Infants will react with anxiety upon seeing pictures of spiders but not of other potentially dangerous items like knives, bears, electrical outlets or sharks.
Previous studies into why so many people have a fear of spiders and snakes involved adults and older children, who had lived long enough to learn or acquire the fear.
Thus, researchers couldn’t really rule out just how much the fear was learned or innate.
A new study, however, involved showing babies as young as six months pictures of spiders, snakes, rhinos, bears, fish or flowers of the same size in the image.
Only for the images of the spiders and snakes did the babies’ pupils notably enlarge, revealing a fight or flight response in their body.
The study was carried out by the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig and the Uppsala University, Sweden.
What’s remarkable is that at the age of six months, the stress response of babies to pictures of spiders and snakes is not learned, because babies this young are still immobile and not in a position to have been exposed naturally to these creatures.
“We conclude that fear of snakes and spiders is of evolutionary origin,” says Stefanie Hoehl in the report; she is a neuroscientist and the lead study author.
Why do spiders, and not rhinos or bears,
Certainly you’d rather be faced with a spider than a charging rhino or bear. You can step on a spider, smash it, blow it away, but you’re powerless over a rhino, bear or other large animal like a tiger.
Dogs maul thousands of babies every year. Spiders and snakes don’t. What’s up with the inborn stress response to pictures of spiders but not of dogs or crocodiles?
Hoehl et al’s report points out that for tens of millions of years, humans and their ancestors coexisted with spiders and snakes rather than with rhinos, bears and lions.
Think about that. Prehistoric peoples would be readily surrounded by very visible spiders and snakes as they crouched around making tools, skinning animals for dinner, creating necklaces, etc.
On the other hand, the big dangerous beasts like lions kept their distance and were not part of man’s ambient habitat.
The innate fear of spiders and snakes is a protective mechanism with an evolutionary basis. Humans had tens of millions of years for this fear to become part of their innate brain wiring.
Modern small objects that are dangerous to babies, such as syringes, knives, electrical sockets, glass shards, guns, etc., do not evoke a stress response.
These items have been in our evolutionary history for only a few minutes, if the evolutionary clock were to be in terms of 24 hours.
So there hasn’t been enough time (millions of years) for the brain to have evolved an innate fear of these objects, which can easily kill or injure a baby or adult.
If all of this is difficult to understand, look at it this way…
Imagine ancient humans gathered around for dinner outside their cave, or just sitting around carving spearheads or grooming each other’s hair.
The ones who instantly grew fearful upon seeing spiders or snakes crawling or slithering nearby were more likely to survive because they scrambled away from these creatures before getting bitten.
Those who had no fear and remained near the spiders and snakes were more likely to get bitten – and die by poisoning.
Many of the survivors, being naturally wired for a stress response, lived long enough to reproduce and pass their “stress response genes” down to their offspring.
Many of the calmer people, having died from poisonous bites, didn’t live long enough to pass down their “calm genes.”
This is why to this day, so many industrialized people, including babies, are so very fearful of these creatures despite never having been bitten.
How many people will pet a tranquilized bear or cuddle a lion cub? Many. When I was in Las Vegas I had a picture taken of me seated while a sleeping lion cub was in my lap.
Yeah, okay, a fuzzy lion cub is a lot cuter than a spider, but still, it could have awakened and taken a nip at my face.
How many people will let a non-poisonous spider crawl up their arm? I once held a fully awake baby alligator that was being passed around as part of a sightseeing tour of the Mississippi River.
I had no fear of this miniature version of a grownup killer alligator. But you’ll never get me to let a house spider crawl up my arm.
I don’t fear snakes and go on hikes all the time, but the idea of encountering a mountain lion has me on guard, and for that reason I carry pepper spray.
Many people will develop intense anxiety at the thought of going on a family hike for fear of snake encounters, yet don’t give the mountain lions and bears a second thought.