> I mean like, how does a binary decision select for things that are not even correlated to survival or reproduction but merely comfort? If you're referring to

> I mean like, how does a binary decision select for things that are not even correlated to survival or reproduction but merely comfort? If you're referring to > For example, lets say the human anorectal angle was specifically "evolved" for pooping while squatting. Is it a "just so" story or did the exact anorectal angle contribute SO MUCH to survival or reprosuction that it became the standard for bipedal humans? I don't think you need to assume that the particular angle and arrangement of organs there was evolved "for comfort", any more than we need to assume that fingers evolved for efficiently typing on keyboards. The simplest explanation is that the particular angle is just one that happened to work - and then, given the way our bodies work, we try to find the most comfortable posture to poop in. It could have easily been the case that any other angle would also have been the default, and maybe we'd be most comfortable pooping while standing, sitting, or some other posture.