Unable to cope, some chimpanzees resort to self-mutilation, including biting themselves, attacking a limb that they dissociate as being their own, pulling their hair out, rubbing their skin raw, or hurting themselves in other ways – behaviors that in humans would be described as having “gone crazy.”

Others develop compulsive behaviors: rocking uncontrollably back and forth; eye or ear poking; head rolling; pacing; or, smearing, playing with, or eating their feces. Faced with similar isolation, human prisoners of war have described their own need to pace endlessly. They explain that it helped remind them that they were alive.

Out of frustration or an effort to get attention, some chimpanzees spit water or throw feces. According to former caregivers, some lab workers don’t have the empathy to tolerate this behavior and retaliate with punishment.

Although there are Animal Welfare Act (AWA) requirements for “psychological enrichment” for nonhuman primates, these guidelines are vague and, according to former caregivers, many facilities meet only the bare minimum or get around them. According to these sources, this minimal “enrichment” can mean no more than providing pieces of old cardboard. The USDA has stalled recommended improvements, read more.