Rossini works. Italian composer Rossini: biography, creativity, life story and best works
The science
According to scientists, life on earth began about 3 billion years ago: During this time, simple organisms developed into complex life forms. However, it is still a mystery to scientists how life began on the planet, and they have put forward several theories to explain this phenomenon:
1. Electric sparks
In the famous Miller-Urey Experiment, scientists proved that lightning could contribute to the emergence of the basic substances necessary for the origin of life: electrical sparks form amino acids in an atmosphere consisting of huge quantities of water, methane, ammonia and hydrogen. More complex life forms then evolved from amino acids. This theory was changed somewhat after researchers discovered that the planet's atmosphere billions of years ago was poor in hydrogen. Scientists suggested that methane, ammonia and hydrogen were contained in volcanic clouds saturated with electrical charges.
2. Clay
Chemist Alexander Graham Cairns-Smith from the University of Glasgow, Scotland, put forward the theory that at the dawn of life, clay contained many organic components located close to each other, and that the clay helped organize these substances into structures similar to our genes.
DNA stores information about the structure of molecules, and DNA's genetic sequences indicate how amino acids should be built into proteins. Cairns-Smith suggests that clay crystals helped organize organic molecules into ordered structures, and later the molecules themselves began to do this, “without the help” of clay.
3. Deep sea vents
According to this theory, life began in underwater hydrothermal vents that spewed out hydrogen-rich molecules. On their rocky surface, these molecules could come together and become mineral catalysts for the reactions that led to the origin of life. Even now, such hydrothermal vents, rich in chemical and thermal energy, are home to quite a few a large number of Living creatures.
4. Icy start
3 billion years ago, the Sun did not shine as brightly as it does now, and, accordingly, less heat reached the Earth. It is quite possible that the surface of the earth was covered with a thick layer of ice, which protected fragile organic matter, located in the water underneath, from ultraviolet rays and cosmic exposure. In addition, the cold helped the molecules to exist longer, as a result of which the reactions that led to the origin of life became possible.
5. RNA world
DNA needs proteins to form, and proteins need DNA to form. How could they have formed without each other? Scientists have suggested that RNA, which, like DNA, stores information, was involved in this process. From RNA, proteins and DNA were formed, respectively., which replaced it due to their greater efficiency.
Another question arose: “How did RNA appear?” Some believe that it spontaneously appeared on the planet, while others deny this possibility.
6. "Simple" theory
Some scientists have suggested that life evolved not from complex molecules like RNA, but from simple ones that interacted with each other. They may have been contained in simple shells similar to cell membranes. As a result of the interaction of these simple molecules, complex, which reacted more efficiently.
7. Panspermia
In the end, life could not have originated on our planet, but was brought from space: In science this phenomenon is called panspermia. This theory has a very solid basis: due to cosmic influences, fragments of stones are periodically separated from Mars, which reach the Earth. After scientists discovered Martian meteorites on our planet, they assumed that these objects brought bacteria with them. If you believe them, then we are all martians. Other researchers have suggested that life was brought by comets from other star systems. Even if they are right, humanity will look for an answer to another question: “How did life originate in space?”
The question of when life appeared on Earth has always worried not only scientists, but also all people. Answers to it
almost all religions. Although there is still no exact scientific answer to this question, some facts allow us to make more or less reasonable hypotheses. Researchers found a rock sample in Greenland
with a tiny splash of carbon. The age of the sample is more than 3.8 billion years. The source of carbon was most likely some kind of organic matter - during this time it completely lost its structure. Scientists believe this lump of carbon may be the oldest trace of life on Earth.
What did the primitive Earth look like?
Let's fast forward to 4 billion years ago. The atmosphere does not contain free oxygen; it is found only in oxides. Almost no sounds except the whistle of the wind, the hiss of water erupting with lava and the impacts of meteorites on the surface of the Earth. No plants, no animals, no bacteria. Maybe this is what the Earth looked like when life appeared on it? Although this problem has long been of concern to many researchers, their opinions on this matter vary greatly. Rocks could indicate conditions on Earth at that time, but they were destroyed long ago as a result of geological processes and movements of the earth's crust.
In this article we will briefly talk about several hypotheses for the origin of life, reflecting modern scientific ideas. According to Stanley Miller, a well-known expert in the field of the origin of life, we can talk about the origin of life and the beginning of its evolution from the moment when organic molecules self-organized into structures that were able to reproduce themselves. But this raises other questions: how did these molecules arise; why they could reproduce themselves and assemble into those structures that gave rise to living organisms; what conditions are needed for this?
According to one hypothesis, life began in a piece of ice. Although many scientists believe that carbon dioxide in the atmosphere maintained greenhouse conditions, others believe that winter reigned on Earth. At low temperatures, all chemical compounds are more stable and can therefore accumulate in larger quantities than at high temperatures. Meteorite fragments brought from space, emissions from hydrothermal vents and chemical reactions occurring during electrical discharges in the atmosphere were sources of ammonia and such organic compounds, like formaldehyde and cyanide. Getting into the water of the World Ocean, they froze along with it. In the ice column, molecules of organic substances came closely together and entered into interactions that led to the formation of glycine and other amino acids. The ocean was covered with ice, which protected the newly formed compounds from destruction by ultraviolet radiation. This ice world could melt, for example, when a huge meteorite fell on the planet (Fig. 1).
Charles Darwin and his contemporaries believed that life could have arisen in a body of water. Many scientists still adhere to this point of view. In a closed and relatively small reservoir, organic substances brought by the waters flowing into it could accumulate in the required quantities. These compounds were then further concentrated on the inner surfaces of layered minerals, which could catalyze the reactions. For example, two molecules of phosphaldehyde that met on the surface of a mineral reacted with each other to form a phosphorylated carbohydrate molecule, a possible precursor to ribonucleic acid (Fig. 2).
