Good time of the day, dear seventh graders!
In this message, we will travel to the beginning of time. We will try to see and find out how the Earth developed, what events took place on it millions, or even billions of years ago. What organisms and how appeared on Earth, how they replaced each other, in what ways and with the help of what evolution proceeded.
But before we look at new material, check your knowledge of the topic.
"Charles Darwin on the origin of species":
- Forms of struggle for existence # 1
- Forms of the struggle for existence No. 2
“Time is long,” said James Hetton, and indeed, it took an incredibly long time for the titanic and amazing transformations that have taken place on our planet. Making a flight in a spaceship about 4 billion years ago in the part of the Universe where our Sun is located today, we would observe a picture different from that which astronauts see today. Recall that the Sun has its own speed of movement - about two dozen kilometers per second; and then it was in another part of the Universe, and the Earth at that time was still just born ...
So, the Earth was just born and was in the initial stage of its development. She was a red-hot little ball, swaddled in vortex clouds, and her lullaby was the rumble of volcanoes, the hiss of steam and the roar of hurricane winds.
The earliest rocks that could have formed during this turbulent infancy were volcanic rocks, but they could not remain unchanged for long, for they were subjected to fierce attacks of water, heat and steam. The earth's crust sagged, and fiery lava poured over them. The rocks of the Archean era, the oldest rocks known to us today, bear traces of these terrible battles. These are mainly shales and gneisses, which occur in deep layers and are exposed in deep canyons, mines, and quarries.
In such rocks - they formed about one and a half billion years ago - there is almost no evidence of life.
The history of living organisms on Earth is studied by the remnants, imprints and other traces of their vital activity preserved in sedimentary rocks. Science does it paleontology .
For ease of study and description, all the history of the earth is divided into lengths of time, having different durations and differing from each other in climate, intensity of geological processes, appearance of some and disappearance of other groups of organisms, etc.
The names of these periods of time are of Greek origin.
The largest such units are EONS, there are two of them - cryptose (hidden life) and phanerozoic (manifest life) .
Eons are divided into eras. There are two eras in the Cryptozoic - Archean (the oldest) and Proterozoic (primary life). Phanerozoic includes three eras - Paleozoic (ancient life), Mesozoic (middle life) and Cenozoic (new life). In turn, the eras are divided into periods, the periods are sometimes divided into smaller parts.
According to scientists, the planet Earth was formed 4.5-7 billion years ago... About 4 billion years ago, the earth's crust began to cool and hardened, conditions arose on Earth that allowed living organisms to develop.
No one knows exactly when exactly the first living cell appeared. The earliest traces of life (bacterial remains) found in ancient deposits of the earth's crust are about 3.5 billion years old. Therefore, presumably the age of life on Earth is 3 billion 600 million years. Let's imagine that this huge period of time fits within one day. Now on our "clock" - exactly 24 hours, and at the time of the emergence of life they showed 0 hours. Each hour contained 150 million years, each minute - 2.5 million years.
The most ancient epoch of the development of life - the Precambrian (Archaean + Proterozoic) lasted for an incredibly long time: over 3 billion years. (from the beginning of the day to 8 pm).
So what was happening at the time?
By this time, the first living organisms were already in the aquatic environment.
The living conditions of the first organisms:
- food - "primary broth" + less fortunate brethren. Millions of years \u003d\u003e broth becomes more and more "diluted"
- depletion of nutrient reserves
- the development of life has come to a standstill.
But evolution has found a way out:
- The emergence of bacteria capable of converting inorganic substances into organic ones using sunlight.
- Need hydrogen \u003d\u003e decompose hydrogen sulfide (to build organisms).
- Green plants get it by splitting water and releasing oxygen, but bacteria do not yet know how to do this. (It is much easier to decompose hydrogen sulfide)
- Limited amount of hydrogen sulfide \u003d\u003e crisis in the development of life
A "way out" has been found - blue-green algae have learned to split water into hydrogen and oxygen (this is 7 times more difficult than splitting hydrogen sulfide). This is a real feat! (2 billion 300 million years ago - 9 am)
BUT:
Oxygen is a by-product. Oxygen accumulation → life threatening. (Oxygen is necessary for most modern species, but it has not lost its dangerous oxidizing properties. The first photosynthetic bacteria, enriching their environment, in fact poisoned it, making it unsuitable for many of their contemporaries.)
From 11 o'clock in the morning, a new spontaneous generation of life on Earth became impossible.
The problem is how to deal with the increasing amount of this aggressive substance?
Victory is the emergence of the first organism to breathe oxygen - the emergence of breathing.
The diversity of the organic world in the present is great, but it will seem literally limitless if you imagine how it happened development of life on Earth over hundreds of millions of years.
Any blade of grass, past which we indifferently pass, had a very long series of generations of its ancestors, and the further back centuries, the less similar these ancestors were to modern forms.Each organism is formed not only under the influence of the present, but also of the entire past, right up to the beginning of life hiding in the darkness.K. A. Timiryazev The picture of the development of the organic world is often graphically depicted as branchy tree... The trunk of a tree is primary green organisms, large branches are groups of still uncomplicated plants that have arisen from them, smaller branches are the changed descendants of these groups, the ends of branches are modern forms. Family tree. Some branches of this tree have dried up - these are extinct groups that have disappeared due to some conditions that turned out to be unfavorable for them; other branches, on the contrary, have grown magnificently, forming many branches - these are groups of plants that have developed in favorable conditions for their life and have given many new forms. Such a visual depiction of the history of the development of organisms, showing not only the origin of a particular group of organisms, but also the relationship of different groups, is called family tree... This evolution can be represented even more clearly in the form river movements, divided into numerous ducts, sometimes fast and impetuous, sometimes slow, narrowing and disappearing. Just as in the channels and branches of a real river, the amount of water carried away and the speed of its movement constantly change, so the forms of the plants of the great river of life changed: some quickly, others remained almost unchanged for a long time. Desiring to emphasize this continuous movement of life as its main property, K.A. Timiryazevnamed biology by the science of the dynamics of the organic world.
Earth changes
Many changes happened on earth for its long history:- The outlines and relief of the land, the area and depth of the world's oceans changed.
- New mountain ranges arose, collapsed, mountainous areas turned into plains.
- The direction and nature of winds and sea currents changed.
- The composition of the atmosphere and water of the oceans and seas has also changed over time.
- The amount of light and heat coming to the earth from the sun was different at different times.
- Scientists believe that even the position of the earth's axis in relation to the plane of motion of the earth around the sun did not remain unchanged.
