penis swelling of sexual skin thrust in vacuum 1-3-1. Maternal behavior: Maternal/alloparental care and infant behavior abandon adopt aid in locomotion balance bounce foot/feet up and down rhythmically care alloparentally care alloparentally for another species care maternally change nipple clamp elbow cling cradle with hand cradle with leg extend arm as ladder extend leg as ladder gestation period give birth grasp hug kidnap kiss with pout face lie and hug mother-offspring relations mummify nuzzle orphan pat pregnancy protect rescue respond to dead chimpanzee retrieve infant return infant rush to embrace scan share bed share food spring suck suck in reassurance suckle travel alone after childbirth wedge 1-3-2. Maternal behavior: Infant transport crutch grasp and push shoulders put dorsal put dorsal from ventral put ventral put ventral from dorsal