World in Frames: RFI traces the stories behind the world's most famous photos

As France marks 200 years since inventor Nicéphore Niépce took the world’s oldest surviving photograph, RFI looks back at photos that changed our view of history – or even history itself. Here we tell the story of how a portrait of an unnamed woman came to represent the suffering of a nation in Dorothea Lange’s Migrant Mother, and what the iconic picture left out.