Past life traces
The most valuable data on these changes are obtained on the basis of the remnants of life preserved in the earth's interior. These traces of a past life studying science paleontology... It largely helps geology figure out what changes were taking place in. The remains of animals and plants are called paleontological documents, that is, very reliable materials by which one can confidently judge what events took place on Earth in the past. Discovered in the bowels of the earth, paleontological documents have long attracted the attention of scientists. For example, MV Lomonosov wrote about this in his work "On the strata of the earth":The earth's surface now has a completely different appearance than what it was since ancient times. In cold climates, traces of Indian herbs are shown in the stone mountains with distinct traces that assure of their nature.Thus, based on the fact that traces of southern plants are found in cold countries, Lomonosov made a completely correct assumption: obviously, in the distant past, living conditions in the north were completely different than now.
Valuable excavations
Unfortunately, detailed valuable excavations are found relatively rarely. After all, rarely have there been such particularly favorable conditions on Earth under which the delicate parts of a plant could leave some kind of lasting mark. It sometimes happened that a leaf, falling on soft silt, was covered with it. Subsequently, the silt thickened, turned into solid rock, and the researcher, splitting such a layered rock into plates, suddenly discovered a distinct trace of a leaf or other part of an ancient plant.Amber
On the south and southeast coasts find pieces amber, and in them there are very well-preserved prints of small arthropods (insects, spiders) and parts of plants (buds, leaves, flowers, seeds, etc.). Amber is the hardened resin of some ancient conifers. When it flowed out of their damaged trunks and branches, small animals and plant parts fell into it.
Amber is the hardened resin of some ancient conifers. It took a long time, the resin turned into amber, and now we sometimes find in it amazingly clear and accurate traces of ancient life. Pieces of petrified wood
Found in the ground and pieces of petrified woodcomposed entirely of mineral matter. They have preserved the structure of the wood so precisely that a researcher examining the thin plates of the fossil under a microscope thinks that he is seeing the wood of a living tree. Such a fossil is formed under special conditions, when there is a very slow replacement of the organic matter of the tree with minerals dissolved in water. As a result, the tree, while maintaining its shape and structure, is completely mineralized.
Mineralized tree. In most cases, a very large and painstaking work is required in order to restore from the preserved half-erased traces the past of plants... Nevertheless, persistent research thought penetrated into the depths of the past and, following these traces, quite fully restored how the plant world has changed over millions of centuries. According to these data, the development of life, like the development of everything that exists, was not smooth - there was an alternation of periods of long, relatively calm and shorter, but stormy ones. The duration of violent geological revolutions is often determined by millions of years. Nevertheless, such revolutionary periods in the development of life passed much faster than periods of calm, evolutionary ones. Scientists who have studied the development of life on Earth have long noted this uneven development in qualitatively different deposits of layers and the remnants of life found in the earth. Hence the division of life history into separate stages arose. The largest periods of time are called eras. Their duration is usually estimated at hundreds of millions of years. Stages in the history of the Earth
Stage in the history of the Earthwhen primary life arose, it received the name proterozoic era - early life... It lasted for about 600 million years. She was replaced era paleozoic - ancient life, the duration of which is determined at 325 million years. She was followed by mesozoic era - average life, which lasted 115 million years, then passed into cenozoic era - new life, or modern era, the beginning of which is about 70 million years away from our time. Thus, life has existed on Earth for at least a billion years. Proterozoic era preceded by a very long period of time, which is called the Azoic, that is lifeless era... Each era is divided into shorter, usually calculated in tens of millions of years, time intervals - geological periods, (more details:Size: px
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Transcript
2 Practical lesson Description of individuals of a species by morphological criterion Purpose: to study the criteria of a species morphological, physiological, genetic, geographic, ecological, biochemical; consider the morphological criterion using specific examples of plant and animal species. Equipment: herbarium material, photographs, drawings of plant and animal organisms. Course of the lesson: 1. Consider the organisms of plants and animals offered to you. Compare them according to the proposed criteria. Fill the table. MORPHOLOGICAL FEATURES OF ORGANISMS Signs for comparison Object 1 Object 2 Appearance: Geographical habitat Lifestyle Ecological value Shoot, leaf arrangement on the stem, leaf shape and size, type of venation, root system, flower, inflorescence Shape of body, head, body proportions, structure of limbs ; color of skin, wool; height, size 2. Arrange in the correct sequence the categories included in the structure of the species: population, subspecies, individual, variety 3. Two types of twin can be distinguished by characteristics: habitat, behavioral features, karyotype of somatic cells, features of the external structure, size and number chromosomes, genotype of cells of an organism 4. Modern ideas about biological species: species are created and unchanged; species do not really exist; the species really exists, the species are unstable and dynamic; the species exists for a certain time, and then either dies out or changes; any variability in nature is speciation 5. How does the concept of cosmopolitan differ from endemic? Explain the answer. Give examples. Conclusion: Make a conclusion by answering the question, Why cannot only one of the species criteria be used when determining the species?
3 Practical lesson Analysis of adaptations of organisms to the environment Purpose: to form the concept of the adaptability of organisms to the environment, to study the mechanism of the emergence of adaptations, to be able to classify adaptations, to reveal their significance for organisms. Equipment: reference books "General biology" p.102, photographs and drawings of organisms of animals and plants. Work progress: Task 1 Determine the correspondence between the shape of the body and the organism that has it. Expand its meaning: Body shape: torpedo, knotty, leafy, bizarre Shark, stick insects, moth caterpillar, dolphin, seahorses, anglers Task 2 Determine the correspondence between body color and the organism that has it. Expand its meaning: Body color: protective, dismembering, warning Zebra, tiger, ptarmigan, bees, wasps, cabbage butterfly caterpillar, white hare, Madagascar beetle, young gray monitor lizards, spotted salamander, walrus cubs, aphids, giraffes. Activity 3 What is the difference between masking and demonstrating? Give examples. Activity 4 Give examples of mimicry. How is Bates's one different from Muller's? Conclusion: Expand the mechanism of formation and the meaning of adaptations. Why fitness is never absolute Practical lesson "Analysis and evaluation of various hypotheses of the origin of life" Purpose: acquaintance with various hypotheses of the origin of life on Earth. Progress. Read the text "The variety of theories of the origin of life on Earth." Fill in the table: Theories and hypotheses The essence of the theory or hypothesis Evidence 3. Answer the question: What theory do you personally adhere to? Why? "Variety of theories of the origin of life on Earth." 1. Creationism. According to this theory, life arose as a result of some supernatural event in the past. It is adhered to by the followers of almost all the most common religious teachings. The traditional Judeo-Christian concept of the creation of the world, as set out in Genesis, has caused and continues to cause controversy. Although all Christians acknowledge that the Bible is the Lord's testament to men, there is controversy over the length of the "day" mentioned in Genesis. Some believe that the world and all organisms inhabiting it were created in 6 days for 24 hours. Other Christians do not regard the Bible as a scientific book and believe that the Book of Genesis contains the theological revelation about the creation of all living beings by the omnipotent Creator in a form understandable to people. The process of divine creation of the world is thought of as having taken place only once and therefore inaccessible for observation. This is enough to take the whole concept of divine creation out of scientific research. Science deals only with those phenomena that are observable, and therefore it will never be able to prove or disprove this concept. 2. The theory of a stationary state. According to this theory, the Earth never arose, but existed forever; it is always capable of supporting life, and if it has changed, then very little; species have always existed too.
