Eibl-Eibesfeldt, I.; Eibl-Eibesfeldt, E.: Das Parasitenabwehren der Minima-Arbeiterinnen der Blattschneiderameise (Atta cephalotes). Zeitschrift für Tierpsychologie 24 (3), pp. 278 - 281 (1967)
Scientists studying a rare population of tool-using chimpanzees have found that aging can have a profound impact on their abilities—but not all chimps decline equally.