How do you react when you are startled by a loud noise? Or when spooked by a scene in a scary movie? Today our frightened reactions may not be caused by life-threatening events but at one point in history they would have helped our ancestors survive.

For many of us the scares we receive set off a number of different responses throughout our bodies.  And they are all thanks to a part of the brain called the amygdala. While we are relaxed and going about our day the amygdala is always on the lookout for anything that may be perceived as a threat to our safety. And while that threat may only be your best friend shouting ‘Boo’ your amygdala alerts your body to danger.

When threatened our bodies immediately respond to either defend against attack or flee from a dangerous predator or situation. Quite often a good scare will get your heart pounding so hard it feels as if it is going to come out of your chest. That’s your heart rate and blood pressure increasing to direct more blood to the muscles that will be tensed and ready for action. 

Fear may also have you breathing quickly. Extra oxygen is needed throughout the body to both help muscles work harder and increase alertness in our brains. Even the opening of the throat will widen to allow more oxygen to enter the airways. This can lead to an uncomfortable feeling often described as a ‘lump’ in your throat.

Even your eyes react physically to danger. The eyelids open wider to increase visibility and the pupils dilate to let in more light, improving your vision.

There’s a reason why author R.L. Stine named his popular series of spine-tingling stories, Goosebumps. Those funny little bumps that break out across your body are a common response to being scared. Strangely enough goose bumps are the human body’s attempt at making ourselves look scary to a predator.

Looking like a plucked chicken may not be most people’s idea of an intimidating spectacle. On early, hairier humans, however, it would have made quite the impression. As the body tenses in preparation for attack, tiny muscles under the skin pull at the hair roots, making them stand on end. This hair-raising trick would make the threatened prey look bigger and hopefully less of an easy lunch.

Another frequent response to being scared does not resemble fight or flight. Freezing in place might not seem like a sensible reaction to a threat but may be the body’s way of attempting to avoid detection. 

The Smell of Fear

Some researchers believe that the chemical pheromone that is released in our sweat when we are scared, can actually be detected by those around us. They found that when volunteers inhaled the scent of perspiration collected from terrified skydivers, the regions in the volunteer’s brains associated with fear showed a response. 

Fast fact: Famed scientist Charles Darwin once investigated his theories on the origin of goose bumps by frightening zoo animals with a stuffed snake!

Article originally published in Brainspace Magazine Fall 2018