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Visualizing the Relationship Between Cancer and Lifespan

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Visualizing the Relationship Between Cancer and Lifespan

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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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The Anthropocene: A New Epoch in the Earth’s History

We visualize Earth’s history through the geological timeline to reveal the planet’s many epochs, including the Anthropocene.

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The Anthropocene: A New Epoch in the Earth’s History

Over the course of Earth’s history, there have been dramatic shifts in the landscape, climate, and biodiversity of the planet. And it is all archived underground.

Layers of the planet’s crust carry evidence of pivotal moments that changed the face of the Earth, such as the ice age and asteroid hits. And scientists have recently defined the next major epoch using this geological time scale—the Anthropocene.

In this infographic we dig deep into the Earth’s geological timeline to reveal the planet’s shift from one epoch to another, and the specific events that separate them.

Understanding the Geological Timeline

The Earth’s geological history is divided into many distinct units, from eons to ages. The time span of each varies, since they’re dependent on major events like new species introduction, as well as how they fit into their parent units.

Geochronologic unitTime spanExample
EonSeveral hundred million years to two billion yearsPhanerozoic
EraTens to hundreds of millions of yearsCenozoic
PeriodMillions of years to tens of millions of yearsQuaternary
EpochHundreds of thousands of years to tens of millions of yearsHolocene
AgeThousands of years to millions of yearsMeghalayan

Note: Subepochs (between epochs and ages) have also been ratified for use in 2022, but are not yet clearly defined.

If we were to cut a mountain in half, we could notice layers representing these changing spans of time, marked by differences in chemical composition and accumulated sediment.

Some boundaries are so distinct and so widespread in the geologic record that they are known as “golden spikes.” Golden spikes can be climatic, magnetic, biological, or isotopic (chemical).

Earth’s Geological Timeline Leading Up to the Anthropocene

The Earth has gone through many epochs leading up to the modern Anthropocene.

These include epochs like the Early Devonian, which saw the dawn of the first early shell organisms 400 million years ago, and the three Jurassic epochs, which saw dinosaurs become the dominant terrestrial vertebrates.

Over the last 11,700 years, we have been living in the Holocene epoch, a relatively stable period that enabled human civilization to flourish. But after millennia of human activity, this epoch is quickly making way for the Anthropocene.

EpochIts start (MYA = Million Years Ago)
Anthropocene70 Years Ago
Holocene0.01 MYA
Pleistocene2.58 MYA
Pliocene5.33 MYA
Miocene23.04 MYA
Oligocene33.90 MYA
Eocene56.00 MYA
Paleocene66.00 MYA
Cretaceous145.0 MYA
Jurassic201.40 MYA
Triassic251.90 MYA
Lopingian259.50 MYA
Guadalupian273.00 MYA
Cisuralian300.00 MYA
Pennsylvanian323.40 MYA
Mississippian359.30 MYA
Devonian419.00 MYA
Silurian422.70 MYA
Ludlow426.70 MYA
Wenlock432.90 MYA
Llandovery443.10 MYA
Ordovician486.90 MYA
Furongian497.00 MYA
Miaolingian521.00 MYA
Terreneuvian538.80 MYA

The Anthropocene is distinguished by a myriad of imprints on the Earth including the proliferation of plastic particles and a noticeable increase in carbon dioxide levels in sediments.

A New Chapter in Earth’s History

The clearest identified marker of this geological time shift, and the chosen golden spike for the Anthropocene, is radioactive plutonium from nuclear testing in the 1950s.

The best example has been found in the sediment of Crawford Lake in Ontario, Canada. The lake has two distinct layers of water that never intermix, causing falling sediments to settle in distinct layers at its bed over time.

While the International Commission on Stratigraphy announced the naming of the new epoch in July 2023, Crawford Lake is still in the process of getting approved as the site that marks the new epoch. If selected, our planet will officially enter the Crawfordian Age of the Anthropocene.

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