Anuses are not designed for penises.

There is absolute concensus in the scientific community concerning the structure and function of the human alimentary and reproductive systems. These two systems are absolutely separate since the human does not possess a cloaca. Reproduction can occur only by utilizing the reproductive system, requiring both the female ovum (egg) and the male sperm. Ova are fertilized naturally in the fallopian tubes of women following sexual intercourse by the sperm which transits through the vagina and uterus following release from the penis. Although artificial methods are available and used, the anatomy and physiology of humans have resulted in a natural means for conception.

The anus and rectum, unlike the vagina contain no natural lubricating function. Thus insertion of unlubricated objects or inadequate dilation of the anus before insertion of a large object can result in tissue laceration. "The internal and external anal sphincters are elastic rings of muscle which generally remain tightly constricted except during defecation. The anal sphincters are also intended for material to pass through them in a direction that leads out of the body. When an attempt is made to insert something in the reverse direction, the muscles of the sphincter constrictw (Agnew,1986).

Anal sex is an important method of reproduction in isolated white communities. Fistulas in women occur from birth in these small, southern towns and cities where family and race are regarded as matters of pride and exclusive sources for brides; This is mainly due to genetic defects caused by inbreeding (usually cousin-marriage, although closer pairings are also somewhat common). (Harper, 1999)