baboons. In addition, it is selectively more resistive against tensil force to the glenoid in the cranioventral direction, whereas the baboon scapula does not show such directionality in structural strength. This suggests that the chimpanzee scapula may be mechanically adapted to the resultant force applied to it in unimanual suspension. The strength of the acromion is found to be relatively low in the chimpanzee model, but it was selectively rigid against a force in the lateral cranioventral direction, suggesting its mechanical relevance to suspension as well. In contrast, the relatively rigid baboon acromion seems to be adaptive to compressive force acting on it in terrestrial quadrupedal locomotion. The scapula of the spider monkey basically shows similar mechanical tendencies with those of chimpanzee since both are brachiators, but mechanical characteristics of its scapula happened to be unique, inferring that mechanical demands in their suspensory locomotion are essentially different, probably because of the use of the prehensile tail in locomotion in spider monkeys.

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The skull of Proconsul heseloni (KNM-RU-7290A) is three-dimensionally reconstructed in a virtual environment for morphological analyses of the evolution of Miocene hominoid skulls by the means of Computer Assisted Anthropology. The volume of the fossil is extracted from the CT-scan images and the surface is approximated by very tiny triangles. Such a computerized technique enables visualization, manipulation and measurements of its 3 D shape in a computer. Moreover, a replica of the virtually constructed model can be created by stereo-lithography.
Taking advantage of the computerized system, non-homogeneous taphonomic deformation of the fossil is corrected based on skull’s basic geometry, that is, bilateral symmetry with respect to its midsagittal plane. Morphological landmarks of the skull are transferred so as to fulfill the geometrical conditions, and the entire shape of the skull is transformed according to the movements of the landmarks using a thin-plate spline function. Although the reconstruction is still incomplete due to inherent lack of information that can be extracted from the fossil for reversal of deformation, tentative results indicate efficacy of the proposed computerized system for advanced morphometrical and biomechanical studies of fossil skulls.

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The introduction of a group of foreign macaque species was confirmed in the southernmost part of the Bousou peninsula, Chiba prefecture, in 1995. The group, living in a 10 km2 range of habitat, consisted of more than 96 monkeys and its habitat was located approximately 20 km south to the core distribution area of native Japanese macaques.
We collected information by interviewing the local authorities or resident people in order to evaluate the group’s origin. The founders of the exotic group seem to have been released or escaped from a breeding facility. After the establishment of its home range around Shirahama town, the group became a pest for farmers. The conditions of vegetation and crop raiding are described here. We also conducted observations and radio tracking to investigate the movement patterns of the group and the possibility of individual transfer between groups of the two species. Two such cases of long distance migration by adult males between the introduced and native populations were observed during the period from 1997 to 1999.
Sequencing of mitochondrial DNA extracted from feces suggested that the alien species was rhesus macaque, Macaca mulatta. Electrophoretic examination of diagnostic blood proteins (adenosine deaminase, NADH-dependent diaphorase and transferrin) for the samples collected during 1996 to 2002 gave no evidence of hybridization in the area of native Japanese macaques.

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van Schaik’s socioecological model (van Schaik, 1989) hypothesized that predation risk and food distribution determine female gregariousness and their social relationships through the type of food competition females experience. Also, it predicts that the distribution of males is dependant upon female gregariousness. This model was later modified by van Schaik and colleagues (Sterck et al., 1997). The modified model incorporated ’habitat saturation’ and ’infanticide risk’ as selective forces to explain several phenomena that van Schaik’s classical model did not. At present, the main focus of the discussion in primate socioecology has shifted to ’infanticide risk’.
We review here the evidence for and against van Schaik’s classical and modified models, and point out the following problems to be solved. 1) The modified model cannot be a socioecological model until it is combined with the classical model mainly because it does not address the determining factors of each type of food competition (i.e., food distribution). 2) Out of four social categories addressed in the modified model (Dispersal-Egalitarian, Resident-Nepotistic, Resident-Egalitarian and Resident-Nepotistic-Tolerant), the ecological factors of RNT do not seem valid. In our opinion, RNT is expected where primates equally subsist on both types of food: a) high quality, scattered patches large enough to accommodate all group members, and b) high quality patches that are too small to accommodate all group members. 3) In RE and RNT categories, there is not yet enough evidence to prove either the relationship between food distribution and food competition or the relationship between food competition and social category. 4) The sooty mangabey (Cercocebus torquatus atys) may be categorized into the fifth category (Female-Resident-Despotic) but this may not be explained by ’habitat saturation’ as incorporated into the modified model. If so, ecological factors of FRD should be investigated in more detail. 5) There is little evidence that dispersed females in DE species choose males with a greater ability to defend against infanticide, although high infanticide risk forces females to permanently associate with males as the modified model hypothesizes. 6) Female dispersal in most DE species seems to reduce infanticide risk since larger female groups are more attractive to incoming males. However, we should not jump to conclusions because convincing counter-evidence exists. That is, groups with a larger number of females are more successful than groups with fewer females in reducing infanticide through defensive female coalitions.

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