Development of object manipulation in wild chimpanzees

Abstract

Chimpanzees' natural propensity to explore and play with objects is likely to be an important precursor of tool use. Manipulating objects provides individuals with pivotal perceptualmotor experience when interacting with the material world, which may then pave the way for subsequent tool use. In this study, we were interested in the influence of social models on the developmental patterns of object manipulation in young chimpanzees (Pan troglodytes schweinfurthii) of the Sonso community of Budongo Forest, Uganda. This community is interesting because of its limited tool repertoire, with no records of stick-based foraging in over 20 years of continuous observations. Using cross-sectional data, we found evidence for social learning in that young individuals preferentially played with and explored materials manipulated by their mothers. We also found that object manipulation rates decreased with age, whereas the goal-directedness of these manipulations increased. Specifically, stick manipulations gradually decreased with age, which culminated in complete disregard of sticks around the age of 10 years, a pattern not found for other tool materials, which were all used throughout adulthood. Overall, young chimpanzees initially explored and played unselectively with any object found in the environment before becoming increasingly influenced by their mothers' goal directed object manipulations.

An Evaluation of Ethograms Measuring Distinct Features of Enrichment Use by Captive Chimpanzees (Pan troglodytes)

“…Social toy manipulation consisted of toy use, active tactile manipulation, and affiliative contexts, which may represent object play. This pattern is consistent with observations that small objects promoted fine motor engagement and object play with other individuals in wild chimpanzees [ 39 , 40 , 41 ]. However, object play may serve different functions in wild compared to captive chimpanzees.…”

The ontogeny of exploratory object manipulation behaviour in wild orangutans

“…However, our data was unbalanced in terms of the age-sex distribution which means that the negative result we find here may need to be treated with caution. These findings are consistent with findings on wild immature bonobos but contrasted by findings on wild immature chimpanzees where males show higher rates of object manipulations than females Lamon et al, 2018), whereby the opposite pattern was found for specific forms object carrying (Kahlenberg & Wrangham, 2010).…”

“…In line with our prediction, our results showed that the overall age trajectory of immature orangutans’ exploratory objects manipulation rates is very similar to the human pattern, with a peak during the early dependency period (Belsky & Most, 1981; Bock, 2005; Power, 1999; Power et al, 1985). In wild chimpanzees, with increasing age, rates of object manipulation decrease while the manipulations become more goal-directed (Lamon et al, 2018). If exploratory object manipulations are an expression of learning processes, one would predict that humans show a higher exploration rate than orangutans and other great apes, owing to their advanced cognitive capacity.…”

Behavioural Development of Three Former Pet Chimpanzees a Decade after Arrival at the MONA Sanctuary

“…The first years of an infant’s life are important for the acquisition of ecological skills as well. Object manipulation in the form of play and exploratory behaviour, for instance, was found to occur frequently at early ages in wild-living chimpanzees but declines gradually with age, and stops in older individuals once they become habitual tool users [ 29 ].…”