Ключевые слова: animal expression, animal rights, behind bars, caged animal, captive animal, captive wildlife, captivity, chimpanzee, cognitive, confined, confinement, conservation, emotional, empathetic gaze, encased, enclosed space, enclosure, endangered primate, endangered species, imprisoned, imprisonment, introspection, introspective look, locked in, locked up, nature, pensive, pondering, primate, reflective, restricted, sad eyes, sentient being, thoughtful expression, trapped, wild animal, wildlife, zoo, zoo enclosure,