When Ron Weasley was a child, he reveals in Harry Potter and the Chamber of Secrets, his brothers Fred and George magically transformed his teddy bear into a giant spider, thus triggering in their younger sibling a life-long and totally understandable fear of spiders. What’s harder to comprehend is that one in three (Muggle) women and one in four men have arachnophobia—even though none of them has witnessed the transformation of a favorite toy into an oversized arachnid, and most have never had a traumatic encounter with a spider (one study found that out of 118 adults with a fear of spiders, only eight had ever had a “traumatic” experience involving spiders).
Myths and misconceptions about spiders abound despite the fact that, with the exception of a few species, they’re basically harmless. In a study of 200 elementary-school children, 62 percent indicated that they believed spiders are dangerous to humans, especially when humans are asleep; 72 percent thought—wrongly—that tarantula bites could be fatal. Fear of spiders is so severe today that mere depictions of them on TV can provoke anxiety in viewers. Did our ancestors have the same reaction to representations of spiders on rock art? In December, archaeologists working in Egypt’s western desert discovered our first example of spiders on rock art in the entire Old World. Based on nearby finds, they estimate that the spiders date to about 4,000 B.C. How did our ancestors feel about spiders? Why are we so afraid of spiders—and has it always been this way?
One of the most widely cited explanations for our fear of spiders, put forth by psychologist Martin Seligman in 1971, is the “hypothesis of biological preparedness.” According to this theory, humans developed an aversion to spiders because at some point in our history, spiders presented a real threat to our ancestors. Different strains of this theory have also been used to explain fears of snakes, darkness, and heights—all of which clearly did pose problems for our ancestors, and can be pretty healthy fears even today.
Slovakian biologist Pavol Prokop found further support for the evolutionary hypothesis in a comparison of high school students’ attitudes toward spiders in Slovakia and South Africa. When he surveyed 300 high school students in each country, he found that South Africans admitted a greater fear of spiders. This makes sense in light of the biological preparedness hypothesis: South Africa is home to more poisonous spiders than Europe.
Other researchers, however, have argued that the fear of spiders has a cultural origin. When Graham Davey, then a psychologist at London’s City University, surveyed 260 British adults on their attitudes towards different animals, he found that people who are afraid of spiders are also more likely to fear animals such as cockroaches, snails and slugs. None of these animals is predatory, but they all have one thing in common: They evoke disgust. Davey believes there is a single variable, “disgust sensitivity,” underlying all these fears—and that it’s cultural, not evolutionary. “It is unlikely that this single underlying factor is an evolutionary predisposition to fear either venomous or harmful animals, because it is difficult to conceive of the selection pressures that would have selected for fear of some of the animals in this covarying group," wrote Davey. “It is unlikely that our ancestors ever had to avoid packs of predatory slugs or snails.”
Davey suggests three ways these animals could have taken on their “disgust-evoking status”: by being associated with the spread of disease (like rats); by having features that resemble things associated with disease, like mucus (slugs); or by being associated with dirt or rotten food (maggots). The historical association between spiders and disease, according to Davey, dates back to the Middle Ages:
In most of Europe during the Middle Ages, spiders were considered a source of contamination that absorbed poisons in their environments (e.g. from plants). Any food which had come into contact with a spider was considered infected. Similarly, if a spider fell into water that water was then held to be poisoned (Renner, 1990). In Central Europe during the Great Plagues, spiders were seen as harbingers of the plague and death… Until the late seventeenth century many European spiders were thought to be ‘poisonous’ in the sense that their bites caused a variety of illnesses.
And though fear of spiders is widespread, it’s hardly universal. In some African cultures, the spider is honored as a wise creature; in Ashanti cosmology, the god Anansi sometimes takes the form of a spider. In parts of Indo-China and the Caribbean, spiders are traditionally eaten as a delicacy, and Hindus in eastern Bengal even consider them a sign of good luck.