Why are spiders scary?



Image of spiderweb by Peter Shanks via Flickr

As a child, watching the second Harry Potter movie left me in tears. I found Aragog, the giant spider nothing short of terrifying. From then on, spiders have always given me the creeps. These days, even looking at a photo of a spider is enough to trigger a wave of panic.

But I’m not alone. Having a fear of spiders is frighteningly common. Up to 75% of people report feeling uneasy around spiders. Around 5% of people suffer from a severe fear of spiders, or arachnophobia, which can be debilitating. But why are so many people afraid of spiders?



Fear is in the eye of the beholder

While having a fear of being bitten by a spider seems rational, only 0.1% of spiders are actually venomous enough to harm humans. But research suggests most people aren’t afraid of the danger of spiders but rather their weird looks.

Arachnophobes report the “leginess” and “sudden movement” of spiders as what scares them the most. Their creepy looks may freak us out because our brains can’t predict their quick erratic movement.

One bad spider spoils the bunch

A fear of spiders may have evolved to help early humans survive.

Back in the day, spiders were more of a threat. Getting bitten had more dire consequences so those who avoided spiders were more likely to survive. While other animals like poison dart frogs have bright colours to ward off predators, deadly spiders often look just like their harmless cousins. We may have evolved over time a kind of survival instinct to avoid all spiders in case they are poisonous.

A fear of spiders could also be a cultural. Since the middle ages, spiders have been associated with carrying disease in European culture. Some psychologists think that spiders became a target for anxieties related to outbreaks of disease. In many countries in South America, rates of arachnophobia are much lower and spiders are commonly eaten as food.

In the womb where it happens

But there is biological evidence that suggests a fear of spiders is innate. Using crickets, scientists found a fear of spiders could develop while still in the womb.

Researchers put pregnant crickets in a tank with a wolf spider. The spider’s fangs were covered in wax so it could hunt the crickets but not kill them. The newborn crickets whose mothers were exposed to this spider torment were twice as likely to seek shelter and hide as those whose mothers lived a spider-free existence. These crickets also froze when they came across spider faeces or silk. As a result, they were dramatically better at surviving.

These results showed that a fear of spiders may develop before you are even born. This is an interesting concept in the world of epigenetics– where genes can be altered in response to the environment.

Like these crickets, phobias may be written into your genes from your mother’s own emotional experiences. This experience may have happened in an ancestral human- which explains why a fear of spiders is so widespread. We could have an instinctual response to spiders because we carry genes altered by an ancestors’ arachnid encounter.

A cure for arachnophobes?

Luckily, there are ways of overcoming this phobia. Unfortunately, most of them involve confronting your fears.

Exposure therapy is very successful with helping people deal with phobias by gradually introducing the triggering stimuli (spiders). There are also promising results using virtual reality computer games as a part of exposure therapy.

In the meantime- let’s just leave each other alone, spider.