Ancient chaos, death of all living things, superpowerful explosions: four ends of the world that we have experienced

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Ancient chaos, death of all living things, superpowerful explosions: four ends of the world that we have experienced
Ancient chaos, death of all living things, superpowerful explosions: four ends of the world that we have experienced
Anonim

Two million years ago, the planet entered a state of highly unusual instability. Time after time, she wiped out the ecosystems of Africa from the face of the earth, which is why our ancestors again and again found themselves in a difficult situation. Seventy thousand years ago, their number decreased tenfold - another, completely unexpected factor struck. A couple of hundred thousand years ago, not only humanity, but in general all terrestrial species could die from an even more destructive force. 12, 9 thousand years ago, many people died and millions of square kilometers were completely burned out due to explosions in the atmosphere and fire rain. How exactly did our species survive all this?

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From time to time, Russian popular science media publish materials on possible scenarios of the “end of the world”. Five years ago (and not only) the author of these lines did something similar. Adding something new to this is not easy. Therefore, we decided to go from a completely different side: to describe those four apocalypses that mankind has already managed to overcome.

Mind from grief: how ancient chaos made us an intelligent species

Seven to eight million years ago, unusual events began to occur on the planet: the climate became colder and colder. Lower temperatures extracted less water from the oceans, so the planet became even drier. It was then that the Sahara Desert first appeared - first for a short time during the Ice Age. From the data on later glaciations, it follows that the temperatures in the ice age are not only lower than usual, but also sharply unpredictably change from year to year, especially in high latitudes. Greenland - which had previously lived up to its modern name, that is, completely green - began to be covered with ice. The arid cold climate led to powerful dust storms: the level of dust in the atmosphere, based on the experience of later glaciations, should have risen 15-20 times.

At that time, our ancestors lived in Africa, and it may seem that all this was not too dangerous for them. But it only seems to be. We do not have accurate landscape maps of Africa for the glaciations seven to eight million years ago (scientists have not yet collected the required amount of data), but, again, there is a map of the surface of the ancestral home of mankind in the last ice age. It is easy to see from it: the Black Continent has almost lost the jungle, which we usually consider it to be an integral feature.

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The cycle "glaciation - desert Sahara -" zeroing "of the jungle" over the past eight million years has been repeated 230 times in a row. There were no glitches in it: all known cold periods made the homeland of our species mostly dry, making life difficult for those who gave life to us.

Our ancestors up to the Australopithecus show clear morphological signs of strong adaptation to the arboreal lifestyle, in many respects similar to those of chimpanzees. Back in the 1980s, the discoverer of global warming, Mikhail Budyko, hypothesized that the transformation of the jungle into savannah put the hominin of that time in very unfavorable conditions.

Large apes can even fight off a leopard in groups. The lion is too tough for them, so they hide from him in the trees.However, when cycles of glaciers almost deprived of trees huge parts of Africa, the situation changed dramatically.

On the plain, it is extremely difficult for primates to flee, even from a leopard, let alone a lion. Normally, when such a strong predator appears, modern savanna monkeys work according to the principle of "save yourself who can" - they scatter in all directions, which is why the lions eat the nearest one. Another problem: in the plains, fruit is difficult, which makes up the bulk of the diet of chimpanzees, our closest living relative. Probably, the ancestors of humans had a similar diet.

Once in the dry savannah, the ancestors found themselves in a situation where the usual methods - developed over millions of years of living in the forest - stopped working. I had to acquire fundamentally different skills. Already Australopithecus and later Homo habilis and erectus have a skeleton unusual for primates, indicating upright posture. Most likely, like modern humans, they were the best long distance runners in existence.

As a reminder, upright walking gives us the ability to perfectly dissipate heat from the body while running. Even the fastest horse starts to run out of steam on long distance runs faster than the mediocre human runner. Lion and other leopards / cheetahs get tired much earlier than horses, literally after a kilometer or a little more. Because of all these advantages, a person can run up to 300 kilometers a day (and even a mediocre, but trained runner - up to 100), and no other land animal in a warm climate is close.

