DEVELOPMENTAL-CHANGES IN MANIPULATION IN TUFTED CAPUCHINS (CEBUS-APELLA) FROM BIRTH THROUGH 2 YEARS AND THEIR RELATION TO FORAGING AND WEANING

This study examined the contributions of physical and sensorimotor dev elopment to manipulation in capuchins (Cebus apella) from birth to 2 y ears. Between months 1-6 and 7-12, manipulation increased significantl y in frequency, in the proportion that was vigorous or required fine m otor control, and in the proportion directed at portable objects. Fine motor 'control, moving objects in relation to the body, and stamina a re largely in place by 12 months, after which little changed. All elem ents of the manipulative repertoire have appeared, and vigorous and de xterous activities have peaked before fully independent foraging. Emer gence of permanent dentition and achievement of approximately half of adult body size accompany the attainment of fully independent foraging at 15 months. Thereafter, increasing strength and specific knowledge probably contribute more to changing foraging competence in young capu chins than do stamina and sensorimotor development.