10 Imagine if Pangaea had never split off.

Between 300 million and 200 million years ago, the Earth’s continents were joined as one massive landmass known as “Pangaea.” As the continents gradually drifted apart, unique events occurred, such as India slamming into the underside of Asia and forcing the Himalayas to rise. Just imagine a world where the enormous Tethys ocean was remained at the center and Pangaea still ruled over one side. What if tectonic drift had never occurred?

Because new species mostly emerge as a result of geographic isolation, which in turn produces selective pressures and the creation of novel genetic features, our world would likely be less biologically varied if this didn’t happen. Due to the limited range of moisture-bearing clouds, a large portion of the interior would remain parched. Due to the extra mass influencing Earth’s rotation, the majority of the planet’s landmass would be located in the scorching equatorial zones.

In the summer, Earth would be around 20 degrees Celsius (36 degrees Fahrenheit) hotter than our planet. Massive typhoons would also hit the area because of the Tethys’s immense circulation system, which would be unbroken by anything other than island chains or shallow continental shelf.

Due in significant part to the fact that mammals expede more water than reptiles do, reptiles ruled the immense desert regions of the second historical Pangaean epoch, while mammals flourished in the tropical and water-rich monsoon regions. Procolophonoids, who looked like stocky lizards and are distantly related to current turtles, inhabited the temperate regions, according to studies of a transection of Pangaean fossil records. In contrast, traversodont cynodonts, an extinct order of pre-mammals, dominated the tropical regions.

Various mammalian and other tropical animals would have inhabited the hot and humid parts of a current Pangaea, while reptiles and pseudoreptiles would have ruled the sway in the arid interior and temperate zones.

9 Imagine a World Without Earth’s Tilt.

The seasons change throughout the year because the Earth’s axial tilt causes the two halves to receive varying amounts of sunlight as the planet revolves around the Sun. Each part of the Earth would see about 12 hours of daylight per day if the Earth’s 23-degree tilt weren’t there, and the Sun would remain permanently on the horizon at the poles.

Though there would be minor changes due to variations in the Earth-Sun distance over the year, the weather would be substantially more consistent. Tropical regions with copious rainfall would be located in the equatorial zones, whereas the northern latitudes would be characterized by a perpetual winter. Continents with year-round summer, mild springs and fall, and a winter wonderland that gets increasingly inhospitable as you go closer to the poles would be encountered on a north-south walking path from the equator.

The formation of the Moon and the Earth’s tilt are both thought to have resulted from a massive impact, according to popular belief. The Rare Earth Hypothesis states that this facilitated the emergence of life. A planet without a tilt might not have an atmosphere because gases at the poles would freeze and fall to Earth, while near the equator they would evaporate into space due to the intense sunlight.

The condition might still be catastrophic for any sentient species like us, even if life were to survive. In the tropics, where seasons don’t exist and rainfall is constant, conventional farming is out of the question. Near the equator, disease would likewise be more common. The invention of sophisticated machinery for heating houses during the winter would not have been enough to spark the industrial revolution, even if sentient beings like ourselves were to evolve.

8 What Would Happen If Earth Rotated Or Had a Different Tilt?

Changing the Earth’s tilt would have far-reaching effects on the ecosystem and climate because the amount of sunlight reaching the planet and the intensity of the seasons are both affected by the angle. Seasonal shifts would be magnified if Earth were tilted by a complete 90 degrees. The poles would alternately face the Sun and be perpendicular to it as the Earth spun around it. It would be extremely cold and sunny in one half of the world, and very dark and chilly in the other. By the end of the third month, the Sun will be at its lowest angle relative to the Earth’s equator, resulting in 12 hours of daylight and 12 hours of darkness each day.

Some Earth-dwelling creatures called extremophiles may be able to endure the extreme temperatures and radiation that characterize such a planet’s summers and winters, but it’s highly improbable that life could evolve there. Strong adaptations to hibernation or migration would likely characterize such extremophiles if they evolved into complex life.

By changing the centers of gravity, artist and visionary Chris Wayan has investigated several possibilities. Even though he changed where the poles were on Earth, he kept the 23.5-degree angle. One scenario he came up with was called “Seapole,” and it involved tilting a globe of the Earth such that both poles were above water. He then projected how this would affect the climate. He made the planet considerably warmer and wetter by removing Greenland’s and Antarctica’s ice domes, which could lead to increased biodiversity and biomass.