However, the ability to run and look around from a height of human growth in itself is not a panacea. To get food on the savannah, you need to be able to beat off competitors. Due to the lack of fruit, the genus Homo began to take meat from hyenas and other predators, and over time began to hunt large herbivores itself. All this could not have been realized without a fundamentally new phenomenon - stone tools.

It should be noted: in principle, even our relatives of chimpanzees can make spears (and they use them to hunt small mammals). It is assumed that the first wooden spears of people were similar and did not have stone tips. But from the experience of a number of tribes with poor material culture, it is known that even a spear without a stone tip in the hands of people is dangerous enough to create great risks for anyone who wants to contact them - including a lion.

As soon as people mastered them, savannahs immediately opened up in front of them in all directions. Constant climate changes (230 times, remember?) Forced all the time to adapt to fundamentally different conditions, to migrate over long distances. So, already 1, 8 million years ago, homo erectus came to the territory of modern Georgia, and then reached Java.

The result of the climatic chaos that forced our ancestors to leave the trees and spread across the vast plains of the Old World was an unprecedented evolution of the brain. Their volume has grown by 300% over the past six million years. Even more precisely, its capabilities allow us to assess the blood flow: the diameter of the arteries leading to the brain, during the same time, has increased so much that the blood supply to our brain has increased eightfold. The intensity of blood flow to the brain correlates well with the number of connections between nerve cells in it, and this number, in turn, is associated with intelligence.

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It is interesting that all the same Budyko was one of the first to pose the question: why terrestrial ecosystems are almost half a billion years old, and an intelligent species only appeared in the last two million years? This is an important question: already 250-300 million years ago, warm-blooded animals lived on Earth, in many ways similar to modern mammals. They also represented the bulk of the dinosaurs. Moreover, among the latter, there were many species with upright posture and free forelimbs. Why has no one before us acquired intelligence?

Budyko, not being an anthropologist, expressed thoughts on this score that it is difficult to disagree with today.Basically, the last 500 million years have been climatically and ecologically calm and smooth. For most of this time, the planet was warm, without sharp seasonal temperature fluctuations - and without strong temperature instability from year to year. In such conditions, the advantages are gained by species-specialists, whose structure gradually and smoothly adapts to the requirements of the environment. The running dinosaurs probably simply did not need weapons and intelligence to make and use them: they had the power of their gradually evolving murderous upper limbs.

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Eight million years ago, regular ice ages began on the planet, which have become especially frequent in the last two million years. The climate change was very rapid. According to modern data, the Sahara passed from the state of the desert to the state of the savannah and back in a matter of decades. Other landscapes changed similarly. 230 repetitions of such a cycle would simply erase species that were not versatile enough to survive successfully in a world of glaciers and in a world without it.

And although the natural evolution of the limbs lagged behind what was needed to survive in an ever-changing landscape, the brain of our ancestors allowed them to adapt spears and stone tools quickly enough.

What is important: having begun to adapt by changing products, and not their own bodies, people dramatically increased the rate of further improvement of their minds. If the same Australopithecines were inferior to modern chimpanzees in terms of the volume of blood entering the brain, then already starting with Homo erectus our ancestors were clearly superior to chimpanzees. This, by the way, is a good level: those, recall, are able to learn how to make and maintain a fire, as well as make decent stone tools.

As a result, for the first time in the history of the Earth, our ancestors became a species that survived at the expense of reason. This trait allowed them to function successfully even in areas for which our body is not specialized enough. They replaced the sharp teeth and claws of a lion with a spear (over time and with a stone tip). And then they compensated for the lack of a warm climate with skins and bonfires.

So the climatic chaos that wiped out the earlier primate species eventually made us human.

The second end of the world: dust in the wind

Seventy thousand years ago, something happened on the territory of modern Indonesia that is so often remembered today in connection with the explosion of Yellowstone. We are talking about a volcanic eruption - only an unusually powerful one. What exactly does the word "extraordinary" mean in this case?