Or maybe life arose in areas of volcanic activity? Immediately after its formation, the Earth was a fire-breathing ball of magma. During volcanic eruptions and with gases released from molten magma, a variety of chemicals necessary for the synthesis of organic molecules were carried to the earth's surface. Thus, carbon monoxide molecules, once on the surface of the mineral pyrite, which has catalytic properties, could react with compounds that had methyl groups and form acetic acid, from which other organic compounds were then synthesized (Fig. 3).
For the first time, the American scientist Stanley Miller managed to obtain organic molecules - amino acids - in laboratory conditions simulating those that were on the primitive Earth in 1952. Then these experiments became a sensation, and their author gained worldwide fame. He currently continues to conduct research in the field of prebiotic (before life) chemistry at the University of California. The installation on which the first experiment was carried out was a system of flasks, in one of which it was possible to obtain a powerful electric discharge at a voltage of 100,000 V.
Miller filled this flask with natural gases - methane, hydrogen and ammonia, which were present in the atmosphere of the primitive Earth. The flask below contained a small amount of water, simulating the ocean. The electric discharge was close to lightning in strength, and Miller expected that under its action chemical compounds were formed, which, when they got into the water, would react with each other and form more complex molecules.
The result exceeded all expectations. After turning off the installation in the evening and returning the next morning, Miller discovered that the water in the flask had acquired a yellowish color. What emerged was a soup of amino acids, the building blocks of proteins. Thus, this experiment showed how easily the primary ingredients of life could be formed. All that was needed was a mixture of gases, a small ocean and a little lightning.
Other scientists are inclined to believe that the ancient atmosphere of the Earth was different from the one that Miller modeled, and most likely consisted of carbon dioxide and nitrogen. Using this gas mixture and Miller's experimental setup, chemists attempted to produce organic compounds. However, their concentration in water was as insignificant as if a drop of food coloring were dissolved in a swimming pool. Naturally, it is difficult to imagine how life could arise in such a dilute solution.
If indeed the contribution of earthly processes to the creation of reserves of primary organic matter was so insignificant, then where did it even come from? Maybe from space? Asteroids, comets, meteorites and even particles of interplanetary dust could carry organic compounds, including amino acids. These extraterrestrial objects could provide sufficient amounts of organic compounds for the origin of life to enter the primordial ocean or small body of water.
The sequence and time interval of events, starting from the formation of primary organic matter and ending with the appearance of life as such, remains and, probably, will forever remain a mystery that worries many researchers, as well as the question of what. in fact, consider it life.
Currently, there are several scientific definitions of life, but all of them are not accurate. Some of them are so wide that inanimate objects such as fire or mineral crystals fall under them. Others are too narrow, and according to them, mules that do not give birth to offspring are not recognized as living.
One of the most successful defines life as a self-sustaining chemical system capable of behaving in accordance with the laws of Darwinian evolution. This means that, firstly, a group of living individuals must produce descendants similar to themselves, which inherit the characteristics of their parents. Secondly, generations of descendants must show the consequences of mutations - genetic changes that are inherited by subsequent generations and cause population variability. And thirdly, it is necessary for a system of natural selection to operate, as a result of which some individuals gain an advantage over others and survive in changed conditions, producing offspring.
What elements of the system were necessary for it to have the characteristics of a living organism? A large number of biochemists and molecular biologists believe that RNA molecules had the necessary properties. RNA - ribonucleic acids - are special molecules. Some of them can replicate, mutate, thus transmitting information, and, therefore, they could participate in natural selection. True, they are not capable of catalyzing the replication process themselves, although scientists hope that in the near future an RNA fragment with such a function will be found. Other RNA molecules are involved in “reading” genetic information and transferring it to ribosomes, where the synthesis of protein molecules occurs, in which the third type of RNA molecules takes part.
Thus, the most primitive living system could be represented by RNA molecules duplicating, undergoing mutations and being subject to natural selection. In the course of evolution, based on RNA, specialized DNA molecules arose - the custodians of genetic information - and no less specialized protein molecules, which took on the functions of catalysts for the synthesis of all currently known biological molecules.
At some point in time, a “living system” of DNA, RNA and protein found shelter inside a sac formed by a lipid membrane, and this one was more protected from external influences the structure served as the prototype for the very first cells that gave rise to the three main branches of life, which are represented in the modern world by bacteria, archaea and eukaryotes. As for the date and sequence of appearance of such primary cells, this remains a mystery. In addition, according to simple probabilistic estimates, there is not enough time for the evolutionary transition from organic molecules to the first organisms - the first simplest organisms appeared too suddenly.
For many years, scientists believed that it was unlikely that life could have emerged and developed during the period when the Earth was constantly subject to collisions with large comets and meteorites, a period that ended approximately 3.8 billion years ago. However, recently, traces of complex cellular structures dating back at least 3.86 billion years have been discovered in the oldest sedimentary rocks on Earth, found in southwestern Greenland. This means that the first forms of life could have arisen millions of years before the bombardment of our planet by large cosmic bodies stopped. But then a completely different scenario is possible (Fig. 4).
