The History of Pandemics
Pan·dem·ic /panˈdemik/ (of a disease) prevalent over a whole country or the world.
As humans have spread across the world, so have infectious diseases. Even in this modern era, outbreaks are nearly constant, though not every outbreak reaches pandemic level as COVID-19 has.
Today’s visualization outlines some of history’s most deadly pandemics, from the Antonine Plague to the current COVID-19 event.
A Timeline of Historical Pandemics
Disease and illnesses have plagued humanity since the earliest days, our mortal flaw. However, it was not until the marked shift to agrarian communities that the scale and spread of these diseases increased dramatically.
Widespread trade created new opportunities for human and animal interactions that sped up such epidemics. Malaria, tuberculosis, leprosy, influenza, smallpox, and others first appeared during these early years.
The more civilized humans became – with larger cities, more exotic trade routes, and increased contact with different populations of people, animals, and ecosystems – the more likely pandemics would occur.
Here are some of the major pandemics that have occurred over time:
|Name||Time period||Type / Pre-human host||Death toll|
|Antonine Plague||165-180||Believed to be either smallpox or measles||5M|
|Japanese smallpox epidemic||735-737||Variola major virus||1M|
|Plague of Justinian||541-542||Yersinia pestis bacteria / Rats, fleas||30-50M|
|Black Death||1347-1351||Yersinia pestis bacteria / Rats, fleas||200M|
|New World Smallpox Outbreak||1520 – onwards||Variola major virus||56M|
|Great Plague of London||1665||Yersinia pestis bacteria / Rats, fleas||100,000|
|Italian plague||1629-1631||Yersinia pestis bacteria / Rats, fleas||1M|
|Cholera Pandemics 1-6||1817-1923||V. cholerae bacteria||1M+|
|Third Plague||1885||Yersinia pestis bacteria / Rats, fleas||12M (China and India)|
|Yellow Fever||Late 1800s||Virus / Mosquitoes||100,000-150,000 (U.S.)|
|Russian Flu||1889-1890||Believed to be H2N2 (avian origin)||1M|
|Spanish Flu||1918-1919||H1N1 virus / Pigs||40-50M|
|Asian Flu||1957-1958||H2N2 virus||1.1M|
|Hong Kong Flu||1968-1970||H3N2 virus||1M|
|HIV/AIDS||1981-present||Virus / Chimpanzees||25-35M|
|Swine Flu||2009-2010||H1N1 virus / Pigs||200,000|
|SARS||2002-2003||Coronavirus / Bats, Civets||770|
|Ebola||2014-2016||Ebolavirus / Wild animals||11,000|
|MERS||2015-Present||Coronavirus / Bats, camels||850|
|COVID-19||2019-Present||Coronavirus – Unknown (possibly pangolins)||535.0K (Johns Hopkins University estimate as of 7:33am PT, July 6, 2020)|
Despite the persistence of disease and pandemics throughout history, there’s one consistent trend over time – a gradual reduction in the death rate. Healthcare improvements and understanding the factors that incubate pandemics have been powerful tools in mitigating their impact.
Wrath of the Gods
In many ancient societies, people believed that spirits and gods inflicted disease and destruction upon those that deserved their wrath. This unscientific perception often led to disastrous responses that resulted in the deaths of thousands, if not millions.
In the case of Justinian’s plague, the Byzantine historian Procopius of Caesarea traced the origins of the plague (the Yersinia pestis bacteria) to China and northeast India, via land and sea trade routes to Egypt where it entered the Byzantine Empire through Mediterranean ports.
Despite his apparent knowledge of the role geography and trade played in this spread, Procopius laid blame for the outbreak on the Emperor Justinian, declaring him to be either a devil, or invoking God’s punishment for his evil ways. Some historians found that this event could have dashed Emperor Justinian’s efforts to reunite the Western and Eastern remnants of the Roman Empire, and marked the beginning of the Dark Ages.
Luckily, humanity’s understanding of the causes of disease has improved, and this is resulting in a drastic improvement in the response to modern pandemics, albeit slow and incomplete.
