Fungi are eukaryotes whose main nutrition is absorption. Fungal cells have cell walls, at least at some stage in their life history. The cell wall contains chitin and cellulose. Chitin is a polysaccharide containing glucosamine, which is the main component of animal bones such as insects. Plant cell walls never contain chitin. Fungal cells have no plastids and photosynthetic pigments. Some fungi are unicellular, such as yeast. The basic structure of multicellular fungi is branched or unbranched hyphae. A whole mass of mycelium is called mycelium. Some hyphae divide into multiple cells with diaphragm, each cell has one or more nuclei, and some hyphae become multinucleate without diaphragm. Mycelium has the function of absorbing water and nutrition. Mycelia is often loose as a spider web to expand the absorption area. Fungi have strong reproductive ability and various reproductive modes, mainly taking spores produced by asexual or sexual reproduction as reproductive units. Fungi are widely distributed. In the ecosystem, fungi are important decomposers, and the scope of decomposition may be larger than that of bacteria. Myxomycetes are a special kind of fungi. Its life history is partly fungi and partly animals, and its structure, behavior and feeding mode are similar to those of amoeba. Myxomycetes are considered to be between fungi and animals.
Animals are eukaryotes and feed on swallowing. Swallowing heterotrophy includes a series of complex processes such as capture, swallowing, digestion and absorption. The structure of animal body develops in the direction of adapting to swallowing heterotrophy. Single-celled animals swallow food to form food vacuoles. Food is digested in food vacuoles, then enters the cytoplasm through the membrane, and lysosomes in the cytoplasm fuse with them for intracellular digestion. In the evolution of multicellular animals, intracellular digestion was gradually replaced by extracellular digestion. After food is caught, it is digested by enzymes secreted by digestive glands of digestive tract. After digestion, small molecular nutrients are absorbed by the digestive tract and transported to cells in various parts of the body through the circulatory system. In line with this, multicellular animals gradually formed a complex excretory system, an external respiratory system for gas exchange, and complex sensory organs, nervous system, endocrine system and motor system. The nervous system and endocrine system constitute a complex self-regulation and self-control mechanism, which regulates and controls all physiological processes. Of all living things, only the animal's body structure has developed to such a complicated and advanced degree. In the ecosystem, animals are consumers of organic food. At the early stage of life development, when there were only cyanobacteria and bacteria on the earth, the ecosystem was a double-ring system composed of producers and decomposers. With the appearance and development of eukaryotes, especially animals, the double-ring ecosystem has developed into a three-ring system composed of producers, decomposers and consumers. Today's colorful biological world has emerged.
From viroids and viruses to plants and animals, there are many different types of organisms. There are a series of intermediate links between each type, forming a continuous pedigree. At the same time, the three evolutionary directions determined by nutritional methods present an interactive spatial relationship in the ecosystem. Therefore, evolution is both a time process and a spatial development process. Judging from the historical origin of time and the living relationship of space, biology is a whole. In this whole, every moment, every minute, it shows the existence of mutual coordination, struggle and unity between the biological whole self and the specific individual self, and also shows the existence of mutual struggle, coordination and unity between the biological whole self and the objects outside the biological system (that is, nature). Creatures are not only diverse, but also have some characteristics and attributes that are the same. The ego of this biological system is more obvious in the inheritance and variation of organisms.
In the inheritance and variation of matter, relative to nature, the whole organism is the subject, while nature is the object. The existence of the subject and the tendency to maintain the existing state and form are contradictory to the tendency of the object to maintain the status quo. The individual of an organism has the same contradiction with the whole organism and nature. Protein in the organism and other individual tissues that make up the organism have the same contradiction with the individual itself. All contradictions, through struggle and coordination, compromise with each other, forming a compromise method to solve contradictions, that is, heredity and variation. The whole organism not only struggles with nature, but also has fierce competition for survival inside. Compared with individual organisms, in competition, it makes them better adapt to the object, that is, the biological world and nature they face. Natural selection and survival of the fittest are the logic of biological survival. This logic has promoted the continuous evolution of biology from simple to complex, from low to high.
Chapter iv evolution of human beings and evolution of human society.
Section 1 The Formation and Development of Evolutionary Thought
The establishment of any theory is a breakthrough and development of human society and nature, including religion. Any theory comes into being under a certain background, but it also has its limitations. Every word can't be true. Any correct theory comes from the demonstration and overthrow of the wrong theory. The original theory of Mongolian taste created the original Mongolian culture of mankind, and it also contains a considerable part of the philosophy of human existence, which is the product of an era. After a theory is established, it needs future generations to develop and innovate. Darwin's theory of evolution represents an era and is still an enlightened understanding for human beings and nature. The core of his theory is based on numerous practices and explorations by himself and his predecessors. No matter what anyone says, it is impossible to overthrow the reasonable elements in his theory.
