Nature Timespiral: The Evolution of Earth from the Big Bang
Since the dawn of humanity, we have looked questioningly to the heavens with great interest and awe. We’ve called on the stars to guide us, and have made some of humanity’s most interesting discoveries based on those observations. This also led us to question our existence and how we came to be in this moment in time.
That journey began some 14 billion years ago, when the Big Bang led to the universe emerging from a hot, dense sea of matter and energy. As the cosmos expanded and cooled, they spawned galaxies, stars, planets, and eventually, life.
In the above visualization, Pablo Carlos Buddassi illustrates this journey of epic proportions in the intricately designed Nature Timespiral, depicting the various eras that the Earth has gone through since the inception of the universe itself.
Evolutionary Timeline of the World
Not much is known about what came before the Big Bang, but we do know that it launched a sequence of events that gave rise to the universal laws of physics and the chemical elements that make up matter. How the Earth came about, and life subsequently followed, is a wondrous story of time and change.
Let’s look at what transpired after the Big Bang to trace our journey through the cosmos.
The Big Bang and Hadean Eon
The Big Bang formed the entire universe that we know, including the elements, forces, stars, and planets. Hydrogen and massive dissipation of heat dominated the initial stages of the universe.
During a time span known as the Hadean eon, our Solar System formed within a large cloud of gas and dust. The Sun’s gravitational pull brought together spatial particles to create the Earth and other planets, but they would take a long time to reach their modern forms.
Archean Eon (4 – 2.5 billion years ago)
After its initial formation, the surface of the Earth was extremely hot and entirely liquid. This subsequent eon saw the planet cool down massively, solidifying some of the liquid surface and giving rise to oceans and continents, as well as the first recorded history of rocks.
Early in this time frame, known as the Archean eon, life appeared on Earth. The oldest discovered fossils, consisting of tiny, preserved microorganisms, date to this eon roughly 3.5 billion years ago.
Paleoproterozoic Era (2.5 – 1.6 billion years ago)
The first era of the Proterozoic Eon, the Paleoproterozoic, was the longest in Earth’s geological history. Tectonic plates arose and landmasses shifted across the globe—it was the beginning of the formation of the Earth we know today.
Cyanobacteria, the first organisms using photosynthesis, also appeared during this period. Their photosynthetic activity brought about a rapid upsurge in atmospheric oxygen, resulting in the Great Oxidation Event. This killed off many primordial anaerobic bacterial groups but paved the way for multicellular life to grow and flourish.
Mesoproterozoic Era (1.6 – 1 billion years ago)
The Mesoproterozoic occurred during what is known as the “boring billion” stage of Earth’s history. That is due to a lack of widespread geochemical activity and the relative stability of the ocean carbon reservoirs.
But this era did see the break-up of the supercontinents and the formation of new continents. This period also saw the first noted case of sexual reproduction among organisms and the probable appearance of multicellular organisms and green plants.
Neoproterozoic Era (1 billion – 542.0 million years ago)
In some respects, the Neoproterozoic era is one of the most profound time periods in Earth’s history. It bookends two major moments in the planet’s evolutionary timeline, with predominantly microbial life on one side, and the introduction of diverse, multicellular organisms on the other.
At the same time, Earth also experienced severe glaciations known as the Cryogenian Period and its first ice age, also known as Snowball Earth.
The era saw the formation of the ozone layer and the earliest evidence of multicellular life, including the emergence of the first hard-shelled animals, such as trilobites and archaeocyathids.
Paleozoic Era (541 million – 252 million years ago)
The Paleozoic is best known for ushering in an explosion of life on Earth, with two of the most critical events in the history of animal life. At its beginning, multicellular animals underwent a dramatic Cambrian explosion in aquatic diversity, and almost all living animals appeared within a few millions of years.
At the other end of the Paleozoic, the largest mass extinction in history resulted in 96% of marine life and 70% of terrestrial life dying out. Halfway between these events, animals, fungi, and plants colonized the land, and the insects took to the air.
Mesozoic Era (252 million – 66 million years ago)
The Mesozoic was the Age of Reptiles. Dinosaurs, crocodiles, and pterosaurs ruled the land and air. This era can be subdivided into three periods of time:
- Triassic (252 to 201.3 million years ago)
- Jurassic (201.3 to 145 million years ago)
- Cretaceous (145 to 66 million years ago)
The rise of the dinosaurs began at the end of the Triassic Period. A fossil of one of the earliest-known dinosaurs, a two-legged omnivore roughly three feet long-named Eoraptor, is dated all the way back to this time.
