Wild chimpanzees show population-level handedness for tool use

Area of Science:

• Primate Behavior
• Evolutionary Anthropology
• Neuroscience

Background:

• Population-level handedness in nonhuman primates is debated, particularly whether it exists in wild populations.
• Previous studies often focused on captive animals, leaving the prevalence in wild primates unclear.

Purpose of the Study:

• To investigate population-level handedness in wild chimpanzees for the tool-use task of termite-fishing.
• To compare handedness across different tool-use tasks (termite-fishing, nut-cracking, wadge-dipping) in wild primates.
• To determine if hand preferences for tool use in wild chimpanzees are heritable.

Main Methods:

• Observational study of wild chimpanzees performing termite-fishing.
• Analysis of handedness data from termite-fishing and comparison with published data on nut-cracking and wadge-dipping.
• Statistical analysis of combined tool-use data to assess heritability of hand preferences.

Main Results:

• Evidence of population-level handedness in wild chimpanzees for termite-fishing.
• Task-specific differences in handedness were observed across different tool-use behaviors.
• Hand preferences for tool use in wild chimpanzees were found to be heritable.

Conclusions:

• Population-level handedness is evident in wild chimpanzees, challenging previous assumptions.
• The findings suggest that the evolutionary antecedents of lateralization of hand function predate the split between chimpanzees and humans.
• Handedness in primates is influenced by both genetic factors and task-specific requirements.