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Fear of Spiders & Snakes is Innate

S u m m a r y :
The fear of spiders and snakes is innate; having an evolutionary origin, it is hereditary, suggests a new study published in the journal Frontiers in Psychology.

Fear of Spiders & Snakes

Why do we fear spiders and snakes? Most of us will be gripped by stress, anxiety and aversion upon seeing any of these creatures, regardless of whether they are harmful or not. Moreover, even if we haven’t experienced a situation where we were directly threatened by them, we will still hate them with a passion. From where does this fear come? Why are humans wired like this? Scientists have attempted to explain this reaction in terms of innate and learned behaviours; some argue that we are born with the fear of these creatures while others believe that we learn to be fearful of them as we grow in our environment.

The new research suggests that the former is more probable: the fear of spiders and snakes is deeply embedded within us. Conducted by a team of investigators from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS), the study shows that babies display stress reactions upon viewing pictures of either of the two.

Why Study Babies?

The research, led by neuroscientist Stefanie Hoehl, is different from other studies focusing on this subject because it involves the observation of the reactions of 6-month-old infants. Previous works were conducted with adults or older children such that it was challenging to determine whether the fear was inborn or learned. But, studying babies at a time when they would not yet have learned such behaviour would allow the scientists to make the distinction more clearly. This seems to be line with reality as the majority of us, specially those from developed countries where people are not normally exposed to poisonous spiders and snakes, will shiver at the sight of them.

Furthermore, Hoehl and her team mention a direct physiological fear reaction in their subjects.

Eyes of Babies Tell The Truth

The infants showed a clear stress reaction when they were made to view pictures of spiders and snakes which were of the same colour as flowers and fish in pictures to which they were also exposed. Hoehl and her colleagues observed a significant increase in the size of the pupils of the babies when they saw snakes and spiders. It is to be noted that at their age, they would not have learned that these animals were dangerous.

“When we showed pictures of a snake or a spider to the babies instead of a flower or a fish of the same size and colour, they reacted with significantly bigger pupils,” says Hoehl. “In constant light conditions this change in size of the pupils is an important signal for the activation of the noradrenergic system in the brain, which is responsible for stress reactions. Accordingly, even the youngest babies seem to be stressed by these groups of animals.”

A Fear With An Evolutionary Origin

These findings have led to the conclusion that the fear of snakes and spiders are the product of evolution. Brain mechanisms allow us to react fast upon identifying creatures like snakes and spides, a trait that is an “obviously inherited stress reaction”, argue the authors, according to whom, it predisposes us to learn that these animals are harmful or disgusting.

If other factors come into play, a real fear or even phobia can be developed.

“A strong panicky aversion exhibited by the parents or a genetic predisposition for a hyperactive amygdala, which is important for estimating hazards, can mean that increased attention towards these creatures becomes an anxiety disorder.”

Why Spider and Snakes?

Now, why would babies react in this way to pictures of spiders and snakes but not to those of other potentially harmful animals like bears or rhinos? The authors explain that this might be due to spiders and snakes that were actually harmful coexisting with us for over 40 to 60 million years, a much longer time than other animals. This fear might have been incorporated in the human brain over time.


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