Chimpanzees are humanity's closest living relatives, with cognitive and emotional complexity that creates profound welfare obligations for the institutions that keep them in captivity.
The psychological suffering of chimpanzees in inadequate captive environments is well-documented and profound. Self-injurious behavior, prolonged depression, and the blank staring associated with learned helplessness indicate that cognitively sophisticated animals are experiencing chronic psychological distress. Solitary housing — historically common in biomedical research — causes severe, lasting harm. Social disruptions from introductions, deaths of companions, and management changes cause observable grief and behavioral disturbance in survivors. The intelligence that makes chimpanzees valuable to research also makes their suffering in poor conditions particularly acute. The transition of research chimps to sanctuaries has revealed the extent of behavioral abnormalities that develop from inadequate early environments — many retired research chimps require years of rehabilitation.