As exile, marooning, and solitary confinement indicate, isolation is a scarring punishment. Senator John McCain described his two years alone as a Vietnam War prisoner as worse than the permanent injuries he suffered, and the United Nations deems more than 15 days of isolation as inhumane. A University of Virginia study found that most men would prefer mild electric shocks than being alone for 15 minutes, and a University of Wisconsin experiment discovered that rhesus monkeys would suffer lasting behavioral damage if kept from others for three months. Unwanted loneliness is as much as a risk factor for death as smoking.

Those who pursue voluntary isolation are still at risk. The cave explorer Véronique Le Guen committed suicide shortly after staying in an underground cavern without a clock for 111 days, which ruined her biological rhythms and sense of purpose. One competitor of a global sailing race enjoyed the days alone so much that he abandoned the race to complete a second lap, while another fell into despair and went overboard.

Humanity’s ability to form relationships is the key to its evolutionary success. Knight seems to be the exception; the thought of solitary confinement even brings him joy. Hooley notes that, between the intense winters and the moral quandaries of the burglaries, suffering is “the price Knight paid in order to remain in the woods” (140).