The Theory of Evolution describes the development of the species that inhabited or inhabit planet Earth.
Thus, current species descend from other species that have undergone modifications over time and have transmitted new characteristics to their descendants.
Charles Darwin, author of « Origin of Species » (1859) is one of the great names in theories related to evolutionism. His theory is based on the natural selection of species and continues to be accepted today.
In any group of species, all individuals have common ancestors at some point in evolutionary history. Therefore, they are their descendants with modifications and are the result of natural selection.
Individuals of the same species, even close relatives, have variations among themselves, which is the result of mutations and/or sexual reproduction.
Some of these variations are hereditary, that is, they can be transmitted from generation to generation.
The limitation in the availability of resources causes individuals in a population to fight, directly or indirectly, for these resources and for their survival.
Of these variations, some may be advantageous, allowing some, in this context, to stand out and others not. The latter may not survive or reproduce.
Those who survive (the fittest) can transmit to their offspring the characteristic that allowed their survival, if it is hereditary.
This process, called natural selection, results from the adaptation of certain individuals to the environment and also from the appearance of new species.
Natural selection is very similar to artificial selection, but the latter is the result of human actions (direct or indirect) on a given organism.
Penicillin, for example, was widely used a few decades ago as the main agent to combat bacteria and is currently not effective in the treatment of some diseases, as a consequence of the selection of resistant bacteria due to the indiscriminate use of this substance.
What are the theories of evolution?
When we refer to the evolution of species, the theories created are based on two aspects:
Creationist: Divine forces are responsible for the emergence of the planet and all existing species. In this case, there was no evolutionary process and the species are immutable. This theory is related to religious issues.
Evolutionist: Proposes the evolution of species through natural selection as environmental changes occur.
The Theory of Creation or ” creationism ” refers to the origin of the Universe and life through mythical-religious explanations, which would not be subject to the evolutions or transformations that occur in the evolution of species, but to that of a Creator.
Creationism is characterized by being the opposite of evolutionary science, being discussed by several civilizations and originating various hypotheses about the creation of the world, and each of the religions approaches it differently.
The French naturalist Jean-Baptiste de Lamarck (1744-1829) was very important for the development of evolutionary ideas, having published the book ” Zoological Philosophy ” with its conclusions in 1809. The set of his theories is called “Lamarckism.”
He proposed the “Law of use and disuse” which consisted of the development or atrophy of the parts of the body, according to their use or disuse, respectively. With this, such characteristics would be transmitted over time to subsequent generations, which was explained in the “Law of transmission of acquired characteristics.”
The main articulator of the theory of the evolution of species is the British naturalist Charles Darwin (1809-1882), and the set of his evolutionary theories is called “Darwinism.”
Darwin stated that living beings, including man, descend from common ancestors, who change over time. Thus, existing species evolved from simpler species that lived in the past.
Natural selection was the principle used by Darwin to defend his theory. In this way, only species adapted to environmental pressures are capable of surviving, reproducing and creating descendants.
Charles Darwin (1809-1882)
For Lamarck, evolution was characterized by the use and disuse of body parts. Meanwhile, Darwin believed that the environment acted in the selection of favorable characteristics.
From his observations and research, Darwin’s main ideas were:
- Individuals of the same species present differences among themselves, as a result of variations in their characteristics.
- Individuals with characteristics that are favorable to environmental conditions are more likely to survive than those that do not have such characteristics.
- Individuals with favorable characteristics are also more likely to leave offspring.
When we talk about Charles Darwin’s theory of evolution we cannot fail to mention another character, the British naturalist Alfred Russell Wallace (1823-1913). He developed a theory similar to Darwin’s on the evolution of species.
Wallace sent Darwin his manuscripts and in 1858 the theory of evolution was published in the names of the two naturalists. However, as Charles Darwin was more recognized, he ended up receiving the merit and prestige of being the creator of the theory.
Neo-Darwinism or synthetic theory of evolution emerged in the 20th century and is characterized by the union of Darwin’s studies, mainly natural selection, with discoveries in the field of genetics.
This is because at the time of the first evolutionary studies, it was not yet known how the mechanism of inheritance and mutation worked, which were revealed only some time later from the studies of Gregor Mendel.
The current influence of studies on evolution can be observed in all areas of biology, especially in cytology, which studies cells, and in systematics, which is responsible for biological classification.
Neo -Darwinism is the theory accepted by science to explain the evolution of species.