The oldest living organisms on earth. How life originated on Earth: history, features of origin and interesting facts

How did life originate on Earth? The details are unknown to mankind, but the cornerstone principles have been established. There are two main theories and many minor ones. So, according to the main version, the organic components came to Earth from outer space, according to another, everything happened on Earth. Here are some of the most popular teachings.

Panspermia

How did our Earth come about? The biography of the planet is unique, and people are trying to unravel it in different ways. There is a hypothesis that the life that exists in the universe is distributed with the help of meteoroids (celestial bodies intermediate in size between interplanetary dust and an asteroid), asteroids and planets. It is assumed that there are life forms that can withstand exposure (radiation, vacuum, low temperatures, etc.). They are called extremophiles (including bacteria and microorganisms).

They get into debris and dust, which are thrown into space after saving, thus, life after the death of small bodies of the solar system. Bacteria can travel at rest for long periods of time before another random collision with other planets.

They can also mix with protoplanetary disks (dense gas cloud around a young planet). If in a new place "persistent but sleepy soldiers" fall into favorable conditions, they become active. The process of evolution begins. History is unraveled with the help of probes. Data from instruments that have been inside comets indicate that in the vast majority of cases, the likelihood is confirmed that we are all "a little alien", since the cradle of life is space.

Biopoiesis

And here is another opinion on how life originated. On Earth there is living and non-living. Some sciences welcome abiogenesis (biopoesis), which explains how, in the course of natural transformation, biological life emerged from inorganic matter. Most amino acids (also called the building blocks of all living organisms) can be formed using natural chemical reactions that are not related to life.

This is confirmed by the Muller-Urey experiment. In 1953, a scientist ran electricity through a mixture of gases and produced several amino acids in laboratory conditions that mimic those of the early Earth. In all living beings, amino acids are transformed into proteins under the influence of nucleic acids, the genetic memory custodians.

The latter are synthesized independently by biochemical means, and proteins accelerate (catalyze) the process. Which of the organic molecules is the first? And how did they interact? Abiogenesis is in the process of finding an answer.

Cosmogonic trends

This is the doctrine of space. In a certain context of space science and astronomy, the term refers to the theory of creation (and study) of the solar system. Attempts to gravitate toward naturalistic cosmogony do not stand up to scrutiny. First, the existing scientific theories cannot explain the main thing: how did the Universe itself appear?

Secondly, there is no physical model that explains the earliest moments of the existence of the universe. In the mentioned theory, there is no concept of quantum gravity. Although string theorists say that elementary particles arise from the vibrations and interactions of quantum strings), those who study the origin and consequences of the Big Bang (loop quantum cosmology) do not agree with this. They believe they have formulas to describe the model in terms of field equations.

With the help of cosmogonic hypotheses, people explained the uniformity of the movement and composition of celestial bodies. Long before life appeared on Earth, matter filled all space and then evolved.

Endosymbiont

The endosymbiotic version was first formulated by the Russian botanist Konstantin Merezhkovsky in 1905. He believed that some organelles originated as free-living bacteria and were taken into another cell as endosymbionts. Mitochondria evolved from proteobacteria (specifically Rickettsiales or close relatives) and chloroplasts from cyanobacteria.

This suggests that multiple forms of bacteria entered into symbiosis with the formation of a eukaryotic cell (eukaryotes are cells of living organisms containing a nucleus). The horizontal transfer of genetic material between bacteria is also facilitated by symbiotic relationships.

The emergence of a variety of life forms may have been preceded by the Last Common Ancestor (LUA) of modern organisms.

Spontaneous birth

Until the early 19th century, people generally dismissed "suddenness" as an explanation for how life began on Earth. The unexpected spontaneous generation of certain forms of life from inanimate matter seemed implausible to them. But they believed in the existence of heterogenesis (a change in the method of reproduction), when one of the forms of life comes from another species (for example, bees from flowers). Classical ideas about spontaneous generation boil down to the following: some complex living organisms appeared due to the decomposition of organic substances.

