[Column] How the evolving brain handles anxiety

The brain is the most energy-consuming organ in the body, using 20 to 25 percent of the energy your entire body uses in a day, depending on usage. Without its significant survival benefits, the brain would be a very expensive organ to maintain. It's much more energy-efficient to survive solely on the genetic program in your DNA, like an amoeba or bacterium. However, living according to your genetic program only makes you less able to cope with changes in the world, as you can't alter your genetic program while alive.

The first brains, dating back to the Cambrian period hundreds of millions of years ago, are believed to have evolved from ganglia connecting the sensory and motor systems into the central nervous system, leading to something resembling the modern brain. What was the most primitive brain capable of? It could perceive information from the world with its sensory organs, remember important information, and change its behavior using its motor organs. Though seemingly simple, the ability to perceive new information and adjust behavior accordingly was significant. This is because the brain can learn, remember, and reprogram itself to recognize changes in the world during its lifetime.

The brain has allowed us to compensate for the limitations of DNA through learning and memory. In other words, the primary reason we have a brain is to actively respond to changes in the world and predict the future.

If I were to describe the brain in one word, I would call it a “prediction machine.” Much of what the brain does is create and store a model of the world to predict future events. Recent neuroscience theories explaining emotions suggest that emotions arise from differences between our brain's predictive model and our actual experiences. Emotions such as surprise, anger, disgust, and joy occur when the brain's predictions are wrong. We feel emotions because the brain is trying to reconcile our experiences with its internal models and update them accordingly.

One of the most common emotions we experience these days is anxiety. In a fast-paced world, we face anxiety daily, wondering how we will live in the future and whether we will survive in the age of AI and robots. Interestingly, anxiety is a result of our brain's ability to predict the future. A newborn baby's brain, which can't predict the future, doesn't experience anxiety. This is because the anxiety we experience is mostly anticipatory, based on our memories and imagination. We can only experience anticipatory anxiety when we have enough experience to create memories or the ability to imagine things that haven't happened. In other words, our brains' ability to remember and learn from the past, or to predict the future, has led to the ability to experience anxiety.

So which brain feels more anxious?

It is believed that brains that are more flexible to uncertainty feel less anxious, while brains that cannot tolerate having their predictions of the future broken based on their own experience feel much more anxious and stressed. Brains that can't accept that the world is constantly changing and uncertain are more anxious.

The physical world we live in and the world our brains experience are not the same. The world we experience is just a model created by our brain to favorably predict the future. However, when that model breaks down in the face of real-world experiences, we get hurt, stressed, and experience a variety of negative emotions. To avoid getting stuck in these negative emotions, we need to remember why our brains evolved the way they did.

Our brains evolved to constantly break and update their models in an ever-changing world. In other words, they evolved to push beyond our innate limitations.

Chang Dong-seon is the CEO of Curious Brain Lab and resides in Seoul. He studied Biology at Uni Konstanz, Neuroscience at the International Max Planck Research School, and Cognitive Science at Rutgers University. Chang's career includes roles as an Assistant Professor at Hanyang University and a Researcher at the Max Planck Institute for Biological Cybernetics. He also served as the Head of the Future Technology Strategy Team at Hyundai Motor Group. His extensive expertise spans biology, neuroscience, and cognitive science. This column was originally published in Segye Ilbo in Korean on June 12, 2024. -- Ed.