Human beings need both emotional and physical care to grow. During the second world war, there were many infants in over crowded orphanage who were only given physical care. Many of them died from what was later called "failure to thrive". Later research, by Harry Harlow, who studied Rhesus monkeys, showed that monkeys given a choice between wire "mother monkeys" that had a bottle attached and a cloth-covered wire monkey without a food source, preferred the cloth-covered monkey. Babies need the closeness, comfort and loving attention to feel safe. When they feel safe, and not alone, then they can eat and grow. Without the love and safety of another human being, many will feel afraid, alone and will withdraw and stop eating. In addition, those babies and small children who don't get the social interaction and comfort from safe loving adults and siblings, may become sociopaths if they survive childhood.