There’s a reason “go with your gut” has become such a tried and true adage: that gut feeling is your inner caveman-like instinct trying to keep you alive. (As in, it’s almost literally a life or death situation, yes.) But it turns out those urges and instincts have a little more to do with your brain than your belly.
We can trace our inner urges to one of two types of memory: explicit and implicit. Explicit memory is the knowledge that you have actively studied and forcibly learned, like back in school when you crammed all of those treaty dates and names of generals into your brain the night before a big history test. Implicit memory, on the other hand, is all the information that wanders into your head through no conscious effort of your own. Like, how do you still remember that one movie quote from a film you watched in English class in seventh grade? It more likely than not got in there – and stayed in there – on its own.
So in the case of gut instinct, the memory that comes into play is that implicit memory. It can warn us about dangerous situations, like how you know not to stick your hand in a fire or take a deep breath under water. So even if you aren’t having a conscious, linear thought process about an action, you inherently know what to do because of those things that you may have passively learned over time. That gut feeling that you get, then, is kind of like your body’s cue to behave a certain way in a certain situation.
Bottom line: explicit memory functions may have developed with our frontal lobes to help us strategize through more complicated decisions, but that gut feeling is a sign that we’ve all still got a little bit of cave-dweller deep down inside, and it serves us well.