C.F. Kettering Professor of Medicine, Chief, Division of Endocrinology, Metabolism and Molecular Medicine Northwestern University Medical School, Chicago, IL. Dennis L. Kasper, MD, MA (Hon)William Ellery Channing Professor of MedicineProfessor of Microbiology and Molecular GeneticsExecutive Dean for Academic ProgramsHarvard Medical SchoolDirector, Channing LaboratoryDepartment of MedicineBrigham and Womens Hospital Stephen L. Hauser, MDChairman and Betty Anker Fife ProfessorDepartment of NeurologyUniversity of California, San Francisco Dan L. Longo, MDScientific DirectorNational Institute on AgingNational Institutes of HealthBethesda, Maryland Anthony S. Fauci, MDChief, Laboratory of ImmunoregulationDirector, National Institute of Allergy and Infectious DiseasesNational Institutes of Health. In 2008, Dr. Fauci was awarded the Presidential Medal of Freedom, the Nation's highest civil award. McGraw-Hill authors represent the leading experts in their fields and are dedicated to improving the lives, careers, and interests of readers worldwide Hersey Professor of the Theory and Practice of Medicine, Harvard Medical School; Chairman, Department of Medicine; Physician-in-Chief, Brigham and Womens Hospital, Boston, Massachusetts CYNTHIA STOKES BROWN (PhD, Johns Hopkins University) spent most of her career directing the secondary teaching credential program at Dominican University of California. She taught selected courses in the history department and wrote books about civil rights history and teachers, Browns book Big History: From the Big Bang to the Present was published in 2007. Since then her interests have been consulting with the big history program at Dominican, serving on the board of the International Big History Association since its inception, and writing big history essays for high school students through the Big History Project funded by Bill Gates.