
In 1998, The Atlantic published an essay by biologist, philosopher, and real life Ant-Man Dr. E. O. Wilson titled “The Biological Basis of Morality.” This essay had a profound impact on me. As a young atheist, I was amazed to discover that a great deal of “gut level” moral inclination feels as though it is gut-level for good genetic reasons. It was an eye-opening experience to have one of the pillars of human philosophy, the question of ethical behavior, explained quite handily in terms of human evolution and our commensurate biological drives. I have since come to view evolutionary psychology as a discipline that has tremendous potential but is still in its infancy; it’s an exciting field and one that I hope develops more fully with time.
The important takeaway for me still applies today; that we are biological, physical beings, and that much of our seemingly mysterious existence can be understood in purely biological terms. So; given that fact, and given my everyday morbid fascinations, the question was bound to arise eventually in my mind: what are the biological bases of horror?

Why we love horror is quite easy to explain; it’s exciting, and as experiences ranging from roller coasters to Carolina Reaper peppers indicate, humans love danger and even a little pain, provided that it’s experienced within certain parameters of safety (these vary from person to person, as what I find exciting and what a BASE jumper find exciting are worlds apart). We like to be scared because fear triggers chemical cocktails inside of us that can, in the proper context, be quite enjoyable.
What about the biological bases of what we find frightening? Now, thereby hangs some very interesting evolutionary biology. I’m not talking about the obvious; jump scares are frightening because they surprise us, and scenes of visceral, bone-wrenching carnage scare us because of our natural human empathy and ability to project ourselves into the unfortunate victims on our screen. But what about subtler, more atmospheric scares? Where do those come from?
Some horror is culturally contingent, based on myths or religious traditions handed down over time in a region or among a specific group of people. I put The Exorcist in this category, as well as Ringu and Ju-On (although both of those latter examples were “translated” from Japanese and Korean culture to American culture via remakes). Other forms of horror seem to cross all cultures; the sound of a deep, distorted human voice or a rippling growl can put us on edge, as can shrill or discordant music in a film’s score. The biological effects of deep sound and discordant sound are explained on the excellent podcast Twenty Thousand Hertz. Deeper growling sounds, for example, are generally produced by larger animals and thus we are biologically programmed to find them scary. There are also techniques, such as binaural mis-mixing, that confuse our brains and produce anxiety – an effect explained (in somewhat disappointing detail, actually) in the post-credit scenes of Antrum: the Deadliest Film Ever Made.
Antrum also played with some visual triggers for angst, including the use of subliminal imagery. While I do not share the silly view that subliminal flashes of the Sigil of Astaroth are going to “mess viewers up,” I do think that the inclusion of subliminal imagery in Antrum was, at times, effective. The Satanic Panic aside, however, research is mixed at best regarding any real effect from subliminal imagery writ large. More effectively, many horror films play with the floor palate in ways that can be pleasantly upsetting. When talking about this subject, I always cite Dario Argento’s 1977 film Suspiria (a chromatically oversaturated and utterly brilliant nightmare and the last film made with true Technicolor) and 1975 giallo film Deep Red as examples of films where the use of color has a triggering effect on audiences. Bright “warning colors” are a feature of the natural world that we have become deeply attuned to, and, of course, the color of human blood is upsetting to us in that it indicates danger, misfortune, and death. Directors of horror films will often also play with light and shadow; to humans, who are poorly equipped to see in the dark, this represents a threatening environment.

Sound, sight – both are effectively harnessed by horror cinema to provide us with a biological thrill. In the 1950s, there were even attempts made to expand the sensory experience by equipping seats with vibrating mechanisms, the better to “shock” audiences at key moments in a film. This was deployed to great (if gimmicky) effect in William Castle’s 1959 The Tingler, presented in “Percepto.” Obviously, having one’s theater seat unexpectedly vibrate is startling and induces the same delicious fear cocktail as a good jump scare. In the age of IMAX theaters, could we see a resurgence of William-Castle style vibratory gimmicks wired into our seats? I would personally find this to be a rather unpleasant development if it became widespread, but used on rare occasion and with artistry, the return of “Percepto” (were it to happen) might be fun.

Sight, sound, feel – our senses are how we experience the world, and have been since long before the age of cinema. The fact that deep-seated evolutionary impulses may (in part) drive our sense of horror and our approaches to horror cinema should not be surprising, yet it is easy to forget. We are intelligent, emotional beings, but at our core, our root, we are also animals. Our approaches to the theater of fear are, thus, deeply biological.