Lesson topic:
"Stages of the development of life on Earth."
What science studies the history of living organisms from preserved remains?
Paleontology.
Development of life on Earth.
Eons
cryptozoic
Phanerozoic
manifest life
hidden life
Paleozoic
Cenozoic
Development of life on Earth.
Duration
Archaea
Main events
Paleozoic
Mesozoic
Cenozoic
Development of life on Earth.
Duration
Main events
Archean era
Age of Prokaryotes: bacteria And cyanobacteria. Photosynthesis appears, and as a result, oxygen begins to accumulate in the atmosphere.
from 3.5 to 2.5
billion years ago
Stromatolites
Development of life on Earth.
Duration
Main events
Proterozoic era
Formation of the ozone layer. Appear first eukaryotes – unicellular algae And protozoa. The process of soil formation has begun. The sexual process and multicellularity appeared.
End of an era - eukaryotic diversity (protozoa, jellyfish, algae, sponges, corals, annelids.
from 2.5 billion to 534 million years ago
Development of life on Earth.
Duration
Main events
Palaeozoic
appeared on Earth trilobites , as well as organisms with mineral skeletons (foraminifera, mollusks).
from 534 to 248 million years ago
foraminifera
mollusk
trilobites
Development of life on Earth.
Duration
Main events
Palaeozoic
Appear Cancerscorpios , echinoderms , first true vertebrates . The most important event is the emergence of plants, fungi and animals onto land.
from 534 to 248 million years ago
echinoderms
cancerscorpio
armored fish
Development of life on Earth.
Duration
Main events
Palaeozoic
In the middle of an era dominate cartilaginous fish (sharks, rays), the first ones appear bony fish , dipnoi , which gave rise to amphibians .
from 534 to 248 million years ago
Stegocephalus
Coelacanth
Development of life on Earth.
Duration
Main events
Palaeozoic
Appeared mosses, horsetails, mosses, ferns (at the end of the Paleozoic they died out, forming coal deposits). At the end of an era appear reptiles, insects And gymnosperms.
from 534 to 248 million years ago
Development of life on Earth.
Duration
Main events
Mesozoic era
Appear crocodiles And turtles , first mammals (oviparous, marsupials).
from 248 to 65 million years ago
Echidna
Platypus
Development of life on Earth.
Duration
Main events
Mesozoic era
Appear Archeopteryx (ancestors of birds). At the end of an era appear higher mammals , real birds , angiosperms. Almost all reptiles die out at the end of the Mesozoic.
from 248 to 65 million years ago
Getteria
Gorgonopsid
Cynodont
Archeopteryx
Development of life on Earth.
Duration
Main events
Cenozoic era
Dominate mammals , birds , insects And angiosperms .
Appear first apes , species of plants and animals close to modern ones are formed.
End of an era - emergence person .
from 65 million years to the present
Homework:
Earth Development
like planetsPart 1 Lesson No. 4
“LITHOSPHERE OF THE EARTH”
The Universe is the entire material world
Origin of the Earth and Solar System
The question of how the Earth came into being has occupied the minds of people for more than one millennium. Depending on the level of knowledge about the Universe, it was answered differently. At first these were legends about the creation of the flat world. Then, in the constructions of scientists, the Earth acquired the shape of a ball in the center of the Universe. The next step was the revolutionary theory of Copernicus, which reduced the Earth to the position of an ordinary planet revolving around the Sun. Nicolaus Copernicus opened the way for a scientific solution to the problem of “the creation of the world,” which, nevertheless, has not been fully resolved to this day.
Currently, there are several hypotheses, each of which has strengths and weaknesses, each in its own way interprets the development of the Universe, the origin of our planet and its position in the solar system.
Structure of the Solar System
Mercury
Structure of the solar system
Earth -
“younger sister of the Sun” The first, truly serious from a scientific point of view, attempt to recreate a picture of how the Solar system originated and developed was made by the French mathematician Pierre Laplace and the German philosopher Immanuel Kant at the end of the 18th century. They drew attention to that the fact that all the planets revolve around the Sun almost in circles in the same direction and in the same plane.
Moreover, the Sun is many times larger than all the planets and is the only hot cosmic body in the system.
Kant and Laplace were the first to put forward the ideas of evolutionary, consistent development of nature. They believed that the solar system did not exist forever. Its progenitor was a gas nebula, shaped like a flattened ball and slowly...
The hypothesis of the origin of the Earth by Immanuel Kant and Pierre Laplace
... rotating around a dense core at the center. Subsequently, the nebula, under the influence of the forces of mutual attraction of its constituent particles, began to flatten at the poles, along the axis of rotation, and turn into a huge disk. Its density was not uniform, so separation into separate gas rings occurred in the disk. Each ring contained its own condensation of matter, which gradually began to attract the rest of the ring’s substance to itself, until it turned into a single gas clump rotating around its own axis. This ball of gas, in turn, repeated, as if in miniature, the path that the nebula as a whole had traversed: at first, a dense core surrounded by rings emerged in it. Subsequently, the nuclei cooled and turned into planets, and the rings around them into satellites.
