Metabolism is life’s foundational biological function and its processes are highly conserved among all of the forms life has adopted. This makes metabolism an excellent candidate for a definition of a living system. When organisms evolved into animals these metabolic functions became encapsulated inside a larger system enabling movement, leading eventually to the bipedal organization humans employ. However, the shared core of all organisms is metabolism. In animals these are the gut processes related to the digestion and assimilation of nutrients, as well as the cellular level functions.
GUT: cyclical / hunger