主催: Japan Primate Society and Mammalogical Society of Japan
In nonhuman primates, age-related changes in the postcranial skeleton have been studied (DeReousseau, 1988; Kimura, 1994) but little is known about such changes in the skull. This study aimed to elucidate changes in skull patterns in Japanese macaques Macaca fuscata, with implications for aging in the human skull. A total of 140 (68 male; 72 female) skulls from macaques of known age were measured for 21 craniometric items. Facial and mandibular dimensions showed a greater and significant increase than neurocranial dimensions, e.g., facial length, facial height, bizygomatic breadth, mandibular angle, mandibular body height, and ramus breadth in both sexes from 7.04 to 1219.1 years of age in males (8.07 to 13.69%) and 7.04 to 22.1 years or more in females (4.65 to 16.37%). Peak skull size tended to occur later in females than in males, which might relate to reproductive costs in females. After the increase phase, these dimensions stabilized or decreased only slightly. Similarly, facial length, facial height, cranial base length, and bizygomatic breadth also continue to increase in humans (Ruff, 1980; Israel, 1973). The significant decrease in inter-temporal distance and increase in cranial length in males may be related to the development of insertion processes (tubercles) on which muscles attach and/or the accumulation of physical stress, those dimensions may relate to tooth loss and/or dental disorders, both of which are evident in humans but were found to be minimal in the present study.