The practice of quarantine began during the 14th century, in an effort to protect coastal cities from plague epidemics. Cautious port authorities required ships arriving in Venice from infected ports to sit at anchor for 40 days before landing — the origin of the word quarantine from the Italian “quaranta giorni”, or 40 days.
One of the first instances of relying on geography and statistical analysis was in mid-19th century London, during a cholera outbreak. In 1854, Dr. John Snow came to the conclusion that cholera was spreading via tainted water and decided to display neighborhood mortality data directly on a map. This method revealed a cluster of cases around a specific pump from which people were drawing their water from.
While the interactions created through trade and urban life play a pivotal role, it is also the virulent nature of particular diseases that indicate the trajectory of a pandemic.
Scientists use a basic measure to track the infectiousness of a disease called the reproduction number — also known as R0 or “R naught.” This number tells us how many susceptible people, on average, each sick person will in turn infect.
Measles tops the list, being the most contagious with a R0 range of 12-18. This means a single person can infect, on average, 12 to 18 people in an unvaccinated population.
While measles may be the most virulent, vaccination efforts and herd immunity can curb its spread. The more people are immune to a disease, the less likely it is to proliferate, making vaccinations critical to prevent the resurgence of known and treatable diseases.
It’s hard to calculate and forecast the true impact of COVID-19, as the outbreak is still ongoing and researchers are still learning about this new form of coronavirus.
Urbanization and the Spread of Disease
We arrive at where we began, with rising global connections and interactions as a driving force behind pandemics. From small hunting and gathering tribes to the metropolis, humanity’s reliance on one another has also sparked opportunities for disease to spread.
Urbanization in the developing world is bringing more and more rural residents into denser neighborhoods, while population increases are putting greater pressure on the environment. At the same time, passenger air traffic nearly doubled in the past decade. These macro trends are having a profound impact on the spread of infectious disease.
As organizations and governments around the world ask for citizens to practice social distancing to help reduce the rate of infection, the digital world is allowing people to maintain connections and commerce like never before.
Editor’s Note: The COVID-19 pandemic is in its early stages and it is obviously impossible to predict its future impact. This post and infographic are meant to provide historical context, and we will continue to update it as time goes on to maintain its accuracy.
Update (March 15, 2020): We’ve adjusted the death toll for COVID-19, and will continue to update on a regular basis.
The 44 Closest Stars and How They Compare to our Sun
This graphic visualizes the 44 closest stars, revealing key facts such as distance from Earth, brightness, and whether potential planets are in orbit.
44 Closest Stars and How They Compare to our Sun
Humans have been fascinated by the stars in the night sky since the dawn of time.
We’ve been decoding the mysteries of celestial bodies for many centuries, but it is only in the last 200 years or so that we’ve been able to glean more detailed information on the lights that dot the night sky. Friedrich Bessel’s method of stellar parallax was a breakthrough in accurately measuring the positions of stars, and opened new doors in the effort to map our universe. Today, high-powered telescopes offer even more granular data on our cosmic neighborhood.
The infographic above, from Alan’s Factory Outlet, categorizes the 44 closest stars to Earth, examining the size, luminosity, constellations, systems, and potential planets of each star.
Our Nearest Stellar Neighbors
Our closest neighboring stars are all part of the same solar system: Alpha Centauri. This triple star system – consisting of Proxima Centauri, Alpha Centauri A, and Alpha Centauri B – attracts a lot of interest because it hosts planets, including one that may be similar to Earth.
The planet, Proxima Centauri b, is a lot closer to its star than Earth is to the Sun. However, because Proxima Centauri is a smaller and cooler red dwarf type star, the planet’s orbit is within the habitable zone. It’s thought that Proxima Centauri b receives approximately the same amount of solar energy as Earth does from our Sun.
