They have some behavioral features that tell them apart from a chimpanzee. Apparently they use sex as a greeting. It is (sort of) anthropomorphized in a hilario

They have some behavioral features that tell them apart from a chimpanzee. Apparently they use sex as a greeting. It is (sort of) anthropomorphized in a hilarious way in the Will Self novel 'Great Apes'. However that may be colouring my memory of how common this is in the real creatures...