Anxiety is a strange beast.

As a psychiatrist, I have learned that anxiety and its close cousin, panic, are both born from fear. As a behavioral neuroscientist, I know that fear’s main evolutionary function is helping us survive. In fact, fear is the oldest survival mechanism we have. Fear helps us learn to avoid dangerous situations in the future through a process called negative reinforcement.

For example, if we step out into a busy street, turn our head and see a car coming right at us, we instinctively jump back onto the safety of the sidewalk. Evolution made this really simple for us. So simple that we need only three elements in situations like this to learn: an environmental cue, a behavior and a result. In this case, walking up to a busy street cues us to look both ways before crossing. The result of not getting killed helps us remember to repeat the action again in the future.

Sometime in the last million years, humans evolved a new layer on top of our more primitive survival brain, called the prefrontal cortex. Involved in creativity and planning, the prefrontal cortex helps us think and plan for the future. It predicts what will happen in the future based on past experience. If information is lacking, our prefrontal cortex lays out different scenarios about what might happen, and guesses which will be most likely. It does this by running simulations based on previous events that are most similar.

Enter anxiety.

Defined as “a feeling of worry, nervousness or unease, typically about an imminent event or something with an uncertain outcome,” anxiety comes up when our prefrontal cortexes don’t have enough information to accurately predict the future. We see this right now with coronavirus.