Here’s a full list of the 44 of the closest stars to Earth:
|Star Name||Distance (light years)||MoE|
|α Centauri A||4.37||±0.0068|
|α Centauri B||4.37||±0.0068|
|Luyten 726-8 A||8.79||±0.012|
|Luyten 726-8 B||8.79||±0.012|
|EZ Aquarii A||11.11||±0.034|
|61 Cygni A||11.40||±0.0012|
|61 Cygni B||11.40||±0.0012|
|Struve 2398 A||11.49||±0.0012|
|Struve 2398 B||11.49||±0.0012|
|Groombridge 34 A||11.62||±0.0008|
|Groombridge 34 B||11.62||±0.0008|
|Kruger 60 A||13.07||±0.0052|
|Kruger 60 B||13.07||±0.0052|
|Wolf 424 A||14.05||±0.26|
|Van Maanen's star||14.07||±0.0023|
Even though we see many of these stars in the night sky, humans aren’t likely to see them in person any time soon. To put these vast distances into perspective, if the Voyager spacecraft were to travel to Proxima Centauri, it would take over 73,000 years to finally arrive.
The Brightest Stars in the Sky
The closest stars aren’t necessarily the ones most visible to us here on Earth. Here are the top 10 stars in terms of visual brightness from Earth:
|Rank||Proper name||Constellation||Visual magnitude (mV)||Distance (light years)|
|4||Rigil Kentaurus & Toliman||Centaurus||−0.27 (0.01 + 1.33)||4.4|
Excluding our Sun, the brightest star visible from Earth is Sirius, or the Dog Star. Sirius, which is about 25 times more luminous than the sun, visually punctuates the constellation Canis Major.
Filling in the Gaps
The next step in learning more about our surroundings in the cosmos will be seeing which of the stars listed above have planets orbiting them. So far, the 44 stars in the infographic have over 40 planets scattered among them, though new discoveries are made all the time.
With each new mission and discovery, we learn a little bit more about our pocket of the universe.
Visualizing the True Size of Land Masses from Largest to Smallest
Maps can distort the size and shape of countries. This visualization puts the true size of land masses together from biggest to smallest.
The True Size of Land Masses from Largest to Smallest
Is Greenland the size of the entire African continent?
But looking at a map based on the Mercator projection, you would think so.
Today’s infographic comes from the design studio Art.Lebedev and shows the true size of the world’s land masses in order from largest to smallest using data from NASA and Google.
Check out the actual shape and size of each land mass without any distortions.
Distorting Reality: Mercator Misconceptions
Maps can deceive your eyes but they are still powerful tools for specific purposes. In 1569, the legendary cartographer, Gerardus Mercator, created a new map based on a cylindrical projection of sections of the Earth. These types of maps were suited for nautical navigation since every line on the sphere is a constant course, or loxodrome.
Despite the map’s nautical utility, the Mercator projection has an unwanted downside. The map type increases the sizes of land masses close to the poles (such as in North America, Europe, or North Asia) as a side effect. As a result, Canada and Russia appear to take up approximately 25% of the Earth’s surface, when in reality these nations only occupy 5%.
“Things are not always what they seem; the first appearance deceives many.” – Phaedrus
This collection of images above represents the world’s land masses in their correct proportions. Measurements are based on Google Maps 2016 and NASA Earth Observatory maps, with calculations based on the WGS84 reference ellipsoid, or more simply, a specific model of the Earth’s shape in two dimensions.
We take for granted Google Maps and satellite imaging. Making these accurate representations is no small task – the designers went through six steps and many different iterations of the graphic.
Countries are arranged by descending size and shown without external or dependent territories. For example, the total area for the contiguous United States shown does not include Hawaii, Alaska, or overseas territories.
Top 10 Largest Land Masses
Although Mercator maps distort the size of land masses in the Northern Hemisphere, many of these countries still cover massive territories.
|United States (contiguous)||7,654,643|
The top 10 land masses by size account for 55% of the Earth’s total land. The remainder is split by the world’s 195 or so other countries.
Top 10 Smallest Land Masses
Here are the 10 tiniest jurisdictions highlighted on the map:
While the Earth’s land surface has been claimed by many authorities, the actual impact of human activity is less than one would think.
Human Impact: Humbled by Nature
Political borders have claimed virtually every piece of land available. Despite this, only 20% of land on the planet has been visibly impacted by human activity, and only 15% of Earth’s land surface is formally under protection.
The remaining 80% of the land hosts natural ecosystems that help to purify air and water, recycle nutrients, enhance soil fertility, pollinate plants, and break down waste products. The value of maintaining these services to the human economy is worth trillions of U.S. dollars each year.
While some nations are not as big as they look on the map, every piece of land counts.
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