According to Aristotle, this was an easily observable truth: aphids arise from dew that falls on plants; flies - from spoiled food, mice - from dirty hay, crocodiles - from rotting logs at the bottom of reservoirs, and so on. The theory of spontaneous generation (refuted by Christianity) secretly existed for centuries.

It is generally accepted that the theory was finally refuted in the 19th century by the experiments of Louis Pasteur. The scientist did not study the origin of life, he studied the appearance of microbes in order to be able to fight infectious diseases. However, Pasteur's evidence was no longer controversial, but strictly scientific.

Clay Theory and Sequential Creation

The emergence of life on the basis of clay? Is that possible? A Scottish chemist named A.J. Kearns-Smith from the University of Glasgow in 1985 is the author of such a theory. Based on similar assumptions by other scientists, he argued that organic particles, being between the layers of clay and interacting with them, adopted the way of storing information and growing. Thus, the scientist considered the “clay gene” to be primary. Initially, the mineral and the nascent life existed together, but at a certain stage they “ran up”.

The idea of ​​destruction (chaos) in the emerging world paved the way for the theory of catastrophism as one of the forerunners of the theory of evolution. Its proponents believe that the Earth has been affected by sudden, short-lived, turbulent events in the past, and that the present is the key to the past. Each next catastrophe destroyed the existing life. The subsequent creation revived it already different from the previous one.

materialistic doctrine

And here is another version of how life originated on Earth. It was put forward by the materialists. They believe that life appeared as a result of gradual chemical transformations extended in time and space, which, in all likelihood, took place almost 3.8 billion years ago. This development is called molecular, it affects the area of ​​deoxyribonucleic and ribonucleic acids and proteins (proteins).

As a scientific trend, the doctrine arose in the 1960s, when active research was carried out affecting molecular and evolutionary biology, population genetics. Scientists then tried to understand and validate recent discoveries regarding nucleic acids and proteins.

One of the key topics that stimulated the development of this field of knowledge was the evolution of the enzymatic function, the use of nucleic acid divergence as a "molecular clock". Its disclosure contributed to a deeper study of the divergence (branching) of species.

organic origin

About how life appeared on Earth, supporters of this doctrine argue as follows. The formation of species began a long time ago - more than 3.5 billion years ago (the number indicates the period in which life exists). Probably, at first there was a slow and gradual process of transformation, and then a fast (within the Universe) stage of improvement began, a transition from one static state to another under the influence of existing conditions.

Evolution, known as biological or organic, is the process of changing over time one or more inherited traits found in populations of organisms. Hereditary traits are special distinguishing features, including anatomical, biochemical and behavioral, that are transmitted from one generation to another.

Evolution has led to the diversity and diversification of all living organisms (diversification). Our colorful world was described by Charles Darwin as "endless forms, the most beautiful and the most wonderful." One gets the impression that the origin of life is a story without beginning or end.

special creation

According to this theory, all forms of life that exist today on planet Earth are created by God. Adam and Eve are the first man and woman created by the Almighty. Life on Earth began with them, believe Christians, Muslims and Jews. Three religions agreed that God created the universe within seven days, making the sixth day the culmination of labor: he created Adam from the dust of the earth and Eve from his rib.

On the seventh day God rested. Then he breathed in and sent to look after the garden called Eden. In the center grew the Tree of Life and the Tree of the Knowledge of Good. God allowed the fruits of all the trees in the garden to be eaten, except for the Tree of Knowledge (“for on the day that you eat them you will die”).

But the people disobeyed. The Qur'an says that Adam offered to taste the apple. God forgave sinners and sent both of them to earth as his representatives. And yet... Where did life come from on Earth? As you can see, there is no single answer. Although modern scientists are increasingly inclined towards the abiogenic (inorganic) theory of the origin of all living things.

