Wild capuchin monkeys prefer stones showing prior nut‑cracking use

A recent experimental study has shown that wild capuchin monkeys (Cebus spp.) do more than simply assess the physical properties of stone tools when deciding which to use. Researchers observed that the monkeys also consider visible evidence that a stone has previously been employed for tool‑making, indicating a form of social or observational learning about tool efficacy.

The investigation, conducted in a tropical forest setting, involved presenting capuchins with a range of stones that varied in shape, hardness, and prior use. Monkeys consistently preferred stones that bore wear marks or other signs of previous use, even when those stones were not the most physically optimal choice. These findings suggest that capuchins possess a nuanced understanding of tool history, challenging the assumption that primate tool selection is driven solely by immediate physical cues and highlighting a more sophisticated cognitive capacity in wild primates.