Space objects falling to Earth could have played a central role in the emergence of life on our planet, since, according to a number of researchers, cells similar to bacteria could have arisen on another planet and then reached Earth along with asteroids. One piece of evidence supporting the theory of extraterrestrial origins of life was found inside a meteorite shaped like a potato and named ALH84001. This meteorite was originally a piece of Martian crust, which was then thrown into space as a result of an explosion when a huge asteroid collided with the surface of Mars, which occurred about 16 million years ago. And 13 thousand years ago, after a long journey within the solar system, this fragment of Martian rock in the form of a meteorite landed in Antarctica, where it was recently discovered. A detailed study of the meteorite revealed rod-shaped structures resembling fossilized bacteria inside it, which gave rise to heated scientific debate about the possibility of life deep in the Martian crust. It will be possible to resolve these disputes no earlier than 2005, when the US National Aeronautics and Space Administration will implement a program to fly an interplanetary spacecraft to Mars to take samples of the Martian crust and deliver samples to Earth. And if scientists manage to prove that microorganisms once inhabited Mars, then we can speak with a greater degree of confidence about the extraterrestrial origin of life and the possibility of life being brought from outer space (Fig. 5).
Rice. 5. Our origin is from microbes.
What have we inherited from ancient life forms? The comparison below of single-celled organisms with human cells reveals many similarities.
 1. Sexual reproduction |
 2. Eyelashes |
 3. Capture other cells |
 4. Mitochondria |
 5. Flagella |
The evolution of life on Earth: from simple to complex
At present, and probably in the future, science will not be able to answer the question of what the very first organism that appeared on Earth looked like - the ancestor from which the three main branches of the tree of life originated. One of the branches is eukaryotes, whose cells have a formed nucleus containing genetic material and specialized organelles: energy-producing mitochondria, vacuoles, etc. Eukaryotic organisms include algae, fungi, plants, animals and humans.
The second branch is bacteria - prokaryotic (prenuclear) single-celled organisms that do not have a pronounced nucleus and organelles. And finally, the third branch is single-celled organisms called archaea, or archaebacteria, whose cells have the same structure as prokaryotes, but a completely different chemical structure of lipids.
Many archaebacteria are able to survive in extremely unfavorable environmental conditions. Some of them are thermophiles and live only in hot springs with temperatures of 90 ° C or even higher, where other organisms would simply die. Feeling great in such conditions, these single-celled organisms consume iron and sulfur-containing substances, as well as a number of chemical compounds that are toxic to other life forms. According to scientists, the thermophilic archaebacteria found are extremely primitive organisms and, in evolutionary terms, close relatives of the most ancient forms of life on Earth.
It is interesting that modern representatives of all three branches of life, most similar to their ancestors, still live in places with high temperatures. Based on this, some scientists are inclined to believe that, most likely, life arose about 4 billion years ago on the ocean floor near hot springs, erupting streams rich in metals and high-energy substances. Interacting with each other and with the water of the then sterile ocean, entering into a wide variety of chemical reactions, these compounds gave rise to fundamentally new molecules. So, for tens of millions of years, the greatest dish - life - was prepared in this “chemical kitchen”. And about 4.5 billion years ago, single-celled organisms appeared on Earth, whose lonely existence continued throughout the Precambrian period.
The burst of evolution that gave rise to multicellular organisms occurred much later, a little over half a billion years ago. Although microorganisms are so small that a single drop of water can contain billions, the scale of their work is enormous.
It is believed that initially there was no free oxygen in the earth’s atmosphere and the oceans, and under these conditions only anaerobic microorganisms lived and developed. A special step in the evolution of living things was the emergence of photosynthetic bacteria, which, using light energy, converted carbon dioxide into carbohydrate compounds that served as food for other microorganisms. If the first photosynthetics produced methane or hydrogen sulfide, then the mutants that appeared once began to produce oxygen during photosynthesis. As oxygen accumulated in the atmosphere and waters, anaerobic bacteria, for which it is harmful, occupied oxygen-free niches.
Ancient fossils found in Australia dating back 3.46 billion years have revealed structures believed to be the remains of cyanobacteria, the first photosynthetic microorganisms. The former dominance of anaerobic microorganisms and cyanobacteria is evidenced by stromatolites found in shallow coastal waters of unpolluted salt water bodies. In shape they resemble large boulders and represent an interesting community of microorganisms living in the limestone or dolomite rocks formed as a result of their life activity. At a depth of several centimeters from the surface, stromatolites are saturated with microorganisms: photosynthetic cyanobacteria that produce oxygen live in the uppermost layer; deeper bacteria are found that are to a certain extent tolerant of oxygen and do not require light; in the lower layer there are bacteria that can only live in the absence of oxygen. Located in different layers, these microorganisms form a system united by complex relationships between them, including food relationships. Behind the microbial film is a rock formed as a result of the interaction of the remains of dead microorganisms with calcium carbonate dissolved in water. Scientists believe that when there were no continents on the primitive Earth and only archipelagos of volcanoes rose above the surface of the ocean, the shallow waters were replete with stromatolites.
As a result of the activity of photosynthetic cyanobacteria, oxygen appeared in the ocean, and approximately 1 billion years after that, it began to accumulate in the atmosphere. First, the resulting oxygen interacted with iron dissolved in water, which led to the appearance of iron oxides, which gradually precipitated at the bottom. Thus, over millions of years, with the participation of microorganisms, huge deposits of iron ore arose, from which steel is smelted today.
Then, when the bulk of the iron in the oceans was oxidized and could no longer bind oxygen, it escaped into the atmosphere in gaseous form.
After photosynthetic cyanobacteria created a certain supply of energy-rich organic matter from carbon dioxide and enriched the earth's atmosphere with oxygen, new bacteria arose - aerobes, which can exist only in the presence of oxygen. They need oxygen for the oxidation (combustion) of organic compounds, and a significant part of the resulting energy is converted into a biologically available form - adenosine triphosphate (ATP). This process is energetically very favorable: anaerobic bacteria, when decomposing one molecule of glucose, receive only 2 molecules of ATP, and aerobic bacteria that use oxygen receive 36 molecules of ATP.
