Tracing Zika's Path through the Americas, Looking at the 'Also-Rans' of the 1960s

American politician US Senator Barry Goldwater (1909 - 1998) waves to supporters during his Presidential campaign, Prescott, Arizona, September 3, 1964.

Donald G. McNeil Jr., science reporter at The New York Times, charts the history, path and potential danger posed by the Zika virus. Author Peter Spiegelman on his latest novel about a troubled doctor's journey to reunite a child with his parents in Los Angeles. Princeton history professor Julian Zelizer on the presidential Also-Rans of the 1960s. Mark Zwonitzer on Mark Twain's unlikely friendship with Secretary of State John Hay at the turn of the 20th century.