Here’s a question you probably haven’t asked out loud: How does your body know when it’s just gas — and not something messier? It turns out that even scientists don’t fully understand it.
The ability to distinguish between flatulence and feces is something most of us take for granted. But according to experts, the precise biological mechanism behind this internal judgment call remains a mystery. While we know there are a dense network of nerve endings in the rectum and anus — including pressure and stretch receptors — exactly how they differentiate between gas and solid stool isn’t entirely clear.
What’s especially mind-blowing? This distinction is so finely tuned that your body can even make it while you’re unconscious. Yes — your nervous system is smart enough to let out a fart while you’re asleep, without accidentally triggering a much less pleasant surprise.
Scientists believe that mechanoreceptors — specialized nerve cells that respond to pressure, texture, and volume — help analyze what’s sitting near the exit. These receptors likely relay information to the brainstem and spinal cord, which then interpret the signal as “safe to release” or “better hold back.”
However, this system isn’t flawless. Gastrointestinal disorders, nerve damage, or inflammation can all interfere with the body’s ability to make this call, leading to the occasional misfire (also known as a shart). And as people age, that finely calibrated control can weaken.
Still, for most of us, the fact that our bodies are silently analyzing gas vs. solids 24/7 — even while we sleep — is a testament to the gut-brain connection working in overdrive.
