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Field studies have been, and continue to be, important contributors to theunderstanding of great ape cognition-especially with regard to questions of cognitiveecology or the key cognitive challenges in the evolution of primate intelligence. Theyare also critical to resolving a current debate, whether human enculturation boosts greatapes' cognition, because only studies of problem-solving in feral contexts can resolvethe question of whether abilities are higher in enculturated than non-enculturated greatapes. To this debate, this paper offers findings from observational field studies on freerangingrehabilitant orangutans' cognitive capabilities, as revealed in their foodprocessing and arboreal positioning, and on the possible social transmission of thatexpertise. These findings are combined with published findings on wild andenculturated great apes as a basis for assessing the effects of human enculturation ongreat ape cognition. This assessment joins several others in showing that free-ranginggreat apes independently achieve cognition of the same order of complexity asenculturated great apes, in concluding that claims for the effects of human enculturationare likely inflated, and in suggesting that the basis for the effectiveness of humanenculturation is that great apes normally "enculturate" themselves.

We report an observational field study that aimed to identify innovative processes in rehabilitant orangutans' (Pongo pygmaeus) water innovations on Kaja Island, Central Kalimantan, Indonesia. We tested for the basic model of innovating (make small changes to old behavior), 4 contributors (apply old behavior to new ends, accidents, independent working out, social cross-fertilization), development, and social rank. Focal observations of Kaja rehabilitants' behavior over 20 months yielded 18 probable innovations from among 44 water variants. We identified variants by function and behavioral grain, innovations by prevalence, and innovative processes by relations between innovations, other behaviors, and social encounters. Findings indicate innovating by small changes and some involvement of all 4 contributors: midrank orangutans were the most innovative; and rehabilitants' adolescent age profile, orphaning, and intense sociality probably enhanced innovativeness. Important complexities include: orangutan innovating may favor certain behavioral levels and narrowly defined similarities, and it may constitute a phase-like process involving a succession of changes and contributors. Discussion focuses on links with great ape cognition and parallels with innovating in humans and other nonhuman species. Keywords: orangutan, great ape, innovation, innovative processes, creativity DOI: 10.1037/a0017929

This paper presents the combined results of two separate orangutan survey efforts and an assessment of land cover change analysis in the Danau Sentarum National Park (DSNP), West Kalimantan, Indonesia. [...]

We discuss selectivity in great ape imitation, on the basis of an observational study of spontaneous imitation in free-ranging rehabilitant orangutans (Pongo pygmaeus). Research on great ape imitation has neglected selectivity, although comparative evidence suggests it may be important. We observed orangutans in central Indonesian Borneo and assessed patterns in the models and actions they spontaneously imitated. The patterns we found resembled those reported in humans. Orangutans preferred models with whom they had positive affective relationships (e.g., important caregiver or older sibling) and actions that reflected their current competence, were receptively familiar, and were relevant to tasks that faced them. Both developmental and individual variability were found. We discuss the probable functions of imitation for great apes and the role of selectivity in directing it. We also make suggestions for more effective elicitation of imitation.

We made an observational study of spontaneous imitation in orangutans (Pongo pygmaeus). Previous studies may have underestimated great apes' imitative capacities by studying subjects under inhibiting conditions. We used subjects living in enriched environments, namely, rehabilitation. We collected a sample of spontaneous imitations and analyzed the most complex incidents for the likelihood that true imitation, learning new actions by observing rather than by doing, was involved in their acquisition. From 395 hr of observation and other reports on 26 orangutans, we identified 354 incidents of imitation. Of these, 54 complex incidents were difficult to explain by forms of imitation based on associative processes grounded in experiential learning alone; they were, however, congruent with acquisition processes that include true imitation. These findings suggest that orangutans may be capable of true imitation and point to critical eliciting factors.