Zoo-Housed Chimpanzees Can Spontaneously Use Tool Sets But Perseverate on Previously Successful Tool-Use Methods

Abstract

Tool use is documented in both wild and captive chimpanzees, but the creation of tool sets (e.g., two, or more, tools used in a sequence to solve a task), seems to be less common. This has raised the question of whether tool sets are a culture-dependent trait (CDT), or can be re-innovated independently, and thus fall within chimpanzees' Zone of Latent Solutions (ZLS). To test this, we provided a group of zoo-housed chimpanzees with a novel task that mimicked the wild conditions, required a tool set to solve, and all necessary materials to do so. We therefore enhanced the necessary conditions for the tool-set behavior, but without providing demonstrations of toolset manufacture or use. We baited an artificial termite mound with six ketchup-filled tubes, each with a 45-degree bend and with a cellophane barrier across the top. The chimpanzees needed a rigid tool to pierce the barrier and then a flexible tool to reach the reward. Overall, chimpanzees did use both tool types in order, thus demonstrating that this tool-set form is not a CDT. Yet, few attempts were successful, and the majority were not made using a tool set. This suggests that the behavioral pattern did not stabilize, which may have been due to unintentional difficulty created by the opacity of our task. Overall, our study showed that the form of tool sets can be within the ZLS of chimpanzees, but future studies need to determine what stabilizes the behavioral patterns in the wild.

Wild Goffin’s cockatoos flexibly manufacture and use tool sets

“…In terms of emergence, tool sets were suggested to arise from technical innovation and cumulation based on the ability to use a single tool. 28,29 Our observations resemble previous reports of wild chimpanzees using tool sets to access bee or termite nests. 19,30 While chimpanzees used between two and five types of objects, the core functions seem to parallel Fixed effects estimates presented together with standard errors, confidence limits, and range of estimates obtained when excluding levels of random effects one at a time.…”

The Method of Local Restriction: in search of potential great ape culture‐dependent forms

“…Boesch et al (2020) based this conclusion on their observation that specific combinations of termite-fishing elements were more similar within communities than among them (although the exact range of overlap in element combinations among communities was not clear). However, the effects that factors such as genetics, environmental differences, social structure and non-copying social learning (see also Bernstein-Kurtycz et al, 2020) play in determining which programs of termite fishing are used in different populations, were not accounted for.…”

Can Comparative Psychology Crack its Toughest Nut?

“…41 Here, I simply wish to explore whether the fact of anthropomorphism 38 Again, none of what I have said here should be construed as downplaying the importance of collecting such information from free-ranging populations of chimpanzees and other animals. Data from the wild is indispensable for building and testing evolutionary and socio-ecological theories of tool use (including the current controversy over whether the intra-and intergenerational transmission of tool use is driven by cultural or individual learning, see Bandini & Tennie, 2017;Tennie et al, 2009; see also Bernstein-Kurtycz et al, 2020). The issue at hand is not (and never was) about the relative importance of data derived from the field versus the laboratory, but about how such data sets match up with the interpretative level one seeks to address.…”

“…Detailed recent analyses by his team reveal these effects are all but nonexistent(Estienne et al, 2019; see also footnote 82). A similar picture may be emerging for behaviors once thought to be 'culturally' transmitted (seeBandi et al, 2020;Bernstein-Kurtycz et al, 2020;Fiore et al, 2020). This does not mean maternal inputs are unimportant to development, just that our folk psychology is probably not a good guide to uncovering the causal pathways involved.…”

“…From the beginning, her caretakers and peers played a strong role in her interactions with objects. The precise impact of these social inputs remains highly contested (see Bernstein-Kurtycz et al, 2020). Indeed, some of the most seemingly rock-solid folk psychological assumptions about the causal role of maternal input in the development of tool use in wild chimpanzees have collapsed under close empirical scrutiny (Estienne et al, 2019, and footnote 72).…”