Splanchnon, the Greek word for the intestinal organs, was frequently used by the ancients to indicate affections, tender mercies, and compassion. While the Greeks regarded the bowels as the seat of the more violent passions, the Hebrews thought them to be the source of our tender affections.
In the book of Job, long regarded as the most ancient of the biblical texts, Job laments: “My bowels boiled, and rested not; the days of affliction came upon me.” The prophet Jeremiah cried in his distress: “My bowels, my bowels! I am pained at my very heart!” And again, in the book of Lamentations: “Behold, O Lord; for I am in distress. My bowels are troubled; mine heart is turned within me.”
The apostle John admonishes us: “But whosoever hath this world’s good, and seeth his brother have need, and shutteth up his bowels of compassion from him, how dwelleth the love of God in him?”
Thoreau echoes this sentiment in a line from Walden: “If anything ail a man, so that he does not perform his functions, if he have a pain in his bowels even,—for that is the seat of sympathy….”
We still carry the vestiges of this idea in modern English idioms when we refer to “gut feelings,” “going with your gut,” “gutting it out,” or having “butterflies in the stomach.” Somehow the gut and our feelings seem to be intricately bound together.
Medical research has borne this out. We now know that the gut, rich with over 500 million nerve cells, is regulated by the same set of neurotransmitters found in the brain. Amazingly, 90 percent of the neurotransmitter serotonin is synthesized by enterochromaffin cells in the gastrointestinal tract. Serotonin — 5-hydroxytryptamine (5 HT) — stimulates a variety of chemoreceptors, triggering peristaltic motion in the gut and dilation of the stomach during the digestive process.
Serotonin also turns out to be a key factor in irritable bowel syndrome (IBS) as well as clinical depression. Researchers now think of IBS as a recurrent symptom complex initially triggered by life-altering stressful events, altered bowel motility and heightened visceral hypersensitivity. The result is increased sensitivity to stress coupled with an overblown visceral response, something akin to PTSD in the brain.
Gastroenterologists now routinely prescribe antidepressant medications to patients who suffer from chronic abdominal pain syndromes, such as functional abdominal pain. At low doses, tricyclic antidepressants work in the gut much in the same way that they work in the brain.
As it turns out, the ancients knew what they were talking about: the passionate gut has a mind of its own.