With the advent of oxygen sufficient for an aerobic lifestyle, eukaryotic cells also made their debut, which, unlike bacteria, have a nucleus and organelles such as mitochondria, lysosomes, and in algae and higher plants - chloroplasts, where photosynthetic reactions take place. There is an interesting and well-founded hypothesis regarding the emergence and development of eukaryotes, expressed almost 30 years ago by the American researcher L. Margulis. According to this hypothesis, the mitochondria that function as energy factories in the eukaryotic cell are aerobic bacteria, and the chloroplasts of plant cells in which photosynthesis occurs are cyanobacteria, probably absorbed about 2 billion years ago by primitive amoebae. As a result of mutually beneficial interactions, the absorbed bacteria became internal symbionts and formed a stable system with the cell that absorbed them - a eukaryotic cell.
Studies of fossil remains of organisms in rocks of different geological ages have shown that for hundreds of millions of years after their origin, eukaryotic life forms were represented by microscopic spherical single-celled organisms such as yeast, and their evolutionary development proceeded at a very slow pace. But a little over 1 billion years ago, many new species of eukaryotes emerged, marking a dramatic leap in the evolution of life.
First of all, this was due to the emergence of sexual reproduction. And if bacteria and single-celled eukaryotes reproduced by producing genetically identical copies of themselves and without the need for a sexual partner, then sexual reproduction in more highly organized eukaryotic organisms occurs as follows. Two haploid sex cells of the parents, having a single set of chromosomes, fuse to form a zygote that has a double set of chromosomes with the genes of both partners, which creates opportunities for new gene combinations. The emergence of sexual reproduction led to the emergence of new organisms, which entered the arena of evolution.
Three quarters of the entire existence of life on Earth was represented exclusively by microorganisms, until a qualitative leap in evolution occurred, leading to the emergence of highly organized organisms, including humans. Let's trace the main milestones in the history of life on Earth in a descending line.
1.2 billion years ago there was an explosion of evolution, caused by the advent of sexual reproduction and marked by the appearance of highly organized life forms - plants and animals.
The formation of new variations in the mixed genotype that arises during sexual reproduction manifested itself in the form of biodiversity of new life forms.
2 billion years ago, complex eukaryotic cells appeared when single-celled organisms complicated their structure by absorbing other prokaryotic cells. Some of them - aerobic bacteria - turned into mitochondria - energy stations for oxygen respiration. Others - photosynthetic bacteria - began to carry out photosynthesis inside the host cell and became chloroplasts in algae and plant cells. Eukaryotic cells, which have these organelles and a clearly distinct nucleus containing genetic material, make up all modern complex life forms - from molds to humans.
3.9 billion years ago, single-celled organisms appeared that probably looked like modern bacteria and archaebacteria. Both ancient and modern prokaryotic cells have a relatively simple structure: they do not have a formed nucleus and specialized organelles, their jelly-like cytoplasm contains DNA macromolecules - carriers of genetic information, and ribosomes on which protein synthesis occurs, and energy is produced on the cytoplasmic membrane surrounding cell.
4 billion years ago, RNA mysteriously emerged. It is possible that it was formed from simpler organic molecules that appeared on the primitive earth. It is believed that ancient RNA molecules had the functions of carriers of genetic information and protein catalysts, they were capable of replication (self-duplication), mutated and were subject to natural selection. In modern cells, RNA does not have or does not exhibit these properties, but plays a very important role as an intermediary in the transfer of genetic information from DNA to ribosomes, in which protein synthesis occurs.
A.L. Prokhorov
Based on an article by Richard Monasterski
in National Geographic magazine, 1998 No. 3
Science cannot yet say even approximately, even with an error of millions of years. What is indisputable is that living matter has changed over hundreds of millions of years of the Earth’s life, depending on environmental conditions, the conditions of existence of organisms.
Development of plant and animal organisms
Comparing plant and animal organisms, deep differences can be found in them. If we move from higher forms to lower ones, from more highly organized to less organized, these differences are gradually smoothed out. The simplest representatives of animals and plants are so close to each other that their division is conditional and it is not possible to establish a sharp boundary here. This strongly suggests unity of life.
Life gradually developed and improved. As a result of continuous changes, new plant and animal organisms appeared that were better adapted to the new environment.
The plant and animal world familiar to us is only one of the stages of that grandiose process of life development, which began a very long time ago.
The history of the origin of life on Earth in the layers of the earth's crust
These layers are like the pages of a special book, a fascinating book about the life of the Earth. You just need to be able to read its dilapidated, sometimes too scattered pages.
In a deep ravine or on the bank of a river you can find shells that are unusual in appearance and shape, imprints of plants and animals on stone, stones that look like a honeycomb or small ram's horns, as well as stone tubes pointed on one side, varying in size and thickness. . They somewhat resemble fragments of stone fingers. For this similarity, they are colloquially called “devil’s fingers.”
damn finger You may also be lucky enough to find unusual shape teeth, bones and even entire skeletons, prints, sometimes of enormous size, of animals never seen before.
The rocks that make up the earth's crust are no less remarkable than the fossil remains of the organisms that are found in them. In some places our attention is attracted by blue, red and black clays, in others by black, red and green sandstones, white and green sands, limestones, sometimes overflowing with the remains of various organisms.
Nature researchers have long noted that the remains of different organisms are found in different layers.
