Janmaat, K.; Boesch, C.; Byrne, R.; Chapman, C.; Goné Bi, Z. B.; Head, J. S.; Robbins, M. M.; Wrangham, R.; Polansky, L.: The spatio-temporal complexity of chimpanzee food: How cognitive adaptations can counteract the ephemeral nature of ripe fruit. American Journal of Primatology 78 (6), pp. 626 - 645 (2016)
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.