As Harold McGee shows in Nose Dive: A Field Guide to the World’s Smells, olfaction is a fascinating landscape that adds much to our sensory experience of the world, if only we would breathe a bit deeper. To answer that question, McGee discovered he had to immerse himself in the volatile world of scent. His account begins with “simple” smells — meaning the sulfurs and ammonia that suffused the Earth during its early formative period. What’s most important, McGee argues, is that readers listen to and interrogate the smells they encounter in the kitchen, the forest, or the city. It pays off as the world expands.”Sara Harrison is a freelance journalist who writes about science, health, and technology.