Sometime about 400,000 years ago, humans learned to fully control fire. This breakthrough radically changed our diets, because we could now cook food, but did it transform our culture as well? A study of evening campfire conversations by the Ju/’hoan people of Namibia and Botswana (pictured above) suggests that by extending the day, fire allowed people to unleash their imaginations and tell stories, rather than merely focus on mundane topics. Back in the 1970s, University of Utah anthropologist Polly Wiessner, well known for her work on the social networks of the Ju/’hoan Bushmen (also known as the !Kung), took detailed notes on 174 of their day and nighttime conversations. At that time, the Ju/’hoan still lived as hunter-gatherers, although that is no longer the case today; they now live in villages and have taken up farming. Wiessner returned in 1998, 2005, and 2013 to discuss these old conversations with the Bushmen and get help with translating them. As she reports online today in the Proceedings of the National Academy of Sciences, whereas daytime talk was focused almost entirely on economic issues, land rights, and complaints about other people, 81% of the firelight conversation was devoted to telling stories, including tales about people from other Ju/’hoan communities. Wiessner suggests that campfires allowed human ancestors to expand their minds in a similar way and also solidified social networks. “Stories told by firelight put listeners on the same emotional wavelength,” she writes in the paper, and “elicited understanding, trust, and sympathy.” Wiessner adds that fire still serves that purpose today: “The power of the flame is reproduced in our homes through fireplaces and candles.”