It’s September and pumpkin spice everything is there. Coffee, candles, cereals, Oreos, dog treats, gum, ​hummus​ and even ​butt wipes​ (entertainingly rebranded as “Dumpkin Spice”). The inescapability of this random ingredient may leave you wondering why exactly it’s so popular … especially since it doesn’t actually include any pumpkin (the term “pumpkin spice” is used to describe an aromatic blend of cinnamon, nutmeg, cloves, and ginger).

The credit for its modern appeal ​often goes to Starb...