...chimpanzees and bonobos also make liberal use of gestures in addition to the sounds and facial expressions that are part of their communication system...
D. Díaz, R. Ramírez, и D. Hernández-Leo. IEEE 15th International Conference on Advanced Learning Technologies (ICALT); 2015 Jul 06-Jul 09; Hualien, Taiwan.Sl: IEEE, 2015. p. 367-369., Institute of Electrical and Electronics Engineers (IEEE), (2015)