That little voice that nudges you when you’re stuck between two choices? It’s real. The human body has two brains, one in our skulls and one hidden but powerful brain in the gut known as the enteric nervous system. The gut has 30 neurotransmitters, just like the brain, and is so extensive that some scientists have nicknamed it our “second brain”.
“The system is way too complicated to have evolved only to make sure things move out of your colon,” says Emeran Mayer of UCLA. For example, scientists were surpised to learn that 90% of the fibers in the vagus nerve carry information from the gut to the brain and not the other way around.
95% of serotonin, the neurotransmitter that is crucial to feelings of well-being, is housed in the gut. It also acts as a go-between, keeping the brain in the skull up to date with what is happening in the second.
The upside of having both brains is that we get powerful (and smart!) signals from our gut that we can trust, even when our neocortex is doing its best to talk us out of what our bodies know to be true.
The downside is the connection between the brains leads to physical and psychological problems like anxiety, depression and irritable bowel syndrome, all of which manifest symptoms at the brain and gut level.
Either way, what is good for one brain is often good for the other.
A team of researchers at Penn State found that biofeedback helped people consciously increase and enhance their gastrointestinal activity. In other words, they used the brains in their heads to help the brains in their guts, proving that at least some of the time two brains really are better than one.
–Scientific American, 2-24-2010
–NY Times, 8-23-2005