In some layers, for example near St. Petersburg, one is struck by the abundance of small flat shells - “obolus”, approximately the size of a two-kopeck coin (“obolos” in Greek small small coin- obol), in other layers, for example near Moscow, there is an abundance of “devil’s fingers”.
Abundance of "devil's fingers" in the layers From this the conclusion was drawn that these layers were formed at different geological times, when these particular organisms became widespread in sea waters.
Obolus inhabited the ancient Silurian Sea, which arose, as geologists estimate, approximately 360 million years ago and existed for 40 million years. This sea occupied a huge area starting from the eastern borders Western Europe before Aral Sea in the east and approximately from the latitude of Tula in the north to Caucasus Mountains on South.
Modern seas, for example the Black Sea, also throw out huge masses of all kinds of shells. On the Evpatoria “golden” beach you will be amazed by the abundance of shells. Local craftsmen skillfully decorate their simple souvenirs with it - boxes, photo frames and various trinkets. Along with artistic purpose shell is well used instead of ballast sand for railway tracks.
The thicknesses of the Black Sea shell served as the starting material for the formation of layers of shell rock - beautiful building material, easy to process.
Shell rock is an excellent building material The “devil’s finger” has an equally interesting story. The devil here is remembered only out of ignorance: this is nothing more than fragments of the inner shell of the ancient cephalopod mollusk belemnite, which lived in the distant Mesozoic era, approximately 185 million years ago. The name of the animal comes from the ancient Greek word “belemnon” - an arrow, the tip of which generally resembled a “devil’s finger”.
Descendants of the Belemnites
The few descendants of belemnites - cuttlefish and giant monsters - octopuses, or octopuses, are found in modern seas, both cold and warm, both near the coast and at great depths (up to 3500 meters). Most cephalopods are carnivores; sometimes they reach 17 meters, of which 6 meters are on the body of the animal, the rest on the tentacles - “legs”, numbering up to ten.
Cephalopods swim in a special way: by strong contraction of the muscles of their body, they throw out a stream of water from the mouth. From this push the animal rushes rapidly, like a torpedo. You might think it floats backwards. In case of danger, some cephalopods release the contents of a special ink sac and become invisible to the enemy behind a cloudy curtain.
The famous Chinese ink is made from the contents of the ink sac and brown paint- sepia. Many cephalopods, especially cuttlefish, are eaten (in China) both fresh and dried.
The “devil’s finger” itself was located in the tail part of the animal and provided the predator with speed of movement.
Ancient seas
Ancient cephalopods were found in abundance in Cretaceous sea, which in the first half of the Cretaceous period filled a wide strip along the Ural ridge, extending as a deep bay to the west to the Tver-Kaluga meridian, and in the second half occupied almost the entire southern half of the European part of Russia to the southern borders with Turkey and Iran. In that southern region The Cretaceous Sea has already emerged in the form of a rocky island, the Main Caucasus Range.
Study of the formation of Earth strata
If in layers of the Earth In areas remote from each other, for example, near Moscow and near Ulyanovsk, “devil’s fingers” or other identical organic remains are found in abundance - this convincingly indicates that these layers were formed at the same geological time, otherwise - at the same time geological period, era, century, etc.
Study of the layers of the earth's crust in the Quaternary period
Interesting material can be obtained from studying the layers of the earth's crust formed over the nearest million years to us. This geological period, which continues to this day, is called the Quaternary period.
In the uppermost layers of the Lower and Middle Volga region, for example in the Astrakhan, Volgograd, Saratov and Kuibyshev regions, especially in the Trans-Volga region, there are shells similar to those that now live in the Caspian Sea.
Based on the finds of these shells, it was possible to establish the boundaries of the once-existent huge Aral-Caspian Sea. Volgograd and Saratov are now located on its main bank. Researchers can even establish for sure that the northern narrow bay of the sea ran along the high right bank of the Kama far to the northeast.
This is how this sea looked about 100 thousand years ago, when most of European territory Russia was under the cover of the great glaciation and the thickness of the ice, as geologists believe, reached up to two kilometers.
In the deeper layers in the Volga region, bones of bison bulls, wild horses, huge camels, mammoths, gigantic deer, hairy rhinoceros, cave lions and other now extinct animals are found.
The deeper we penetrate into the layers, the more often we will encounter the bones of animals that are more and more different from modern representatives of the animal world.
Fossilized remains of animals By studying the fossilized remains of life from past eras, geologists seem to be turning over the stone pages of the great book of nature. However, it often does not give an exhaustive answer: many pages are missing, since not all organisms that existed in past eras of the life of our planet left their mark on the stone.
Imprint of the Petrified Worm From the long chain of life, starting from the emergence of living matter to the most perfect form - man, only separate fragments have been preserved; many links of this chain are missing.
The most ancient layers of the earth's crust, greatly altered during its formation, contain almost no signs of organic life.
Formation of fossil organisms
More distinct traces of organisms begin to appear in those rocks that were formed from sediments of ancient reservoirs.
The organisms and their skeletons buried in these sediments gradually turned into stone under favorable conditions, in other words, they became mineralized.
Mineralized finds Their organic matter was replaced from solutions by minerals, such as lime carbonate, silica and other substances. This is how various fossilized shells, bones, pieces of wood and even entire tree trunks were formed.
If you polish a thin transparent plate from a piece of petrified wood ( thinner than a sheet paper), the so-called thin section, then under a microscope we will clearly see the internal structure of ancient wood.
Sometimes it is not the shells themselves, parts of plants, etc., that are preserved, but only their imprints, for example, imprints of plant leaves.
There are also casts formed from material that filled the shell and subsequently hardened.
This creates the “inner cores,” as geologists call them. They resemble metal castings in a specific shape. When the shell itself dissolves, a cast of its outer shape, or “outer core,” is obtained.
