I saw a behind the scenes special some time ago on the making of the original Charlton Heston, "Planet of the Apes." Of course, a major subtext of the movie was a comment on race relations in the USA during the 1960s.
It was observed by, and not lost upon, many on the set that during meal breaks during the shooting, those in chimp, orang and gorilla makeup naturally tended to congregate in groups according to their species make-up and costume.
“It was observed by, and not lost upon, many on the set that during meal breaks during the shooting, those in chimp, orang and gorilla makeup naturally tended to congregate in groups according to their species make-up and costume.”
Considering that the gorillas were portrayed by rough men like Claude Akins, the chimps by effete homos like Rodney McDowell, and the orangs by less effete and closeted queers like Maurice Evans it is then no surprise they didn’t mingle.