The role of individuals in the history of a free-ranging group of Japanese macaques: Some thoughts on the relevance for human behavioural research

Taking the stance that the study of nonhuman primates can be useful in understanding the mechanism of long-term changes in social organisation, this short paper seeks to shed light on the role the individual might play in changes in future human society. This is done by examining the causes of social order change in a group of free-ranging macaque monkeys. The paper suggests that it may be useful to examine the role of genetically transmitted characteristics in human “success” stories, particularly concerning adaptability in times of change, and that the examination of individual life-history data across generations, will be essential for clarifying the mechanism of changes in human social organisation.

Parenting and Family Support in Japan for 6- to 8-year-old Children Weighing under 1000 Grams at Birth

The purpose of this study was to explore the variables related to paternal involvement in the caregiving of 6- to 8-year-old extremely low-birthweight (ELBW) children, specifically, sociodemographic factors related to the family or individual biological factors related to ELBW. Thirty-three children with a mean birthweight of 845.5 grams and a mean gestational age of 27.4 weeks participated in this research. Approximately 29% of their fathers were classified by the mothers as nonco-operative in overall child care. The paternal involvement in caregiving was related to the sociodemographic variables of the family; the co-operative fathers were proportionally more often from families where the child had no older female sibling(s) and/or grandparent(s), whereas the nonco-operative fathers were proportionally more often from families where the child had older female sibling(s) and/or grandparent(s). The individual perinatal risk variables and IQ, and the paternal variables (age, socioeconomic status) were not related to the paternal co-operativeness. Our sample mothers seemed to have raised their children in more difficult parenting and economic situations, and to have received proportionally more support from grandparent(s) than did typical Japanese mothers. The children's relationships with peers differed between the paternal co-operative and nonco-operative groups; there were proportionally more children from the nonco-operative group who preferred to play alone than to play with peer(s) at the ages of 3-5 years. Thus, scarce paternal involvement in the process of caregiving appeared to influence the children's sociability.

Carrying and washing of grass roots by free-ranging Japanese macaques at Katsuyama

The acquisition and transmission of new feeding behaviours in Japanese macaques (Macaca fuscata) such as sweet potato washing [1, 2], wheat washing [2] and caramel eating [3, 4] have been well documented. These behaviours are all related to provisioned food. Here we report carrying and washing of grass roots by Japanese macaques in a free-ranging group. This would appear to be the first report of washing of dirt from natural food, such as grass roots, among macaques. Furthermore, some monkeys in the present study rubbed dirt from roots by rolling them along the surface of a flat rock at the edge of a river. This may be considered a tool-using behaviour.

A computer-based behavior monitoring system for low-birth weight infants under intensive care

For the intensive care of low-birth weight infants, it is important to continuously monitor behavioral changes. From this point of view, we have developed a computer-based monitoring system to analyze the body movements of low-birth weight infants under intensive care. The system consisted of a video recorder with a micro CCD camera for observing infant's body movements and a real time image processor for analyzing video frames. A 16 bit personal computer equipped with an image processor converted a video frame into a binary image that is a 256 by 256 matrix of pixels. The computer assessed each pixel of the matrix to determine whether the brightness changed between successive binary images or not. The number of changed pixels was counted every 1/30 sec, and such change reflected a infant's body movements. Using the system, body movements of a low-birth weight infant in an incubator were videotaped during 24 hours and analyzed. Results indicate that the behavior monitoring system developed in the present study has not only the ability to detect occurrences of movements of low-birth weight infants, but also the ability to qualitatively describe the pattern of movements.