Overview:
Whether you have experienced the leaden weight in your stomach before a speech or had your vision spiral when you stand on a tall building, you have experienced fear. While fear is something most of us are familiar with, why does it exist, and what purpose does it have from an evolutionary point of view?
To unpack this question, we must dive into what fear truly means, if other animals experience it, and how it is characterized in humans.
What is Fear:
Defining an emotion without including subjective language can be arduous, even if the emotion is universal to all humans. Fear is an emotion experienced by most of the population and has many definitions. People specializing in different fields have their own definitions of fear. For instance, a psychologist's definition of fear may focus on how fear influences thoughts and actions. On the other hand, a neuroscientist may view fear through the brain and define fear as a feeling that activates the emotional centers of the brain, such as the amygdala. A clinician might abandon both definitions and perceive fear as a disease to be treated and extricated. Despite the vast variations in these definitions, they all focus on different aspects of fear. We can condense these definitions and define fear as an unpleasant feeling brought on by the suspicion that something dangerous could happen and cause pain.
Different Types of Fear:
While there are many subcategories of fear, the most discussed are rational and irrational fears. Rational fears are justified, while irrational fears are unjustified. An example of rational fear is when you are in a situation with venomous snakes and are afraid of snakes due to the risk of death. On the other hand, an example of an irrational fear is when a person is afraid of spiders even when they are in a situation with no spiders. While rational fears can be healthy, irrational fear in some cases can cause people to lose out on opportunities and develop anxiety.
Though people can be afraid of many things from spiders to public speaking to blood, there are two innate fears that everyone is born with, regardless of their circumstances. These two universal fears are falling and loud sounds. Outside of these universal phobias, there are fears specific to an individual's environment and learned behaviors.
Some fears can be passed down through generations via evolutionary mechanisms of fear and threat detection. These fears are known as ancestral fears. The concept of ancestral fears is derived from biological preparedness— a theory that people are predisposed to pair certain stimuli with a particular experience due to generations of evolution. Some examples of ancestral fears include snakes, spiders, storms, darkness, and small spaces. These phobias tend to be feared by a larger population, which has led researchers to believe that these fearful responses are the byproduct of dangerous stimuli experienced by our ancestors.
Before we fully unpack the implications of living with ancestral fears, we need to know the evolutionary advantages of experiencing fear.
Why Do We Experience Fear:
Despite the adverse emotions fear dredges up in humans, there are a plethora of evolutionary benefits that come from experiencing fear. Fear serves as a defense mechanism meant to protect humans. It forces humans to prevent and avoid pain via preventative measures. In the face of the unknown, fear forces humans to think through decisions instead of blindly making choices. From an evolutionary standpoint, fear exists to ensure the continued survival of a species.
Cheetah Chasing a Running Impala
Fear in Other Species:
It is salient to consider whether fear is experienced by other organisms when discussing the evolutionary aspects of fear. Many mammals experience fear. Fear can be seen in animals through the relationship between predator and prey. The link between predation and fear has been researched extensively, with many agreeing that prey organisms fear their predator counterparts. However, what happens if an organism encounters an unknown predator?
When Charles Darwin visited the Galapagos Islands he observed that the birds there did not experience fear when they came in contact with man. This caused him to realize that fear of humans in those birds was not innate, but rather learned. Building off this, another study found that the prey don’t instinctively fear predators. If predators are removed from an environment, the prey will stop fearing them. This study builds off the conclusions that Darwin established and reinforces the point that fear of predators is not innate but is only developed when predators and prey share the same territories.
Is Fear Hereditary:
While fear can be manipulated by the environment and learned behaviors, it can also be affected by genetics.
Researchers have found genes that directly correspond to fear in the amygdala— a critical region that produces fear. In the amygdala, scientists discovered a protein known as stathmin, which causes fear and anxiety. They proved that stathmin could be a protein behind the expression and development of fear by knocking out the gene coding for it. Knocking out stathmin genes in mice resulted in lower fear responses in mice in different circumstances. Finding genetic markers for fear could go a long way in determining a person’s predisposition to developing anxiety. However, stathmin is not the only protein that plays a part in regulating fear.
Conclusion:
Despite the adverse effects of fear, it is a paramount part of our lives that is affected by biological markers and environmental factors. Evolutionary mechanisms developed fear to ensure the biological success of a species and allow for adaptations. So the next time you see a spider and scream, remember to thank the generations of evolutionary pressures, genetic traits, and environmental factors that allowed you to experience this emotion.
References
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Inside fear and its disorders. Penn Medicine. (n.d.).
Liana Y. Zanette. (2019, May 6). Ecology of fear. Current Biology.
Mcerian. (2020, May 19). Cheetah Versus Impala: Each has a competitive edge. Cheetah Conservation Fund Canada.
Peléšková, Š., Polák, J., Janovcová, M., Chomik, A., Sedláčková, K., Frynta, D., & Landová, E. (2024,
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