There is a good example: the volcano Pinatubo, in 1991, staged a moderate eruption in the Philippines. The energy of the event was equivalent to an explosion of 70 million tons of TNT - that is, more powerful than the Tsar Bomba. As a result, he spewed out 10 cubic kilometers of solid material and 20 million tons of SO2 - sulfur dioxide, which gives a powerful anti-greenhouse effect. Immediately thereafter, global temperatures dropped by 0.5 ° C and remained that way until about 1993.

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Why so long? The eruption of Pinatubo, with a capacity of 70 megatons, carried a column of SO2 to a height of 35 kilometers, from where anti-greenhouse gases cannot be washed out by rains, since there are simply no rain clouds.

The eruption of the supervolcano Toba threw at least 2,800 cubic kilometers of solid material into the air, and according to some estimates, up to 13 thousand cubic kilometers. In other words, this event was either hundreds or a thousand times stronger than Pinatubo. Its power is not reliably known, but it should have been measured in gigatons. And, probably, to be higher than the capacity of all existing nuclear arsenals of the Earth. The notorious Yellowstone volcano 620 thousand years ago gave only a thousand cubic kilometers of ejected material - that is, it was many times weaker than the Toba event.

The exact amount of SO2 anti-greenhouse gas emissions at the time of the destruction of Toba is not known. It was estimated at six billion tons, hundreds of times the size of Pinatubo.

That is why a strange impression is produced by a number of works trying to find evidence that Toba did not cause either a radical decrease in temperatures or the death of a significant number of people. And there are such works: their authors stress that there are no traces of a sharp drop in temperatures in the sediments at the bottom of one African lake during this period. And in India - not so far from Pinatubo - stone artifacts were found, indicating that immediately after the eruption, Homo sapiens, who had already penetrated there, did not completely die out.

These are naive theses already because it is impossible to imagine an event with a force of hundreds of Pinatubos, but for some reason it did not have a serious impact on the climate or people. Models trying to estimate the impact of six billion tons of SO2 on climate show a drop in global temperatures by 15 ° C at once - not by one year, but by about three.

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Of course, this does not mean that it got colder so sharply everywhere at once: some zones near the equator could have suffered much less than others. Someone could survive in the affected territories. However, it is almost impossible to imagine a scenario in which wrapping the planet in a blanket of billions of tons of ash and sulfur dioxide would not lead to extremely unpleasant consequences for the entire complex life on it. In any case, this should have drastically reduced the global temperature - if not by 15 degrees, then at least by a few. And after falling temperatures would inevitably come droughts - with all the ensuing unpleasant consequences.

This is exactly what the data of geneticists show. According to their calculations, at about the same time that the Toba supervolcano exploded, the number of humanity on the planet fell by about a dozen times, dropping to a few thousand - or even a couple of thousand - people of fertile age. Around the same time, the numbers of chimpanzees, Borneo orangutans, rhesus monkeys in Central India, and tigers declined sharply. Such phenomena are collectively called the genetic "bottleneck" - and these populations at that time really passed through the "neck" of survival not without difficulty.

Our ancestors nevertheless survived and soon after these events spread to new regions. In particular, they settled in Australia about 70 thousand years ago, and probably already reached the New World 30-40 thousand years ago.

This "end of the world" in theory could even help them to oust other intelligent species that still existed on the planet at that time. Let's remind: Neanderthals lived simultaneously with Homo sapiens (Europeans and Asians even carry part of their genes), Floresian man and, possibly, the last remnants of erectus. It was more difficult for their species to adapt to the world after Toba. After all, the Neanderthals already then lived in the cold part of the planet, where the drop in temperatures was especially felt. And the Floresian man clearly had a less developed material culture, and he lived too close to the place of the eruption of the Toba supervolcano.

The third end of the world: how the whole complex earthly life almost died

Our planet is arranged in a rather unusual way. More than 90% of its biomass exists on land, and the seas are de facto a biological desert. The existence of terrestrial life is based on plants: they dominate the terrestrial biomass and provide food for herbivores, and those for omnivores and carnivores. Almost all of this pyramid could have been destroyed 130-190 thousand years ago.

