Let us assume that a person next to you coughed without a mask.

If it had been two years ago, you would have thought it was a trivial matter. You could have felt sorry for the person, assuming the person might have caught a cold.

However, the past two years with the Covid-19 pandemic have completely changed the situation. If you hear a cough nearby, you feel uncomfortable and keep away from people without a mask.

If you want to visit a crowded place like a hospital, you have to present a written document that you are free from Covid-19 infection risk.

For over a year since the first outbreak of Covid-19 in early 2020, several groups became “public enemies.” Individuals' private information such as nationality, region, religion, and sexual orientation were disclosed recklessly.

Sensitive social issues -- such as antipathy toward neighboring countries, regional conflicts, hostility to certain religions, and sexual orientation that some are refusing to acknowledge -- have surfaced with the spread of the infectious disease.

However, what if these hostile attitudes towards others result from human evolution in the history of infectious diseases?

Park Han-son, a psychiatrist and professor of neuroanthropology at the Seoul National University, asked this question and wrote the answer in his new book, “Infectious Disease and Human Nature: How Germs Make Us Humans?”. The book explains infectious diseases in human history and human behavioral immune systems that have changed along with the changes in infectious diseases.

Korea Biomedical Review has met with Park to hear why hatred and discrimination are prevalent during the pandemic and how people should reduce hostility in the post-Covid-19 era.

Question: You are a psychiatrist and a neuroanthropologist at the same time. Is there a specific reason why you became a neuroanthropologist?

Answer: I left the clinical field five years ago. Now, I’m studying health or diseases from an evolutionary anthropological perspective. I have neither lost my identity as a clinician nor changed my job completely. Many people think doctors treat patients right next to them, but doctors can also research to resolve health and disease issues in various areas. When I’m older, I might practice medicine again. When doctors were short during the Covid-19 crisis last year, I did some volunteer work at an isolated ward.

In psychiatry, a disease’s definition, causes, treatment, and prevention methods are all uncertain. People call mental disorder “the plague of the 21st century,” and sooner or later, it is expected to beat other infectious diseases, chronic diseases, and cancer to become the top disease that harms health. Although humans have identified the causes of various diseases and found treatments in multiple ways, they have barely produced fruitful results in mental disorders.

This is probably because existing medical approaches did not work. The reason why the human mind gets sick may be different from that of other diseases. I thought that approaching the problem from the perspective of a long evolutionary history could be one way to solve it.

The interest in evolutionary medicine has been rising in the U.S. since 1988. Leading universities in other countries have established evolutionary medicine courses. Evolutionary medical doctors and anthropologists are conducting research together at medical schools in the U.S. However, it is not the case in Korea. Fortunately, the Seoul National University opened the evolutionary medicine course this year.

I have been teaching at the SNU for several years, and Pusan National University and the University of Ulsan also opened evolutionary medicine introduction class recently. Until now, it has only been a semester of brief introductory lessons, but I look forward to seeing the Korean medical community reflect the achievements of evolutionary anthropology in academic courses.

Q: More than a year has passed since the first Covid-19 case was confirmed in Korea. Why did you publish your book, which highlighted the history of infectious diseases, at this particular time?

A: It is good to explain social and psychological reactions related to infectious diseases using evolutionary anthropology and neuroanthropology. But we need not only evolutionary anthropological knowledge but an understanding of the human mind and psychology. Unlike general psychological reactions, those social reactions cause negative emotions such as depression and anxiety and tend to be linked to pathological reactions of psychiatry.

While studying evolutionary anthropology, I participated in the government’s study of mental health related to the MERS (Middle East Respiratory Syndrome) outbreak in 2015. The sudden Covid-19 attack prompted people to search for a way, and they discovered the study of the past. As a result, I provided many consultations and interviews at the beginning of last year and joined the government research again. After receiving a proposal from a publishing company asking to combine the research contents so far, I prepared for the publication for a year and published it. I highlighted behavioral immune system response in my book, as described by evolutionist Mark Schaller (at the University of British Columbia, Canada).

Q: In the book, you said humans’ behavioral immune system has changed according to the history of infectious diseases. What is the concept of the behavioral immune system?

A: Congenital and acquired immunity are relatively well known, but behavioral immunity is still an unfamiliar concept for many people. Behavioral immunity is a kind of strategy that preemptively reduces the likelihood of infection by keeping away from the potentially infected. It's an instinctive distancing. You will instinctively want to keep away from dirty objects, feces, corpses, or sick objects. Why is that? This is because we have already learned through long evolutionary history that such objects have adverse health effects. The behavioral immune system appears even in primitive animals. However, only humans with a good memory who can identify objects and understand the possibility of infection have developed the system to a higher level.

Q: Are there any possible problems that can occur because of the behavioral immune system?

A: Despite the benefits of vaccines, some people are reluctant to get vaccinated because the needle has to get through their bodies. Even doctors do not enjoy getting an injection. This is a natural emotional response to protect our bodies. Isn’t it better to avoid a knife or a sharp object to survive? But many people are aware of a vaccine’s effectiveness, and they can repress the instinctive reaction to refuse the injection.

This is the same with the behavioral immune system. Possible external sources of infection are external groups, that is, people of different races and languages. Many infectious diseases have been foreign diseases coming from the outside world in evolutionary history. During the Covid-19 pandemic, many countries closed their borders. This was the most primitive way of quarantine control. It may have been the only option in the absence of vaccines or treatments. Hate reactions have appeared targeting certain groups such as religious people, LGBTQ people, and even medical professionals.

These kinds of reactions might have been useful in the past but not anymore in modern society. Now we can trace how the virus was transmitted when an infectious disease breaks out. It is the same with Covid-19. We only need to trace the transmission routes and block possible risks, but some people argued that we should have blocked all foreigners from entering Korea or close all the religious facilities. Such methods are inefficient and can undermine cooperation and unity for infectious disease control.

Q: Indeed, many people blamed certain groups for Covid-19 infections. What’s your opinion about this?

A: The behavioral immune system is a mental trait that has kept us healthy and made us survive. However, it does not fit the current situation, causing social problems. Rather than relying on a primitive behavioral immune system, we need to understand hatred and exclusion reactions in our minds and suppress them. A developer of the mRNA vaccine is also an immigrant.

some people tend to show strong hatred towards immigrants and foreigners, it may have been the minorities and immigrants who have saved the human race after all. We have to admit that we are “homo sapiens who hates and excludes others.” Then, we need an attitude to look for ways to act properly.