Who were the first artists? What compelled the Cro-Magnon people to leave behind images of their lives in the caves of Spain and France 40,000 years ago? We’ll explore the caves, the paintings, and the artists who made them this hour with Gregory Curtis, who’ll speak to the Boshell Family Lecture Series at the Dallas Museum of Art this evening. His book is “The Cave Painters: Probing the Mysteries of the World’s First Artists” (Knopf, 2006).