Fear of spiders is an evolutionary hangup from the days when our ancestors knew that a single bite could prove fatal, say scientists who are developing a new theory for the origin of certain phobias.
Just as there are short, tall, fat and thin people, so there are those who, because of some genetic component, have a much stronger fear of spiders.
"It is a biological fear which can occur during normal development and doesn't go away," according to Dr Ross Menzies, director of the anxiety disorder clinic at Sydney University in Australia.
"This 'fear' would have entered the gene pool because in certain areas of the world there are dangerous spiders and fear of them would be a good thing," he said.
Dr Menzies said that fear of water, heights and snakes are other examples of biological fears which may be inbuilt into an individual's psyche. Fear of snakes, for example, in people who live on snake-free islands and who have not travelled or ever seen a live snake, is well documented.
Dr Menzies, who presented the results of his research to the British Psychological Society Conference yesterday, analysed three groups; 15 under-graduate students who claimed to be scared of spiders; 19 men and women with a clinical level of arachnophobia, and a control group of "non- fearfuls".
The "fearfuls" claimed no adverse experience with spiders as children - previously believed to be the origin of such phobia - and said they had always been scared since their first contact.
"They didn't ever remember a time when they weren't scared of spiders," Dr Menzies said. Paradoxically, three of the non-fearful subjects had been bitten by spiders.