" ISOLATION DOES STRANGE THINGS to a person’s mind. This is true for any social creature, human or otherwise. Monkeys taken from their mothers at birth, placed alone in stainless-steel chambers, and deprived of contact with other animals (“human and subhuman” alike, according to the researchers), develop irreversible mental illnesses. As one of the experts in this field, Harry Harlow, put it: “sufficiently severe and enduring social isolation reduces these animals to a social-emotional level in which the primary social responsiveness is fear. "

― Derrick Jensen , A Language Older Than Words