Since childhood, I have had on my shelf an interesting book about the history of our planet, which my children are already reading. I will try to briefly convey what I remember, and I will tell you when living organisms appeared.

When did the first living organisms appear?

The origin occurred due to a number of favorable conditions no later than 3.5 billion years ago - in the Archean era. The first representatives of the living world had the simplest structure, but gradually, as a result of natural selection, conditions developed for complicating the organization of organisms. This led to the emergence of completely new forms.

So, the subsequent periods of development of life are as follows:

• Proterozoic - the beginning of the existence of the first primitive multicellular organisms, for example, mollusks and worms. In addition, algae, the ancestors of complex plants, developed in the oceans;
• the Paleozoic is the time of the flood of the seas and significant changes in the outlines of the land, which led to the partial extinction of most of the animals and plants;
• Mesozoic - a new round in the development of life, accompanied by the emergence of a mass of species with subsequent progressive modification;
• Cenozoic - a particularly important stage - the appearance of primates and the development of humans from them. At this time, the planet acquired the outlines of land familiar to us.

What did the first organisms look like?

The first creatures were small lumps of proteins, completely unprotected from any impact. Most died, but the survivors were forced to adapt, which marked the beginning of evolution.

Despite the simplicity of the first organisms, they had important abilities:

• reproduction;
• absorption of substances from the environment.

We can say that we were lucky - in the history of our planet there were practically no radical climate changes. Otherwise, even a small change in temperature could destroy a small life, which means that a person would not appear. The first organisms did not have a skeleton or shells, so it is quite difficult for scientists to trace history from geological deposits. The only thing that allows us to assert about life in the Archean is the content of gas bubbles in ancient crystals.

Which include plants and animals that survived tens of thousands of years.

However, despite their resilience and seeming immortality, they may soon disappear due to climate change and human interference.

Photographer and artist Rachel Sussman(Rachel Sussman) has traveled around the planet, visiting more than 20 countries and every continent to capture these ancient creatures. She found living plants and organisms that over 2000 years.

The photographer claims that all of these organisms are in danger due to rising temperatures, rising sea levels, acidification of the oceans and melting ice sheets.

All of these organisms, from 5,500-year-old moss in Antarctica to 100,000-year-old seagrass on the ocean floor, have managed to survive against the odds. However, in the last 5 years, two of them have died.

The oldest trees

So, underground forest in South Africa, which is 13,000 years old, was bulldozed to make a new road.

BUT cypress, which is 3,500 years old, died in 2012 when a woman from Florida in the United States, while under the influence of drugs, set it on fire.

Jemonsugi tree or the Japanese cedar, which is 2000 to 7000 years old and has grown since the Jōmon era in Japan, is one of the oldest trees on Yaku Island in Japan.

Baobab Glencoe in the province of Limpopo in South Africa is one of the most resistant trees in the world. Its girth was 47 meters until it was split by two lightning bolts in 2009. Its age is approximately 2000 years.

Pando– An 80,000-year-old clonal colony of aspen poplar in Utah, USA, consisting of 47,000 trunks. This is a single organism, connected by one underground root system.

ancient organisms

brain coral off the east coast of the island of Tobago in the Atlantic Ocean, 5.4 meters in size, which is 2000 years old.

actinobacteria, which is from 400,000 to 600,000 years old, is the oldest living organism, is located in the permafrost of Siberia and can die if it melts.

The most ancient plants

3000 year old Yareta- a small flowering plant (a relative of parsley), growing in South America, grows only 1.2 cm per year. This yareta was photographed in the Atacama Desert in Chile.

Antarctic moss - which is 5500 years old - on Mordvinov Island in Antarctica, was especially difficult to find. It was last seen 25 years ago, but with the help of modern navigation systems and expedition researchers national geographic he was found.

100,000 year old sea ​​grass in the Balearic Islands in Spain, which consists of their ancient giant clones - organisms stretching almost 16 km.