4 Modern dating methods give ever higher estimates of the age of the Earth, which allows proponents of the steady state theory to believe that the Earth and species have always existed. Each species has two possibilities, either a change in numbers or extinction. Proponents of this theory do not recognize that the presence or absence of certain fossil remains may indicate the time of appearance or extinction of a particular species, and cite coelacanth as an example of a representative of cross-finned fish. According to paleontological data, the cross-fin became extinct about 70 million years ago. However, this conclusion had to be revised when live representatives of the crossfin were found in the area of \u200b\u200bMadagascar. Proponents of the stationary state theory argue that only by studying living species and comparing them with fossil remains can a conclusion about extinction be made, and even then it may turn out to be wrong. The sudden appearance of a fossil species in a certain layer is explained by an increase in its population or movement to places favorable for the preservation of remains. 3. Theory of panspermia. This theory does not offer any mechanism for explaining the primary origin of life, but puts forward the idea of \u200b\u200bits extraterrestrial origin. Therefore, it cannot be considered a theory of the origin of life as such; it simply takes the problem to some other place in the universe. The hypothesis was put forward by J. Liebig and G. Richter in the middle of the 19th century. According to the panspermia hypothesis, life exists forever and is transferred from planet to planet by meteorites. The simplest organisms or their spores ("seeds of life"), getting on a new planet and finding favorable conditions here, multiply, giving rise to evolution from the simplest to complex forms. It is possible that life on Earth arose from a single colony of microorganisms, abandoned from space. To substantiate this theory, multiple UFO sightings, rock paintings of objects similar to rockets and "astronauts", as well as reports of alleged encounters with aliens are used. When studying the materials of meteorites and comets, many "precursors of the living" were found in them, such substances as cyanogens, hydrocyanic acid and organic compounds, which may have played the role of "seeds" that fell on the bare Earth. The supporters of this hypothesis were the Nobel laureates F. Crick, L. Orgel. F. Crick was based on two circumstantial evidence: the universality of the genetic code; necessary for the normal metabolism of all living things of molybdenum, which is now extremely rare on the planet. But if life did not arise on Earth, how did it arise outside of it? 4. Physical hypotheses. Physical hypotheses are based on the recognition of the fundamental differences between living matter and non-living matter. Let us consider the hypothesis of the origin of life put forward in the 30s of the XX century by V.I. Vernadsky. Views on the essence of life led Vernadsky to the conclusion that it appeared on Earth in the form of a biosphere. The fundamental, fundamental features of living matter require not chemical, but physical processes for its occurrence. This should be a kind of catastrophe, a shock to the very foundations of the universe. In accordance with the hypotheses of the formation of the Moon as a result of the separation from the Earth of the substance that previously filled the Pacific Trench, widespread in the 30s of the XX century, Vernadsky suggested that this process could cause that spiral, vortex motion of the earth's substance, which did not repeat itself. Vernadsky interpreted the origin of life on the same scales and time intervals as the origin of the Universe itself. In a catastrophe, conditions suddenly change, and living and inanimate matter emerges from protomatter. 5. Chemical hypotheses. This group of hypotheses is based on the chemical specifics of life and connects its origin with the history of the Earth. Let's consider some of the hypotheses of this group. At the origins of the history of chemical hypotheses were the views of E. Haeckel. Haeckel believed that first, under the influence of chemical and physical reasons, carbon compounds appeared. These substances were not solutions, but suspensions of small lumps. Primary lumps were capable of accumulating various substances and growing, followed by division. Then a nuclear-free cell appeared, the original form for all living things on Earth. A certain stage in the development of chemical hypotheses of abiogenesis was the concept of A.I. Oparin, put forward by him in the years. XX century. Oparin's hypothesis is a synthesis of Darwinism with biochemistry. According to Oparin, heredity was the result of selection. In Oparin's hypothesis, the desired will be
5 is valid. First, her features of life are reduced to metabolism, and then its modeling is declared to have solved the riddle of the origin of life. J. Burpap's hypothesis suggests that abiogenically generated small molecules of nucleic acids from several nucleotides could immediately combine with those amino acids that they encode. In this hypothesis, the primary living system is seen as biochemical life without organisms, carrying out self-reproduction and metabolism. Organisms, according to J. Bernal, appear a second time, during the isolation of individual sections of such biochemical life with the help of membranes. As the last chemical hypothesis of the origin of life on our planet, consider the hypothesis of G.V. Voitkevich, put forward in 1988. According to this hypothesis, the occurrence of organic matter is transferred to outer space. Under the specific conditions of space, organic substances are being synthesized (numerous organic substances are found in meteorites, carbohydrates, hydrocarbons, nitrogenous bases, amino acids, fatty acids, etc.). It is possible that nucleotides and even DNA molecules could have formed in outer space. However, according to Voitkevich, chemical evolution on most planets of the solar system turned out to be frozen and continued only on Earth, having found suitable conditions there. During the cooling and condensation of the gas nebula, the entire set of organic compounds appeared on the primary Earth. Under these conditions, living matter appeared and condensed around the abiogenically generated DNA molecules. So, according to Voitkevich's hypothesis, biochemical life initially appeared, and in the course of its evolution, separate organisms appeared.
