The map shows the locations of all chimpanzee populations studied across Africa including the four PanAf temporary research sites (TRSs) where accumulative stone throwing behaviour was observed (white circles; 1: Boé, Guinea-Bissau; 2: Sangaredi, Guinea; 3: Mt. Nimba, Liberia; 4: Comoé GEPRENAF, Côte d’Ivoire). Chimpanzee accumulative stone throwing was not observed at all other research sites: PanAf TRS (light grey circles), PanAf TRS carried out at mid- to long-term chimpanzee research sites (dark grey circles) and PanAf TRS carried out at mid- to long-term research sites of habituated chimpanzees (black circles). See also Supplementary Table 1. (Map created by M. Arandjelovic using QGIS version 2.6.1: http://www.qgis.org/en/site/).