• 
  Monica Bielenstein

  Voice-Over (voice)
• 
  Detlef Bierstedt

  Harold Brown (voice)
• 
  Jane Goodall

  Herself
• 
  Peter Groeger

  Prof. Dr. T. Colin Campbell (voice)
• 
  Joachim Kerzel

  Narrator (voice)
• 
  Anke Reitzenstein

  Voice-Over (voice)
• 
  Norbert Langer

  Dr. Will Tuttle (voice)
• 
  Marc Bekoff

  Himself

• 
  T. Colin Campbell

  Himself
• 
  Caldwell Esselstyn Jr.

  Himself
• 
  Harold Brown

  Himself
• 
  Melanie Joy

  Herself
• 
  Ruediger Dahlke

  Himself
• 
  Claus Leitzmann

  Himself
• 
  Hermann Focke

  Himself