The fact is that terrestrial planets around stars like the Sun have one unpleasant feature: they may have a complete glaciation of the entire surface. For most stars in the Universe (red dwarfs), this is impossible: water ice poorly reflects infrared radiation, which accounts for the bulk of the radiation of red stars.

At the Sun, the bulk of the radiation falls on visible light, which is perfectly reflected by water ice. So good that climatologists half a century ago established that if, for some reason, the ice on our planet reaches the equator, it will be stable there.Because along the way, the planet's reflection of solar radiation will increase so much that it will cool down to a level where the ice at the equator will no longer melt. Moreover, such a state will be stable for at least millions of years, or even much longer (until the accumulation in the atmosphere of a huge "canopy" of the greenhouse carbon dioxide CO2 from volcanoes).

Half a century ago, Soviet climatologists were the first in the world to point out:

The tendency towards a decrease in the concentration of carbon dioxide, which arose at the end of the Phanerozoic, apparently under the influence of the weakening of volcanic activity, created a threat of ecological catastrophe due to the possibility of the death of autotrophic plants and glaciation of our planet. The probability of reaching critical latitude by one of the next glaciations, after which a complete glaciation of the Earth would occur, cannot be considered excluded. Such a possibility was, apparently, close to being realized in the era of the greatest (Rice) glaciation. The ice cover under these conditions passed about 3/4 of the way from the modern ice boundary to the critical latitude [at which the complete glaciation of the Earth is inevitable], further evolution of the Earth's climate could, in natural conditions, lead to a complete and stable glaciation of the planet.

I must say that at that moment the whole complex earthly life hung in the balance. Today, a person can easily prevent the onset of the next ice age, simply by producing a small amount of super-greenhouse gases (for example, SF6 gas). 130-190 thousand years ago, the ancestors did not know anything about the causes of climate change and did not have a civilization capable of influencing it. In those conditions, glaciation would have led to the destruction of humans, mammals and plants.

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A new biological epoch could come in tens of millions of years, when the accumulation of CO2 from volcanoes would melt the ice again. However, this would require the colonization of continents from scratch - first by plants, then by animals, descended from those fish that would have survived in the subglacial oceans for tens of millions of years. It would be a long and painful process. It is absolutely impossible to predict whether it would have ended with the appearance of reason before the next global glaciation.

By the way, let us recall: more than 600 million years ago, such an episode in our history already took place and ended with the complete erasure of the complex pre-Ediacaran biota. Our species and all modern biota almost went the same way 130-190 thousand years ago. It turns out that we all won in the game of dice of colossal proportions - which means that life on earth is really lucky.

The fourth end of the world: super-powerful atmospheric explosions and fiery rain

About 14-15 thousand years ago, the last ice age ended, temperatures reached modern values. However, 12, 9 thousand years ago, everything suddenly changed overnight and temperatures for a thousand years returned to the ice age. A sign of this era in Europe is called the eight-petalled dryad - a wild relative of the rose, today growing mainly in the tundra or in alpine meadows. According to her, the whole epoch was called "late Dryas".

Let's be honest: the appearance of a tundra flower on the plains of Spain and Italy is a disaster. Spain and Italy by that time for more than a thousand years were not tundra at all, but had an approximately modern climate. Of course, the local flora and fauna were swept away by the coming cold snap. Moreover, by all indications it was extremely rapid and came in just one (!) Ten years - or even faster. In Greenland, the doubling of snowfall, marking the onset of the Younger Dryas, occurred in one to three years.

It's about ultra-rapid climate change. The drop in global temperatures by several degrees, which happened at the beginning of the Younger Dryas, appears to have occurred tens of times faster than the increase in temperatures during modern global warming. Suffice it to say that the climate in Britain then changed from modern to minus 5 ° C in a similar, extremely short time.In other words, it has become as it is today in Vorkuta.

