By Bryse Thornwell ’16

Why do most humans jump at the sight of 50 spiders but not at 50 cars on a highway? Why do most humans scream in terror at the sight of a snake, but shrug at, or even welcome, a fast-food restaurant? In America, 38,300 people died in motor vehicle accidents last year alone, but only an average of six people die from spider bites each year. Likewise, over half of America’s adult population is at risk for high cholesterol or high blood pressure related death, while an average of five people die each year from snake bites.

We jump in response to fear through our “fight or flight” system, which is our mechanism that allows us to escape danger. One of the responsibilities of the amygdala, a structure located in the limbic system in our brains, is to associate fear to different situations. While everyone has their own list of fears, evidence proves that certain fears are more widespread than others because they are rooted in our biology.

The evolutionary perspective in psychology is an approach that explains psychological traits such as memory, perception, and language as adaptations. Natural selection, the process where organisms who adapt better to their environment usually survive and reproduce, can explain why certain fears are more widespread throughout humanity than others with the same or even a greater potential to cause harm.

Our ancestors learned to assess what was dangerous and threatening, and to respond with a reaction of fear. Those who successfully avoided dangerous and threatening stimuli were then able to pass their genes and behavior down to future generations.

Since natural selection and evolution take thousands of years, this could easily explain why fears that proved threatening to the survival of our ancestors, such as potentially dangerous predators, heights, and wide open spaces remain prominent while fears of recent inventions like motorcycles or new findings in climate change are not as common.

One way to assess the effects of evolution on widespread fears is to compare humans to lesser evolved animals. A study involving newborn rhesus monkeys proved that they were afraid of toy snakes and toy crocodiles, but not of a toy rabbit. The monkey most likely feared the snake and crocodile because it perceived them as predators, but the monkey was still able to assume the rabbit would not cause it harm. Now, if you expose the monkey to a gun, it would be expected to display the same reaction as to the rabbit because its ancestors have not had enough experience to allow the monkey to perceive a firearm as a threat.

Thus, the evolutionary theory in psychology can help explain why humans are more likely to fear snakes, spiders, and heights than threats from our modern environment. Electricity, motorized vehicles, and global warming are all too new for our biology to adapt to in the near future.