Author and social activist Barbara Ehrenreich will speak at 4 p.m. Friday, Sept. 7, in FA-Watters Theater. Her talk, titled “Dancing in the Streets: The Human Need to Party,” is free and open to the public. Ehrenreich, whose most recent book is titled Dancing in the Streets: A History of Collective Joy, explores the human need for public celebration — and why we need to fulfill it. Ehrenreich, author of books such as Nickel and Dimed and Bait and Switch, will speak as part of the Evolutionary Studies program.