Arachnophobia Might Have Evolutionary Origins

Diya Adhikary, Amity University Kolkata

Have you ever experienced sudden fear on the sight of an eight-legged monster with fangs that’s crawling towards you? Yes I am talking about spiders. According to recent research, arachnophobia, or intense fear of spiders and spider webs can be a product of human evolution. Let us know how that is.

The Experiment

To understand and verify whether or not arachnophobia (derived from Greek words “arachne” and “phobos”; meaning: fear) is an evolutionary response, a group of scientists from the Max Planck Institute for Human Cognitive and Brain Sciences, Germany, conducted an experiment on 48 six-month old infants. And in that experiment, the researchers would measure the innate, untrained responses of the infants to various arachnids.

The infants were shown images of flowers and spiders while they were seated on their parent’s lap. And an infrared eye tracker was used to measure their pupil dilations during the same process. This was done to detect and compare their level of noradrenaline (fight/flight hormone) during both visualisations.

Result of the Experiment

Neuroscientist Stefanie Hoehl, hailing from the Max Planck Institute and University of Vienna in Austria, stated that when the infants were shown the images of spiders instead of flowers, they reacted with significantly wider pupils. Average pupil dilations recorded in case of spiders and flowers were 0.14mm and 0.03mm respectively. This change in pupil size influenced an key signal for the activation of the noradrenergic system in the brain. Thus, they concluded that it was indeed highly likely that arachnophobia had evolutionary origins.

Treatments for Arachnophobia

• Mental Health Counselling proves to be effective in treating arachnophobia. It helps in getting rid of the underlying causes of the phobia.
• Cognitive Behavioural Theory (CBT) is also an effective treatment. In this case, the negative thoughts related to spiders are replaced with rational thoughts by the therapist.
• Desensitization (gradual exposure technique) is a method that combines relaxation techniques with gradual exposure to help people overcome their fear.
• Exposure therapy involves gradual exposure of the sufferer to their phobia. Studies suggest that this therapy leads to quicker improvements.
• Hypnotherapy can also help people to overcome their fear.
• Medications (antidepressants, sedatives, tranquilizers) tend to improve anxiety symptoms.

Conclusion

In ancient civilisations, even a Black Widow Spider’s bite (which is not considered fatal) was enough to keep the victim captivated for days or weeks. Not only that, in Europe during the Middle Ages, spiders were considered to be a source of contamination. When a spider fell in water, it was held to be poisoned.

But with passing time and further scientific studies made into understanding the severity of venoms from different arachnids and animals in general, it became rather clear that these historical annals were rather flawed as the described anomalies were often fuelled by superstitions and myths. To this day, there are many people who love spiders and even keep them as pets, and then there are other people from cultures were a certain types of harmless spiders are consumed and even considered as a nutritious delicacy.

These on the contrary, indicate that arachnophobia might not have genetic origins after all. And that it is rather difficult to conclude its phylogenesis from clinical observations only, without data on the genetic and molecular level to support the claim made in the study.

We learn a lot of things from our parents, as kids we try to imitate them. And they play an important role in shaping your way of perception of the world and the things in it. The inculcation of opinions and perceptions on various objects and substances is often influences by our parents, our friends, our cultures and societies in general. Hence, further scientific studies on molecular and genetic levels are essential to reach to the bottom of the truth behind the phobia of spiders.

Also read: Natural killer cells: Defence against self-destruction

References

1. Peter D (2017) We Really Are Born With a Natural Fear of Spiders And Snakes, New Study Shows. Sciencealert. https://www.sciencealert.com/deep-unshakeable-fear-spiders-no-random-quirk-fate-born-arachnophobia
2. Firdous H, Singh BJ (2020) Arachnophobia (Fear Of Spiders): Symptoms, Causes, Diagnosis And Treatment. Lybrate. https://www.lybrate.com/topic/arachnophobia

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