Life has evolved by natural selection and genetic drift. Natural selection selects for traits that are adapted to the environment, and genetic drift affects them through random changes. How do these two processes work and what role do they play in biodiversity?
Living organisms have adapted to their environment, evolving from simple organic matter to more complex forms. In the process, living organisms have not only competed for survival, but have also evolved into sustainable organisms by passing on their genetic traits to their offspring through reproduction and breeding. Thus, living organisms have been able to adapt more flexibly to their living environment and maintain their survival, and have evolved into more advantageous forms in the competition for survival. This is a complex process that involves more than just biological adaptation, including the behavior of biological populations, physiological changes, and interactions within ecosystems. Charles Darwin is the person who theoretically established the concept of evolution as we commonly know and accept evolution as a fact.
Darwin’s theory of evolution proposed the basic principles of biological evolution, and his theory laid the foundation for modern biology. Although various theories and ideas about evolution existed before Darwin, he was the first to systematically organize and explain them on the basis of scientific evidence. Since the first ideas about evolution emerged and research on genes progressed, the theory of evolution has been continuously modified and supplemented to the present day. In modern times, Lamarck was the first to develop ideas about evolution. Lamarck established a classification system from minerals to plants to animals and understood the overall trend as evolution. He argued for “use it or lose it,” in which organisms acquire characteristics according to their environment and pass them on to the next generation. For example, he explained that the giraffe’s long neck was the result of frequent use of the neck to eat leaves on high branches. However, his theory was later disproved by science.
Charles Darwin then established the theory of evolution. In his book “On the Origin of Species”, he explained the principle of the origin of new species based on the principles of survival of the fittest, natural selection and differentiation. Darwin discovered and systematically organized the principle of natural selection by observing various species. He observed finches in the Galapagos Islands during the Beagle Expedition and realized the importance of adaptation and natural selection to the environment. When “On the Origin of Species” was first published, it caused a lot of social problems and controversy, but over time Darwin’s theory became widely accepted among scientists. By the 20th century, the field of evolutionary theory had branched out in many directions, and scientists combined Darwin’s natural selection with Mendel’s genetics to develop evolutionary theory and present modern evolutionary theory.
Evolution occurs primarily through natural selection, in which beneficial genetic traits are selected for by the interaction between biological populations and the environment, and by genetic drift that occurs within populations. Through natural selection, genetic traits that are advantageous for a population to adapt to the environment are passed on to the next generation, while unfavorable traits are eliminated. The degree of adaptation can be used to determine the rate of natural selection, which is the ratio of the number of individuals with one trait to the number of individuals with the next trait. High fitness means that the conflicting traits will predominate in the group and eventually become the characteristics of the species. This adaptability is not fixed, but continues to change as the environment changes. Natural selection affects not only the survival and reproduction of organisms, but also the social structure and behavioral patterns within the group. For example, if a certain behavior promotes successful survival and reproduction within a group, the genetic traits that cause that behavior will spread.
Interaction with the environment and competition for survival are not the only factors that influence selection. For example, the colorful plumage of a peacock or the antlers of a deer may be detrimental to survival. But the reason these traits are actually highly adaptive is related to female sexual selection in mating. Females prefer peacocks with colorful plumage or male deer with large antlers, so they have evolved to have more colorful and larger plumage and antlers. These genetic traits can sometimes evolve to the point where they affect the survival of males. “Evolution occurs as a result of a number of factors, including the group’s own choices and the environment. It is an important mechanism that promotes biodiversity and provides important clues to understanding how certain traits are fixed within a group.
“Genetic drift refers to the random change in the genetic makeup of a group, and it refers to the random change in the frequency of expression of alleles within a group. This can be easily understood through the bead-filling experiment. Suppose there are 10 red beads and 10 blue beads in a bottle. If you repeat the process of randomly restoring and extracting these 20 beads and placing the resulting color in a new bottle 20 times, you can fill the new bottle with 20 beads. If this process is repeated, all new diseases can be filled with either blue or red beads. In other words, as generations pass, the frequency of expression of a given trait continues to change randomly. In this process of genetic drift, a group of individuals with a new genetic trait is created as a result of the fixation of a given trait, and this group undergoes the process of evolution by genetic drift. The frequency of blood groups A, B, and O is a good example of this. The frequency of people with blood types A, B, and O continues to change over generations as a result of random chance. This genetic drift continues to provide opportunities for independent genetic traits to survive and reproduce, and it occurs mainly in isolated populations with small numbers of people. Natural selection selects for traits that are advantageous to an individual’s survival, while genetic drift is a random process of evolution that occurs regardless of the advantages or disadvantages to an individual’s survival. In this way, living organisms adapt to the environment and evolve into new species through the evolutionary processes of natural selection and genetic drift.
Charles Darwin’s theory of evolution did not explain how species created by natural selection achieved genetic diversity. Darwin believed that all new traits that appear in a species are acquired, and he was unable to offer a theory that went beyond the theory of survival of the fittest, which states that acquired traits can be inherited. It was later shown that acquired traits are not inherited, and Darwin’s theory of evolution had limitations in explaining the principle of inheritance of genetic traits to the next generation. Meanwhile, with the establishment of Mendel’s Law of Inheritance, it became possible to explain the principle by which naturally selected genetic traits are passed on to the next generation. This was later integrated into Charles Darwin’s theory of evolution, forming the basis of evolutionary theory. In the 20th century, different views of evolutionary theory emerged, and the process of integrating these different theories was carried out. In the 1920s and 1930s, evolutionary biologists such as Ronald Fisher studied Mendel’s laws of heredity and Darwin’s theory of evolution in more detail, pioneering a new discipline called population genetics, which became the foundation of modern evolutionary theory. Subsequently, the structure of DNA was revealed by Watson and Crick, and genetics and molecular biology were also fused with evolutionary theory and accepted as important fields of research. This modern evolutionary synthesis is based on Charles Darwin’s theory of natural selection and integrates mutation, Mendel’s genetic theory, and the theory of DNA. In modern evolutionary theory, evolution is explained as the change in the frequency of alleles in the gene pool over generations, and is described as an endless process.
The theory of evolution has caused much controversy since its inception, but it is now accepted by many people and has made many advances to the present day. The impact of evolution on society is not limited to scientific discoveries. It has influenced various fields such as philosophy, ethics, and sociology, providing a new perspective on human existence and life. As technology has advanced, the mechanisms of genes, DNA, etc. have been revealed, and the theory of evolution has been modified and developed accordingly. In the 21st century, it has continued to influence and evolve, expanding its scope from simple biochemistry and genetics to psychology, philosophy, computer programming using evolutionary algorithms, and even artificial life. This multifaceted research and development has taken evolution beyond a simple biological theory to a central role in various fields of the life sciences. This means that evolutionary theory is not a theory of the past, but an important foundation for future scientific and technological development.
