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How Humans Became Social

Look around and it’s impossible to miss the importance of social interactions to human society. They form the basis of our families, our governments, and even our global economy. But how did we become social in the first place? Researchers have long believed that it was a gradual process, evolving from couples to clans to larger communities. A new analysis, however, indicates that primate societies expanded in a burst, most likely because there was safety in numbers.

To the researchers’ surprise, the most sensible solution suggested that the solitary ancestor started banding together not in pairs, as scientists had thought, but as loose groups of both sexes, as the team reports online today in Nature. Given the modern distribution of social organizations, the most likely time for this shift was around 52 million years ago, when the ancestors of monkeys and apes split off from the ancestors of lemurs and other prosimian primates.