“Shiveria” was an alternative scenario that would have made the earth colder and drier by enclosing land in ice caps on either side (in northern South America and China). But the Mediterranean, which he refers to as “the Abyss,” is a hothouse, and Antarctica is tropical.

If the Earth were turned on its head, the flow of water, winds, and precipitation would all be in the opposite direction. In this alternate reality, North America and China would be deserts, but life would likely flourish everywhere else. Shiveria-like scenarios were also considered by XKCD, who proposed spinning the Earth such that the poles would be on the equator. By transforming Moscow into a parched wasteland, London into a scorching city, and Manila into a modern-day Reykjavik, the site investigates the consequences for our global cities.

7 What If the Continent of South America Were an Island?

Between the end of the Jurassic period and approximately 3.5 million years ago, the Atlantic Ocean divided the Americas. While the two continents evolved independently for almost 160 million years, there was some limited biotic contact via the Central American peninsula and the emerging Caribbean islands beginning 80 million years ago and 20 million years ago, respectively.

Similar to Australia, marsupials were the dominant species in South America at that time. However, there were also many strange hoofed creatures, such as the first camels and the edentate (“lacking teeth”) anteaters, armadillos, and sloths. Placental mammals predominated in Africa, Eurasia, and North America, whereas no marsupial species survived.

In reality, all marsupials trace their lineage back to South America; opossums and kangaroos share a common progenitor. We can’t be sure that the South American marsupials truly carried their young in pouches, but it’s possible that many of them were carnivorous, like the so-called “borhyaenoids” that looked like weasels, dogs, bears, and saber-toothed tigers.

After the Americas merged, animals from North America outcompeted most marsupial species in their migration across South America. In the meanwhile, a few of mammals, birds, and reptiles from South America made their way north.

It is quite probable that numerous marsupials would still be living today in a similarly untamed and strange habitat if the two landmasses had stayed apart, giving rise to Australia as we know it today. Unfortunately, similar to the extinction crisis that marsupials in Australia experienced on Earth, placental mammals from Eurasia would have likely been transported by humans or a close relative had they arrived.

6 What if the Mediterranean had remained closed?

Approximately six million years ago, the Mediterranean was linked to the Atlantic Ocean by just two narrow canals after the Strait of Gibraltar closed. The outcome was catastrophic. A saltwater inflow persisted despite the sealing of the outlet channel caused by the movement of Africa toward Europe. The water in the Mediterranean started to evaporate since it couldn’t get out. This caused a huge salty brine to form, similar to the Dead Sea. A layer of salt on the seafloor about 1.6 km (1 mi) thick formed, and most of the marine life in the Mediterranean went extinct. A “Messinian salinity crisis” had occurred.

In the “Zanclean flood,” which occurred hundreds of thousands of years after the Mediterranean was reconnected to the Atlantic, the sea filled up quickly, land bridges flooded between North Africa and Europe, animal species became island-bound and underwent speciation, and marine species from the Atlantic were forced to adapt fast to recolonize the Mediterranean.

Would the Mediterranean still be a dried-up salt pan if this hadn’t occurred? If people hadn’t had to take such a lengthy diversion through the Middle East on their way to Europe, they probably would have arrived considerably sooner, just by migrating across the salty lowlands.

Salt is an important commodity. People in the area probably made good use of this resource when their civilization advanced, sending it to faraway places in Asia and Africa for trade. The rapid and prosperous expansion of agriculture in the Western Hemisphere may have been accelerated by the greater availability of salt, which is essential for human survival when consuming a diet high in cereals.

Having said that, salt may have been seen as less precious due to its abundance, which could have made it a cheap commodity with less religious or symbolic significance. It is possible that the phrase “worth their salt” has transformed into an insult instead of a compliment.

5 Imagine a World Without Massive Metal Deposits.

Metals are essential for the survival of all living things. What if, instead of being concentrated into reserves that early humans could exploit, the metals like copper were really spread out over vast expanses of uncharted territory, like the ocean or ice caps? Better, more sophisticated Stone Age technology would have kept on coming, but a lot of potential growth paths would have been inaccessible to humans (and any sentient life that could have evolved on that planet).