The emergence and evolution of human beings are produced in fierce struggle and cruel environment, and it is impossible to be pampered. China's theory of Yin-Yang Eight Diagrams in the Book of Changes attributed nature to eight basic phenomena: heaven, earth, thunder, wind, water, fire, mountains and ze, trying to explain the complicated changing laws of the material world with Yin-Yang Eight Diagrams. Anaximander, an ancient Greek (about 6th century BC), believed that life was originally produced by mud in the sea, and primitive aquatic creatures were transformed into terrestrial creatures through metamorphosis (similar to the molting of insect larvae).
In the Western Middle Ages, the Christian Bible described everything in the world as a special creation of God. This is called creationism. Teleology, which is accompanied by creationism, holds that the arrangement of nature has a purpose. "Cats are created to eat mice, mice are created to eat cats, and the whole nature is created to prove the wisdom of the creator." From the Renaissance in the second half of the15th century to the18th century, modern natural science was formed and developed. The dominant view of the scientific community in this period is invariance. At that time, this view was expressed by I Newton and C·V· Linnaeus as a scientific law: the earth moves because of the so-called first driving force, and then moves forever. Biological species were like this before, now and in the future.
/kloc-in the second half of the 0/8th century, my Kant's celestial theory first opened the first gap in the unchanging view of nature; Subsequently, the natural view of transformation theory gradually formed in various fields of natural science. Some biologists in this period were often confused between the two concepts. For example, in his later years, Linnaeus deleted the word species invariance in his book Natural Systems. French biologist G.-L.de Buffon introduced transformation theory into biology, but he lingered between transformation theory and invariance theory all his life. J.-B.de Lamarck expounded his views on biotransformation in the book Animal Philosophy published in 1809, and never wavered. From the end of 18 to the end of 19, although the "vitality theory" admitted that biological species can be transformed, it attributed evolution to immaterial internal forces, and thought that the "internal forces" of organisms, that is, vitality, promoted the evolution of organisms, making them more and more complex and perfect. However, the theory of vitality at that time lacked practical evidence and was regarded as an idealistic guess. If it weren't for our egoistic thinking, we might be wronged. The most famous vitalist is the French biologist Lamarck. Later generations call Lamarckianism or Lamarckianism the viewpoint of biological evolution, the main point of which is that species are changeable and species are groups of mutated individuals. Nature has a series of levels (steps) from simple to complex, and organisms themselves have an inherent "willpower" to drive the development and change of organisms from low to high. Biological adaptability to the environment is very strong; Environmental changes will cause biological changes, thus improving its adaptability; The diversification of environment is the fundamental reason of biodiversity. Changes in the environment will cause changes in animal habits. Changes in habits will cause some organs to develop when they are used frequently, while others will degenerate when they are not used. Directional variation under the influence of environment, that is, acquired traits, can be inherited.
If the environment changes in a certain direction, due to the use of organs and acquired inheritance, tiny variations gradually accumulate and eventually organisms evolve. On July 1858, C.R. Darwin and A.R. Wallace read a paper on the origin of species in linnean society of london. Later generations called their theory of natural selection Darwin? Wallace theory. Darwin systematically expounded his theory of evolution in the book Origin of Species published in 1859. The main idea of its core principle of natural selection is that all living things tend to over-breed, and living space and food are limited, so living things must "fight for survival". Individuals in the same population have variation, those individuals who have favorable variation and can adapt to the environment will survive and reproduce, and those individuals who have no favorable variation will be eliminated. If the change of natural conditions is directional, then in the historical process, after long-term natural selection, small variations will accumulate and become significant variations. This may lead to the formation of subspecies and new species. It is understandable that we should reconsider some viewpoints of vitality theory and combine it with evolution theory. We can assert that living things can't compete with nature or even evolve without internal willpower. The development and change of biology from low level to high level has internal motivation. This kind of motivation is the origin of matter, that is, the tendency of self-matter to maintain its own existence. The heredity and variation of organisms are the unity of opposites, and heredity is the embodiment of the subjective desire expressed by the inherent survival motivation of organisms; Variation is the result of compromise due to the limitation of objective environment. In the genetic process, through a long time, due to the change of natural environment, living things have no choice but to die or adapt to the environment and drag out an ignoble existence. In this case, trying to change yourself is the only way out. This effort to change one's achievements is passed down from generation to generation, and changes from generation to generation with the change of environment. When the long-term quantitative change reaches a certain level, it becomes qualitative change and obvious variation. In the process of variation, forced submission gradually becomes a habit, and the accumulation of habits becomes instinct. If Australopithecus lived a carefree life for a long time, they would never evolve into humans. People nowadays