Immanuel Kant
Pierre Laplace
Hypothesis of the origin of the Earth
Immanuel Kant and Pierre LaplaceThe main part of this nebula concentrated in the center and became the Sun. Thus, if we apply degrees of kinship to celestial bodies, according to the Kant-Laplace hypothesis, the Earth is the “younger sister of the Sun.”
The Earth is a “captive of the Sun”
The Soviet geophysicist Otto Yulievich Schmidt imagined the development of the solar system somewhat differently.
In the 20s of the twentieth century, he proposed the following hypothesis: The Sun, traveling through our Galaxy, passed through a cloud of gas and dust and carried part of it along with it. The material of the initial nebula around the hot gas core of the system was not hot. Clots of matter in orbits, which appeared as a result of the sticking together of solid particles of the cloud and subsequently became planets, were also initially cold. Their heating occurred later, as a result of compression and
solar energy receipts. At the same time, the small “embryos” of the planets were unable to retain the gases that were released when they were heated. The largest planets retained their atmosphere and even replenished it by capturing gases from nearby outer space. The Earth, according to this hypothesis, can be considered “captured” by the Sun.
Earth - “daughter of the Sun”
Not everyone accepted the evolutionary scenario of the origin of planets around the Sun. Back in the 18th century, the French naturalist Georges Buffon suggested, later developed by the American physicists Chamberlain and Multon, that once in the vicinity of the Sun there was still
lonely, another star flashed by. Its gravity caused a huge tidal wave on the Sun, stretching into space for hundreds of millions of kilometers. Having come off, this “tongue” of solar matter began to swirl around the Sun and disintegrate into drops, each of which formed a planet. In this case, the Earth could be considered the “daughter” of the Sun.
Slide No. 10
The Earth is “the niece of the Sun”
Another hypothesis was proposed by English astrophysicist Fred Hoyle in the mid-20th century.
According to it, the Sun had a twin star that exploded as a supernova. Most of the fragments were carried into outer space, a smaller part remained in the orbit of the Sun and formed planetary systems (that is, planets with satellites). In this scenario, the Earth is the Sun's “niece.”
Fred Hoyle
1915-2001
Slide No. 11
No matter how various hypotheses interpret the origin of the solar system and the “family” connections between the Earth and the Sun, they agree that all the planets were formed from a single clump of matter. Then the fate of each of them developed differently. The Earth had to travel a path of almost 5 billion years and undergo a series of amazing transformations before appearing before us in its modern form.
Occupying a middle position among the planets in size and mass, the Earth at the same time turned out to be unique as a refuge for future life. Having “freed” itself from some of the supervolatile gases (such as hydrogen and helium), it retained the rest just enough to create an air screen capable of protecting the inhabitants of the planet from deadly cosmic radiation and countless meteorites that burn up every second in the upper layers of the atmosphere. At the same time, the atmosphere is not so dense as to completely shield the Earth from the life-giving rays of the Sun.
The air envelope of the Earth was formed by gases coming from its depths during volcanic eruptions. The same is the origin of all waters: oceans, rivers, glaciers, which were also once contained in the earth’s firmament. Various hypotheses
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Archaeologists discovered traces of living organisms at the beginning of the Archean era, which is limited to 3 billion years ago.
Initial organic compounds were formed as a result of reactions involving atoms of various metals, hydrogen and ammonia at very high temperatures.
The first amino acid was obtained by combining aldehydes and hydrogen cyanide in an ammonia environment.
From hydrogen cyanide, which predominated in the primary atmosphere, the remaining components of nucleic acids arise. At the same time, the formation of the main components of DNA and RNA occurred in the aquatic environment.
Gradually, small molecules combine into larger ones, thereby giving rise to proteins and nucleic acids as they are known today.
After some time, microscopic clots develop rudimentary metabolism, which can be called a prerequisite for the circulation of substances in nature.
However, real life did not exist yet; its beginning can be considered the appearance of cells and the simplest organisms consisting of them.
First, the simplest anaerobic heterotrophic bacteria were formed, consisting of a single cell without a nucleus.
Gradually there is a transition to nutrition through photosynthesis. Chlorophyll appears and, subsequently, oxygen. With the participation of oxygen, the structure of unicellular organisms becomes more complicated. The nucleus, DNA and chromosomes appear.
The next stage of evolution can be called the division of single-celled living organisms into plants and animals. It took place in the Proterozoic era.
Subsequently, sexual reproduction appeared. This happened 900 million years ago.
