It’s easy to laugh at the very wrong things that people once believed, but try not to feel too superior. My friend Susannah Gregg was living in South Korea and working there as an English teacher when she first learned about fan death, a common belief among people in that country that oscillating desk fans are among the most deadly inventions known to man. She was stepping out for a beer with a friend when he noticed, to his horror, she had left her fan running with her pet rabbit still inside her house. Her friend, a twenty-eight-year-old college graduate, refused to leave until she turned off the fan. He explained to her that everyone knows you can’t leave a fan running inside a room with the windows shut. That would mean certain death. It was shocking to him that she was unaware of something so simple and potentially life-threatening. Susannah thought he was kidding. It took several conversations to convince him it wasn’t true and that in her country, in most countries, no one believed such a thing. She successfully avoided absorbing the common belief not because she was smarter than her friend but because she had already done the experiments necessary to disprove the myth. She had slept in a house with a fan running many times and lived to tell about it. Since then, she has asked many friends and coworkers there about fans, and the response has been mixed. Some people think it is silly, and some think fan death is real. In 2013, despite the debunking power of a few Google searches, the belief that you shouldn’t fall asleep or spend too much time in a room with a running electric fan is so pervasive in South Korea that Susannah told me you can’t buy one within their borders without a safety device that turns it off after a set amount of time. The common belief is so deep and strong that fan manufacturers must include a safety switch to soothe the irrational fears of most consumers.

Your ancestors may not have had the toolset you do when it came to avoiding mental stumbling blocks or your immense cultural inheritance, but their minds worked in much the same way. The people who thought the world rested on the back of a great tortoise or who thought dancing would make it rain - they had the same brain as you; that is to say, they had the same blueprint in their DNA for making brains. So a baby born into their world was about the same as one born into yours.