The Great Apes: A Study of Anthropoid Life

activity adaptation animal anthropoid apes appear arms attempt attention behavior body cage called captive certain characteristics chim chimpanzee color Congo considerable considered contrast definitely described discovered early evidence exhibited experience experimental expression extremely fact feet female four frequently gibbon give given gorilla ground habits hand head human imitation important indicate individual intelligence interest knowledge known latter learned less literature living male ment mentioned method modes monkeys natural nest never noted objects observed once orang orang-outan organism perhaps period play possible present primates probably problem quote reach reason references relations relatively remarks reported response seems sense siamang situation social sounds species specimens statement stick structure suggested term tion tree types usually varied Yerkes young