Do We Have a Natural Fear of Snakes and Spiders?

Fagjun | Published 2017-11-04 01:21

Is the fear of snakes and spiders something we learn due to external factors, or something we’re born with?


Trigger warning: lots of creepy-crawlies.



Some people are scared of heights, some are scared of deep waters, some are scared of clowns, and others are scared of things that creep and crawl. We’re all afraid of something. Sometimes, our fears are due to a past traumatic experience. For example, almost drowning in the ocean one summer when you were a kid can give you a long-term fear of going into deep waters. However, there are some fears that don’t seem to have discernible roots in past experiences or traumas.


How about a strong fear of snakes and spiders? About 5% of the population is said to have a debilitating fear of these animals. Is that innate, or something borne out of past experiences? A new study seeks to find out.

How Snakes and Spiders Affect Us

Will babies be able to tell us if some fears are innate and natural?



What do you do if you want to know if fearing something is innate to humans or largely influenced by external factors? A team of researchers chose to study humans that are largely tabulae rasae--babies, who are also the least likely to show fear among all of us.


The researchers tested 48 infants, all of whom were six months old, to see how they would react to images that the researchers deemed frightening. The babies were seated on one of their parents’ lap during the experiment. To make sure that the parents didn’t influence their baby’s reaction to the images, they were asked to wear opaque glasses so they won’t be able to see or react to the images.


The babies were shown pictures of snakes and spiders on a white background, which the babies had to look at for five seconds. According to the findings, the reaction of the babies was consistent. When they saw these particular images, the pupils of their eyes grew larger. They were also shown “un-scary” images of flowers and fish as a control. The pupils of their eyes didn’t grow as much when they were looking at the flowers and fish. This suggested that a fear of snakes and spiders may be innate to us.

An Evolved Fear



Our pupils dilate for a number of reasons. Research has shown that measuring pupil dilation can indicate a variety of emotional and mental states in adults. Pupil dilation is in particular associated with a more active noradrenergic system in the brain. This system is known to process stress. Thus, “[t]here was a definite stress response in the brain," said Stefanie Hoehl, one of the researchers.


These results don’t conclusively indicate that the infants were experiencing fear when their pupils dilated as they looked at images of snakes and spiders. However, what’s definite is that the infants were intensely focused on the images they were look at, and that they were mentally processing.


If a fear of snakes and spiders has become innate to us, it’s not really all that surprising. "It's a very long period of coevolution—nearly 40 to 60 million years of it, that early human ancestors and spiders and snakes have interacted," says Hoehl. A single venomous bite could render our ancestors incapacitated, sick, or dead. Thus, we may have evolved a fear of these creepy-crawlies as a defense mechanism.

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