6 PRACTICAL EXERCISE ANALYSIS AND ASSESSMENT OF DIFFERENT HYPOTHESES OF HUMAN ORIGIN Purpose: to establish similarities and differences in the structure and life of humans and apes; analyze the main stages of anthropogenesis; develop the skills of critical analysis of scientific facts that testify "for" or "against" certain hypotheses. Equipment: figures, tables, photographs, 3D models of the main stages of human anthropogenesis, reference books on general biology. PROCESS OF THE LESSON: 1. Karl Linnaeus in the 18th century first gave the specific name Homo sapiens (Homo sapiens) Determine the systematic position of a person according to the following criteria: Kingdom --- Subkingdom --- Type --- Subtype --- Class --- Order - - Suborder --- Section --- Superfamily --- Family --- Genus --- Species Man, Animals, Mammals, Chordates, Primates, Narrow-nosed, Monkeys, Higher Narrow-nosed, People, Homo sapiens, Multicellular, Vertebrates 2. Choose from the listed factors of human evolution, biological and social. Factors: labor operations, social lifestyle, heredity, struggle for existence, speech, natural selection, consciousness, variability, abstract thinking, social competition, mutations, human genetic diseases 3. Using the data of the reference book, textbooks, tables, models, make a pedigree Homo sapiens. 4. Evaluate the proposed facts from the point of view of argumentation of the main hypotheses about the origin of man: Evolutionary path of Creation Neutral facts 1. The presence of atavisms in a person; 2. the presence of different races of Homo sapiens; 3. a very complex social structure of human society; 4. the generality of the structure of the main organ systems in humans and animals; 5. the presence in the geological layers of fossil remains of animals that do not exist at this time; 6. the presence of a person's hair on the head; 7. impossibility at the moment to make a complete picture of the emergence of man from wild ancestors; 8. complex structure of the human brain in comparison with animals; 9. the complexity of behavior and manifestations of human mental activity; 10. the presence of rudiments in a person; 11. the ability to use tools of labor; 12. the presence of fossil remains of great apes, which could have been the ancestors of modern man; 13. large size of the human brain in comparison with animals; 14. the presence of human tribes leading a primitive lifestyle; 15. the presence of articulate speech only in a person Make a conclusion by answering the question, what are the facts of argumentation of hypotheses of human origin? “Modern biology has accumulated a lot of facts indicating the possible origin of man from ape-like ancestors. At the same time, there are some facts that do not fit into this theory "
7 Test "Development of life on Earth" Option Hypothesis of the origin of life from inanimate matter: A) biogenesis; B) panspermia; C) abiogenesis; D) creationism. 2. Who formulated the biochemical hypothesis of the origin of life: A) Schleiden and Schwann; B) A.I. Oparin; C) Watson and Creek; D) Müller and Haeckel. 3. Indicate what taxon is the ancestor of amphibians: A) Shellfish; B) Quill-finned fish; C) Ray-finned fish; D) Cartilaginous fish. 4. Indicate the correct sequence of the Earth's evolutionary eras, starting with the last one, which lasts now, to the most ancient: A) Archean B) Mesozoic C) Cenozoic D) Paleozoic 5. Eukaryotes appeared: A) in Archea; B) in the Proterozoic; C) in the Paleozoic; D) in the Mesozoic; 6. Indicate when the first chordates appeared: A) in the Cambrian period; B) the Ordovician period; C) the Silurian period; D) Archean era. 7. When Conifers appeared: A) Devonian period; B) Permian period; B) Triassic period; D) Carboniferous period. 8. The heyday of saber-toothed tigers: A) Anthropogenic; B) Paleogene; C) Neogene; D) Cretaceous. 9. Find an unnecessary concept and explain your choice: A) Triassic; B) Jurassic; C) Neogene; D) Cretaceous. 10. Determine the systematic position of the following species: African elephant; Forest dandelion; 11. The main events of the Cretaceous period: A) the flourishing of gymnosperms; B) the appearance of angiosperms; C) the flowering of foraminifera; D) the appearance of placental mammals; E) the flowering of flying dinosaurs. Test "Development of life on Earth" Option 2 1. Hypothesis of the origin of life from living matter: A) biogenesis; B) panspermia; C) abiogenesis; D) creationism. 2. Who formulated the panspermia hypothesis: A) Schleiden and Schwann; B) Watson and Creek; C) Müller and Haeckel; D) Arrhenius and Vernadsky. 3. Indicate from whom the birds originated (one of the hypotheses): A) Brontosaurus; B) Pterodactyl; C) Ichthyosaurus; D) Archeopteryx. 4. Indicate the correct sequence of the Earth's evolutionary eras, from the most ancient to the present time: A) Archean; B) Mesozoic; C) Cenozoic; D) Paleozoic. 5. Prokaryotes appeared: A) in Archea; B) in the Proterozoic; C) in the Paleozoic; D) in the Cenozoic. 6. Indicate when the first mammals appeared: A) the Carboniferous period; B) the Triassic period; C) Cretaceous period; D) Jurassic period. 7. When angiosperms appeared: A) Permian period; B) Cretaceous period; C) Jurassic period; D) Carboniferous period. 8. The heyday of dinosaurs: A) Neogene; B) Paleogene; C) Jurassic; D) Triassic; 9. Find an unnecessary concept and explain your choice: A) Anthropogenic; B) Cambrian; C) Ordovician; D) Silurian. 10. Determine the systematic position of the following species: Himalayan bear; Tiger lily; 11. The main events of the Carboniferous period: A) the appearance of cross-finned fish; B) the formation of the first terrestrial biogeocenoses; C) the appearance of conifers; D) the appearance of the first insects; E) the appearance of the first reptiles
Test 14 option 2 the origin and development of the organic world \u003e\u003e\u003e
Test 14 option 2 the origin and development of the organic world \u003e\u003e\u003e Test 14 option 2 the origin and development of the organic world Test 14 option 2 the origin and development of the organic world The most important
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Contents 1. Biology as a science ........ 10 1.1. Problems and methods of biology .. 10 1.2. Layered organization of life and biological systems ... 12 2. The cell as a biological system .................... 16
STUDY OF EARLY STAGES OF DEVELOPMENT OF LIFE ON EARTH
Plan
1. The scale of geological time.
2. The main divisions of the geological history of the Earth.
3 A sharp increase in the diversity of fossil fauna
1. SCALE OF GEOLOGICAL TIME
Very many sciences are engaged in the study of evolution
development of organisms, exploring various aspects
Fossil remains of plants and animals that exist
lived in ancient geological eras on Earth, study
xia paleontology - a spider about extinct plants and
votnyh, about their change in time and space, about all
explorable manifestations of life in geological
past. To do this, they study the remains of ancient forms.
life and compare them with modern organisms. Them
it is possible to determine the lifetime of extinct forms,
to restore phylogeny on this basis. Phylogenesis
represents the historical continuity of plant
nii and animals, as well as all other groups of organisms,
their evolutionary history. But paleontology is not enough
but exclusively for their data. She definitely needs
information and research results of many other sciences,
which are close to her in direction. These include-
these biological, geological and geographical disciplines
us In addition, it is known that paleontology itself is
at the "junction" of geology and biology. Paleontology is also not
"help" of such sciences as historical geology is needed,
stratigraphy, paleography, paleoclimatology, etc. This
you need to be able to understand and correctly
determine the lifetime of extinct organisms,
understand the conditions of their life and the patterns of their transition
remains n fossil state. data usage
comparative anatomy is simply necessary paleontological
din; to analyze the structure, physiology, image
life and evolution of extinct forms. Moreover, with the help
comparative anatomy, it is quite easy to establish homo-
organ logic and structure of different species What is homo-
logic! - It represents the similarity, which is the basis
is based on kinship. If there are homo-
logical organs: -that is direct evidence
kinship of these organisms. This confirms
that organisms either have common ancestors or are
descendants of extinct organisms. How it came she was homo-
logical organs have the same structure, their development
comes from similar embryonic rudiments, as well as
it should also be pointed out that they occupy the same position
in the body.
