Animation: The World's Rapid Rise in Life Expectancy, in Just 13 Seconds
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Animation: The World’s Rapid Rise in Life Expectancy, in Just 13 Seconds

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Pandemics have been a thorn in the side of humanity for thousands of years.

But despite COVID-19 being the latest iteration in these deadly infectious diseases to strike, we are experiencing it in a very different public health context than past pandemics throughout history.

A New Era of Medicine

Since the onset of the 1918 influenza pandemic, humans have seen a monumental and undeniable leap forward in the health sciences.

Advancements in everything from sanitation to pharmacology have spread globally, resulting in a health landscape that is almost unrecognizable from those during past disease outbreaks.

While it’s not possible to demonstrate every life-saving advancement in medical knowledge in just one chart, the rise of life expectancy at birth can be a useful proxy. In just 65 years, modern medicine has propelled countries around the world to see a rapid surge in this crucial measure:

The above animation, which comes to us from Reddit user u/karthikvcp, provides a helpful reminder of just how much has changed in public health over recent decades.

And although countries seem to move up following a linear line, here’s another look at this surge in global life expectancy on a much longer timeline — since the dawn of human civilization:

Historical life expectancy since 10000 BC

Yes, for most of human history, it’s been estimated that global life expectancy at birth has bounced between 20 and 30 years.

Beginning approximately in the year 1820, global life expectancy started its exponential ascent, seeing its most impressive gains after 1950 as modern sanitation and medical advancements began to trickle down to developing nations.

Life Expectancy: Interactive Version

While the 13-second animation is a fast summation of the revolution that has occurred in public health, here’s an interactive version from Our World in Data that plots the exact same data:

Still at the Mercy of Nature

Although our understandings of epidemiology and disease treatment are better than they’ve been during previous pandemics, other aspects of modern society have still compounded to make COVID-19 a complex challenge for public health officials.

Population density, frequency of travel, and a modern tendency to gather in large groups are all factors that have contributed to an initial spread of the virus that was faster and more widespread than anything humanity has ever seen.

And so, even with our increased level of medical sophistication, it seems we are still at the mercy of Mother Nature — just in a very different set of circumstances than in pandemics past.

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Science

Visualizing the Relationship Between Cancer and Lifespan

New research links mutation rates and lifespan. We visualize the data supporting this new framework for understanding cancer.

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Cancer and lifespan

A Newfound Link Between Cancer and Aging?

A new study in 2022 reveals a thought-provoking relationship between how long animals live and how quickly their genetic codes mutate.

Cancer is a product of time and mutations, and so researchers investigated its onset and impact within 16 unique mammals. A new perspective on DNA mutation broadens our understanding of aging and cancer development—and how we might be able to control it.

Mutations, Aging, and Cancer: A Primer

Cancer is the uncontrolled growth of cells. It is not a pathogen that infects the body, but a normal body process gone wrong.

Cells divide and multiply in our bodies all the time. Sometimes, during DNA replication, tiny mistakes (called mutations) appear randomly within the genetic code. Our bodies have mechanisms to correct these errors, and for much of our youth we remain strong and healthy as a result of these corrective measures.

However, these protections weaken as we age. Developing cancer becomes more likely as mutations slip past our defenses and continue to multiply. The longer we live, the more mutations we carry, and the likelihood of them manifesting into cancer increases.

A Biological Conundrum

Since mutations can occur randomly, biologists expect larger lifeforms (those with more cells) to have greater chances of developing cancer than smaller lifeforms.

Strangely, no association exists.

It is one of biology’s biggest mysteries as to why massive creatures like whales or elephants rarely seem to experience cancer. This is called Peto’s Paradox. Even stranger: some smaller creatures, like the naked mole rat, are completely resistant to cancer.

This phenomenon motivates researchers to look into the genetics of naked mole rats and whales. And while we’ve discovered that special genetic bonuses (like extra tumor-suppressing genes) benefit these creatures, a pattern for cancer rates across all other species is still poorly understood.

Cancer May Be Closely Associated with Lifespan

Researchers at the Wellcome Sanger Institute report the first study to look at how mutation rates compare with animal lifespans.

Mutation rates are simply the speed at which species beget mutations. Mammals with shorter lifespans have average mutation rates that are very fast. A mouse undergoes nearly 800 mutations in each of its four short years on Earth. Mammals with longer lifespans have average mutation rates that are much slower. In humans (average lifespan of roughly 84 years), it comes to fewer than 50 mutations per year.