Velvichia amazing is a plant growing in Namibia and Angola in the extreme arid conditions of the Namib Desert, reaching an age of 2000 years.

Stromatolites- multi-layered structures in Australia, built by microorganisms in shallow water, which are 2000 - 3000 years old.

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What was the earliest life?

Our knowledge of pre-existing organisms is limited. After all, billions of individuals, representing a variety of species, disappeared without leaving any trace. According to some paleontologists, the remains of only 0.01% of all species of living organisms that inhabited the Earth have reached us in the fossil state. Among them are only those organisms that could preserve the structure of their forms through replacement or as a result of the preservation of imprints. All other species simply did not reach us, and we will never be able to learn anything about them.

For a long time it was believed that the age of the oldest imprints of living organisms, which include trilobites and other highly organized aquatic organisms, is 570 million years. Later, traces of much more ancient organisms were found - mineralized filamentous and rounded microorganisms of about a dozen different species, resembling protozoa and microalgae. The age of these remains has been estimated at 3.2–3.5 Ga. They have been found in the siliceous beds of Western Australia. These organisms apparently had a complex internal structure, they contained chemical elements, the compounds of which were capable of photosynthesis. These organisms are infinitely complex compared to the most complex known organic compounds of inanimate (abiogenic) origin. There is no doubt that these are not the earliest forms of life, and that their more ancient predecessors existed.

Therefore, today scientists no longer doubt that the origins of life on Earth go back to that "dark" first billion years of our planet's existence, which left no trace in its geological history. This point of view is supported by the fact that the known biogeochemical cycle of carbon associated with photosynthesis in the biosphere stabilized more than 3.8 billion years ago. This suggests that the photoautotrophic biosphere existed on our planet at least 4 billion years ago. But according to the data of cytology and molecular biology, photoautotrophic organisms were secondary in the process of evolution of living matter. The autotrophic method of feeding living organisms should have been preceded by the heterotrophic method, as it is simpler. Autotrophic organisms, building their body at the expense of inorganic minerals, are of a later origin. The following facts testify to this:

All modern organisms have systems adapted to the use of ready-made organic substances as the initial building material for biosynthesis processes;

The predominant number of species of organisms in the modern biosphere of the Earth can exist only with a constant supply of ready-made organic substances;

In heterotrophic organisms, there are no signs or rudimentary remnants of those specific enzyme complexes and biochemical reactions that are necessary for the autotrophic mode of nutrition.

Thus, we can conclude that the heterotrophic mode of nutrition is primary. The earliest life probably existed as heterotrophic bacteria that received food and energy from organic material of abiogenic origin, formed even earlier, at the cosmic stage of the Earth's evolution. On this basis, the beginning of life as such is pushed even further, beyond the limits of the stone chronicle of the earth's crust, more than
4 billion years ago.

Given the above, it is not difficult to come to the general conclusion that life on Earth has existed for about as long as the planet itself has existed. This is exactly what V.I. Vernadsky, when he spoke about the eternity of life on Earth.

Speaking about the most ancient organisms on Earth, it should also be noted that, according to the type of their structure, they were prokaryotes that arose shortly after the appearance of the archecell. Unlike eukaryotes, they did not have a well-formed nucleus, and the DNA molecule was located freely in the cell, i.e. not separated from the cytoplasm by a nuclear membrane. The differences between prokaryotes and eukaryotes are much deeper than between higher plants and higher animals, both of which are eukaryotic. Representatives of prokaryotes live today. These are bacteria and blue-green algae. Obviously, the first organisms that lived in the very harsh conditions of the original Earth were similar to them.

Scientists also have no doubt that the oldest organisms on Earth were anaerobic organisms that received the energy they needed through yeast fermentation. Most modern organisms are aerobic and use oxygen respiration (oxidative processes) to provide them with the necessary amount of energy for life.