Of great importance for paleontology is the development
sciences such as functional anatomy and comparative
physiology. They help paleontologists understand correctly
how the organs functioned in extinct organisms. For
analysis of the structure, life and conditions of existence
the study of extinct animals, scientists use the principle of
totalism, which was put forward by the geologist D. Getton. In-
as a result, it was developed in detail by one of the largest
geologists XIX and. C. LaYel. According to this) principle, everything
patterns and relationships that can be observed in
phenomena and objects of the inorganic and organic world
in the present, have taken place in the past. Definitely no one
cannot give one hundred percent guarantee, but many scientists
come to the conclusion that in most cases this principle,
faithful. As you know, the fossil record, which
represented by the fossil remains of extinct organisms
mov, sometimes does not give a complete picture due to the numerous
spaces. These gaps arise from the specificity of the
livable burial of the remains of organisms and very small
the probability of the coincidence of all the necessary factors for this
tori. To recreate the phylogeny of organisms completely,
reconstruct the missing links on the tree-tree
ve, only paleontological data and methods
dov. This can be helped by the triple parallelism method, which
which was introduced into the spider by the German scientist Z. Haeckel. He
General Biology 377
based on a comparison of paleontological, comparative
tomic and embryological data. Scientist leaned
to a law that he himself formulated. This is
new biogenetic law. It is based on understanding
the fact that the individual development of the organism (ontogeny
nz) is a condensed repetition of phylogeny. It means that
detailed study and analysis of currently developing organisms
the brain will make it possible to understand how the evolution
ony changes in all living organisms, including those
which have become extinct long ago. Much later, scientist A, N. Se-
vertsov proved that Haeckel was a little wrong. Severtso-
chym deduced the theory of phylembryogenesis, in which he proved
calls that it is precisely due to the evolution of ontogeny that
possible manifestation of phylogenesis. There are private
teas, when the evolutionary restructuring of any of the organ-
new proceeds by changing the late stages of its
individual development, that is, new signs of forming
are formed at the end of ontogeny (this is what Severtsov called anabolism).
Then you can actually observe what Haeckel described
relationship between ontogeny and'philogenesis. Only in
in such cases, it is possible to attract embryological
their data for the study of phylogenesis. Sevsrtsov
interesting examples of reconstruction of hypothetical
some of the missing links in the phylogenetic tree. Ex-
the following ontogenesis of modern organisms is necessary
dimo also in order to have the correct representation
knowledge about possible changes in ontogenesis, which give
push for evolution;
To understand the essence of the evolutionary process and
to make a causal analysis of the course of phylogenesis, it is necessary to conclude
dy of evolutionary history. This science is analogous to the theory
.solution and is called otherwise Darwinism on behalf of the great
the founder of the theory of natural selection C. Darwin. Pre-
the founders of this science study the essence of mechanisms that are common
patterns and directions of the evolutionary process.
Science itself is the theoretical basis of all modern
biology. The evolution of organisms is a special form of being
development of living matter in time. In addition, everything is modern
changing manifestations of life at any level of the organization
living matter can be understood only taking into account evolutionary
new background.
Here is a far from complete list of sciences involved in
study and analysis of the development of life on Earth in the past
pooh. Paleontologists use data from taxonomy, bio-
geography. Also, scientists are very interested in the issues of
the origin of man and his evolution, since there is
significant differences from all other classes of animals
due to the development of labor activity and social
under certain conditions.
To understand the evolution of organisms, you need to know
how it passed in time, take into account the duration
all its stages. Sedimentary rocks help determine the impact
growth of the area. Older rocks lie under more
back strata
To correctly determine the relative age of the
stocks of sedimentary rocks from different regions, it is necessary to compare
to twist the fossil organisms preserved in them. This is
can be done thanks to the paleontological method, pre-
stated in the works of the English geologist W. Smith at the end
XVIII - early XIX century Scientists have found that among the fossils
different organisms that characterize each era,
a number of the most common
unnatural species. These species began to be called guiding not
dug.
The absolute age of sedimentary rocks, that is, that interval
the eerie time that has passed since the beginning of their formation,
it's hard enough to tune. Information about this can be found
radiate by examining volcanic rocks formed from
cooling magma. In magma, the content of
radioactive elements and decay products. It is known that
radioactive decay in such rocks begins with time
nor their crystallization from magma melts, and
it runs at a constant speed until it is exhausted
all stocks of radioactive elements are kept.
Thanks to this, it is enough to determine the age of the breed
easily. To do this, you only need to determine the content in the mountain
rock of this or that radioactive element and product
of its decay, taking into account the decay rate, and it is possible to
but accurately calculate the absolute age of a given breed.
For sedimentary rocks, it is necessary to take into account approximately
age in relation to the absolute age of the
ev volcanic rocks. Long and painstaking use
adherence to the relative and absolute ages of mountain
rocks in different regions of the world, which was carried out
several generations of geologists and paleontologists, allowed
lilo to outline the main milestones in the geological history of the Earth
whether. The boundaries between these units correspond
all kinds of changes in geological and biological
(paleontological) character. It could be changes
sedimentation regime in water bodies that lead to
the formation of other types of sedimentary rocks, increased vol-
canism and mountain building processes, invasion of the sea
(marine transgression) due to the subsidence of significant
areas of the continental crust or rising ocean levels
ana, significant changes in the fauna and flora ...
such events have occurred irregularly in the history of the Earth,
the duration of different eras, periods and eras is not the same.
Sometimes the enormous duration of the ancient
shikh geological eras (Archaeozoic and Proterozoic), which *
which, moreover, are not divided into smaller time intervals
creepy (in any case, there is no generally accepted division).
