“Prepping,” or getting ready to live without societal support, is apparently a largely American activity, and a recent one. Companies that cater to people who want to be self-reliant for food, water, and power have grown their revenue by about 700 percent over the last decade, and prepper products are now offered in places like Costco, Kmart, and Bed Bath & Beyond.

But it’s not at all clear what’s driving this growth—why are more people getting ready for society’s collapse? Some explanations focus on a tendency toward paranoia in American society or fears of terrorism or natural disaster. But actual evidence that directly supports any of these ideas as the main reason is pretty sparse.

So Michael Mills at the UK’s University of Kent decided to correct this gap in our knowledge. Mills went on an American road trip, spending time talking to (and butchering animals with) 39 preppers in 18 different US states. Rather than rampant paranoia, Mills suggests, preppers are motivated by non stop media coverage of natural disasters, as well as a government that encourages them to prepare for the worst.