Social networks act like living systems, retaining memory and allowing flows as members die or relationships change.

An obese friend raises your obesity risk 45%. An obese friend’s friend raises it 25%. Their…

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After a spouse dies, the surviving partner’s risk of death can double during the first year.

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Happy and unhappy people form clusters extending up to three degrees through a network, creating…

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Genes explain 46 percent of the variation in how many friends people have.

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Carbon becomes soft graphite or hard, clear diamond depending entirely on how its atoms connect.

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Peripheral people face less exposure to spreading germs, while central people face more exposure…

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Genes explain 30 percent of the variation in whether people occupy the middle or edge of a network.

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Obesity is a multicentric epidemic: many people change simultaneously, with no single Patient Zero.

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