This arose primarily due to the very factor of time
nor, that is, the antiquity of the Archaeozoic and Proterozoic deposits, which
have undergone significant
metamorphism and destruction, as a result of which the su
The milestones of the development of the Earth and life that once walked. Otlo-
archean and proterozoic eras contain extremely
few fossil remains of organisms; on this basis
archaeozoic and Proterozoic are combined under the name "crypto
zoy "(stage of hidden life), opposing the unification
three subsequent eras - phanerozoic (ethane of an explicit, observable
life). The age of the earth is determined by various scientists
in different ways, but you can specify an approximate figure - 5
billion years
2. MAIN DIVISIONS OF GEOLOGICAL
EARTH HISTORIES
Archeozoic and Proterozoic eras, which were
cryptos', lasted approximately 3.4 billion years. This speaks of
the fact that cryptosis is 7/8 of the entire geological history
ri. It should be noted that in the sediments of rocks of this period
preserved only a small amount of fossil remains
373 Biology
kov of extinct organisms. Therefore, it is difficult for scientists to accurately
determine how life developed during this sufficiency
precisely for an extended period of time.
The oldest remains of extinct organisms scientists
found in the sedimentary strata of Rhodesia. Sedimentary rocks are
here the age is 2.9-3.2 billion years. Traces were found
the vital activity of algae (most likely, blue-green
them). This convincingly proves that approximately 3 billion
years ago, photosynthetic
organisms. This is algae. It is assumed that the appearance
life on Earth should have happened much earlier.
The figure is called 3.5-4 billion years ago. The most studied pro
therozoic flora. It is represented by filamentous forms
up to several hundred micrometers long and 0.6-16 thick
μm. They all have a different structure. Also found wasps
tatars of unicellular organisms with a diameter of 1 - 16 microns. Os-
tats of this Middle Proterozoic flora were found in Ka-
hope. Scientists have studied siliceous shales in the northern
the shores of Lake Superior and stumbled upon the remains of extinct
r ^ ijurganisms. The age of the deposits is approximately
1.9 billion years.
Very often in sedimentary rocks related to the
between 2-1 billion years ago, scientists find
matolites - calcareous or dolomite loaf-like
bodies at the bottom of sea and freshwater bodies, which arose in
as a result of the vital activity of lower algae. This is only
ko confirms the version about wide distribution and active
photosynthetic and reef-building activities
blue-green algae.
The next most important stage in the evolution of life is confirmed
is given by a number of finds of fossil remains in sediments, which
some are 0.9-3 billion years old. Among them, pre-
the red-preserved remains of unicellular organisms are
measure of 2-8 microns, in which it was possible to distinguish between intracellular
a structure similar to the core; stages
division of one of the species of these unicellular organisms, into
commemorating the stages of mitosis, - a way of dividing eukaryotic
kih (i.e., having a nucleus) cells.
If conclusions drawn after careful study
found remains are correct, this only confirms that
about 1.6 billion years ago, the evolution of the orgapismon passed an important
the next frontier: the level of organization of eukaryotes was reached.
About the first traces of the vital activity of worm-like poly-
cellular can be recognized from late Riphean deposits. Already
in Vendian times (about 650-570 million years ago) there is
there were animals that could be attributed to different
types. Imprints of soft-bodied Vendian animals are not
so many, but they are known in all corners of the earth
ball. Scientists have made a number of interesting finds on the ter-
ritories of the former USSR, having discovered them in the Late Proterozoic
some deposits.
In 1947, R. Sprigt discovered a rich late
... rubbed the ozone fauna. The scientist found her in Central Austria
ralia. M. Glessner, who later studied it, suggests
that it consists of three dozen species of the most diverse
multicellular animals that can, tii revenge on different
types. Most of the forms found can be attributed to the
cervical. These include jellyfish '/: common organisms
we, who were supposed to be in the 8 middle layer
waters, and polyploid forms located near the bottom, which
rye in appearance resemble modern alcyonarium or mor-
feathers. Scientists have confirmed that they are all. like similar
animals of the Adiacara fauna do not have a solid skeleton.
In addition to coelenterates in Pound quartzites, where and
the Ediacaran fauna is located, the remains of a worm
different organisms, which are referred to as t m and ringed
worms. Some of the presented remains of t are considered
possible ancestors of arthropods. To that same place, find
the remains of unknown taxonomic affiliation are found.
This only confirms once again that in Jend time
there was a wide variety of multicellular soft
cauldron animals. From this we can conclude: take into account
knowing that in the Vendian time there was a huge variety of
many species, including rather highly organized
animals, then, most likely, before the Vendian period, life
existed for a long time. It is assumed that
multicellular animals appeared much earlier - with
approximately 700-900 million years ago.
3. SHARP GROWTH OF DIVERSITY OF FOSSIL
FAUNA
At the turn of the Proterozoic and Paleozoic eras, there is a strong
but the composition of the fossil fauna will change. Unexpectedly ate
strata of the Upper Proterozoic, in which almost half of
no life, in sedimentary rocks of the Cambrian, starting
from the very bottom of its layers, a huge amount of
and a variety of fossil remains. Among
them and sponges (brachiopods), as well as representatives
extinct arthropods. But by the end of the Cambrian,
almost all types of multicellulars known to scientists
animals. Until now, researchers cannot explain
such a sudden leap in the evolution of living forms.
Apparently, the isolation of all basic types
animals occurred in the upper Proterozoic 600-800 million
years ago. Scientists suggest that primitive representations
bodies of all groups of multicellular animals were small
organisms without a skeleton. Meanwhile, at-
oxygen was accumulating in the sphere and the power
the ozone screen, which led to an increase in the size
the moat of the body of animals and the acquisition of a skeleton by them. As a result
organisms were able to spread widely on
shallow depths of various reservoirs, and this became the reason
the fact that the number of various forms of
life.
The history of the development of life is studied according to the data geologyand paleontology, since many fossil remains produced by living organisms have been preserved in the structure of the earth's crust. In place of the former seas, sedimentary rocks have formed, containing huge layers of chalk, sandstone and other minerals, representing the bottom sediments of calcareous shells and silicon skeletons of ancient organisms. There are also reliable methods for determining the age of terrestrial rocks containing organic matter. Usually, a radioisotope method is used, based on measuring the content of radioactive isotopes in the composition of uranium, carbon, etc., which changes regularly over time.
Immediately, we note that the development of life forms on Earth proceeded in parallel with the geological restructuring of the structure and relief of the earth's crust, with a change in the boundaries of the continents and the world's oceans, the composition of the atmosphere, the temperature of the earth's surface and other geological factors. These changes determined, to a decisive extent, the direction and dynamics of biological evolution.
The first traces of life on Earth date back to about 3.6–3.8 billion years. Thus, life arose soon after the formation of the earth's crust. In accordance with the most significant events of geobiological evolution in the history of the Earth, large time intervals are distinguished - eras, within them - periods, within periods - epochs, etc. For greater clarity, we will depict the calendar of life in the form of a conditional annual cycle, in which one month corresponds to 300 million years of real time (Fig. 6.2). Then the entire period of development of life on Earth will be just one conditional year of our calendar - from “January 1” (3600 million years ago), when the first protocells were formed, to “December 31” (zero years), when we live with you ... As you can see, it is customary to count geological time in reverse order.
