For some Americans, a trip to the ballpark isn’t complete without the bright-yellow squiggle of French’s mustard atop a hot dog. For the French, the slow burn of Dijon is a must-have complement to charcuterie. In the United Kingdom, Sunday’s roast beef is nothing without the punch of Colman’s. Yet few realize that this condiment has been equally essential—maybe more so—for the past 6,000 years. In fact, the first spice that we know prehistoric humans used to pep up their dinners is none other than mustard. But why is the sale of mustard oil for consumption banned in the United States, Europe, and Canada, despite the fact it’s used by millions of people around the world nearly every day? Listen in now for the answer to that mustard mystery and dozens more, including how mustard got its heat, and why we have caterpillars to thank for its particular taste profile.