Objectives: Wild Sapajus libidinosus exploit underground storage organs (USOs) that require extraction and extensive processing before consumption. Since capuchin monkeys are small-sized extractive foragers that cannot perform forceful precision grips, we expected that: (a) they would use other body parts together with their hands, (b) older (and larger) capuchins would be more efficient than younger (and smaller) ones, and (c) capuchins would invest greater effort/time to exploit USOs than other foods. Materials and Methods:We recorded 178 episodes of USO processing performed by 20 individuals. The behavior was videotaped and scored frame-by-frame.Results: We identified six sequential stages of processing: Excavation, extraction, soil removal, transport, peeling, and fragmenting the inner tissues. Capuchins made frequent use of forceful hand postures and manipulation in which the hands were strongly supported by other body parts, principally the mouth. Older capuchins were more efficient than younger individuals in pulling the USOs out of the ground. Finally, exploiting USOs was time-consuming, lasting more than 4 min per item, on average.Discussion: Despite having smaller body-mass and greater manual constraints than catarrhine extractive foragers, capuchins, even smaller individuals, mastered USO processing thanks to their behavioral flexibility and persistence. Our findings reveal that precision grips are not essential for forceful actions during complex food processing and that, unlike catarrhines, capuchins, especially adults, rarely use thumb opposition during forceful grasping of food. In contrast, extended sustained attention and varied manual behavior appear to be convergent features of platyrrhine and catarrhine extractive foragers. K E Y W O R D Sdigging behavior, extractive foraging, manual dexterity, USOs, Sapajus libidinosus

Female wild bearded capuchins (Sapajus libidinosus) living at Serra da Capivara National Park (SCNP) that use stone and stick tools during foraging occasionally toss or throw stones at the male during courtship. We report similar behaviors in a different population that uses stones as tools in foraging. We video-recorded the sexual behavior of four females (27 days during nine proceptive periods) belonging to a group of wild capuchins living in Fazenda Boa Vista (FBV), 320 km from SCNP. Three females used stones or branches when they solicited the alpha male (79 episodes). The female that did not use objects was the sole female to solicit a subordinate male. The vast majority of episodes (95%) involved pushing or dropping branches, both loose and attached to the tree, toward the male. Females used objects only during the one-way courtship phase, before the male reciprocated the female's solicitations. In 93% of the episodes in which a female used objects, she performed affiliative behaviors immediately before or after using the objects. We conclude that throwing or pounding stones and pushing or dropping branches by females in SCNP and FBV in the sexual context have a clear affiliative meaning (to attract the male's attention). Given the tool-using status of both populations where these behaviors have been reported, it is important to determine whether they appear in populations that do not use tools, or are restricted to populations already primed to use objects in other contexts. (PsycINFO Database Record