Finding out where all life on earth came from is a difficult task that humanity has been fighting for a long time. There are quite a few hypotheses, from theological (divine) to fantastic (the theory of the creation of the world by alien creatures). At the same time, one of the most popular was still proposed in the 19th century by C. Darwin. Its essence lies in the fact that all types of living things on Earth (including humans) appeared during evolution, gradually taking on their present shape. Someone agrees with this hypothesis, some do not, however, its significance for the whole science as a whole is undeniable.
The main points of Darwin's evolutionary theory are as follows. All living species on the planet have never been created by anyone. Organic forms, which arose naturally, gradually changed in accordance with the conditions surrounding them. The basis of this transformation is heredity, variability and natural selection. The latter was named Darwin as a struggle for existence. As a result of evolution, a variety of different species appeared in nature, while they are all maximally adapted in the environment in which they are located.
The main points of Darwin's theory are described in his book, published in 1859. Here, the scientist clearly demonstrated how minor changes in individual organisms lead to the transformation of domestic animals and agricultural plants. As a result, a person chooses those species that are most valuable to him, and receives offspring from them. A similar process, the scientist believes, occurs in nature. In his book, Darwin describes the origin of the species as a long, natural process, however, absolutely nonrandom.
So, variability can be of two types: definite and indefinite. The first arises as a result of exposure to the body of external factors, and, as a rule, if they disappear, then these features do not appear in the next generation. Uncertain variability is inherited regardless of environmental conditions. It is she who is the driving factor in the development of species.
The main points of Darwin's theory are based on the fact that the material of evolution is hereditary variability. It leads to the fact that the individual appears successful or unsuccessful properties as a result of crossing it with a close view. Modern biology has introduced the name "mutation."
In the struggle for existence, those organisms that have less adaptability to environmental conditions either die or begin to multiply less. The closer the structure of individuals located in the same territory, the greater competition is between them, as a result of which many of them die. Mostly those who acquire various properties remain alive (they use a variety of food, remedies, attacks, etc.). As a result of divergence (divergence of characters), one species may be split into varieties, which may eventually become an independent unit.
The main provisions of Darwin's theory suggest that living in stable conditions leads to a slowdown in evolution. That is, it is global climate change that can cause the emergence of a new species, significantly different from its proposed ancestors. The scientist provides a lot of evidence that it is natural selection that determines the adaptability of organisms to changing environmental conditions. For example, in animals this is coloring, in some plants and trees it is the ability to reproduce by dispersing seeds and fruits, etc.
It should be noted that the main provisions of Darwin's theory are important enough for the further development of science. His works are still being studied; a large number of studies and experiments are being conducted on them.