Further evolution follows the path of multicellularity. Scientists suggest its formation as a result of unfinished cell division, as a result of which the new one did not move away from the mother one.
Gradually, cells begin to perform different functions, and organisms become more and more complex.
The first multicellular organisms were arthropods and coelenterates.
The nervous system of the inhabitants of the Earth is becoming more and more complex.
After a long time, living organisms begin to populate various parts of the earth, leaving their usual aquatic habitat and increasingly increasing species diversity.
Natural selection occurs, forcing some living beings to give way to others, more adapted to changing environmental conditions.
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The original atmosphere did not contain oxygen, and this is called one of the reasons for the emergence of life itself. Gradually, amino acids and other organic substances begin to form in the waters of the primary ocean. This cannot yet be called life, but quite the beginnings of it.
According to recent studies, the approximate age of the oldest bacterial remains that have been discovered in the earth is from 3 to 4 billion years. These organisms could absorb sunlight and thus transform inorganic substances.
Gradually, some algae acquire the ability to break down water molecules. The atmosphere is filled with oxygen, giving a powerful impetus to the further development of more complex organisms.
A nucleus appears in the cells, facilitating the occurrence of sexual reproduction. Evolution is now moving at a faster pace. The waters of the oceans are inhabited by invertebrates - flatworms, a number of jellyfish and polyps.
An important step was the appearance of animals whose body was covered with a shell or protected by a shell. The beginning of the next Paleozoic era is associated with this circumstance.
In one of the initial periods of the Paleozoic, cyclostomes became the first predators, setting a new branch of evolution.
At the same time, plants begin to fill the shores of the seas, spreading more and more widely over land. These were ferns, mosses and horsetails, providing suitable habitat for the ancestors of modern insects.
Over time, plants become more and more complex. Now these are forests growing on swampy soils, which existed until the beginning of the Mesozoic era and the cooling that came with it.
Aquatic animals, and in this period these were mollusks and ammonites, evolve into reptiles, which become the most common in most areas. In parallel with them, a new branch is developing - mammals.
The Jurassic period of the Mesozoic era can be called the time of the appearance of the first birds. Archeopteryx had many similarities with reptiles, but it is considered the ancestor of most modern birds.
As the temperature drops, huge dinosaurs cannot feed themselves, so they gradually die out and other animals take their place.
This significant period was the beginning of a new era, which continues to this day - the Cenozoic. At this time, the main species of birds and mammals, as well as most plants, appeared in their modern form or as close as possible to it.
Archaean Antiquity: from 3500 to 2500 ± 100 million years ago, duration about 900 million. Conditions: Active volcanic activity, anaerobic conditions in a shallow ancient sea, gradual accumulation of oxygen as a result of the activity of photosynthetic prokaryotes. Life: the appearance of the first cells.
Proterozoic Antiquity: from 2600 ± 100 to ± 20 million years ago, duration about 2000 million years Conditions: the planet is a bare desert, at the end of the era the oxygen content in the atmosphere was about 1%. The process of soil formation has begun. Life: The flourishing of eukaryotic organisms, which in their diversity are far ahead of prokaryotes. Invertebrate animals, single-celled green algae, and the first representatives of chordates, the skullless ones, appeared. The emergence of multicellularity and respiration led to the progressive development of heterotrophs and autotrophs.
Paleozoic Antiquity: from 570 ± 20 million years ago to 230 ± 10 million years ago, duration 340 ± 10 million years ago Conditions: glaciation gives way to a warm climate. The era of active mountain building, which took place in many places on Earth. Life: characterized by fairly large finds of fossil organisms. They indicate that during this period representatives of almost all main types and classes of invertebrate animals lived in the aquatic environment of salt and fresh water bodies.
Silurian period Conditions: mountain building (Scandinavian, Sayan), emergence of the first coral reefs. Life: the oldest fish and the first air-breathing land animals, scorpions, appear. When plants reach land, psilophytes appear.
Devonian period Conditions: glaciation in southern America and Africa, complete liberation from the sea of Siberia and Eastern Europe. Life: diversity of fish, the emergence of the main groups of spore plants, the development of land by arthropods, the first terrestrial stegocephalic vertebrates.
The Mesozoic is divided into 3 periods: Triassic, Jurassic and Cretaceous. Antiquity of the era: from 251 million to 65 million years ago Conditions: the formation of the main contours of modern continents and mountain building on the periphery of the Pacific, Atlantic and Indian oceans. The climate was warm throughout the entire time period. Life: by the end of the era, the bulk of the species diversity of life approached its modern state.
Jurassic period Conditions: arid climate in the equator region, movement of continents, formation of the Atlantic Ocean. Life: the dominance of reptiles, the appearance of the first birds - Archeopteryx, a well-defined botanical and geographical zonation appears.