Scientists believe the Eoraptor (and a few other early dinosaurs still being discovered today) evolved into the many species of well-known dinosaurs that would dominate the planet during the Jurassic period. They would continue to flourish well into the Cretaceous period, when it is widely accepted that the Chicxulub impactor, the plummeting asteroid that crashed into Earth off the coast of Mexico, brought about the end of the Age of Reptiles.
Cenozoic Era (66 million – Present Day)
After the end of the Age of Dinosaurs, this era saw massive adaptations by natural flora and fauna to survive. The plants and animals that formed during this era look most like those on Earth today.
The earliest forms of modern mammals, amphibians, birds, and reptiles can be traced back to the Cenozoic. Human history is entirely contained within this period, as apes developed through evolutionary pressure and gave rise to the present-day human being or Homo sapiens.
Compared to the evolutionary timeline of the world, human history has risen quite rapidly and dramatically. Going from our first stone tools and the Age of the Kings to concrete jungles with modern technology may seem like a long journey, but compared to everything that came before it, is but a brief blink of an eye.
*Editor’s note: An earlier version of this article contained errors in the header graphic and an incorrect citation, and has since been updated.
This article was published as a part of Visual Capitalist's Creator Program, which features data-driven visuals from some of our favorite Creators around the world.
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.
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.
Is it Possible to Bring Back Extinct Animal Species?
This graphic provides an introduction to de-extinction, a field of biology focused on reviving extinct animal species.
Is it Possible to Bring Back Extinct Animal Species?
View a higher resolution version of this infographic.
Humanity has been tinkering with natural life for thousands of years.
We’ve become remarkably good at it, too—to date, we’ve modified bacteria to produce drugs, created crops with built-in pesticides, and even made a glow-in-the-dark dog.
However, despite our many achievements in the realm of genetic engineering, one thing we’re still working on is bringing extinct animals back to life.
But scientists are working on it. In fact, there’s a whole field of biology that’s focused on reviving extinct species.
Using data published in Science News, this graphic provides a brief introduction to the fascinating field of science known as resurrection biology—or de-extinction.
The Benefits of De-Extinction
First thing’s first—what is the point of bringing back extinct animals?
There are a number of research benefits that come with de-extinction. For instance, some scientists believe studying previously extinct animals and looking at how they function could help fill some gaps in our current theories around evolution.
De-extinction could also have a beneficial impact on the environment. That’s because when an animal goes extinct, its absence has a ripple effect on all the flora and fauna involved in that animal’s food web.
Because of this, reintroducing previously extinct species back into their old ecosystems could help rebalance and restore off-kilter environments.
There’s even a possibility that de-extinction could slow down global warming. Scientist Sergey Zimov believes that, if we were to reintroduce an animal that’s similar to the woolly mammoth back to the tundra, it could help repopulate the area, regrow ancient plains, and possibly slow the melting of the ice caps.
How Does it Work?
The key element that’s needed to re-create a species is its DNA.
Unfortunately, DNA slowly degrades, and once it’s gone completely, there’s no way to recover it. Researchers believe DNA has a half-life of 521 years, so after 6.8 million years, it’s believed to be completely gone.
That’s why species like dinosaurs have virtually no chance of de-extinction. However, many organisms that went extinct more recently, like the dodo, could have a chance of conservation.
When it comes to de-extinction, there are three main techniques:
This is the only way to create an exact DNA replica of something.
However, a complete genome is needed for this, so this form of genetic rescue is most effective with recently-lost species, or species that are nearing extinction.
② Genome Editing
Genome editing is the manipulation of DNA to mimic extinct DNA.
There are several ways to do this, but in general, the process involves researchers manipulating the genomes of living species to make a new species that closely resembles an extinct one.
Because it’s not an exact copy of the extinct species’ DNA, this method will create a hybrid species that only resembles the extinct animal.
A form of breeding where a distinguishing trait from an extinct species (a horn or a color pattern) is bred back into living populations.
This requires the trait to still exist in some frequency in similar species, and the trait is selectively bred back into popularity.
Like genome editing, this method does not resurrect an extinct species, but resurrects the DNA and genetic diversity that gave the extinct species a distinguishing trait.
Is Bringing Back Extinct Animal Species Really Worth it?
While there’s a ton of buzz and potential around the idea of bringing back extinct animal species, there are a few critics that believe our efforts would be better spent on other things.
Research on the economics of de-extinction found that the money would go farther if it was invested into conservation programs for living species—approximately two to eight times more species could be saved if invested in existing conversation programs.
In an article in Science, Joseph Bennett, a biologist at Carleton University in Ottawa, said “if [a] billionaire is only interested in bringing back a species from the dead, power to him or her.”
Bennett added, “however, if that billionaire is couching it in terms of it being a biodiversity conservation, then that’s disingenuous. There are plenty of species out there on the verge of extinction now that could be saved with the same resources.”
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