When “Rise of the Planet of the Apes” was first shown to the public last month, a group of excited animal activists gathered on Hollywood Boulevard. But they weren't there to throw red paint on fur­coat­wearing film stars. Instead, one activist, dressed in a full­body monkey suit, had arrived with a sign praising the filmmakers: “Thanks for not using real apes (猿)!”

Why did the animal activists gather on Hollywood Boulevard?