The reasons for this event remained unexplained for decades. All attempts to show the purely climatic mechanisms of the transformation of Southern England into Vorkuta in an ultrashort time did not give convincing results.

Then came a theory that showed such results, and easily and organically: a comet. In different regions of the Earth, in the layers of the indicated antiquity, glass microspheres were found, usually formed during high-power atmospheric explosions. In our time, these are nuclear explosions, but it is clear that there were no such bombs a dozen thousand years ago. But, as we well know after the Tunguska and Chelyabinsk meteroites, celestial bodies easily give high-power air explosions after entering the Earth's atmosphere.

Like an ultra-high-power nuclear explosion, the explosion of a celestial body produces a lot of radiation that can set fire to dry grass over great distances. If a celestial body is large enough to at least partially reach the surface, it additionally raises a mass of dust into the stratosphere, and it does not rain from the stratosphere, so the dust does not settle for years. It all ends in the so-called asteroid winter. Unlike standard climatic phenomena, it is able to give the south of England the climate of Vorkuta almost immediately. All this, objectively, did a good job of explaining the mysterious events of the Younger Dryas.

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Alas, the hypothesis had its drawbacks. First, its authors are not exactly professionals in the field of paleontology or paleoclimatology. One worked at a nuclear center, the other, Allen West, most likely did not have a university education and was not an expert on the topic. This is a catastrophic, insurmountable flaw: most people without special education who try to create hypotheses are charlatans. A minority of them are Schliemann and Heyerdahl, but, we repeat, it is the minority. And the same Schliemann, despite his discovery of Troy, archaeologists either hate or despise. In other words, even if West's hypothesis is correct, the scientific community will never treat him well.

It should come as no surprise that after their publication in 2007 a lot of works appeared that “successfully refuted” the cometary hypothesis. Like, we tried to find glass microspherules in the same layers - and found nothing. In 2017, the hypothesis was even declared finally disproved.

Science, however, is good in that you can always find justice for everyone who wants to refute new conclusions - if, of course, these conclusions were correct. Now, 14 years later, a wealth of data has accumulated showing that during this period, microspherules of carbon and glass appear - simultaneously with traces of powerful fires - immediately in North America, Europe and parts of Asia. Thus, the hypothesis was brilliantly confirmed. In Greenland, NASA also found a candidate for the crater left by that impact.

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In passing, it can be noted that the reluctance to accept this assumption resembles the reluctance of a number of Russian paleontologists to accept the theory of the asteroid extinction of dinosaurs: the reluctance to abandon the usual line of thinking about "smooth and gradual" changes forced scientists of our country for a third of a century to reject the asteroid version of the extinction of the end of the Cretaceous period recognized throughout the world - in spite of all the facts.

To roughly imagine what happened at the time of the impact, it is best to cite the traditions of the North American Indians, which clearly narrate about the same events (hereinafter, quotes are given from this book).

Ojibwe:

“The star fell to the ground and covered the world with its long, flying, luminous tail. Tall trees lit up like gigantic torches, lakes and rivers began to boil, and even the rocks heated and began to collapse; a terrible fire consumed the whole world."

Iroquois:

“Stars fell from the sky and some of them fell to the ground. Shooting stars of fire hissed straight into the Iroquois camp.With violent explosions and searing heat, one star hit the ground near the camp, scattering trees and earth in all directions.”

Matamuskites:

“[The princess] heard a loud, sharp noise and the sound of a huge explosion, and then the sounds of one blow after another. Hundreds of stars fell from the skies and exploded on the forested mountains around her, shaking the earth with such force that the princess could barely stay on her feet. Furious orange-red flames and pillars of black smoke rose into the sky as the forest around the site was burning."

Aztecs:

“A heavy rain of flaming stones of fire and blood began to fall from the sky. He fell on houses - and they burst into flames. He fell on the forests - and swallowed them. People sought refuge, but their clothes were engulfed in flames, and they died. Falling hot stones shook the ground. Finally, when it was all over, thick dark clouds covered the earth for a long twenty-five years."

