This week Short Wave is celebrating our sense of taste with an entire week of themed episodes, covering everything from sugar and spice to what's beyond our classic ideas of taste. It's a series we're calling, "Taste Buddies."In today's encore episode with Atlantic science writer Katherine Wu, we take a tour through the mysteries of sourness — complete with a fun taste test. Along the way, Katie serves up some hypotheses for the evolution of sour taste because, as Katie explains in her article, "The Paradox of Sour," researchers still have a lot to learn about this weird taste.Baffled by another seemingly mundane aspect of our existence? Email the show at shortwave@npr.org and who knows — it might turn into a whole series!