Doctors Prefer to Explain Anxiety As an Evolutionary Response

Anxiety disorders affect millions of people. But what is the most beneficial way to explain what causes anxiety?

By Helen Petre

Explaining the cause of a mental disorder to a patient experiencing that disorder can have a beneficial or detrimental effect on the patient, and on how the patient perceives the condition. 

Researchers at the University of Cambridge asked 171 practicing mental health clinicians in the United Kingdom and Ireland to attend a 30-minute session on either an evolutionary explanation or a genetic explanation for anxiety. After the session, they asked the clinicians to rate whether the explanation was beneficial in explaining the condition to the patient. Presenting an evolutionary explanation for anxiety is a viable alternative to the accepted genetic explanation, and the results of this study show that clinicians think an evolutionary explanation is more useful for patients. 

Anxiety as a mental health disorder

According to the World Health Organization, 359 million people worldwide had a diagnosed anxiety disorder in 2021, an increase of 55 percent since 1990. Anxiety disorders are the most common mental health disorder worldwide. A quarter of 16- to 24-year-olds in England report having an anxiety disorder or similar mental health condition. Why is everyone so anxious? 

Anxiety is a normal response to stressful situations. It becomes a disorder when it interferes with normal daily life. Anxiety is beneficial when it helps us perceive dangerous situations or focus on difficult tasks. Sometimes, and in some people, anxiety is an out of proportion response to something that really is not such a huge threat. The cause of anxiety disorders is often described as brain chemical imbalances, a genetic defect, or an imbalance of neurotransmitters. Medical schools generally teach clinicians that the cause is genetic. 

Diagnosis of anxiety disorder

When patients are diagnosed with anxiety disorder and then are told it is something wrong with their DNA, or their brain chemistry, this could result in additional anxiety and the diagnosis becomes a self-fulfilling prophecy. But is anxiety really something broken, or is it a normal response to danger? For example, if a lion is chasing you, or the house is burning down, you are going to be anxious and hopefully run really fast to safety. When you are looking at a screen waiting to see how many likes you get or wondering when someone will respond to your message, anxiety might just be an overblown response. Yet many of us will feel anxious in the same way as when we are in physical danger. 

Having occasional anxious thoughts about something is not enough to be a disorder. Anxiety disorder is when a person cannot stop thinking about something, or the results of something, to the extent that it prevents them from doing their job or otherwise interferes with normal life. 

According to the researchers, the ability to feel anxious is a normal evolutionary response to protect us from something horrible, like being attacked by a predator. Is being ghosted really that bad? Our bodies may think so.

Evolutionary theory and anxiety

Despite the acceptance of evolutionary theory as the central dogma of biology, evolution is not taught in medical school. Evolution is not included in the psychiatry requirements for the United States Accreditation Council for Graduate Medical Education, nor is it included in the clinical psychology curricula of any country. It is not part of the syllabus of the Royal College of Psychiatrists, and it is not considered as a contributing factor to human behavior. But isn’t evolution what made us human? Haven’t we evolved to be who we are based on which behaviors resulted in survival and which genes were passed on to our surviving offspring? The study designers think so. They think evolution should be included in the medical curriculum, and the results of this study show that clinicians overwhelmingly agree. 

The study researchers claim that anxiety is a relatively sound evolutionary response to dangerous situations. Anxiety results in survival, and being a bit hypersensitive to danger is probably better than being hyposensitive in terms of long-term survival and passing on genes to future generations. 

Dr. Randolph Nesse, at the University of Michigan, called this the “smoke detector principle.” After years of “treating” patients for anxiety, he realized that they were exhibiting a normal response. He described it as the response of a smoke detector. We all want our smoke detectors to detect danger, and therefore we tolerate it if they go off sometimes because of something that is not dangerous. We check around, see nothing is wrong, and reset them. We don’t throw them away, or say they are broken. We actually appreciate the fact that they work, even if a bit too much. Some people, Nesse said, just activate their smoke detectors a little more than they need to. When they see that there is no fire, they can learn to reset the system. The researchers agree. They hypothesize that anxiety is useful and explaining this to patients is more useful than telling them they have something broken that needs drugs to fix. 

Methods of the study

The researchers decided to see if doctors would agree. They showed doctors a 30-minute presentation on either evolution or genetics as a cause of anxiety disorder. Then, they asked the doctors to rate if the explanation was useful for them and their patients. Doctors were asked about their optimism for patient recovery, if they thought the patient could recover, if they thought the patient would be willing to accept the diagnosis, and if they thought the patient would be able to recover. They also asked the doctors if the evolutionary explanation was more helpful than explaining to patients that there may be a genetic disposition for feelings of anxiety. Yes, evolution, logically, made patients believe they were going to be fine. A genetic explanation made patients feel like something was wrong that could not be fixed. 

Results

The results were overwhelming. Clinicians overwhelmingly preferred the evolutionary explanation and they were 60 percent more likely to agree that their patients would recover when they explained that anxiety was a normal, evolutionary response. In fact, doctors thought the evolutionary explanation was positive, while the genetic explanation was negative.

RELATED: Nests, Neurons, and the Evolution of Behavior 

Conclusions for future steps

The researchers concluded that a few hours of evolutionary teaching should be added to psychiatric and mental health training, and public health resources should include evolutionary explanations for anxious behaviors. Dr. Adam Hunt, the first author of this study, said that neuroscientists spent billions of dollars attempting to identify genes in rat brains that will provide us with an identifiable cause for anxiety, but this has not worked out. All biologists know that evolution is the fundamental theory that explains all biology, and it logically explains human behavior. 

Hunt said that having a few people who are a bit neurotic in a community is probably a good survival mechanism. Anxious people are more aware of potential threats. In our society today, where humans are often alone and looking at screens, this hypersensitivity to danger is misplaced. Our lives are just not as dangerous as they were a few hundred thousand years ago. When patients understand that anxiety is a normal evolutionary response to danger that might not exist, they have a better chance of recovering, because they are not blaming themselves and their genetics and thinking they are broken. Patients feel more in control and capable of controlling their anxiety. 

These findings support the idea that evolutionary perspectives deserve greater integration into medical education and science. All organisms must learn what is dangerous and what is not. Anxiety is not something broken. It just may be an overactive smoke alarm. Sometimes it is just a learning experience.

This study was published in the peer-reviewed journal The British Journal of Psychiatry. 

References

Hunt, A. D., Carpenter, T., Brar, G., et al. (2026). Clinicians’ attitudes to evolutionary versus genetic explanations for anxiety: cluster-randomised study of stigmatisation. The British Journal of Psychiatry, 228(6), 539–547. https://doi.org/10.1192/bjp.2026.10615 

Nesse, R. (2001). The smoke detector principle: Natural selection and the regulation of defensive responses. Annals of the New York Academy of Sciences, 935, 75–85. https://websites.umich.edu/~nesse/Articles/SmokeDetectorPrin-Nesse-NYAS-2000.pdf 

World Health Organization. (2025). Anxiety Disorders. https://www.who.int/news-room/fact-sheets/detail/anxiety-disorders