Please view the main text area of the page by skipping the main menu.

Viruses caused by nature's destruction show need for change post crisis: Kyoto U. President

Kyoto University President Juichi Yamagiwa is seen speaking at the institution in this file photo taken on May 7, 2019. (Mainichi/Ryoichi Mochizuki)

The novel coronavirus is spreading across the world. How should modern society, which has been exposed to a crisis by the threat of the virus, interpret what is happening? Juichi Yamagiwa, president of Kyoto University and world-renowned expert in the field of primatology and anthropology, shares his insights on how viruses have come to more frequently ravage ape communities, and what this could mean for us as a species sharing the natural world.


Who expected the novel coronavirus to have this wide an effect? When it emerged from Wuhan in China, the dominant view across the world, and even in Japan, was optimistic. But the numbers of the infected and deceased have become so large so fast that state of emergency declarations are inevitable in any country.

Despite an increase in new infectious diseases in recent decades, including AIDS, Ebola hemorrhagic fever (EHF), SARS, MERS, Zika and others, what has allowed circumstances this time to create such a disruption? Furthermore, even when this virus is quelled, it's doubtful that we'll easily be able to return to the way things were before this point.

Along with the formulation of a robust plan to combat infectious diseases, considerations must be made as soon as possible for what a new economic order, new international relations and new lifestyles will look like.

When fears surrounding the spread of the novel coronavirus were starting to be raised, what came to my mind wasn't Albert Camus' "The Plague," or Sakyo Komatsu's novel "Virus: The Day of Resurrection," but the science fiction movie "Planet of the Apes." The first installment in the film series opened to huge popularity in 1968, and since then many sequels have been produced.

In it, four astronauts depart Earth on a U.S. spaceship for a six-month expedition. On their return to Earth, they find that 700 years have passed. There, the astronauts encounter primates (orangutans, gorillas and chimpanzees) who speak human languages and lead civilized existences, as well as humans who have lost the ability of speech and are kept as animals.

Why the planet has ended up in this situation becomes clear over a collection of sequels. The catalyst is when a male chimpanzee used as a test subject in research for a new drug against infectious diseases mutates, and becomes able to speak human languages. He devises a plan to free other apes who have suffered as he has, and together they create their own society in the area isolated from humans.

After that, an infectious disease spreads among humanity quickly, and humankind stands on the brink of extinction. The few who do remain become unable to use language, and are subjugated by the apes, who have a stronger resistance to the pathogen.

A popular gorilla nicknamed "Ninja" by Kyoto University President Juichi Yamagiwa during his research on apes is seen in this image provided by the writer.

In reality, infectious viral diseases have their origins in wild animals. And among those viruses, many theories point to bats as the original source. In the case of SARS, it's thought that the virus transferred from a bat to a masked palm civet before making its way to humans. For MERS, the route of infection is believed to be from bats via camels to humans.

Concerning the novel coronavirus, there have been reports of its genetic configuration resembling one found in a virus detected in bats to pangolins. Wild animal trading takes place at markets in Wuhan, and there is speculation that it was there that, either from bats to humans or from bats through to pangolins and then humans, the virus first crossed over to our species.

Bats' customary behavior of gathering in caves and tree-tops to sleep makes them an ideal host for viruses. They have already had long contact with the pathogen, and so even if they are infected they don't exhibit symptoms. As infections repeat and multiply, so the virus mutates, until it takes on characteristics that make it easier for it to enter other animals and humans.

There are suspicions that apes have been intermediate hosts to pathogens. In the Democratic Republic of the Congo and Gabon, where I have spent a long time observing gorillas, there are frequent outbreaks of EHF. It's said that the source of this too is fruit bats, and in Gabon many gorillas and chimpanzees have been killed by the disease.

I have been to a place where this happened, and there the gorillas have been almost completely wiped out. But strangely, while on one side of the river that runs through it there is now no trace of the gorillas, a few groups survive on the other side of its banks. It's thought that, probably because the gorillas don't cross the river, the virus couldn't make it over either. Furthermore, the only survivor in the infected area was a male leading an isolated existence. Chimpanzees also live in this region, and many were killed by EHF, but their survival rate was still somewhat higher than that of the gorillas.

