Everybody has been in a situation where suddenly, sometimes for no apparent reason, they get 'the creeps.' Everybody experiences the creeps differently, but some common feelings include a slight chill, a feeling of unease, even getting goosebumps or the feeling of the hair on the back of your neck standing up. Why does this happen? Because your brain notices something might not be right and wants you to pay attention.

When the brain notices we are in a dangerous situation (like when we see a tiger), it responds with the ‘fight or flight’ response and releases adrenaline to increase our heart rate and give us the energy and reaction time to survive. Sometimes, however, the brain isn’t sure if the situation is dangerous or not. Maybe it sees a shadow that looks like a tiger, but might not be. In that case, it gives us ‘the creeps’ to make us pay more attention.

The feeling of unease makes us more likely to pay attention to our surroundings and notice if there is a threat. You might get the goosebumps so that your body hair stands up and is more likely to notice if something brushes it.

So, to summarize, we get the creeps because the brain notices something isn’t right but isn’t sure if it is dangerous or not yet.

I guess there are two ways we can get “the creeps.” One way is when something is scary. We get a fight or flight response from a burst of adrenaline. The response sends blood to our heart and muscles and away from our digestive system. We bring in more oxygen by breathing more. Our hearts beat faster to send the blood with its supply of oxygen and sugar where it’s needed. All of this makes it easier us to fight or flee. (The word flight comes from flee, not fly.) Our hair stands up to make us look bigger. (Okay, that doesn’t work to well for us, but it worked for our hairier ancestors.)

Another meaning of “the creeps” is disgust. The sight, smell, taste, or even thought of some things makes us uncomfortable. Disgust can even make us physically sick. What’s the point of that? It may help keep us healthy. If we avoid smelly dead things, we are less likely to get sick.

Our distant ancestors probably never travelled very far. They learned what was good to eat by eating what everyone else ate. Eating a brand new thing is a risk. If there was nothing else to eat and someone was hungry enough to overcome their disgust, things might go well and everyone would have a new thing to eat. If not, oops. So foods we’re not used to can disgust us. A friend of mine was travelling in another country and had some really good rice. She asked about it the next day and found out that the “rice” was ant eggs. There is nothing unhealthy about ant eggs. She liked the taste when she didn’t know what the dish was. But she was raised in a society where eating bugs gives people the creeps.

A lot of what disgusts us--whether it’s a food, a smell, or something else--is emotional and has nothing to do with the quality of something. I’m not saying that you should eat those smelly leftovers in the back of the refrigerator. I am saying that disgust is an emotion. It should tell us to pay attention to a possible risk. Then we should use our reasoning to decide whether it really makes sense to be disgusted. Potential food poisoning is something to avoid. A food that is just unfamiliar is probably worth a try. I’m not really shopping for ant eggs, though.

Obviously, not all species are disgusted by the same thing. Dogs don’t seem to be disgusted by much. Do a bit of research on what wolves eat and see if you can figure out why they would not have a strong sense of disgust.

If questions like this interest you, you may want to study behavior or psychology.

Fear is an evolutionary advantage for an animal to have of things that are dangerous to it. Our ancestors evolved to fear things that are either dangerous or likely to appear with dangerous things (for example, if you see a dead body, the corpse might not be dangerous, but whatever killed it is and may still be nearby!).

To me, getting the creeps means you’re feeling a few different emotions, maybe like fear or disgust. Some psychologists think that these emotions are adaptive, or help us to survive when faced with dangerous things. For instance, no one ever told you to think that a spider is creepy or dangerous, but most people certainly don’t like them. So when we see a spider we instinctively don’t like them, or we feel the creeps, because some part of the brain (likely a part called the amygdala) is aware of the potential danger and creates an emotion, like fear, that motivates us to get away or to fight the threat.

Feeling disgusted at something is another reason why we may feel the creeps. We don’t like the sight or smell of rotting food because that’s our brain sensing some chemicals in the air (that’s what smelling is), and determining that those chemicals are produced by things that are not healthy for us. So again our brain is trying to protect us by making us feel these emotions, by making us get the creeps. It’s fun to think about these things with Halloween coming up. It seems like sometimes we like to feel the creeps.

I've heard that called the Yuck factor and different people respond to different things. Maybe it evolved because we lived longer if we didn't die from eating things like rotten food. We don't understand everything about it yet.