You are many things, including a person, a member of a species, a collection of cells, a collection of atoms, and a gene-replication machine. In You: A Natural History, William B. Irvine explores your many identities and describes the remarkable series of events that led you to possess them.

Introduction : Your multiple identities -- Part I : Your deep ancestry. Your people -- You and I are related -- You have a great throwing arm -- Your place on the tree of life -- Your sex problem(s) -- The neanderthal in your family tree -- The code(s) by which you live -- Your (alien?) roots -- Part II : The cellular you. Your are complex -- Your ancestors were boring -- Your "cellmates" -- Your "boarders" -- Part III : The atomic you. Your are what you eat, ate -- Your windblown past -- Your cosmic connection -- Pulling yourself together -- Part IV : Your place in the universe. You are a gene machine -- You are (merely) part of life -- Your many afterlives -- Why are you here?.