The reason for this disparity has something to do with the different ways gorillas and chimpanzees form groups. Gorillas create close groups; eating and resting is done together, and they make their beds close to each other to sleep. Their groups don't mark out territories either, so they often come into contact with others. They eat herbsfrom the ground, meaning they often touch the same vegetation as other groups. Therefore, Ebola virus infections spread among them quickly, and soon reached many gorillas across the same region. The solitary male appeared to have avoided infection because he had minimal contact with both groups and other lone gorillas.

Conversely, chimpanzees have fission-fusion features in grouping, and tend to move in small gatherings or alone. They also adhere to their territories, creating limits to where each group can go. For these reasons the virus spread at a slower rate, and it's thought that more chimpanzees than gorillas survived without being infected.

Infections from bats to chimpanzees and gorillas are thought to have taken place when the disparate species came into contact while eating the same fruits found on treetops, or when the apes touched fruit that had been bitten into by infected bats. But why have recent years seen more outbreaks of EHF? It's posited that because logging has split up forests, there are now more opportunities for species including bats and apes to come into contact with the same fruit where they previously wouldn't have.

Ordinarily, nocturnal bats and diurnal apes don't cross paths. But as the number of fruit trees becomes more limited by deforestation, chimpanzees and gorillas may forage for food where bats are sleeping, thereby coming into contact with them. Additionally, gorillas and chimpanzees typically make their bedding in trees at night. In that state, they may have physical contact with bats that fly onto the trees.

A family of gorillas that Kyoto University President Juichi Yamagiwa studied during his research on apes is seen in this image provided by the writer.

Yet however transmission is happening, it certainly appears to be the case that human development in old-growth forests that had remained untouched until now is limiting animals' movement and altering their chances of encountering one another, and widening the paths of infection for viruses.

At the same time, the movement of humans has become more pronounced, furthering the possibility of an unknown virus infecting us. Since long ago, people in Gabon and the Congo have known of undocumented pathogens. But in the depths of the forest, humans did not travel over wide areas, and if an infectious disease was discovered, whole villages would be burned down to contain it.

However, in recent years deforestation has accelerated, and roads have been built through the areas that allow large trucks to travel freely through them, thereby making the relaying of goods to cities easier. Widespread adoption of mobile phone technology has also meant that people in the depths of nature can contact others in cities. Deforestation also produces jobs for the local area, and with the introduction of generators and other amenities, it has become possible to lead a life like one in a city in those places. For people who have become accustomed to electricity and the cash economy, ending logging puts them in great difficulty.

With no income, people can't use their televisions, fridges or washing machines, and how they will cook becomes a concern. Under these circumstances, hunting wild animals and using roads created in the deforested areas to take them to cities and sell them as bushmeat in large quantities becomes a quick solution. Orders from urban areas can be accepted on mobile phones, and guns are easily obtainable, thereby making hunting more efficient.

If a hunted animal infected with a virus is then transported to a city, the virus can spread. Chances for villagers infected with pathogens to travel between populated areas before they begin to exhibit symptoms have also increased, allowing viruses to suddenly spread. These factors saw EHF, a disease originally limited to the rain forests of Africa, cross borders and appear even in the United States.

The novel coronavirus pandemic we're seeing now is the expanded edition of these other viral infectious diseases. The virus displays greater ingenuity when compared to past transmittable diseases. Viruses alone cannot replicate, so they parasitically occupy the cells of living beings to create copies of themselves, and then burst the cells' membranes to propagate further. If a virus quickly kills its host then it can no longer distribute itself.

But the new coronavirus has a long incubation period upon infection, and it also infects many people who go on to show no symptoms or only light ones. It is also highly infectious, and can be transmitted through coughs and sneezes, and healthy people can contract it by touching their eyes or nose after coming into contact with surfaces and items previously handled by infected individuals. Its survivability is also high, and can remain on plastic surfaces for three days. Because it has evolved itself into a stubborn form, it has been able to transmit itself while infected individuals are unaware they have it, and take advantage of people's movements and gatherings to spread quickly.

The novel coronavirus has exploited the blind spots of modern human society. In the case of gorillas and chimpanzees, viral infections were limited within the scope of the animals' movement. For that reason, the spread was halted with the death of the infected, and there was no great change in society and the way life is lived.

