#1051255
GodotIsWaiting4U
People know how to shit when they're born. I am, however, curious as to why your designer placed so many sensitive nerve endings near the anus and made it an erogenous zone; seems like he may have indeed set it up accounting for the possibility of buttsex.
Evolution gives the answer to this question.
Mammals (except for the monotremes and echidnae) are the only animals with a vagina. All other animals have cloacae (or an analogous organ) which includes the anus, the urethera, and an opening into the "womb" in females and a penis in the males. The cloaca itself is merely sheathing structure surrounding, moistening, and protecting the abovementioned three openings into the body.
The presence of erogenous zones in the mammalian recto-anal area is vestigial, a remnant of the cloaca, and are likely necessary to reproduction in non-mammalian species, but not in mammals.
Animals having cloacae perform sex in much the same manner as a human might sodomize another, inserting the penis into the sheathing structure, and sometimes directly into the "womb." Friction is then applied and the resulting sperm finds its way to the ova, etc. In these animals the cloaca performs much the same function as vaginal lips.
If you are the natural parent of a female human, you probably know already that in the first few weeks and months or her life, her "crotch" actually is a cloaca. It soon develops into the adult structure with which most of us are familiar. This is clearly advanced fetal development going on after birth where the fetus recapitulates the various stages of pre-mammalian development until the human form is attained.
As for Nutbunny's remark about the rectum being designed for long cylindrical objects such as bananas and penises, don't forget that that the filled shape of the colon mostly determines the shape of the fecal loaf. This does not mean that the colon is eager to admit materials from the outside (wrong direction).
The colon was not adapted as a copulatory organ, but in a pinch, it'll do. But before you do it, get some reliable knowledge on the subject to avoid injuries, disease, and butthurt.