The environment in which the remains of animals were preserved determined their preservation: in coarse-grained sands, the remains of animals were dissolved by circulating waters, in clays they were crushed, and in metamorphic rocks they completely disappeared.
Only fine-grained silty sediments, peat, natural asphalt and especially resin coniferous trees determined the exceptional preservation of organic remains. Insects, for example, and flowers, trapped millions of years ago in liquid tree resin, were preserved entirely without the slightest change, as if they were alive. How can this be explained?
The fact is that the resin gradually hardened, turned to stone, turning into amber - a semi-precious golden stone, often completely transparent. Amber is used to make beads, mouthpieces, brooches, etc. Various insects, especially ants, are often found in amber.
Here is what Lomonosov wrote about these wonders approximately 260 years ago:
An ant walking in the poplar shade
I got my foot stuck in the sticky resin.
Although he was despicable among people in his life:
After death, they became precious in amber.
Not always, especially in the old days, geological finds received the correct definition and purpose. There were also unforgettable oddities. In one, for example, Spanish cathedral in the 17th century, the molar tooth of a mammoth was revered as the undoubted tooth of a saint.
Those suffering from toothache applied themselves to the Mammoth tooth and generally gave a good income to the “holy fathers”. Note that the approximate dimensions of a mammoth tooth are: the length of the root is 12 centimeters, the length of the chewing surface is 14 centimeters, and its width is 7 centimeters. Every person is supposed to have thirty-two teeth (with a full set of them). How big was the saint’s mouth, judging by the indisputable data of the shrine itself.
It should be noted that legends about giants, twenty times taller than humans, were also found in ancient, “scientific” treatises of that time.
There were even more severe cases with geological finds. The imprint of the skeleton of an ancient lizard was recognized, for example, with the blessing of the “learned men” of the first quarter of the 18th century, as the skeleton of a man who drowned during the “flood.”
From the archives of "Continent"
It is well known that our Universe was formed about 14 billion years ago as a result of a giant explosion known in science as the Big Bang. The emergence of the Universe “out of nothing” does not contradict the known laws of physics: positive energy matter formed after the explosion is exactly equal to the negative energy of gravity, so the total energy of such a process is zero. IN Lately Scientists are also discussing the possibility of the formation of other universes - “bubbles”. The world, according to these theories, consists of an infinite number of universes about which we still know nothing. It is interesting that at the moment of the explosion not only three-dimensional space was formed, but, and what is very important, time associated with space. Time is the reason for all the changes that have occurred in the Universe after Big Bang. These changes occurred sequentially, step by step as the arrow of time increased, and included the formation of a huge number of galaxies (on the order of 100 billion), stars (the number of galaxies multiplied by 100 billion), planetary systems and, ultimately, life itself, including intelligent life. To imagine how many stars there are in the Universe, astronomers make this interesting comparison: the number of stars in our Universe is comparable to the number of grains of sand on all the beaches of the Earth, including seas, rivers and oceans. A universe frozen in time would be unchanged and of little interest and there would be no development in it, i.e. all those changes that occurred later and ultimately led to the existing picture of the world.
Our Galaxy is 12.4 billion years old, and our solar system 4.6 billion years. The age of meteorites and the oldest rocks on Earth is slightly less than 3.8-4.4 billion years. The first unicellular organisms, devoid of prokaryotic nuclei and green-blue bacteria, appeared 3.0-3.5 billion years ago. These are the simplest biological systems capable of forming proteins, chains of amino acids consisting of the basic elements of life C, H, O, N, S, and leading an independent lifestyle. Simple green-blue “algae”, i.e. aquatic plants without vascular tissues and “archaebacteria” or old bacteria (used for the preparation of medicines) are still an important part of our biosphere. These bacteria are the first successful adaptation of life on Earth. It is interesting that green-blue bacteria and other prokaryotes have remained almost unchanged for billions of years, while extinct dinosaurs and other species can never be reborn again, because conditions on Earth have changed greatly, and they can no longer go through all the stages of development that they went through in those distant years. If for one reason or another life on Earth ceases (due to a collision with a giant meteorite, as a result of the explosion of a supernova adjacent to the solar system, or our own self-destruction), it cannot begin again in the same form, because current conditions are fundamentally different from those that were about four billion years ago (for example, the presence of free oxygen in the atmosphere, as well as changes in the Earth's fauna). Evolution, unique in its essence, can no longer repeat itself in the same form and go through all the stages through which it has passed over the past billions of years. Dr. Payson from the Los Alamos National Laboratory in the USA expressed a very interesting idea about the role of evolution in the organization of a system of living structures: “Life is a sequence of molecular interactions. If we discover a principle other than evolution in biology, we will learn to create living systems in the laboratory and thus understand the mechanism of the formation of life.” The reason why we cannot carry out the transformation of species in the laboratory (for example, the Drosophila fly into some other species) is that under natural conditions it took millions of years, and today we do not know any other principle how to cause such a transformation .
