Why Halloween Spooks

What are the evolutionary underpinnings of our fears during Halloween?

Reading Time: 3 minutes

Cover Image
By Francesca Nemati

As we approach October 31, grinning Jack-o’-Lanterns and wispy spider webs begin adorning storefronts. Most Halloween decorations and costumes are fun, but there’s always the occasional lifelike witch or monster that looks a bit too realistic. Sometimes, even the plastic spiders and fluttering bedsheet ghosts can seem spooky. It’s strange how mere holiday decor can scare us, but such fears can be traced back to associations etched in our biology. From zombies to skeletons, the costumes and decorations that line the streets on Halloween all evoke fear because of their proximity to one thing: our mortality.

Take the fake spiders dangling from doorways. Though they pose no threat to us, we still jump back or feel uncomfortable at the sight of arachnids. This instinctive reaction is accredited to be evolutionarily advantageous. Venomous spiders inhabited Africa before the first humans evolved, posing a threat to our survival throughout human evolution. Thus, the ability for our ancestors to react immediately upon recognizing spiders maximized their chances of survival. The connection spiders have to disease and death is innate to us and makes arachnophobia so prevalent. In fact, nearly a third of the global population has arachnophobia, making it the third most common phobia in the world behind only necrophobia, the fear of death itself, and glossophobia, the fear of public speaking.

To understand fear, we must take a look at our brain’s amygdala, almond-shaped structures that control how we respond to strong emotions, particularly fear. They determine whether stimuli, such as an image of a tarantula, warrant initiating physiological changes, specifically the fight-or-flight response.

It isn’t just individual objects that spark fear. Halloween festivities commonly run well past sundown, and being immersed in the dark causes sensory deprivation, which takes away visual stimuli in particular. Subconsciously, this leaves us exposed to attacks and other dangers. This fear of the unknown also explains our aversion to ghosts. Though we can see the figures meant to represent ghosts on Halloween, the idea of a spirit haunting us, hidden by invisibility, is chilling. Ghosts, along with skeletons and zombies, are also embodiments of death, and are thus clear reminders that our own lives will end.

Our fear of zombies, distorted versions of human beings, can also be attributed to a phenomenon known as the “uncanny valley”, which describes the uneasiness humans feel about human-like representations. Dolls and clowns are also variations of the human form, bearing clear similarities to humans but dissimilar enough to be creepy. In fact, the most significant element of humanity they lack is emotions. The callousness that infamous movie characters like Annabelle and Pennywise share, as well as other attributes like dominance and untrustworthiness, are all traits that the human mind links to psychopathy. Being psychopathic or in the presence of a psychopath has been associated with danger and subsequently death.

The way we respond to fear is also driven by our instinct to survive. Our stress response is designed to maximize our chances of survival during an emergency. Upon sensing an external threat, the amygdala communicates to the hypothalamus, which then signals the adrenal glands to secrete adrenaline. This activates the sympathetic nervous system, triggering the fight-or-flight response. If the threat persists, the hypothalamus triggers the pituitary gland to release the adrenocorticotropic hormone, which stimulates the adrenal glands to release cortisol, a hormone capable of sustaining the stress response for a longer period of time.

The activation of the sympathetic nervous system produces several changes in the body, including an increased heart rate, decreased digestion, dilated respiratory airways, and increased glucose levels. A faster heart rate increases blood flow, allowing more oxygen and glucose to reach muscles, and the dilation of bronchi allows for an increased uptake of oxygen. Converting glycogen stores to glucose provides the body with a greater supply of energy, and diverting energy away from processes like digestion also provides more energy for surviving an emergency. This explains why our heart races after we see something that our brain perceives as a threat, such as a terrifying clown with a twisted smile.

While evolutionary experiences shaped our aversions, humans have also forged some of our fears through folklore. In addition to reminding us of our ultimate deaths, zombies themselves are said to be predators, capable of turning living humans into decaying bodies. In the past and to a lesser extent today, witches were similarly believed to have the power to harm, a fear that had fueled countless witch trials. Witches are also humanoid figures, and like zombies, dolls, and clowns, fall into the Uncanny Valley and are thus seen as creepy.

Our invention of entities for ourselves to fear suggests that fear isn’t an emotion we always seek to avoid. In fact, Halloween is a celebration of the scary, and the eeriness of this holiday is exciting for many due to the adrenaline rush that fear induces, making us feel more lively. While we enjoy Halloween night, our amygdala must interpret the onslaught of stimuli around us and decide whether we’re in danger. Thanks to human evolution, our overactive amygdala make Halloween the spooky but thrilling holiday that it is.