(1) Archaea
Archean era(the era of the most ancient life) - from 3600 to 2600 million years ago, the length of 1 billion years - about a quarter of the entire history of life (on our conventional calendar these are “January”, “February”, “March” and several days of “April”).
Primitive life existed in the waters of the world's oceans in the form of primitive protocells. There was still no oxygen in the Earth's atmosphere, but there were free organic substances in the water, so the first bacteri-like organisms ate heterotrophically: they absorbed ready-made organic matter and received energy through fermentation. In hot springs rich in hydrogen sulfide and other gases, at temperatures up to 120 ° C, autotrophic chemosynthetic bacteria or their new forms, archaea, could live. As the primary reserves of organic matter were depleted, autotrophic photosynthetic cells arose. In the coastal zones, bacteria emerged on land, and soil formation began.
With the appearance of free oxygen in the water and the atmosphere (from photosynthetic bacteria) and the accumulation of carbon dioxide, opportunities are created for the development of more productive bacteria, and behind them the first eukaryotic cells with a real nucleus and organelles. They subsequently developed various protists (unicellular protozoa) and further plants, fungi, and animals.
Thus, in the Archean era, pro- and eukaryotic cells with different types of nutrition and energy supply appeared in the oceans. Preconditions have been created for the transition to multicellular organisms.
(2) Proterozoic
Proterozoic era(the era of early life), from 2600 to 570 million years ago, is the longest era, covering about 2 billion years, that is, more than half of the entire history of life.
Figure: 6.2. Eras and periods of development of life on Earth
Intensive mountain building processes have changed the ratio of ocean and land. There is an assumption that at the beginning of the Proterozoic, the Earth underwent the first glaciation, caused by a change in the composition of the atmosphere and its transparency for solar heat. Many pioneer groups of organisms, having done their job, died out, and new ones came to replace them. But on the whole, biological transformations took place very slowly and gradually.
The first half of the Proterozoic was in full bloom and dominance of prokaryotes - bacteria and archaea. At this time, the iron bacteria of the world's oceans, precipitating generation after generation to the bottom, form huge deposits of sedimentary iron ores. The largest of them are known near Kursk and Krivoy Rog. Eukaryotes were represented mainly by algae. Multicellular organisms were few in number and very primitive.
About 1000 million years ago, as a result of the photosynthetic activity of algae, the rate of oxygen accumulation increases rapidly. This is also facilitated by the completion of the oxidation of iron in the earth's crust, which until now absorbed the bulk of oxygen. As a result, the rapid development of the simplest and multicellular animals begins. The last quarter of the Proterozoic is known as the "age of jellyfish", since these and similar coelenterates constitute the dominant and most progressive form of life at that time.
About 700 million years ago, our planet and its inhabitants are going through the second ice age, after which the progressive development of life becomes more and more dynamic. During the so-called Vendian period, several new groups of multicellular animals were laid, but life is still concentrated in the seas.
At the end of the Proterozoic, triatomic oxygen O 3 accumulates in the atmosphere. It is ozone that absorbs the ultraviolet rays of sunlight. The ozone shield reduced the mutagenicity of solar radiation. Further neoplasms were numerous and varied, but they were less and less radical - within the already formed biological kingdoms (bacteria, archaea, protists, plants, fungi, animals) and the main types.
So, during the Proterozoic era, the dominance of prokaryotes was replaced by the dominance of eukaryotes, there was a radical transition from unicellularity to multicellularity, the main types of the animal kingdom were formed. But these complex life forms existed exclusively in the seas.
The terrestrial land at this time represented one large continent; geologists gave it the name Paleopangea. In the future, global plate tectonics of the earth's crust and the corresponding drift of continents will play an important role in the evolution of terrestrial life forms. In the meantime, in the Proterozoic, the rocky surface of the coastal areas was slowly covered with soil, bacteria, lower algae, the simplest unicellular animals settled in damp lowlands, which still existed perfectly in their ecological niches. The land was still waiting for its conquerors. And on our historical calendar there was already the beginning of “November”. Before the “New Year”, before our days, there were less than “two months”, only 570 million years.
(3) Paleozoic
Palaeozoic(era of ancient life) - from 570 to 230 million years ago, the total length is 340 million years.
Another period of intense mountain building led to a change in the relief of the earth's surface. Paleopangaea split into the giant continent of the Southern Hemisphere, Gondwana, and several small continents in the Northern Hemisphere. Former land areas were under water. Some groups died out, but others adapted and mastered new habitats.
The general course of evolution, starting from the Paleozoic, is shown in Fig. 6.3. Please note that most of the evolutionary trends of organisms that originated at the end of the Proterozoic continue to coexist with newly emerging young groups, although many are reducing their volume. Nature parted with those who do not correspond to changing conditions, but retains the most successful options, selects and develops of them the most adapted and, in addition, creates new forms, among them are chordates. Higher plants appear - the conquerors of land. Their body is divided into a root and a stem, which allows it to be well fixed in the soil and extract moisture and minerals from it.
Figure: 6.3. Evolutionary development of the living world from the end of the Proterozoic to our time
The area of \u200b\u200bthe seas either increases or decreases. At the end of the Ordovician, as a result of a decrease in the level of the world ocean and a general cooling, there was a rapid and mass extinction of many groups of organisms, both in the seas and on land. In the Silurian, the continents of the Northern Hemisphere are connected to the supercontinent Laurasia, which is divided with the southern continent of Gondwana. The climate becomes drier, milder and warmer. Armored “fishes” appear in the seas, and the first articulated animals emerge on land. With a new rise in land and shrinking seas in the Devonian, the climate becomes more contrasting. Mosses, ferns, mushrooms appear on the ground, the first forests are formed, consisting of giant ferns, horsetails and lymphoids. Among animals, the first amphibians, or amphibians, appear. In the Carboniferous, swampy forests of huge (up to 40 m) tree ferns are widespread. It was these forests that left us with deposits of coal ("coal forests"). At the end of the Carboniferous there is an uplift of land and a cooling, the first reptiles appear, finally freed from water dependence. In the Permian period, the next uplift of the land led to the unification of Gondwana with Laurasia. The united continent of Pangea was formed again. As a result of the next cold snap, the polar regions of the Earth are subject to glaciation. Treelike horsetails, ploons, ferns, many ancient groups of invertebrates and vertebrates are dying out. In total, by the end of the Permian period, up to 95% of marine species and about 70% of terrestrial species became extinct. But reptiles (reptiles) and new insects are rapidly progressing: their eggs are protected from drying out by dense shells, the skin is covered with scales or chitin.
