According to evolutionary biologist Zuk, germs and disease don't deserve their bad rep. Drawing on recent research and her own studies, she explains why disease is mankind's best friend, indeed the key that jump-started the entire evolutionary explosion. Along the way, she answers questions many of us dare not ask, such as: Why don't male birds have penises? Why are we attracted to our mates? Zuk also describes the function of STDs and explains why women live longer than men. Her wide-ranging sampling of stories from the natural will appeal to everyone who enjoys popular science.--From publisher description.