Cenozoic Paleogene, Neogene, Anthropogene periods. Antiquity of the era: 60-70 million years to this day. Conditions: climate change, continental movement, large glaciations of the Northern Hemisphere. Life: flora and fauna are close to modern ones, humans appear and develop.
CONCLUSIONS: Complication of the organic world; Increase in the biomass of living organisms; Adaptation of organisms to new living conditions; Transformation of the inanimate part of the biosphere; Great unevenness in the development of life is noticeable; With the emergence and development of some forms of organisms, others become extinct; The composition of the atmosphere is changing.
1 slide
2 slide
In the process of formation of the evolutionary paradigm, three stages are distinguished: Stage 1 - TRADITIONAL BIOLOGY (C. Linnaeus). Stage 2 - CLASSICAL THEORY of biological evolution (C. Darwin). Stage 3 - SYNTHETIC THEORY OF EVOLUTION (S. Chetverikov and others)
3 slide
The Swedish natural scientist Carl Linnaeus (1707-1778) was the first to consistently apply binary nomenclature and built the most successful artificial classification of plants and animals.
4 slide
Evolution is a process of long-term, gradual, slow changes, which ultimately lead to radical, qualitative changes, culminating in the emergence of new material systems, structures, forms and species.
5 slide
W century BC Aristotle The Ladder of Beings 1749 J. Buffon The unity of origin of all living beings 1762 J. Bonnet The term “evolution” 1804 J. Cuvier The principle of correlation, the theory of catastrophes 1809 J. B. Lamarck The term “biology”, the first evolutionary doctrine, the inheritance of acquired characteristics 1846 A.R.Wallace The idea of gradual change in all types of living beings 1859 C.R. Darwin Biological theory of evolution
6 slide
Lamarck was the first to identify the two most general directions of evolution: 1) ascending development from the simplest forms of life to more and more complex and perfect ones; 2) the formation of adaptations in organisms depending on changes in the external environment (development “vertical” and “horizontal”).
7 slide
8 slide
Darwin's theory of evolution is based on the concept of heredity, which is understood as the property of organisms to repeat similar types of metabolism and individual development in general over a series of generations. Heredity, together with variability, is an integral property of living things and ensures the constancy and diversity of life forms and underlies the evolution of living nature.
Slide 9
The second principle of Darwin's theory is to reveal the internal contradiction in the development of living nature. It consists in the fact that, on the one hand, all types of organisms tend to reproduce exponentially, and on the other hand, only a small part of the offspring survives and reaches maturity.
10 slide
11 slide
The main theses of this theory are as follows: 1. The various species of plants and animals currently existing on Earth arose through continuous changes that lasted millions of years.
12 slide
2. From the primary simplest clumps of living matter, more complex and highly organized forms gradually formed.
Slide 13
3. In nature, there is a continuous struggle between different species, as well as the intraspecific struggle of individuals for a place on Earth.
Slide 14
4. Only those who are better adapted to environmental conditions survive this fierce struggle for life.
15 slide
The struggle for existence includes relationships with the surrounding natural conditions (abiotic) and biotic conditions - the struggle among themselves. There are three main types of struggle for existence: Interspecific - the struggle for an ecological niche between species. Intraspecific - most often, between males for territory, for a harem. Combating unfavorable environmental conditions.
16 slide
The inevitable result of the struggle for existence and hereditary variability of organisms, according to Darwin, is the process of survival and reproduction of organisms most adapted to environmental conditions, and the death during the evolution of those who are unadapted, i.e. natural selection (the main mechanism of evolution). The inevitable result of selection is species diversity.
Slide 17
18 slide
Slide 19
20 slide
stabilizing selection - all noticeable deviations from some average norm are eliminated, as a result of which new species do not arise. Such selection plays a minor role in evolution. leading (driving) form of selection - picks up the smallest changes that contribute to progressive transformations of living systems and the emergence of new, more advanced species;
21 slides
destructive (cutting off) selection occurs when the conditions of existence of organisms suddenly change; a large group of individuals of the average type finds themselves in unfavorable conditions and dies; balanced selection leads to the existence and change of adaptive, or adaptive, forms. When selecting for increased variability, those populations that are distinguished by the greatest diversity in certain traits receive an advantage in selection.
22 slide
Synthetic theory of evolution (STE) is a synthesis of various disciplines, primarily genetics and Darwinism. Differences from Darwin's: the elementary structural unit of evolution is a population and not an individual or species; an elementary phenomenon or process of evolution - a sustainable change in the genotype of a population;
Slide 23
factors and driving forces of evolution are divided into basic and non-basic. The leading factors include mutation processes, population waves and isolation. The material for evolution is mutation and recombination variability. Natural selection is the main reason for the development of adaptations, speciation and the origin of supraspecific taxa.
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