But in modern human society the movement of goods and people has become global, creating conditions apt for explosive viral transmission. Sports, music and other events have increased in number, and there are more opportunities for people to be packed in close together. It's not just this way in cities. Regional areas hold big festivals and events that attract tourists, and the movement of people across national and international borders has increased, too. Goods also are touched by many others on their way to being handed over to us. Cities, where eating out is popular, now bristle with restaurants and bars. More and more people enjoy singing and dancing in enclosed spaces such as karaoke booths. The novel coronavirus is denying all human behavior like this.

Now, when a total cure is not being developed, all that can be done to prevent infection is to avoid contact between people, and to exclude communal items that many individuals will touch. This is equivalent to cutting off our connection to other humans all brought up until now through evolution and the history of civilization. Over the long course of evolution, humans have increased their connections with others they can trust. With larger brains came a greater capacity for empathy, and the birth of music and language was also to further our social circles. Families and communities emerged, as did the agricultural, industrial and information revolutions that have brought us to the present day. If there is a cause behind all of these developments, it is because humans believed that connecting with many others was the more fortunate path.

For humans, among the most vital sources of happiness is getting together with people we care about, and encounters that satisfy our curiosity. Since long ago, dining has brought us together as it supported families and cooperative communities, and acted as a lubricant for meeting new people. Now with eating alone encouraged, and movements limited, humanity's fundamental desires are being repressed.

I have long felt that the internet, smartphones and other information devices impede physical interaction between people, and have warned that it would be better to limit the ways we use the technology. But in the present circumstances, I think that it would be better to use these devices wisely, and secure some minimal connection with others.

A gorilla is seen mediating between two others that were quarreling in this image provided by Kyoto University President Juichi Yamagiwa.

There are negative influences coming from the use of such technology, including hate speech and false information, as well as people being absorbed in smartphones, but in these circumstances where many people are forced to be shut inside their homes, it's better to frequently get in touch with each other. Without relying too much on our phones, we should interact appropriately with accurate information, and avoid deeply argumentative texts that could spark controversy. The most alarming thing is that through these separations we can lose empathy in society. That is the quality that most clearly separates us from apes, and there can be no human society without compassion.

It is unlikely people will lose the ability to speak in words, as they did in "Planet of the Apes," but there is the possibility that communication and relationships between humans will change because we are avoiding infection. If we are isolated from one another and become able only to think of our own benefit, then even if the pandemic is overcome, we won't be able to build a successful society. If separation of people continues, and international borders remain closed, then any nation could become even more intolerant of other countries, other ethnicities or other cultures. To avoid inciting those kinds of circumstances, people should reach out to each other from across borders, and search for a new kind of solidarity which is global in its scale.

One other concern I have is that each country could pursue drastic post-pandemic economic revitalization policies, bringing about greater destruction of the planet than we have seen up to now. Recent viral infectious diseases have emerged from the greater frequencies in which wild animals now come into contact as the natural world is torn up. If the development of natural resources goes further, then microorganisms and viruses we still don't know about that lie deep in the oceans, or dormant under glaciers, may be dragged out into the world of humans.

Even if we slow the hand of these developers, global warming will change the way animals live, and may bring with it a new threat. What is necessary for us now is a thorough consideration of what is most important for us as human beings with regard to activities of global countries as well as our everyday lives. I think that in the world after the coronavirus, that will produce a decisive result.

(Japanese original by Juichi Yamagiwa, President of Kyoto University)

-- Ebola hemorrhagic fever (EHF)

An infectious disease caused by the Ebola virus. Usually it is transmitted by bodily fluids from an infected person, as well as other substances, and presents sudden symptoms including a fever and headache. It has a high mortality rate of around 50%. Outbreaks have occurred repeatedly in Africa since the 1970s.

-- Juichi Yamagiwa

Juichi Yamagiwa was born in Tokyo in 1952. He is a Doctor of Science from Kyoto University. Working in the field of anthropology and primatology, his research on gorillas is known internationally. He has been a professor at Kyoto University, and fulfilled other roles at the institution including as the dean of its Graduate School and Faculty of Science, before becoming its president in 2014. He has served as the president of the Science Council of Japan since 2017.

Also in The Mainichi

The Mainichi on social media