• socially biased learning;
  • social information transfer;
  • behavioral traditions;
  • primate cognition


Nutcracking capuchins are mentioned in reports dating as far back as the sixteenth century,1, 2 as well as in Brazilian folklore.3 However, it was barely a decade ago that primatologists “discovered” the spontaneous use of stones to crack nuts in a semi-free ranging group of tufted capuchin monkeys. Since then, we have found several more capuchin populations in savanna-like environments which employ this form of tool use.5–7 The evidence so far only weakly supports genetically based behavioral differences between populations and does not suggest that dietary pressures in poor environments are proximate determinants of the likelihood of tool use. Instead, tool use within these capuchin populations seems to be a behavioral tradition that is socially learned and is primarily associated with more terrestrial habits. However, differences in the diversity of “tool kits” between populations remain to be understood.