As the number of prokaryotes increased, they “invented” the phenomenon of photosynthesis, i.e. a complex chain of chemical reactions in which the energy sunlight together with carbon dioxide and water it is converted into oxygen and glucose. In plants, photosynthesis occurs in chloroplasts, which are contained in their leaves, resulting in atmospheric oxygen. An oxygen-saturated atmosphere appeared 2-2.5 billion ago. Eukaryotes, multicellular cells containing a nucleus with genetic information, as well as organelles, formed 1-2 billion years ago. Organelles are found in prokaryotic cells, as well as in animal and plant cells. DNA is the genetic material of any living cell that contains hereditary information. Hereditary genes are located on chromosomes, which contain proteins bound to DNA. All organisms - bacteria, flora and fauna - despite the enormous diversity of species, have a common origin, i.e. have a common ancestor. The tree of life consists of three main branches - Bacteria, Archaea, Eukaria. The last group includes the entire flora and fauna. All known living organisms make proteins using only 20 basic amino acids (although the total number of amino acids in nature is 70), and also use the same energy molecule ATP to store energy in cells. They also use DNA molecules to pass genes from one generation to the next. A gene is the fundamental unit of heredity, a piece of DNA that contains the information necessary for protein synthesis. Different organisms have similar genes, which can be mutated or improved over long periods of evolution. From bacteria to amoebae and from amoebae to humans, genes are responsible for the characteristics of organisms and the improvement of species, while proteins support life. All living organisms use DNA to pass on their genes to the next generation. Genetic information is transferred from DNA to protein through a complex chain of transformations via RNA, which is similar to DNA, but differs from it in its structure. In the chain of transformations chemistry®biology®life, an organic molecule is synthesized. Biologists are well aware of all these transformations. The most amazing of them is the decoding genetic code(The Human Genome Project), which is amazing in both its complexity and perfection. The genetic code is universal for all three branches of the tree of life.
Most interest Ask, some humanity has been searching for an answer throughout its history to how the first life arose and, in particular, whether it originated on Earth or was brought from the interstellar medium with the help of meteorites. All the basic molecules of life, including amino acids and DNA, are also found in meteorites. The theory of directed panspermia suggests that life arose in interstellar space (I wonder where?) and migrates through vast space, but this theory cannot explain how life can survive in the harsh conditions of space (dangerous radiation, low temperatures, lack of atmosphere etc.). Scientists subscribe to the theory that natural, albeit primitive conditions on Earth led to the formation of simple organic molecules, as well as the development of forms of varying chemical activity, which ultimately launched the tree of life. In a very interesting experiment by Miller and Urey, performed in 1953, they proved the formation of complex organic molecules (aldehydes, carboxyls and amino acids) by passing a powerful electrical discharge - analogous to lightning in natural conditions - through a mixture of gases CH4, NH3, H2O, H2, which were present in the Earth's primary atmosphere. This experiment demonstrated that the basic chemical components of life, i.e. biological molecules can be naturally formed by simulating primitive conditions on Earth. However, no forms of life, including the polymerization of DNA molecules, were discovered, which, apparently, could only arise as a result of long-term evolution.
Meanwhile, more complex structures began to appear, huge cells - organs and large living formations consisting of millions and billions of cells (for example, a person consists of ten trillion cells). The complexity of the system depended on the passage of time and the depth of natural selection, which preserved species most adapted to new living conditions. Although all simple eukaryotes reproduced by fission, more complex systems were formed through sexual intercourse. In the latter case, each new cell takes half the genes from one parent and the other half from the other.
Life for a very long period of its history (almost 90%) existed in microscopic and invisible forms. Approximately 540 million years ago, a completely new revolutionary period began, known in science as the Cambrian era. This is a period of rapid emergence of a huge number of multicellular species with a hard shell, skeleton and powerful shell. The first fish and vertebrates appeared, plants from the oceans began to migrate throughout the Earth. The first insects and their descendants contributed to the spread of the animal world across the Earth. Insects with wings, amphibians, the first trees, reptiles, dinosaurs and mammoths, the first birds and the first flowers began to appear successively (dinosaurs disappeared 65 million years ago, apparently due to a giant collision of the Earth with a massive meteorite). Then came the period of dolphins, whales, sharks and primates, the ancestors of monkeys. About 3 million years ago, creatures with unusually large and powerful developed brain, hominids (the first ancestors of people). The appearance of the first man (homo sapiens) dates back 200,000 years ago. According to some theories, the appearance of the first man, who is qualitatively different from all other species of the animal world, may be the result of a strong mutation of hominids, which was the source of the formation of a new allele (allele) - a modified form of one of the genes. Appearance modern man dates back approximately 100,000 years ago, the historical and cultural evidence of our history does not exceed 3000-74000 years, but we became a technologically advanced civilization only recently, only 200 years ago!
Life on Earth is a product biological evolution, dating back approximately 3.5 billion years. The appearance of life on Earth is the result of a large number favorable conditions– astronomical, geological, chemical and biological. All living organisms, from bacteria to humans, have a common ancestor and consist of several basic molecules that are common to all objects in our Universe. The main properties of living organisms are that they react, grow, reproduce and transmit information from one generation to another. We, the earthly civilization, despite our youthful age, have achieved a lot: we have mastered atomic energy, deciphered the human genetic code, created complex technologies, began experimenting in the field of genetic engineering (synthetic life), are engaged in cloning, and are working to increase our life expectancy (even today scientists are discussing the possibility of increasing life expectancy to 800 years or more), began to fly into space, invented computers and are even trying to make contact with extraterrestrial civilization (SETI program, Search for Extraterrestrial Intelligence). Because another civilization will go through a completely different path of development, it will be completely different from ours. In this sense, each civilization is unique in its own way - perhaps this is one of the reasons why the SETI program was unsuccessful. We began to interfere in the holy of holies, i.e. into processes that would take millions and millions of years in the natural environment.
To better understand how young we are, let's assume that the total history of the Earth is one year and that our history began on January 1st. In this scale, prokaryotes and blue-green bacteria appeared as early as June 1, which soon led to an oxygenated atmosphere. The Cambrion era began on November 13th. Dinosaurs lived on Earth from December 13 to December 26, and the first hominids appeared on the afternoon of December 31. By the New Year, we, already modern people, sent the first message into space - to another part of our Galaxy. Only in about 100,000 years (or in 15 minutes on our scale) will our message (not yet read by anyone) leave our Galaxy and rush to other galaxies. Will it ever be read? We won't know. Most likely not.
