Wild chimpanzees show population-level handedness for tool use

TLDR

Population-level handedness in nonhuman primates is debated, with questions about whether it occurs only in captive animals or also in wild populations. The study reports population-level handedness in wild chimpanzees during termite‑fishing and compares it to other tool‑use tasks to examine task‑specific differences. We found task‑specific differences in handedness, demonstrated that hand preferences are heritable, and showed that population‑level handedness exists in wild chimpanzees, implying that lateralization of hand use predates the Pan–Homo split by at least five million years.

Abstract

Whether nonhuman primates exhibit population-level handedness remains a topic of considerabe theoretical and empirical debate. One continued subject of discussion is whether evidence of population-level handedness in primates is confined to studies in captive animals or whether it is in both captive and wild subjects. Here, we report evidence of population-level handedness in wild chimpanzees for a tool-use task known as “termite-fishing.” We subsequently compared the handedness for termite-fishing with other published reports on handedness for nut-cracking and wadge-dipping and found task-specific differences in handedness. Last, when combing all of the published data on tool use in wild chimpanzees, we show that hand preferences are heritable. Contrary to previous claims, our results demonstrate that populationlevel handedness is evident in wild chimpanzees and suggest that the antecedents of lateralization of function associated with hand use were present at least 5 million years ago, before the Pan - Homo split.