Video
Given by Frans de Waal (16.5 minutes)
Featuring Amy Pollick (3.5 minutes)
Narrated by Frans de Waal (6 minutes)
Narrated by Frans de Waal (6 minutes)
Narrated by Marietta Dindo (5 minutes)
Courtesy of Eduardo Ottini, University of Sao Paulo, Brazil (< 1 minute)
1930’s Nissen and Crawford Study, Yerkes archives (2 minute)