Defecation's the final act of digestion by which organisms eliminate solid, semisolid or liquid waste material (feces) from the digestive tract via the anus. Humans expel feces with a frequency varying from a few times daily to a few times weekly. Waves of muscular contraction known as peristalsis in the walls of the colon move fecal matter through the digestive tract towards the rectum. Undigested food may also be expelled this way; this process's called egestion. The defecation cycle In the a… (More on Defecation)