Scientists have recently discovered that the fear of spiders and snakes is hereditary and babies as young as six months old feel stressed when seeing these creatures—long before they could have learnt this reaction.
Scientists at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig and the Uppsala University recently made a crucial observation: Even in infants, a stress reaction is evoked when they see a spider or a snake. And this already at the age of six months, when they are still very immobile and have had little opportunity to learn that these animals can be dangerous.
“When we showed pictures of a snake or a spider to the babies instead of a flower or a fish of the same size and colour, they reacted with significantly bigger pupils”, says Stefanie Hoehl, lead investigator of the underlying study and neuroscientist at MPI CBS and the University of Vienna.
Interestingly, it is known from other studies that babies do not associate pictures of rhinos, bears or other theoretically dangerous animals with fear.
“We conclude that fear of snakes and spiders is of evolutionary origin. Similar to primates, mechanisms in our brains enable us to identify objects as ‘spider’ or ‘snake’ and to react to them very fast.This obviously inherited stress reaction, in turn, predisposes us to learn these animals as dangerous or disgusting,” she said.
For modern risks such as knives, syringes or sockets, presumably the same is true. From an evolutionary perspective, they have only existed for a short time, and there has been no time to establish reaction mechanisms in the brain from birth.
“Parents know just how difficult it is to teach their children about everyday risks such as not poking their fingers into a socket”, Hoehl adds with a smile
This fear can even develop into anxiety which limits a person’s daily life. Such people are always on edge and cannot enter a room before it is declared “spider free” or cannot venture out into nature for sheer fear that they may encounter a snake. In developed countries, one to five percent of the population is affected by a real phobia of these creatures.
Until now, it was not clear where this widespread aversion or anxiety stems from. While some scientists assume that we learn this fear from our surroundings when we are a child, others suppose that it is innate.
The drawback of most previous studies on this topic was that they were conducted with adults or older children — making it hard to distinguish which behaviour was learnt and which was inborn. Such studies with children only tested whether they spot spiders and snakes faster than harmless animals or objects, not whether they show a direct physiological fear reaction.