that's about the most basic instinctual behaviour the body has. you cannot "LEARN" or "UNLEARN" how to poop...the bowels have their own ways of doing things and the body just goes along with instinct. When you feel like going, you simplly let go...

Instinct is a type of subconscious behavious which ought to be one that preserves the body and life...hence the body ejects all that it as ingested after fulle and due assiimilation. Like wise, gasping for air...it is an instinctual behaviour. Pooping, eating sleeping and fucking...all great instincs.