Judson, Olivia. Dr. Tatiana's Sex Advice to All Creation: The Definitive Guide to the Evolutionary Biology of Sex. Oh my.
Sobel, Dava. Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. The first time I read this, I stayed up half the night to finish it.
Weiner, Jonathan. The Beak of the Finch: A Story of Evolution in Our Time. Won the Pulitzer Prize.
Zimmer, Carl. Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures. This will gross you right out.