Of course, we cannot be sure of the accuracy of all the details. For blood, the Indians 12, 9 thousand years ago could take stones red-hot to red heat. When a celestial body hits the Earth, part of the debris flies into space, but not everyone has enough speed to leave the planet forever: part falls back, and when the atmosphere passes, it heats up to a thousand degrees or more. Naturally, when falling on the planet, such pieces set fire to all dry vegetation. Nor can one be sure that the "thick dark clouds" - the cometary-asteroid winter - actually floated above the Earth for 25 years. More likely, it ended earlier.

But the facts are that after the impact of the beginning of the Late Dryas, the sites of the Clovis culture, which had previously dominated in North America, became much less common (or even disappeared). Spores of fungi growing on mammoth dung have also become less common. And no wonder. Other Indian tribes describe not only colorful fiery rain and explosions, but also direct victims:

Toba and Pilago:

“Suddenly, a giant fireball escaping from the disk of the sun (such an impression should be created by a celestial body approaching the planet from the direction of the Sun. - Ed.). flew to the ground. Thousands of burning stones and huge chunks of ice hail fell at the same time. They wrought tremendous havoc among the trees and ignited the jungle. A roaring fire lit everything around the village until the flames almost surrounded it."

Ojibwe:

“After the world cooled down, people covered with mud cautiously left the swamp and looked around. They were shocked that the world had changed completely. There were only smoking black trees and burnt grass everywhere. People who did not listen to Chimantu [and did not take cover in advance] died along with all the giant animals. Only skeletons remained of them."

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Iroquois on the same event:

"Only a sixth of the tribe made it to safety."

Lakota:

“The fiery explosion shook the whole world, reaching the tops of the mountains and starting a fire in the forests and prairies. The flame spread throughout the sky and did not touch only the people on the highest peaks. It was so hot that all the lakes in the world evaporated and dried up literally before our eyes. Even the rocks were red-hot, giant animals and evil people burned where they stood."

In principle, the events described are similar to a super-powerful thermonuclear explosion - only, of course, more destructive.

How did our ancestors survive at that time? To be honest, in the area closest to the explosions themselves, most might not have survived. However, the rest were decently hardened by a couple of million years of migrations across the plains of the Earth, which became either dry cold steppe (ice ages), then covered with wet forests (interglacial). So even those who saw the fireballs of super-powerful explosions (it is possible that more than one debris of a celestial body fell to the Earth), not all of them died.

The Ojibwe describe how their ancestors covered their bodies with wet mud in a swamp, which protected them from burns and dehydration during continuous fires.The Arawak myths about those events contain mini-instructions, in principle indistinguishable from the recipe for a primitive anti-nuclear shelter: “Go and dig a large hole, cover it with trees, and pile up sand. After this is done, lock yourself up and bury yourself for safety."

In general, Homo sapiens met the comet of the Younger Dryas as a real fighter, tempered by the extremely difficult conditions of the changeable and unstable Pleistocene. From this, many of its representatives were able to reasonably improvise, even when faced with an unfamiliar threat of truly cosmic proportions.

Looking back at the four corners of the world, which have erased many from the face of the Earth, but could not overcome humanity, it is hard not to notice this.

Today, the ice age cannot destroy us: even the unintentional efforts of people are more than enough to keep the planet quite warm. We are not threatened with a tenfold reduction in numbers from supervolcanoes like Toba: in the era of greenhouses and large power plants, food can be grown even with a sharp drop in temperatures.

An asteroid and a comet, however, can still destroy humanity, but for this they need to be much larger than the comet of the Younger Dryas. And astronomers should notice such bodies in advance - unless, of course, it is an interstellar asteroid like Oumuamua. Knowing about the asteroid in advance, we can deflect it with nuclear warheads (however, we will have to try to deliver them exactly to the target within a reasonable time).

It's easy to see that our reduced vulnerability is a consequence of our intelligence. It turns out that the very difficulties that prevented Homo from living for so long made him so strong that he can no longer die from them. What is not a reason for optimism?

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