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.
Visualized: The Many Shapes of Bacteria
We introduce the visual diversity of bacteria and illustrate how they are categorized by appearance—from a single cell to an entire colony.
Invisible Diversity: The Many Shapes of Bacteria
Bacteria are amazing.
They were the first form of life to appear on Earth almost 3.8 billion years ago.
They make up the second most abundant lifeform, only outweighed by plants.
And most interesting of all: they exist in practically every environment on our planet, including areas where no other lifeforms can survive. As a result, bacteria exhibit a wide variety of appearances, behaviors, and applications similar to the lifeforms we see in our everyday lives.
The incredible diversity of bacteria goes underappreciated simply because they are invisible to the naked eye. Here, we illustrate how researchers classify these creatures on the basis of appearance, giving you a glimpse into this microscopic world.
A Life of Culture
Though bacteria may look similar to other microorganisms like fungi or plankton, they are entirely unique on a microscopic and genetic level.
Bacteria make up one of the three main domains of life. All life shares its earliest ancestor with this group of microbes, alongside two other domains: the Archaea and the Eukarya.
Archaea are very similar to bacteria, but have different contents making up their cell walls.
Eukarya largely consists of complex, multicellular life, like fungi, plants, and animals. Bacteria are similar to its single-celled members because all bacteria are also unicellular. However, while all Eukarya have nuclear membranes that store genetic material, bacteria do not.
Bacteria have their genetic material free-floating within their cellular bodies. This impacts how their genes are encoded, how proteins are synthesized, and how they reproduce. For example, bacteria do not reproduce sexually. Instead, they reproduce on their own.
Bacteria undergo a process called binary fission, where any one cell divides into two identical cells, and so on. Fission occurs quickly. In minutes, populations can double rapidly, eventually forming a community of genetically identical microbes called a colony.
Colonies can be visible to the human eye and can take on a variety of different shapes, textures, sizes, colors, and behaviors. You might be familiar with some of these:
Superstars of a Tiny World
The following are some interesting bacterial species, some of which you may be familiar with:
This species is unusually large, ranging from 200-700 micrometers in length. They are also incredible picky, living only within the guts of sturgeon, a type of large fish.
D. radiodurans is a coccus-shaped species that can withstand 1,500 times the dose of radiation that a human can.
Despite being known famously for poisoning food and agriculture spaces from time to time, not all E.coli species are dangerous.
Down in the depths of a South African gold mine, this species thrives without oxygen, sunlight, or friends—it is the only living species in its ecosystem. It survives eating minerals in the surrounding rock.
Known for causing stomach ulcers, this spiral-shaped species has also been associated with many cancers that impact the lymphoid tissue.
Most living things cease to survive in cold temperatures, but P. halocryophillus thrives in permafrost in the High Arctic where temperatures can drop below -25°C/-12°F.
‘Bact’ to the Future
Despite their microscopic size, the contributions bacteria make to our daily lives are enormous. Researchers everyday are using them to study new environments, create new drug therapies, and even build new materials.
Scientists can profile the diversity of species living in a habitat by extracting DNA from an environmental sample. Known as metagenomics, this field of genetics commonly studies bacterial populations.
In oxygen-free habitats, bacteria continuously find alternative sources of energy. Some have even evolved to eat plastic or metal that have been discarded in the ocean.
The healthcare industry uses bacteria to help create antibiotics, vaccines, and other metabolic products. They also play a major role in a new line of self-building materials, which include “self-healing” concrete and “living bricks”.
Those are just a few of the many examples in which bacteria impact our daily lives. Although they are invisible, without them, our world would undoubtedly look like a much different place.
Visualizing the Evolution of Vision and the Eye
The eye is one of the most complex organs in biology. We illustrate its evolution from a simple photoreceptor cell to a complex structure.
Roadmapping the Evolution of the Eye
Throughout history, numerous creatures have evolved increasingly complex eyes in response to different selective pressures.
Not all organisms, however, experience the same pressures. It’s why some creatures today still have eyes that are quite simple, or why some have no eyes at all. These organisms exemplify eyes that are “frozen” in time. They provide snapshots of the past, or “checkpoints” of how the eye has transformed throughout its evolutionary journey.
Scientists study the genes, anatomy, and vision of these creatures to figure out a roadmap of how the eye came to be. And so, we put together an evolutionary graphic timeline of the eye’s different stages using several candidate species.
Let’s take a look at how the eye has formed throughout time.
Where Vision Comes From
The retina is a layer of nerve tissue, often at the back of the eye, that is sensitive to light.
When light hits it, specialized cells called photoreceptors transform light energy into electrical signals and send them to the brain. Then the brain processes these electrical signals into images, creating vision.
The earliest form of vision arose in unicellular organisms. Containing simple nerve cells that can only distinguish light from dark, they are the most common eye in existence today.
The ability to detect shapes, direction, and color comes from all of the add-ons evolution introduces to these cells.
Two Major Types of Eyes
Two major eye types are dominant across species. Despite having different shapes or specialized parts, improved vision in both eye types is a product of small, gradual changes that optimize the physics of light.
Simple eyes are actually quite complex, but get their name because they consist of one individual unit.
Some mollusks and all of the higher vertebrates, like birds, reptiles, or humans, have simple eyes.
Simple eyes evolved from a pigment cup, slowly folding inwards with time into the shape we recognize today. Specialized structures like the lens, cornea, and pupil arose to help improve the focus of light on the retina. This helps create sharper, clearer images for the brain to process.
Compound eyes are formed by repeating the same basic units of photoreceptors called ommatidia. Each ommatidium is similar to a simple eye, composed of lenses and photoreceptors.
Grouped together, ommatidia form a geodesic pattern that is commonly seen in insects and crustaceans.
Our understanding of the evolution of the compound eye is a bit murky, but we know that rudimentary ommatidia evolved into larger, grouped structures that maximize light capture.
In environments like caves, the deep subsurface, or the ocean floor where little to no light exists, compound eyes are useful for producing vision that gives even the slightest advantage over other species.
How Will Vision Evolve?
Our increasing dependency on technology and digital devices may be ushering in the advent of a new eye shape.
The muscles around the eye stretch to shift the lens when staring at something close by. The eye’s round shape elongates in response to this muscle strain.
Screen time with cellphones, tablets, and computers has risen dramatically over the years, especially during the COVID-19 pandemic. Recent studies are already reporting rises in childhood myopia, the inability to see far away. Since the pandemic, cases have increased by 17%, affecting almost 37% of schoolchildren.
Other evolutionary opportunities for our eyes are currently less obvious. It remains to be seen whether advanced corrective therapies, like corneal transplants or visual prosthetics, will have any long-term evolutionary impact on the eye.
For now, colored contacts and wearable tech may be our peek into the future of vision.
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