That we eat in public but poop in private . If you took an alienistic viewpoint of the act , it would seem downright confusing . Both acts are of the same method . We eat and chew up our food , but when it comes time to expel the processed food , we need to hide it . A logical sense would be that both should be done in private or public . I remember seeing an episode of Star Trek TNG where aliens came to visit and saw humans eating together in the mess hall and we ' re appalled . They attributed it as shocking as walking in on an orgy . They believed eating should be done in privacy . It actually made sense . This social activities could have easily been that way if a few early humans saw it that way . Our entire society would be different , and restaurants would be seen as sex clubs are today .