can't imagine how cruel the environment was to them at that time. In terms of mouth, they can't compare with carnivores such as dogs and cats, and in terms of legs, they can't compare with herbivores such as deer. The forests on which they live are destroyed due to natural or geological reasons, and they are often attacked by other carnivores. Their desire for survival and harsh conditions forced them to live in groups and survive through the strength of unity. Due to the change of environment, they have to change their original lifestyle and develop their brains and front legs; In social life, they should cooperate with each other and exchange information in cooperation, which forces them to develop organs that make sounds, so that the sounds they make show cadence, pitch, speed, thickness and change; After a long process, they stand out from a wide variety of animals and become human beings. Paleoanthropologists believe that 78 million years ago, the * * * ancestors of human beings and apes-ancient apes began to evolve in different directions, and this process was carried out under specific environmental conditions. Cenozoic Tertiary refers to the geological age from 70 million years ago to 23 million years ago. The Cenozoic Quaternary refers to the geological age after two or three million years ago. The world-wide orogeny is very active, with Himalayas and Alps appearing one after another, and 8 000 km long broken valleys appearing in East Africa. Due to such a large-scale crustal movement, the world climate has undergone tremendous changes, especially in the Cenozoic Quaternary, where climate changes intensified and a series of ice ages appeared. Under the influence of great changes in topography and climate, some original continuous forests are gradually sparse, and the open space in the forest is constantly expanding, and finally it is replaced by savanna. At this time, some ancient apes living here gradually changed from arboreal life to terrestrial life, and finally evolved into human beings; And the part of the ape that stayed in the forest evolved into an ape.
After human ancestors came to live in the open field, they were gradually able to defend wild animals with branches and stones, or dig roots for food. In this process, the ancient ape gradually changed from walking on all fours to walking upright on two feet. This transformation not only enhanced the survival ability of human ancestors, but also caused a series of adaptive changes in their body structure, such as the downward movement of body center of gravity, the growth of lower limb bones, the shortening and widening of pelvis, and the transformation of spine from arch to S-shape. In addition, bipedal walking also liberated the forelimbs of human ancestors from walking and supporting the body, creating conditions for various activities and further development and expansion of the brain. The significance of bipedal walking makes anthropologists regard this condition as an important criterion for the demarcation between humans and apes.
In the process of using natural tools, human ancestors gradually learned to make tools. The tools made by early humans were all stone tools. These stone tools are usually found with animal remains and artificially broken bones. Paleoanthropologists have come to the conclusion that the appearance of stone tools is closely related to early human hunting and carnivorous behavior. In the process of making and using tools, the brains of human ancestors became more and more developed, and languages gradually came into being, forming human society. Up to now, most of the ancient human fossils found around the world are incomplete, often only fragmentary skulls, jaws, teeth and femur, and the earliest age of fossils is only more than 4 million years ago. Nevertheless, through the efforts of paleoanthropologists, the general process of human evolution has been clarified. This process is usually divided into four stages: Australopithecus, Homo habilis, Homo erectus and Homo sapiens. 1924, a baby skull fossil of Australopithecus was found in Dunn, South Africa, and was named Australopithecus after identification. Subsequently, paleoanthropologists discovered hundreds of Australopithecus fossils in Africa, especially in the eastern part of the fault valley. Through the study of these fossils, we know that Australopithecus lived between 4.2 million and 65.438+0 million years ago and was the earliest primitive human. In addition to walking upright, Australopithecus is mostly anthropoid. For example, their brain capacity is very small, ranging from 450 to 530 ml, which is similar to that of modern apes (average 465,438+05 ml). /kloc-since 0/960, paleoanthropologists have discovered ancient human fossils in Africa with similar characteristics to Australopithecus, and named them homo habilis. Capable people lived 2 million to 6.5438+0.75 million years ago. Compared with Australopithecus, their skull wall is thinner and their brain volume is increased, with an average of about 680 ml. Stone tools have also been found in homo habilis fossils, which shows that homo habilis has been able to make tools. Homo erectus lived 2 million to 200 thousand years ago, and their fossils were found in many places in Asia, Africa and Europe. The more famous are the Java Homo erectus in Indonesia and the Beijing Homo erectus in Zhoukoudian, Beijing. Among them, Peking man has the richest fossil data and the most comprehensive research. The brain capacity of Beijingers has obviously increased. The average brain volume of adults is as high as 1.088ml, and the length and shape of limbs bones are basically the same as those of modern people, which shows that their upright walking posture is the same as that of modern people, and there has been an obvious division of labor between upper and lower limbs. However, Beijingers still have many primitive features, such as backward forehead, thick brow ridge and chin-less jaw (Homo erectus is also called ape-man because of its many characteristics similar to ape-man). A large number of stone tools have been found in the site of Peking man, which have different functions and fine processing, proving that the ability of Homo erectus to make