Today there is no doubt that V.I. Vernadsky, who suggested that life arose immediately in the form of a primitive biosphere, was right. Only a variety of species of living organisms could ensure the fulfillment of all the functions of living matter in the biosphere. After all, life is the most powerful geological force, quite comparable in terms of energy costs and external effects with such geological processes as mountain building, volcanic eruptions, earthquakes, etc. Life does not just exist in its environment, but actively forms this environment, transforming it “for itself”. It should not be forgotten that the entire face of the modern Earth, all its landscapes, all sedimentary rocks, metamorphic rocks (granites, gneisses formed from sedimentary rocks), mineral reserves, and the modern atmosphere are the result of the action of living matter.

These data allowed Vernadsky to argue that from the very beginning of the biosphere, the life included in it should already have been a complex body, and not a homogeneous substance, since the biogeochemical functions of life, due to their diversity and complexity, cannot be associated with only one form of life. . Thus, the primary biosphere was initially represented by a rich functional diversity. Since organisms do not manifest themselves singly, but in a mass effect, the first appearance of life should have occurred not in the form of any one kind of organisms, but in their totality. In other words, primary biocenoses should have appeared immediately. They consisted of the simplest unicellular organisms, since without exception all the functions of living matter in the biosphere can be performed by them.

And, finally, it should be said that the primary organisms and the biosphere could exist only in water. We have already said above that all organisms on our planet are closely connected with water. It is bound water, which does not lose its basic properties, is the most important component of living organisms and makes up 60–99.7% of the weight.

It was in the waters of the primary ocean that the "primary soup" was formed. After all, sea water itself is a natural solution containing all the chemical elements. It formed first simple, and then complex organic compounds, among which were amino acids and nucleotides. It was in this "primordial soup" that the leap took place that gave rise to life on Earth. Of no small importance for the emergence and further development of life was the radioactivity of water, which then was 20-30 times greater than now. Although the original organisms were much more resistant to radiation than modern organisms, mutations in those days occurred much more often, so natural selection was more intense than today.

In addition, we should not forget that the Earth's primary atmosphere did not contain free oxygen, so it did not have an ozone screen that protects our planet from the ultraviolet radiation of the Sun. For these reasons, life simply could not arise on land, and water served as a sufficient obstacle to these rays.

So, summing up, it should be noted that the primary organisms that arose on Earth more than 4 billion years ago had the following properties:

They were heterotrophic organisms, that is, they fed on ready-made organic compounds accumulated at the stage of the Earth's cosmic evolution;

They were prokaryotes - organisms lacking a formalized nucleus;

They were anaerobic organisms using yeast fermentation as an energy source;

They appeared in the form of a primary biosphere, consisting of biocenoses, including various types of unicellular organisms;

They appeared and existed for a long time only in the waters of the primary ocean.

Imprints of mollusk shells are sometimes found on stones. Probably, many, many years ago there was a sea here. The sea became the first habitat for living beings on Earth. Rocky rocks contain the imprints of ancient plants and unicellular organisms, very different from their modern counterparts.
The first living creatures living in the water had no head, no legs, no mouth. These were small masses of living matter.

Quite a long time after the appearance of the first living beings in the sea, living beings began to develop, emerging from colonial forms. These were the first multicellular animals - sponges. Since then, two billion years have passed, and the sponges have not changed.
Also appeared:

• jellyfish
• trilobites
• flatworms
• onycophores
• sponges
• polychaete worms
• sea ​​lilies
• ancient corals
• nautiluses
• sea ​​stars
• shell scorpions
• horseshoe crabs
• ammonites

At the bottom of the sea

400 million years ago, various types of algae lived at the bottom of the sea, since plants at that time could only live in water. On the ground that protruded above the surface of the water, not a single blade of grass had yet grown.

Rolled up house

Several thousand years passed, and nautiluses appeared in the seas - mollusks with a shell folded into a spiral. This was their "home". In those days, ammonites were very numerous - extinct animals with this type of shell. And nautiluses swim in the seas to this day.