Sir Winston Churchill once said, “All great things are simple”. This statement concerns discoveries as well. Today, all great discoveries seem to be simple, from wheel machines to the Einstein’s theory of relativity. Thus, there are just two criteria determining a great discovery. First, it should affect the fundamentals of people’s knowledge. Second, it should be simple to show that there is no more concise explanation, on the one hand, and to make people wonder why no one has noticed this explanation before, on the other hand. If one uses such a “yardstick” for measuring genius, then one of the most brilliant discoveries of humankind is Charles Darwin’s theory of evolution.
Darwin’s Theory of Evolution by Natural Selection
The British scientist Charles Darwin was the first to express the idea that nature has a mechanism similar to the artificial selection. The meaning of the idea lies in the fact that nature does not necessarily understand and analyze what it does to create organisms that are more advanced. It just can act randomly, which is enough to create a wide range of different qualities in species constantly. Ultimately, the fittest ones survive, preserve, and transmit those properties that will prove useful to the descendants.
According to Darwin, evolution is described by three principles, namely heredity, variation, and natural selection. At first, there is a species with new and totally random properties. Then, a species produces offspring or dies in the process of interaction with the environment and competing with others. Finally, if the outcome of the previous step is positive and a species reproduces, its offspring will inherit the newly acquired properties and take a natural selection test as well.
All the properties of a living organism are encoded in a set of chromosomes called the genome. Each chromosome is composed of gene sequences. The type and location of genes in the chromosome determine exact characteristics that will be encoded. In asexual reproduction, the offspring receives the same characteristics as its predecessor because the genes are just copied. However, some mutations can occur under the influence of the external environment such as natural radiation, chemicals, or viruses that result in changes in the genome. Changing of genes leads to new and sometimes quite unexpected properties. If they are not negative, then the creature survives and passes these genes to the descendants. If the mutation is harmful, then the creature is likely to die. A habitat creates nutritional restrictions, and many creatures have enemies who feed on them. Naturally, the one who is the most adapted in such a competitive environment survives.
The main mechanism of the emergence of new genes is duplication. As a result of a random doubling of a nucleotide sequence, one of the copies of the gene continues to perform the original function while the other copy goes into the standby mode and thereby can accumulate mutations without damage to the organism. A number of generations later, overall changes can lead to the appearance of the copy of new functions that are beneficial to the body. An example of such an evolution is myoglobin, whose ancestor is hemoglobin. Myoglobin binds with oxygen, but it has adapted to perform this function in skeletal and cardiac muscles.
The evolution happens faster if there is an exchange of genes between different species in addition to mutations. For example, there is a cross-pollination in plants, and their progeny receives hereditary properties of two parents: partly from the first one, partly from the second one. The exchange of genes significantly increases the rate of evolution. If someone has a useful feature, the descendants will have it as well. If another creature of the same species has another useful feature, the exchange of genes gives a chance of the birth of a creature that will have these two useful features crossed.
The driving force of evolutionary change is horizontal gene transfer where one bacterium transfers genetic material of another one, which is not a descendant. Now, it is believed that horizontal gene transfer plays a huge role in the evolution of bacteria since it allows a valuable feature that appeared in one population of bacteria to spread quickly among a large number of species. Furthermore, sexual reproduction, which is characteristic of humans and also serves as a driving force of evolution, creates additional tools of competition within the species. In addition, it enables genetic exchange, thereby leading to far-reaching consequences.
Pre-Darwinian Evolutionary Thought
Darwin’s theory of evolution by natural selection is quite simple but rather convincing. However, there were also other ideas of the way organisms have changed over time. History of views on evolution is certainly older than Darwin’s theory. One can consider philosophers and representatives of other sciences, the first evolutionary biologists, who tried to solve the traditional questions of evolutionary theory based on the knowledge of their time.
The peak of the natural sciences and evolutionary knowledge of the past were the studies of the Swedish naturalist Carl Linnaeus and the French naturalist Georges Buffon. The creator of a unified system of classification of flora and fauna and the founder of the binomial nomenclature Linnaeus placed a human in a single order of primates. In the famous 10th edition of Systema Naturae, he first identified the order Primates, added the genus Homo, and divided it into two species, namely Homo sapiens and Homo troglodytes. Linnaeus described the latter as being similar to a man. However, he was a supporter of creationism. Darwin advanced Linnaeus’ ideas by abandoning the idea of creationism.
In contrast to Linnaeus, Buffon defended the idea of the mutability of species under the influence of environmental conditions. French naturalist called a human ‘dual’ and, thereby, identified the species’ position. In his multi-volume and popular work Histoire Naturelle, he not only described the variety of animals and plants but also expressed the idea of the mutability of species and the unity of flora and fauna. This work has put forward Buffon as a number one predecessor of Darwin. Unfortunately, Buffon did not provide the reasons for the origin of living creatures. Darwin advanced his ideas by detailing the mechanisms of the evolution and describing the ways the origin of species was performed by.
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Charles Darwin’s theory of evolution is one of the greatest discoveries in human history. When Darwin formulated this theory, he used and advanced the ideas of various scientists and philosophers, but the most profound contributions were made by Carl Linnaeus and Georges Buffon. One can say that the theory might never have existed without the contribution of these two scientists. The essence of the theory is that each quality that is acquired in the course of evolution is advantageous for the carrier when it emerges. Then, it serves as the foundation for the emergence of new qualities after having arisen and entrenched. Thus, the theory is quite simple, but it has been significant for the further development of the evolutionary biology.