Viruses and Humanity — An Old Story

17th-century German “plague panel” depicting the triumph of death. Panels of this kind were placed on the walls of houses to warn against the plague. A plague epidemy raged in Augsburg, Bavaria between 1607 and 1636.

Amid funny television sitcoms, exciting football games, and eating out at your favorite Thai food restaurant, it’s easy to forget about plagues. But they’ve always been part of human existence. Millions of us have died with these periodic outbreaks. Fortunately for us, we (well, most of us) now understand that these are not curses sent by angry gods but rather a natural invasion of one or another micro-organism seeking its own place in the sun. Er, in us.

A side note here: A virus is technically NOT an organism like bacteria but rather a microscopic parasite much smaller than bacteria which can’t reproduce outside of a host body.


A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. [Since their discovery in] 1898, more than 6,000 virus species have been described in detail, of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.[2]

So keeping in mind that these infinitesimally small entities can’t move, reproduce, or live except inside another organism, we can look back and marvel at the enormous impact these entities have wrought on the human race. Research has found that an astonishing thirty percent of all protein adaptations for humans have been driven by viruses.[3],[4]  As noted in the 2007 scientific article by Christian W. McMillan, “Epidemic Disease and Their Effect on History,”

There is perhaps no longer-lasting historical relationship than that between humans and disease, especially epidemic disease. The relationship predates agriculture, the formation of cities, and, if current research on the emergence of diseases like tuberculosis is correct, human migration out of Africa. From the earliest times to the present, epidemics have affected human history in myriad ways: demographically, culturally, politically, financially, and biologically. Humans have never known a time in history when epidemics did not loom large.[5]

Studies of prehistory suggest that bottlenecks in human evolution may have been the result of epidemics where most of a population died off leaving only a few survivors to repopulate that area or continent. Aside from restarting populations, these virulent invaders also affect the genome by selecting survivors with particular DNA profiles which then become the prevailing type. Epigenetic effects also become part of the remaining population, an inheritance by mechanisms other than through the DNA sequence of genes. … It works through chemical tags added to chromosomes that function to switch genes on or off.

The discovery of a 5,000-year-old house in China filled with skeletons is evidence of a deadly epidemic. (Image credit: Photo courtesy Chinese Archaeology)

The earliest evidence of a widespread plague is found in China where the 5,000 year old remains of prehistoric villagers had been stuffed inside a house that was subsequently burned to the ground.

No age group was spared, as the skeletons of juveniles, young adults and middle-age people were found inside the house. The archaeological site is now called “Hamin Mangha” and is one of the best-preserved prehistoric sites in northeastern China. Archaeological and anthropological study indicates that the epidemic happened quickly enough that there was no time for proper burials, and the site was not inhabited again.

Before the discovery of Hamin Mangha, another prehistoric mass burial that dates to roughly the same time period was found at a site called Miaozigou, in northeastern China. Together, these discoveries suggest that an epidemic ravaged the entire region.[6]

There’s no question that epidemics have changed not only the physical make-up of humanity but also the course of history. Among the earliest records of such events are Sanskrit notations from 1200 BC documenting a type of flu that spread through Babylon, Central Asia, Mesopotamia and Southern Asia. Since these were the first areas of the world to create written records, it follows these would be the places where such chronicles would exist. But without doubt, plagues didn’t select only advanced societies to infect.

The first well documented outbreak of epidemic disease may be the Plague of Athens, an illness which Thucydides described as starting in the head with illness that included fever, redness and inflammation in the eyes, sore throat that led to bleeding, sneezing, coughing, vomiting, and ulcers on the body. The opinions of scholars on the cause range from hemorrhagic fevers such as Ebola to epidemic typhus fever.

The Plague of Athens was an epidemic that devastated the city-state of Athens in ancient Greece during the second year of the Peloponnesian War (430 BC) when an Athenian victory still seemed within reach. The plague killed an estimated 75,000 to 100,000 people and is believed to have entered Athens through Piraeus, the city’s port and sole source of food and supplies. Much of the eastern Mediterranean also saw an outbreak of the disease, albeit with less impact.

The plague had serious effects on Athens’ society, resulting in a lack of adherence to laws and religious belief. In response laws became stricter, resulting in the punishment of non-citizens claiming to be Athenian. In addition, Pericles, the leader of Athens, died from the plague. The plague returned twice more, in 429 BC and in the winter of 427/426 BC. Some 30 pathogens have been suggested as having caused the plague.[7]

The Roman Empire suffered its first massive epidemic in the so-called Antonine Plague circa 165-180 AD. Soldiers returning to Rome from campaigning along with empire’s boundaries developed what scientists now believe was smallpox. The result in Rome’s crowded streets was the death of up to five million people. The long-lasting outbreak ended the long peaceful “Pax Romana” for the empire, with barbarian invasions weakening the government and undermining the old religious belief systems with their multiple gods, opening the door to the growth of Christianity.

