Naïve, unenculturated chimpanzees fail to make and use flaked stone tools

Naïve, unenculturated chimpanzees fail to make and use flaked stone tools. E Bandini et al. European Human Behaviour and Evolution Association, 15th Conference, Mar 2021. https://ehbea2021.com/

Abstract

Objective: Despite extensive research on early hominin lithic technology, the mechanisms underlying flake manufacture and use are still debated. To draw phylogenetic inferences on the potential cognitive processes underlying these abilities in early hominins, we examined whether our closest living relatives, chimpanzees (Pan troglodytes), could learn to make and use flakes.

Methods: We provided naïve unenculturated chimpanzees from two independent populations (n=11) with baited puzzle boxes that could only be accessed with cutting tools, stone cores, and hammerstones to test for their ability to spontaneously make and use flakes.

Results: Despite the fact that the chimpanzees demonstrated an understanding of the requirements of the task and were sufficiently motivated, none of the chimpanzees made or used flakes in any of the experimental conditions.

Conclusions: These results differ from previous ape flaking experiments, which found flake manufacture and use in bonobos and one orangutan. However, these earlier studies tested only enculturated apes and provided them with demonstrations. The contrast between these earlier positive findings and our negative findings (despite using a much larger sample size) suggests that enculturation and/or human demonstrations may be necessary for chimpanzees to acquire these abilities. The data obtained here is consistent with the hypothesis that flake manufacture and use might have evolved in the hominin lineage after the split between Homo and Pan 7 million years ago, a  scenario further supported by the apparent absence of flaked stone tools in the archaeological record after this split.