(Repeat) Whether you yawn, gasp, sniff, snore, or sigh, you’re availing yourself of our very special atmosphere.  It’s easy to take this invisible chemical cocktail for granted, but it’s not only essential to your existence: it unites you and every other life form on the planet, dead or alive. The next breath you take likely includes molecules exhaled by Julius Caesar or Eleanor Roosevelt. And for some animals, air is an information superhighway. Dogs navigate with their noses. Their sniffing snouts help them to identify their owners, detect trace amounts of drugs, and even sense some diseases. Find out what a dog’s nose knows, and why no amount of bathing and dousing in perfume can mask your personal smelliness. Plus, why your own schnoz is key to not only enjoying a fine Bordeaux, but to survival of our species. Guests: Sam Kean – Science writer, author of “Caesar’s Last Breath: Decoding the Secrets of the Air Around Us”  Alexandra Horowitz – Dog cognition researcher, Barnard College, author of “Being A Dog: Following the Dog Into a World of Smell”  Rachel Herz – Cognitive neuroscientist, Brown University, author of “Why You Eat What You Eat,” and “The Scent of Desire: Discovering Our Enigmatic Sense of Smell”  Ken Givich – Microbiologist, Guittard Chocolate company Learn more about your ad choices. Visit megaphone.fm/adchoices