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With records of 30 billion electronic conversations among 180 million people from around the world, researchers have concluded that any two people on average are distanced by just 6.6 degrees of separation, meaning that they could be linked by a string of seven or fewer acquaintances. The database covered all of the Microsoft Messenger instant-messaging network in June 2006, or roughly half the world's instant-messaging traffic at that time, researchers said.

Why does it matter that people from around the world are closely tied together? Researchers said that the knowledge might have applications for political organizations, charity efforts, natural disaster relief and missing-person searches. "They could create large meshes of people who could be mobilized with the touch of a return key," Horvitz said.