How life was born on Earth: history, features of origin and interesting facts

How did life begin on Earth? Details of mankind are unknown, but the cornerstone principles are established. There are two basic theories and many secondary ones. So, according to the main version, organic components got to Earth from space, on the other - everything happened on Earth. Here are a few of the most popular exercises.

Panspermia

How did our Earth come about? The biography of the planet is unique, and people try to solve it in many ways. There is a hypothesis that the life that exists in the universe is spread by means of meteoroids (celestial bodies intermediate in size between interplanetary dust and an asteroid), asteroids and planets. It is assumed that there are forms of life capable of withstanding the impact of airless space (radiation, vacuum, low temperatures, etc.). They are called extremophiles (including bacteria and microorganisms).

They fall into the wreckage and dust that are thrown into space after the collisions of the planets , thus saving life after the death of the small bodies of the solar system. Bacteria can travel at rest for a long period of time until another accidental collision with other planets.

They can also be mixed with protoplanetary disks (a 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. The history of the origin of life on Earth is solved with the help of probes. The data from the devices that have been inside the comets, testify: in the overwhelming majority of cases, the probability is confirmed that we are all "little aliens," since the cradle of life is cosmos.

Biopoiesis

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

This is confirmed by the experiment of Mueller-Urey. In 1953, the scientist missed electricity through a mixture of gases and obtained several amino acids under laboratory conditions simulating the conditions of the early Earth. In all living beings, amino acids are transformed into proteins under the influence of the custodians of the genetic memory of nucleic acids.

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 get into the interaction? Abiogenesis is in the process of finding the answer.

Cosmogonic trends

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

Secondly, there is no physical model explaining the earliest moments of the existence of the universe. In this theory there is no concept of quantum gravity. Although string theorists (string theory says that elementary particles arise as a result of vibrations and interactions of quantum strings), investigating the origin and consequences of the Big Bang (loop quantum cosmology), disagree. They believe that they have formulas that allow describing the model in the framework of field equations.

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

Endosymbiont

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

This suggests that multiple forms of bacteria have entered symbiosis with the formation of a eukaryotic cell (eukaryotes are cells of living organisms that contain 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 generation

Until the beginning of the 19th century, people generally denied "suddenness" as an explanation of how life was born on Earth. The unexpected spontaneous generation of certain forms of life from inanimate matter seemed to them implausible. But they believed in the existence of heterogeneity (a change in the mode of reproduction), when one form 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 observed truth: aphids arise from dew which falls on plants; Flies - from spoiled products, mice - from dirty hay, crocodiles - from decaying logs at the bottom of reservoirs and so on. The theory of the spontaneous generation (refuted by Christianity) secretly existed for more than one century.

It is generally accepted that the theory was finally disproved 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 get the opportunity to fight infectious diseases. However, Pasteur's proofs were no longer controversial, but strictly scientific.

Theory of clay and sequential creation

The emergence of life based on clay? Is it possible? A Scottish chemist named AJ Cairns-Smith of the University of Glasgow in 1985 is the author of such a theory. Relying on similar assumptions of other scientists, he argued that organic particles, being between clay layers and interacting with them, adopted a way of storing information and growth. Thus, the scientist considered the "clay gene" primary. Initially, the mineral and the nascent life existed together, and at a certain stage they "fled".

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

Materialistic teaching

And here is another version of how life began on Earth. It was put forward by materialists. They believe that life has emerged as a result of time-consuming and expansive gradual chemical transformations, which, in all likelihood, occurred 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 teaching arose in the 1960s, when active research was carried out, involving molecular and evolutionary biology, the genetics of populations. Scientists then tried to understand and confirm recent discoveries concerning 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 the divergence of nucleic acid 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, the proponents of this teaching reason like this. Formation of species began long ago - more than 3.5 billion years ago (the figure denotes the period in which life exists). Probably, at first a slow and gradual process of transformation was going on, and then a fast (within the framework of the universe) stage of perfection, transition from one static state to another under the influence of existing conditions, began.

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 distinctive features, including anatomical, biochemical and behavioral, which are transmitted from one generation to another.

Evolution has led to the diversity and versatile development of all living organisms (diversification). Our colorful world, Charles Darwin described as "endless forms, the most beautiful and the most remarkable." It seems that the birth of life is a story without a beginning and an end.

Special creation

According to this theory, all forms of life that exist today on the 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, - Christians, Muslims and Jews consider. Three religions agreed that God created the universe within seven days, making the sixth day the culmination of labor: he created from the dust of the earth Adam and from his rib Eve.

On the seventh day God rested. Then he breathed life into people and sent him to take care of a garden called Eden. In the center grew the Tree of Life and the Tree of Knowledge of Good. God allowed to eat the fruits of all the trees in the garden, except the Tree of Knowledge ("for in that day that you eat of them, you will die").

But people disobeyed. The Koran says that Adam tried to try an apple. God forgave the sinners and sent both to the earth as their representatives. And yet ... Where on earth did life come from? As you can see, there is no unequivocal answer. Although modern scientists are increasingly inclined to the abiogenic (inorganic) theory of the emergence of all living things.