It would not only take billions of years for a civilization similar to ours to emerge in another part of the Universe. It is important that such a civilization has enough time for its development and transformation into a technological one, and most importantly does not destroy itself (this is another reason why we cannot find another civilization, although we have been looking for it for more than 50 years: it may perish before manages to become technological). Our technology may have a detrimental effect on the atmosphere. Already today we are concerned about the appearance of ozone holes in our atmosphere, which have greatly increased over the past 50 years (ozone is a triatomic oxygen molecule, which, in general, is poison). This is the result of our technological activity. The ozone shell protects us from dangerous ultraviolet radiation from the Sun. Such radiation, in the presence of ozone holes, will lead to an increase in the earth's temperature and, as a result, to global warming. The surface of Mars today is sterile due to the absence of an ozone layer. Over the past 20 years the ozone hole in the Earth's atmosphere grew to the size of a large continent. An increase in temperature of even 2 degrees will lead to melting of ice, rising ocean levels, as well as their evaporation and a dangerous increase in carbon dioxide in the atmosphere. Then a new warming of the atmosphere will occur, and this process will continue until all the seas and oceans evaporate (scientists call this phenomenon the runaway greenhouse effect). After the evaporation of the oceans, the amount of carbon dioxide in the atmosphere will increase by about 100,000 times and amount to about 100%, which will lead to the complete and irreversible destruction of not only the ozone layer of the earth's atmosphere, but also all life on Earth. This development of events has already taken place in the history of our solar system on Venus. 4 billion years ago, conditions on Venus were close to those on Earth and, perhaps, there was even life there, because... The sun in those distant times did not shine so brightly (it is known that the intensity of solar radiation gradually increases). It is possible that life from Venus migrated to Earth, and from Earth, as solar radiation increases, migrates to Mars, although, apparently, such a development is unlikely due to the problems of living cell migration through space. The amount of carbon dioxide in the atmosphere of Venus today is 98%, and the atmospheric pressure is almost a hundred times higher than on Earth. This may be the result of global warming and the evaporation of the Venusian oceans. Venus and Mars teach us important lesson, i.e. we know today what can happen to our planet if no measures are taken. Another problem is related to the increase in solar radiation, which will ultimately cause a runaway greenhouse effect on Earth with a known result.
Our development is exponential and accelerating. The Earth's population doubles every 40 years and has increased from approximately 200 thousand to 6 billion over the past 2000 years. However, do not such rapid development contain the seeds of danger to our existence? Will we destroy our civilization? Will we have time to become a highly developed civilization and understand our history? Will we be able to fly deep into space and find another civilization like ours? According to Einstein, the most amazing thing in the world is that the world is knowable. Perhaps this is one of the most intriguing features of human civilization - the ability to reveal the secrets of the world. We can understand the world we live in and understand the laws that govern it. However, why do these laws exist? Why is the speed of light, for example, equal to 300,000 km/sec or why the well-known number i in mathematics (the ratio of the circumference of a circle to its diameter) is exactly 3.14159...? American physicist A. Michelson received the Nobel Prize for measuring the speed of light with unprecedented accuracy (let me remind you that this is a gigantic value: moving at such a speed we would find ourselves on the Moon in about one second, on the Sun in 8 minutes, and in the center of the Galaxy in 28,000 years ). Another example is that decoding the genetic code, consisting of 30 million pieces, each 500-600 letters long, required 15 years of work using complex programs and computers. It turned out that the length of the entire code is equal to the length of 100 million letters. This discovery was made at the turn of the two millennia and showed that we may be able to treat diseases of any complexity by correcting errors in the corresponding section of the damaged gene. Mathematicians, with the help of fast computers, calculated the number I with incredible accuracy to a trillion decimal places in order to know its exact value and describe this number using some simple formula. Who came up with these numbers and why are they what they are? How could the genetic code be so perfect? How are physical constants related to our universe? Of course, they reflect the geometric structure of our Universe and apparently have different meanings for different universes. We do not know this today, as well as many other things. But we strive to find general laws of our world or even a single law from which we could derive all other laws in a particular case, and also, which is very important, to understand the meaning of world constants. We also do not know whether our existence is connected with the fulfillment of some kind of mission.
But let's return to our history and our evolution. Has it ended and what is its meaning? What will happen to us in millions of years, if, of course, we manage to solve our technological problems and do not destroy ourselves? What is the meaning of the appearance in our history of such brilliant personalities as Einstein, Shakespeare or Mozart? Is it possible to have a new mutation and create another more perfect species than humans? Can this one the new kind solve the problems of the universe and understand the meaning of our history? We have discovered the laws and measured the constants of the world with breathtaking precision, but we do not understand why they are the way they are or what their role is in the universe. If those constants were changed just a little, then our whole history would look different. Despite all the complexity and mystery of the genetic code, the mysteries of the Universe itself seem endless. What is the essence of these mysteries and will we be able to decipher them? Of course we will change. But how? Are we the highest and last link in the long history of our development? Is our history the result of some ingenious plan or is it simply the result of hundreds and thousands of favorable conditions made possible by time and long evolution? There is no doubt that there is no limit to our development and it is also endless, just as the world is endless, consisting of millions and millions of universes that are constantly being destroyed and formed again.
Ilya Gulkarov, Professor, Doctor of Physical and Mathematical Sciences, Chicago
June 18, 2005
