Innate fears and aversion - why we fear spiders and snakes

Fear of spiders and snakes is innate to humans

Many people feel disgust, discomfort or even fear at the sight of a spider. Even more pronounced is this feeling at the sight of snakes. Whether these are learned behaviors or we follow an innate instinct has remained controversial. A research team from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig and Uppsala University (Sweden) has now proven that these fears are inherent in us from birth.

Already six months old babies react stressed at the sight of snakes and spiders, the scientists report. This was "long before they could have learned this reaction." So it seems clearly to be an innate instinct. However, this can take extremely different forms in the further course of life. The study results were published in the journal "Frontiers in Psychology".

The aversion to spiders and snakes is innate to humans. It can easily develop into a phobia. (Image: pegbes / fotolia.com)

Fear of spiders and snakes widespread

Although in Germany (almost) no poisonous spiders and snakes occur and people rarely have contact with the animals, the fear of snakes and spiders is also widespread in Germany. Whether it is learned fears or a congenial aversion remained controversial. The researchers at the Max Planck Institute for Human Cognitive and Brain Sciences have now investigated this on six-month-old babies.

"Presumably, in Germany, most have never met a poisonous spider or snake in the wild" and "there are simply no spiders in this country that could be dangerous to humans," reports the MPI CBS. The snakes are only two native species poisonous, but so rare that they can hardly be found. The dislike of these animals remains still widespread and "hardly anyone is not nervous at the thought, a spider, and no matter how harmless, could crawl up his trouser leg," the scientists report.

Threatening development of anxiety disorders

It is not uncommon for fear to develop into a true anxiety disorder (phobia) that can severely restrict sufferers in their everyday lives. Those affected are constantly on alert and enter, for example, in a spider phobia no room, before he was not declared "spider-free". Or they do not go into nature in a snake phobia, for fear that they might encounter a snake. About one to five percent of the population are affected by a phobia to these animals, the experts report.

According to the researchers, previous studies have looked at adults, older children, which behavior is learned and which one is innate. However, this can hardly be separated with increasing age. Even so far, children have only been tested "whether they can detect spiders and snakes faster than harmless creatures and objects, but not whether they show a direct physiological anxiety reaction."

Reaction in babies examined

In their current study, the scientists have now been able to prove that even in babies at the age of six months, a stress response is triggered when they see snakes or spiders. This is an age when they are still very immobile and barely had the opportunity to learn that these two groups of animals could be bad. "When we showed the little pictures of a snake or a spider instead of a flower or a fish of the same color and size, they reacted with significantly enlarged pupils," reports neuroscientist Stefanie Hoehl from the MPI CBS.

Stress reaction detectable

According to the researchers, the enlarged pupils are "a significant signal under steady light conditions that activates the so-called noradrenergic system in the brain, which is associated with stress reactions." The babies respond to the sight of the animals stressed. It can therefore be assumed that "the fear of snakes and spiders has an evolutionary origin." Obviously, in our brain, and also in other primates, mechanisms are anchored in the brain from birth through which we very quickly identify objects as "spiders" or "spiders" Identify and respond to "snake".

The innate stress response, combined with other factors, can lead to real anxiety or even phobia, the researchers explain. Thus, "a strong, panicky aversion of the parents or even the genetic predisposition to an overactive amygdala, which is important for the evaluation of dangers, can quickly develop from an increased attention to these animals a real anxiety disorder," says Stefanie Hoehl.

Evolutionary development of fears

Interestingly enough, the babies did not experience a stress reaction in images of rhinos, bears, or other animals that theoretically could also be dangerous. The researchers therefore suspect that "the separate reaction to the sight of spiders or snakes is related to the fact that potentially dangerous reptiles and arachnids coexist with humans and their ancestors for 40 to 60 million years - and thus much longer than with us today dangerous mammals. "The now innate reaction to certain groups of animals could thus anchor themselves in the brain over an evolutionarily very long period of time. (Fp)