" The point of making children sleep alone, according to Western psychologists, is to make them “self-soothing,” but that clearly runs contrary to our evolution. Humans are primates—we share 98 percent of our DNA with chimpanzees—and primates almost never leave infants unattended, because they would be extremely vulnerable to predators. Infants seem to know this instinctively, so being left alone in a dark room is terrifying to them. Compare the self-soothing approach to that of a traditional Mayan community in Guatemala: “Infants and children simply fall asleep when sleepy, do not wear specific sleep clothes or use traditional transitional objects, room share and cosleep with parents or siblings, and nurse on demand during the night. "

― Sebastian Junger , Tribe: On Homecoming and Belonging