The study also compares the number of mutations at time of death with other traits, like body mass and lifespan. For example, a giraffe has roughly 40,000 times more cells than a mouse. Or a human lives 90 times longer than a mouse. What surprised researchers was that the number of mutations at time of death differed only by a factor of three.

Such small differentiation suggests there may be a total number of mutations a species can collect before it dies. Since the mammals reached this number at different speeds, finding ways to control the rate of mutations may help stall cancer development, set back aging, and prolong life.

The Future of Cancer Research

The findings in this study ignite new questions for understanding cancer.

Confirming that mutation rate and lifespan are strongly correlated needs comparison to lifeforms beyond mammals, like fishes, birds, and even plants.

It will also be necessary to understand what factors control mutation rates. The answer to this likely lies within the complexities of DNA. Geneticists and oncologists are continuing to investigate genetic curiosities like tumor-suppressing genes and how they might impact mutation rates.

Aging is likely to be a confluence of many issues, like epigenetic changes or telomere shortening, but if mutations are involved then there may be hopes of slowing genetic damage—or even reversing it.

While just a first step, linking mutation rates to lifespan is a reframing of our understanding of cancer development, and it may open doors to new strategies and therapies for treating cancer or taming the number of health-related concerns that come with aging.

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Misc

Explainer: What to Know About Monkeypox

What is monkeypox, and what risk does it pose to the public? This infographic breaks down the symptoms, transmission, and more.

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Explainer: What to Know About Monkeypox

The COVID-19 pandemic is still fresh in the minds of the people around the world, so it comes as no surprise that recent outbreaks of another virus are grabbing headlines.

Monkeypox outbreaks have now been reported in multiple countries, and it has scientists paying close attention. For everyone else, numerous questions come to the surface:

  • How serious is this virus?
  • How contagious is it?
  • Could monkeypox develop into a new pandemic?

Below, we answer these questions and more.

What is Monkeypox?

Monkeypox is a virus in the Orthopoxvirus genus which also includes the variola virus (which causes smallpox) and the cowpox virus. The primary symptoms include fever, swollen lymph nodes, and a distinctive bumpy rash.

There are two major strains of the virus that pose very different risks:

  • Congo Basin strain: 1 in 10 people infected with this strain have died
  • West African strain: Approximately 1 in 100 people infected with this strain died

At the moment, health authorities in the UK have indicated they’re seeing the milder strain in patients there.

Where did Monkeypox Originate From?

The virus was originally discovered in the Democratic Republic of Congo in monkeys kept for research purposes (hence the name). Eventually, the virus made the jump to humans more than a decade after its discovery in 1958.

It is widely assumed that vaccination against another similar virus, smallpox, helped keep monkeypox outbreaks from occurring in human populations. Ironically, the successful eradication of smallpox, and eventual winding down of that vaccine program, has opened the door to a new viral threat. There is now a growing population of people who no longer have immunity against the virus.

Now that travel restrictions are lifting in many parts of the world, viruses are now able to hop between nations again. As of the publishing of this article, a handful of cases have now been reported in the U.S., Canada, the UK, and a number of European countries.

On the upside, contact tracing has helped authorities piece together the transmission of the virus. While cases are rare in Europe and North America, it is considered endemic in parts of West Africa. For example, the World Health Organization reports that Nigeria has experienced over 550 reported monkeypox cases from 2017 to today. The current UK outbreak originated from an individual who returned from a trip to Nigeria.

Could Monkeypox become a new pandemic?

Monkeypox, which primarily spreads through animal-to-human interaction, is not known to spread easily between humans. Most individuals infected with monkeypox pass the virus to between zero and one person, so outbreaks typically fizzle out. For this reason, the fact that outbreaks are occurring in several countries simultaneously is concerning for health authorities and organizations that monitor viral transmission. Experts are entertaining the possibility that the virus’ rate of transmission has increased.

Images of people covered in monkeypox lesions are shocking, and people are understandably concerned by this virus, but the good news is that members of the general public have little to fear at this stage.

I think the risk to the general public at this point, from the information we have, is very, very low.
–Tom Inglesby, Director, Johns Hopkins Center for Health Security

» For up-to-date information on monkeypox cases, check out Global.Health’s tracking spreadsheet

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