【C1】______the way it feels, loneliness often has nothing to do with being alone. For some people, feelings of【C2】______are sharpest during times that are in fact defined by togetherness—celebrations or the holidays, for instance. 【C3】______a bustling shopping mall or a buzzing holiday party, and even within a crowd—or perhaps especially in a crowd—it's possible to feel unbearably alone. New research from experts in neuroscience and social science may give us some【C4】______as to why. Although we tend to think of it as a self-contained emotional state—a condition that【C5】______people individually, either by circumstance or by means of an antisocial personality—researchers now say that loneliness is more far-reaching than that. John Cacioppo, a psychologist at the University of Chicago, believes it is a social【C6】______that exists within a society and can【C7】______through it like a disease. And while everyone feels lonely once in a while, for some it becomes a(n)【C8】______condition, one that has been【C9】______with more serious psychological ills like【C10】______, sleep disfunction, high blood pressure and even a(n)【C11】______risk of dementia in older age. Cacioppo and his team【C12】______on the children in Framingham. The results were【C13】______: If one person reported feeling lonely at one【C14】______, his closest connections (either family or close friends) were 52% more【C15】______to also report feeling lonely two years later. The effect was strongest among those in close relationships, declining【C16】______the connections became more distant, but remained【C17】______up to three degrees of separation—【C18】______one lonely person could influence whether his friend's friend's friend felt lonely. "Loneliness has been【C19】______in the past as depression, introversion, shyness or poor social skills," says Cacioppo. "Those turn out not to be right. Research we and others have done suggests that it really is a fundamental human motivational state very much like hunger, thirst or pain."【C20】______simply reflecting the emotional state of one person, Cacioppo says, loneliness is more like an indicator of the social health of our species on the whole—a temperature reading.