The general result of the Paleozoic is the settlement of land by plants, mushrooms and animals. At the same time, both those, and others, and the third in the process of their evolution become more complex anatomically, acquire new structural and functional adaptations for reproduction, respiration, nutrition, contributing to the development of a new habitat.
The Paleozoic ends when our calendar shows “December 7th”. Nature is “in a hurry”, the rate of evolution in groups is high, the time of transformations is being compressed, but the first reptiles are only entering the scene, and the time of birds and mammals is still far ahead.
(4) Mesozoic
Mesozoic era (era of average life) - from 230 to 67 million years ago, total length 163 million years.
The land uplift, which began in the previous period, continues. In the beginning there is a single continent called Pangea. Its total area is much larger than the land area at present. The central part of the continent is covered with deserts and mountains, the Urals, Altai and other mountain ranges have already been formed. The climate is becoming more arid. Only river valleys and coastal lowlands are inhabited by monotonous vegetation of primitive ferns, cicadas and gymnosperms.
In the Triassic, Pangea gradually splits into northern and southern continents. Among animals on land, herbivores and carnivorous reptiles, including dinosaurs, begin their "triumphant procession". Among them there are already modern species: turtles and crocodiles. Amphibians and various cephalopods still live in the seas, bony fishes of a completely modern species appear. This abundance of food attracts predatory reptiles to the sea, and their specialized branch, ichthyosaurs, is separated. From some early reptiles, small groups separated, giving rise to birds and mammals. They already have an important feature - warm-bloodedness, which will give great advantages in the further struggle for existence. But their time is still ahead, but for now, dinosaurs continue to explore terrestrial spaces.
In the Jurassic period, the first flowering plants appeared, and among the animals, giant reptiles dominate, having mastered all habitats. In warm seas, in addition to marine reptiles, bony fishes and various cephalopods, similar to modern squids and octopuses, thrive. The continents continue to split and drift with a general direction towards their present state. This creates conditions for isolation and relatively independent development of fauna and flora on different continents and island systems.
In the Cretaceous period, in addition to oviparous and marsupial mammals, placental mammals appear, carrying young for a long time in the mother's womb in contact with blood through the placenta. Insects begin to use flowers as a food source while contributing to pollination. This cooperation has benefited both insects and flowering plants. The end of the Cretaceous period was marked by a decrease in ocean level, a new general cooling and mass extinction of many groups of animals, including dinosaurs. It is believed that 10–15% of the former species diversity remains on land.
There are different versions of these dramatic events at the end of the Mesozoic. The most popular scenario is a global catastrophe caused by a giant meteorite or asteroid falling to the Earth and leading to the rapid destruction of the biosphere balance (shock wave, dusty atmosphere, powerful tsunami waves, etc.). However, everything could have been much more prosaic. The gradual restructuring of the continents and climate change could lead to the destruction of the existing food chains built on a limited circle of producers. First, some invertebrates, including large cephalopods, became extinct in the colder seas. Naturally, this led to the extinction of sea lizards, for which cephalopods were the main food. On land, there was a reduction in the growth zone and biomass of soft succulent vegetation, which led to the extinction of giant herbivores, followed by carnivorous dinosaurs. The food supply for large insects was also reduced, and flying lizards began to disappear behind them. As a result, over several million years, the main groups of dinosaurs became extinct. We must also bear in mind the fact that reptiles were cold-blooded animals and were not adapted to existence in a new, much more severe climate. Under these conditions, small reptiles - lizards, snakes - survived and developed further; and relatively large ones, such as crocodiles, turtles, and tuataras, survived only in the tropics, where the necessary food supply and a mild climate remained.
Thus, the Mesozoic era is rightfully called the era of reptiles. For 160 million years, they have experienced their heyday, the broadest divergence in all habitats and died out in the fight against the inevitable element. Against the background of these events, warm-blooded organisms - mammals and birds - have gained tremendous advantages, which have moved on to the development of liberated ecological niches.But this was already a new era. There were “7 days” left before the “New Year”.
(5) Cenozoic
Cenozoic era (era of new life) - from 67 million years ago to the present. This is the era of flowering plants, insects, birds and mammals. In this era, a man appeared.
At the beginning of the Cenozoic, the location of the continents is already close to the present, but there are wide bridges between Asia and North America, the latter is connected through Greenland with Europe, and Europe is separated from Asia by a strait. South America was isolated for several tens of millions of years. India is also isolated, although it is moving gradually northward, towards the Asian continent. Australia, which at the beginning of the Cenozoic was associated with Antarctica and South America, about 55 million years ago, completely isolated and gradually moves north. On isolated continents, special directions and rates of evolution of flora and fauna are created. For example, in Australia, the absence of predators made it possible for the ancient marsupial and oviparous mammals to survive, long extinct on other continents. Geological restructuring has contributed to the emergence of increasing biodiversity, as it created great variations in the living conditions of plants and animals.
About 50 million years ago, a detachment of primates appeared in the class of mammals on the territory of North America and Europe, which subsequently gave rise to monkeys and humans. The first people appeared about 3 million years ago (“7 hours” before the “New Year”), apparently in the eastern Mediterranean. At the same time, the climate became more and more cool, the next (fourth, counting from the early Proterozoic) ice age began. In the northern hemisphere, there have been four periodic glaciations over the last million years (as phases of an ice age alternating with temporary warming). During this time, mammoths, many large animals, ungulates became extinct. A large role in this was played by people who were actively engaged in hunting and farming. A modern human was formed only about 100 thousand years ago (after "23 hours 45 minutes on December 31" of our conditional year of life; we exist this year only for the last quarter of an hour!).
In conclusion, we emphasize once again that driving forces biological evolution must be seen in two interconnected planes - geological and biological... Each next large-scale restructuring of the earth's surface entailed inevitable transformations in the living world. Each new cold snap led to the mass extinction of poorly adapted species. Continental drift determined the difference in the rates and directions of evolution in large isolates. On the other hand, the progressive development and reproduction of bacteria, plants, fungi and animals also affected geological evolution itself. As a result of the destruction of the mineral base of the Earth and its enrichment with metabolic products of microorganisms, the soil arose and was constantly rebuilt. The accumulation of oxygen at the end of the Proterozoic led to the formation of the ozone screen. Many waste products remained forever in the bowels of the earth, transforming them irreversibly. These are organogenic iron ores, and deposits of sulfur, chalk, coal, and much more. A living thing, generated from inanimate matter, evolves with it, in a single biogeochemical flow of matter and energy. As for the inner essence and direct factors of biological evolution, we will consider them in a special section (see 6.5).