tools has been greatly improved than that of Homo habilis. In addition, a thick layer of ashes was found in the cave where they lived, including charred bones, stones and Pu Shu seeds, indicating that Beijingers already knew how to use fire. Fire can be used not only to keep warm and drive away wild animals, but also to cook food, making it easy to digest and absorb, promoting the development of human ancestors' physique, especially providing rich nutrition for the development of the brain. Homo sapiens, including early Homo sapiens and late Homo sapiens, lived 200,000 ~ 65,438+0,000 years ago, which was closer to modern people than Homo erectus. They are not only completely upright, but also have the brain capacity of modern people (average 1.360ml), which shows that their intelligence has developed to a higher level. So paleoanthropologists classify them as the same species as modern humans, that is, homo sapiens. Early Homo sapiens lived 200,000 ~ 50,000 years ago, such as Neanderthals in Germany, Maba in Guangdong, Ding Cun in Shanxi, etc. Homo sapiens in this period still has some primitive characteristics. For Neanderthals, the brow bone was still thick, the skull tilted backward and the jaw protruded forward. But the tools they made were more advanced than those made by Homo erectus, except stone tools and bone tools. Judging from the relics of life, they not only use natural fires, but also make artificial fires. Late Homo sapiens appeared 50000 ~ 1000 years ago, and their fossils were found on all continents, such as the French farmer Kroma and the Neanderthals in China.
In the process of heredity and variation, organisms often become polarized. In the evolution of microorganisms, plants and animals appeared, followed by males and females, and humans appeared among animals. In the process of survival and evolution, bacteria and other microorganisms struggle with the natural environment. In the struggle, a large number of microorganisms died and disappeared, while the viable microorganisms survived and produced the next generation, which gradually differentiated in the new generation. Some of them can live and work in peace and contentment because of their own conditions and environment. On the other hand, because of their own conditions and environment, they struggled further, and because of the harsh environment, they had to develop their own initiative, so the biological differentiation began. In order to survive, they have to move themselves. We must change the environment by our own ability, and only by moving ourselves can we survive. Under such conditions, animals were born. In the survival competition and evolution of biological groups, facing the objective natural environment, there are always two aspects of differentiation within biological groups. Can be compared to radicals and conservatives. Conservatives tend to be natural in general group competition; Radicals always pursue perfection because of their relatively superior internal forces in the group. Objective natural conditions are always relatively unable to meet their needs, which makes them have to develop their own internal forces. Therefore, in the evolution process of biological groups, some relatively represent objective natural factors, and some relatively represent the survival and development of biological groups and the factors that evolve in a more perfect direction. Differentiated animals, further differentiated, produced a progeny and a maternal line. In the progeny population, a part which also represents the perfect tendency of the population gradually differentiates and becomes male; The natural environment that represents the objective existence and the part that produces its own matrilineal tendency gradually differentiate and become women; In the early days of sexual separation, they were just variants of the previous generation, or two different subtypes, with little difference. In the reproduction of this creature at that time, the reproduction of cell division and the reproduction of male and female mating existed at the same time; However, because the offspring produced by mating reproduction are better than those produced by splitting reproduction, the reproductive mode of male and female mating is accepted by higher biological groups. In this group, the reproductive mode of male and female mating gradually replaced the reproductive mode of cell division. This transformation process is also a rather long process, however, the reproduction of male and female mating is still completed by cell division, only through struggle for existence, the two subtypes of this population bear different genetic tasks. This transformation process is accompanied by the transformation from microorganisms to animals and plants, which has become an important symbol of biological evolution from simple to complex.
In the long history of biological evolution, we don't need to look for the continuity of evolution in the concept of evolution. On the basis of finding fossil evidence, we have to accept the inference. Science always comes from reasonable inference based on recognized facts. Evolution is painful for the organism itself. For the creature itself, keeping the original state is the best state. But this state is only a yearning and pursuit in its reality. If possible, it is their best choice to live and work in peace and contentment and muddle along. The beginning of evolution is the beginning of pain, because it means that the original living resources and habits have been broken, a large number of similar lives have been sacrificed, and only a few relatively rational and strong lives have survived, changing their original lifestyle and developing their inherent potential to adapt to the new living environment. This is evolution. The variation of biological groups in the process of evolution is equivalent to a cruel war, and there has been a situation of "one will succeed and ten thousand bones will wither". Biological evolution is a form of self-defense, which is the perfection of self-defense of the whole organism. Human beings were born under such conditions, and they are the product of the struggle and compromise between biological system and objective nature.