[virgil]

Humans are naturally social beings, so, they’re going to set rules about who they associate with. That’s just the way it is. People who live together have to set rules to make it work. If you don’t like the rules, find another group.

[Joe 6-pack]

During the making of the original, "Planet of the Apes," the cast would report during the very early morning hours for the elaborate prostheses and make up for the film, which took several hours to apply. As anyone familiar with the film knows, actors portrayed highly intelligent Chimpanzees, Orangutans and Gorillas.

It was noted during cast lunch breaks during filming, the three, "species"(chimps, orangs and gorillas) would all sit in groups with those wearing like make up and costume.

It's human nature.