In the long documentary Bij de beesten af / Ape and Super-Ape (1973), for which he collaborated with Frans de Waal and Jane Goodall, among others, he compared the behavior of animals and human beings.
Frans Hals | Lange Frans | Frans van der Hoff | Thomas de Waal | Frans Widerberg | Frans Helmerson | Frans Brüggen | Frans Bauer | Edmund de Waal | Frans Pourbus | Frans de Waal | Frans Bruggen | Frans Wiertz | Frans van der Mijn | Frans van der Hoeven | Frans Tumbuan | Frans Post | Frans Koppelaar | Frans Hals Museum | Frans Alfons Janssens | WAAL | Waal | Victor de Waal | ''Meeting of Arenberg with his troops'', 1662, by Adam Frans van der Meulen | Lange Frans & Baas B | Joseph Frans Lescrauwaet | Frans Wilhelm Lindqvist | Frans Wildenhain | Frans Weisz | Frans van Mieris the Younger |
The issue of good and evil in the human visuality, often associated with morality, is regarded by some biologists (notably Edward O. Wilson, Jeremy Griffith, David Sloan Wilson and Frans de Waal) as an important question to be addressed by the field of biology.