FIGURE 2.

Ages of perforating tool use relative to fishing probe tool use. Dots represent individuals. Dotted lines connect observations for immature chimpanzees observed for both “Insert fishing probe” and “Extract termites”; solid lines connect observations for three individuals for whom we could document ages for these elements as well as for the age at which they first exhibited perforating tool use. While all three of these individuals could extract termites by age 2.4, the ages at which they were first observed perforating an epigeal nest (4.3, 8.4, and 10.5 years) varied widely. At left, a juvenile male inserts a fishing probe (a) and feeds on termites he has swept from the fishing probe after a successful extraction (b). At right (c), he uses a twig to perforate an epigeal nest, while holding a fishing probe in his mouth