Is reason and logic a by product of digestion?

Even the development of reason and logic Nietzsche consistently shows to be but a spiritual development of the physiological function of digestion which compels an organism to make things "like" (to "assimilate") before it can absorb them

With the question of Truth we find Nietzsche quite as ready to uphold his thesis as with all other questions. He frankly declares that "the criterion of truth lies in the enhancement of the feeling of power