The traditional Neolithic period would have ended regardless of the presence or absence of metals because of the agricultural revolution, which brought about the development of towns and the concentration of people. However, the growth of mining, trade, and social classes may have been impeded due to a scarcity of valuable metals, even though the plow and wheel would have continued to transform life for this Stone Age population. The fact that advanced societies in the Americas did not rely on metals implies that a comparable phenomenon would have arisen in Eurasia. Those civilizations’ arts and economy would have looked quite dull if the absence of metal deposits also included silver and gold.

The Mesoamericans made excellent use of volcanic glass obsidian, a material that is both extremely fragile and as sharp as a contemporary scalpel, due to the scarcity of metals in the region. Obsidian was a common material for the ancient Aztecs to carve arrowheads, spears, knives, and swords with many glass blades. One of the reasons the Aztecs were so enamoured with self-sacrifice was because of its inherent sharpness and the profound religious meaning it carried. The sharp knives made the practice of cutting one’s tongue or ear to shed blood during religious rites considerably less painful than it seems.

Egypt also made use of obsidian that had been brought there from the Near East and Ethiopia. Although it maintained a role as an ornamental material, its usage for making knives and sickle blades in the predynastic period was gradually replaced by metallurgy. The Egyptians may have felt a stronger need to control obsidian if they had been short on metals, prompting them to extend into East Africa and the Near East to acquire crucial sources. The area surrounding the Carpathian Mountains in Europe was one of the most prolific producers of obsidian, suggesting the possible emergence of a second society that used swords with glass edges.

It’s hard to say how advanced a civilization that relied solely on pottery, glass, and stone may have been. Without it, we might not have made as many strides in the fields of engineering, cooking, and transportation. Undoubtedly, the modern industrial revolution would not have been possible. Cultures may have mastered astronomy and medicine, but they probably wouldn’t have gotten to the Moon.

4 Suppose the Sahara remained damp.

The Sahara was home to hippos and giraffes until around 5,000 years ago, when it was a verdant wasteland filled with lakes and grasslands. Scientists still don’t know when the African humid era started and when it ended. Because of the weather, early people were able to leave Africa. If it weren’t the case, the Sahara would have been an enormous obstacle. About three thousand years ago, the area became desertified, causing the locals to seek out more hospitable habitats.

But suppose the rainy season had persisted indefinitely. Several major lakes in southern Libya existed during this time. Also, Lake Chad was substantially bigger. Many skeletons and relics from the tool-using and art-creating cultures that once lived in the area around these lakes lie dormant in the hostile desert. Several human remains were discovered in southern Niger in 2000 by a team of paleontologists who were looking for dinosaur bones. Hundreds of crocodile, fish, clam, turtle, and hippos’ bones were among the artifacts unearthed, along with pottery shards, beads, and stone implements.

A subsequent mission in 2003 found a minimum of 173 graves. The Kiffian and Tenerian peoples, whose names have now disappeared, were recognized by the patterns on the ceramic fragments. In the meanwhile, fossil evidence suggests that large herds of cattle previously roamed the Sudanese desert.

The desert has long served as a physical divide between the civilizations of North Africa and the Mediterranean and those of sub-Saharan Africa. Many Eurasian technologies either never materialized in sub-Saharan Africa or had to be independently created since technological achievements from the Fertile Crescent could not easily move across the Sahara.

Conversely, the early establishment of centralized governments, towns, and cities in the region would have been spurred by a lush Sahara. There would have been more genetic, linguistic, and cultural mixing between Eurasia and Africa, and the region inhabited by civilized peoples and the reach of the great ancient trade networks would have grown.

Tropical diseases may have posed a challenge in certain regions. Cultures in a moist Sahara, like in other places, would have developed to different degrees. On the whole, nevertheless, human civilization would have been more advanced, and progress would have accelerated. Potentially influencing the rise of European and Mediterranean civilizations, the Sahara may have housed a massive unified culture comparable to China.

3 Did the Gulf Stream Exist?

From Florida to northwest Europe, the Gulf Stream forms the northern hemisphere’s most significant ocean circulation system. By way of the Atlantic, it transports warm waters from the Caribbean to Europe. Northern Europe would be just as frigid as Canada at the same latitude if the Gulf Stream weren’t there. Seawater temperature and salinity gradients drive the system, with colder, denser water moving southward from the North Atlantic as it heats up and loses some of its density. It then turns northward once more.

