PARENTAL INVESTMENTS AND DEMANDS OF INFANTS

抄録

The theme of this symposium is the behavioral resolution of parent-offspring conflicts in primates. From an evolutionary perspective, Trivers theorized that an offspring demands more investment than the parents are willing to provide because their evolutionary interests are not identical. At the behavioral level, parent-offspring conflicts in primates are complicated due to the long periods of juvenility, various forms of maternal investments, and high intelligence. Maternal visual monitoring of the infant is an important aspect of maternal care as it helps to prevent predation or harassment of the infant. ONISHI will show that mothers optimally direct maternal monitoring efforts in keeping with (1) the activity (e.g., social grooming or foraging) that she is engaged in and (2) the vulnerability of infant. YAMADA will discuss weaning conflict in Japanese macaques. During the weaning period, mothers often actively reject their infants to prevent them from suckling. YAMADA found that maternal activities affected the frequency of maternal rejection. On the other hand, infants were more likely to attempt nipple contact when their mothers were involved in activities during which they tended to accept their infants. The other members will elaborate on infant carrying in Japanese macaques, mother-child interaction during meals in humans, and gestures used by human infants to attract the attention of their caretakers, etc. Through the symposium, we would like to emphasize the following two points: mothers regulate their efforts on the basis of the situation, and infants are aware of the situations when their mothers tend to satisfy their demands.