Stone handling, an object play behaviour in macaques: welfare and neurological health implications o f a hio-culturally driven tradition

Abstract

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Object play in primates is view ed as generally having no immediate functional purpose, lim ited for the m ost part to immature individuals. A t the proximate level, the occurrence o f object play in immatures is regarded as being intrinsically self-rewarding, with the ultimate function o f supporting motoneuronal developm ent and the acquisition o f skills necessary to prepare them for survival as adults. Stone handling (SH ), a solitary object play behaviour occurs, and has been studied, in m ultiple free-ranging and captive troops o f provisioned Japanese macaques, as w ell as rhesus and long-tailed macaques for over 35 years now. A review o f our com bined findings from these observations reveal that infants acquire SH in the first 3-4 months o f life and exhibit increasingly more com plex and varied behavioural patterns with age. The longitudinal data show s that many individuals maintain this activity throughout life, practicing it under relaxed ecological and social conditions. The ultimate function may be bim odal, promoting motor developm ent in young and neural maintenance and regeneration in adult and aging individuals