This system has seen multiple shutdowns as a result of changes in the quantity of solar energy reaching the Earth and floods of freshwater. A resumption of the Gulf Stream at 11,700 years ago, at the last ice age’s end, could not have occurred without more solar energy. That being the case, the ice age would have persisted for a longer duration in northwest Europe, resulting in a bigger Arctic ice cap and more widespread Alpine glaciers.

There was no way that the area could have supported farming and civilization. Northwestern Europeans may have resembled the Saami or the Inuit more than any of our world’s ancient civilizations. Only the Middle East, North Africa, and the Mediterranean would have been accessible to Western civilizations. The cold may have prevented savage Central Asian tribes like the Huns and the Mongols from charging in and slaughtering everyone.

It would be fascinating to see what would happen if the Gulf Stream made a comeback after civilization had calmed down. With the melting ice, the crowded cities on the southern Mediterranean coast would have a new frontier to settle and conquer.

2 Could Doggerland Still Be Around?

Long ago, 8,200 years ago, there was a low-lying landmass in the North Sea that has been called “Doggerland” or “Britain’s Atlantis.” This was actually a remnant of a larger Doggerland that extended across the whole North Sea region; the larger Doggerland was a huge expanse of hilly terrain, marshland, heavily forested valleys, and swamps populated by Mesolithic people who moved with the seasons, subsisting on berries and hunting. From time to time, fishermen in the North Sea will come upon their artifacts, along with animal bones. The area was gradually inundated due to climate change, which compelled the locals to relocate.

Dogger Bank, which is located close below the North Sea waters, was the hub of the last part of greater Doggerland. A 5-meter (16 ft) tsunami, produced by the fall of 3,000 cubic kilometers (720 mi3) of silt, or the “Storegga slide,” swept off this last vestige and its residents 8,200 years ago, according to recent analyses.

Imagine, however, if Dogger Bank had been just a hair higher or if the Storrega slide had never happened.

Even though civilization advanced at a slower pace because to their seclusion, if people had managed to thrive there, their influence would have been immense. As in the British Isles, the Mesolithic population would have been supplanted by Neolithic mainland invaders, who might have been swept aside by Celtic invaders.

Since the Celts’ population density in Doggerland was likely lower than in the British Isles and continental Europe, their displacement by later Germanic invaders is plausible. It is possible that the North Germanic Doggerlanders bridged the gap between Norse and British civilization. The Balts, an extinct race, or a race that has never been in our world could have invaded Doggerland.

Climate change would still pose a significant threat to any Doggerland that managed to survive. Like low-lying Pacific islands, low-lying islands would face existential threats from global warming. On the other hand, environmental policy in Europe may be better addressed by a rich, industrialized Northern European nation that is on the verge of extinction.

1 Can You Imagine the Ice Ages If There Had Been Just A Little Less Ice?

University of Wisconsin professor Steven Dutch spoke at the 2006 Geological Society of America meeting on the subject of somewhat milder ice eras. He wondered what would have transpired if the ice sheets of Scotland and Scandinavia had never melted and the North American ice sheets had never gone below the Canadian border. Not only would the Great Lakes and the Ohio River never have formed, but the English Channel would not exist either. The Missouri River would have continued on its original route into Hudson Bay instead of shifting to its current course.

In our solar system, the English Channel was formed when the ice caps of Scotland and Scandinavia combined to produce a huge proglacial lake. This lake then overflowed into the old Rhine-Thames river system. Had the two ice caps never fused, the water would have redirected northward, creating a land bridge that now links England to the rest of Europe. Major changes to Western patterns of migration, settlement, and cultural dissemination would have occurred if the historical British defensive advantage relative to continental Europe had been nonexistent.

North America’s drainage patterns would have been different due to the absence of ice caps; for example, the Niagara River would have kept its old course and the pre-Pleistocene Teays River would still be around today. Without it, there would be no Niagara Falls. A different pattern of colonization would have resulted had the St. Lawrence River been the simplest way to cross the Appalachians. Meanwhile, the efficient east-west canals utilized by Lewis and Clark’s voyage would no longer exist in our reality due to the modifications made to the Missouri River.

If it had persisted, the number of navigable waterways in North America would have been far fewer, making the spread of European invasions much slower. It seems likely that this happened in the North, either by a people who resemble a cross between the English and the French, or by someone even more alien to our civilization than we can fathom.

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