The remains found where a bonfire incinerated many of the victims of the Cyprian Plague epidemic in the city of Thebes in Egypt. (Image credit: N.Cijan/Associazione Culturale per lo Studio dell’Egitto e del Sudan ONLUS)

About 100 years later, a new virus hit the Roman Empire that wiped out over one million people.  “Named after St. Cyprian, a bishop of Carthage (a city in Tunisia) who described the epidemic as signaling the end of the world, the Plague of Cyprian is estimated to have killed 5,000 people a day in Rome alone. In 2014, archaeologists in Luxor found what appears to be a mass burial site of plague victims. Their bodies were covered with a thick layer of lime (historically used as a disinfectant). Archaeologists found three kilns used to manufacture lime and the remains of plague victims burned in a giant bonfire.”[8] Thought by scholars to be another outbreak of smallpox, the disease is believed to have transferred from animal hosts to humanity and may have included measles.  The outbreak continued for nearly twenty years and contributed greatly to the fall of the empire.

In 541-542, up to 100 million died across Europe and West Asia in the epidemic known first as the Plague of Justinian (emperor of the Eastern Roman Empire at Istanbul),[9] wiping out up to 50% of the European population. The disease, later known as the Black Death (Bubonic plague) hopped over to the British Isles 100 years later and reappeared in 746-747 in the Byzantine Empire, West Asia, and Africa to ill an unknown number of victims. Meanwhile, an outbreak of smallpox in Japan killed about half the population.

A bubo on the upper thigh of a person infected with bubonic plague. Wikipedia

The Black Death is perhaps the most famous of pandemics, believed carried by fleas and also spread by human to human contact. Credited with depopulating Europe during the Middle Ages, the outbreak lasted from 1331-1353 and wiped out up to 200 million people, up to 60% of the population.

The Black Death, also known as the Pestilence and the Plague, was the most fatal pandemic recorded in human history… the bacterium Yersinia pestis is believed to have been the cause. Y. pestis infection most commonly results in bubonic plague… it most likely originated in Central Asia or East Asia, from where it travelled along the Silk Road, reaching Crimea by 1347. From there, it was most likely carried by fleas living on the black rats that travelled on Genoese merchant ships, spreading throughout the Mediterranean Basin and reaching Africa, Western Asia, and the rest of Europe via Constantinople, Sicily, and the Italian Peninsula.[10]

A recurrence of Black Death in the mid-1500s wiped out over 20,000 Londoners and another estimated 20,000 thirty years later. Various plague outbreaks around the globe continued to occur, but the biggest death toll in Britain of over 100,000 people happened in the mid-1600s. Subsequent ripples of this infection have made way through various populations since that time, and the virus remains active even in the United States.

One of greatest advantages Europeans had in its conquest of the New World were the diseases that came with them. Smallpox, measles, and yellow fever wiped out upwards of twenty million natives who had never been exposed and had no immunity. For a full list of epidemics and their impact, see

Today, we have the advantage of knowing such disease outbreaks are not signals of the end of the world wrought by supernatural powers, but rather by invisible creatures that breed in our cells. We shouldn’t be at all surprised that yet another such eruption has occurred, given the role such entities have played throughout human history. Due to modern science, we stand at a far greater advantage than any of our forefathers in fighting such devastating illnesses. But as we’re witnessing, science is only as effective as the public and our leaders will allow.

And as far as science goes, no one yet knows exactly how COVID-19 kills people, or how long asymptomatic carriers continue to spread the virus, or whether those who’ve survived infection are vulnerable to re-infection. The horizon for a vaccine remains distant despite our advanced technology, and no one can predict whether a vaccine will be more or less as effective as the flu vaccine at its average of 50%.

Even when (if) we manage to craft an effective vaccine and discover treatments that address the viral infection with relatively useful interventions, we still must face the fact that the flip side of our advanced scientific status in the modern world is a far greater rate of intercontinental disease transmission and expansion of human population into areas previously left to nature, to name only two.

There will be new viruses.



  1. With new viruses occurring approximately ONE EACH YEAR, the majority are viruses originating from an animal host. Of the many factors responsible, CHANGES TO LOCAL ECOSYSTEMS that perturb the balance between pathogen and principal host species is one of the major drivers, together with increasing urbanization of mankind and changes in human behavior. Many emerging viruses have RNA genomes and as such are capable of rapid mutation and selection of new variants in the face of environmental changes in host numbers and available target species. [Emphasis mine]
  2. Scientists studying ice cores from melting glaciers have discovered previously unknown viruses that are tens of millions of years old. “The experiment revealed 33 groups of virus genuses (also known as genera) in the ice cores. Of these, 28 were previously unknown to science, the researchers said. “The microbes differed significantly across the two ice cores,” the researchers wrote in the study, ‘presumably representing the very different climate conditions at the time of deposition.’” See
  3. We still have plenty of existing, known viruses waiting at our doorstep for a fresh host population. See
  4. Graphics of viruses.









