Understanding innate fears: Scientists study why snakes and spiders evoke a stress response, even in babies

Why are human babies afraid of creepy-crawlies such as spiders or snakes? Is it something that they learn as they grow older? What about extremely young infants who have never been exposed to these creatures beforehand? According to new research from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS), the answers to these questions all involve some form of, “it’s in the baby’s genes.”

It turns out that the exact reason why babies as old as only a few months exhibit signs of fear and alarm upon seeing a spider or a snake is because they had inherited the fear of those creatures from their parents. That would explain why, even without having seen any of those creatures before, a baby would know to be afraid of them when they appear.

The common knowledge

It has been known for a long time that snakes and spiders cause people to feel fear and sometimes disgust. Some even refer to these animals as monsters and often portray them as such, which obviously doesn’t help their reputation of being so-called creepy-crawlies.

The surprising thing is that, even in places where it’s not that common for these animals to appear, the people who are living there still show show signs of unexplained fear. Scientists and experts from the Max Planck Institute and Uppsala University have now decided to find out why.

Their research was performed with Germany as a setting, where most people never have and never will come across a poisonous snake or spider in the wild. Somehow, these people still had a fear of these creatures. The fear, in some cases, can become so bad that it turns into a form of anxiety or even a phobia, which ends up limiting a person’s daily life.

The researchers decided that in order to get to the root of the problem, they should try to find out if and why even young babies can feel and exhibit these fears, even at their early age. What they learned was that infants do experience a stress reaction upon seeing a spider or a snake; even those who are only six months old apparently know that these animals are dangerous and should be avoided.

An early but old reaction

“Even the youngest babies seem to be stressed by these groups of animals,” says Stefanie Hoehl, lead investigator of the underlying study and neuroscientist at MPI CBS and the University of Vienna. “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 Hoehl. And that’s a huge signal that an individual is feeling stress at that very moment.

As for why, the researchers conclude that the fear of creatures like snakes or spiders “is of evolutionary origin.” That’s mainly why they can induce stress reactions even in babies who have never seen them before. “This obviously inherited stress reaction in turn predisposes us to learn these animals as dangerous or disgusting.”

It also explains why, despite the more obvious danger of modern risks like knives or sockets in the home, children don’t seem to fear those very much. As Hoehl explains, “Parents know just how difficult it is to teach their children about everyday risks such as not poking their fingers into a socket.” And the biggest reason for that is because from an evolutionary perspective, humans still have not been able to establish reaction mechanisms for these because they have only existed for a short time. Compare that to the millions of years of knowing about snakes, spiders, and other truly dangerous things.

Perhaps in the future, the brain will be able to catch up.

Sources include:

MPG.de

Frontiersin.org