RNA can serve both as a catalyst for chemical reactions and as a carrier of information, providing a basis for considering it the first step toward complex biological life.
The spontaneous origin of life and the absence of an external goal in this process supports the idea that the evolution of life is a random process, not aimed at a specific goal, but driven by the natural laws of chemistry and physics.
2.2 The Emergence of the First Cells and Evolution
The process of the origin of life continued with the formation of the first cells – primitive organismal structures surrounded by a membrane. These cells could facilitate the exchange of substances and protect chemical reactions within themselves from the external environment. In this way, evolution began its course. The formation of cells marked the beginning of living organisms capable of metabolism, reproduction, and interaction with their surroundings
In 1859, Charles Darwin, in his work On the Origin of Species, proposed the theory of natural selection. Darwin argued that organisms better adapted to their environment are more likely to survive and pass their genes on to the next generation. This process occurs without any purposeful intent or predestination; rather, it is the result of random variations leading to increased adaptation to a specific environment.
Evolution is a process of change and adaptation without a final goal or predetermined endpoint. It is a mechanism driven by random mutations, which lead to changes in populations of organisms, with death acting as the process of removing less adapted individuals. In this context, death is not the end of life but an inevitable part of it, necessary for more adapted organisms to continue their existence. Death, thus, plays a crucial role in maintaining the balance and progress of species, ensuring the “cleansing” of less adapted genes.
2.3 The Discovery of the DNA Structure and Genes as Units of Inheritance
The discovery of the structure of DNA in 1953 by James Watson and Francis Crick, based on X-ray crystallography data, marked a significant turning point in biology. DNA was decoded as a molecule that encodes genetic information passed down from generation to generation. Genes became the fundamental units of heredity, containing the instructions for synthesizing proteins that play a crucial role in the functioning of an organism.
Genetics further revealed how mutations occur, with random changes in genes leading to alterations in organisms. These mutations can be beneficial, neutral, or harmful, and depending on their impact on the organism’s survival, they can be passed on to the next generation. The process of gene expression and their regulation through epigenetic mechanisms (such as DNA methylation) adds additional layers to our understanding of how organisms adapt to their environment. This intricate interplay of genetic and epigenetic factors shapes the evolutionary trajectory of life..
The significance of mutations and their impact on organisms is revealed through the concept of “negative selection,” which eliminates organisms with harmful mutations, and “positive selection,” which enhances the existence of those better adapted. The inclusion of epigenetics in the modern understanding of evolution allows for a fuller appreciation of how the external environment can influence genetic changes and species adaptation.
2.4 Theory of Multilevel Selection and Modern Understanding of Evolution
The theory of multilevel selection, proposed by scientists such as William Hamilton and Richard Dawkins, significantly expands our understanding of evolution. In his famous book The Selfish Gene (1976), Dawkins suggested that the primary units of evolution are not organisms, but genes, which strive for self-replication and spread. From his perspective, the organism is merely a vessel for genes, and evolution is essentially not about the survival of individuals but about the preservation and dissemination of genetic information passed down through generations.
According to this theory, evolution does not view the organism as an independent goal, but rather as a means for transmitting genes to the next generations. This leads to the concept of the “selfish gene,” where each gene acts as a kind of “instrument” concerned with its own preservation within the population. Thus, evolution operates at the level of genes rather than individual organisms.
An important aspect of the development of this theory is the concept of multi-level selection. Selection can occur not only at the level of individual organisms but also at the level of genes, groups, and even species. In this context, evolution can be seen as a process in which not only the most adapted individuals are selected, but also genetic combinations that increase the chances of survival of populations or groups.
One example illustrating multi-level selection is the phenomenon of organisms with similar traits, such as the “green beard effect.” Imagine a group of animals within a population randomly developing a unique trait – a green beard. This concept, proposed by Richard Dawkins, illustrates how traits that are disadvantageous at the individual level can be preserved and spread through group selection. In this case, individuals with a “green beard” (a symbolic trait that distinguishes them from others) may not have obvious survival advantages, but if such individuals form a group, their shared trait can promote cooperation and support within the group, thereby increasing the chances of survival for its members. Thus, this trait could be advantageous at the group level, even if it does not directly benefit the individuals. The green beard can be selected through group selection, where cooperation or even “signals” for interaction with other individuals emerge within the group, supporting the survival of the whole community. Therefore, group-level evolution can lead to the spread of this trait if it promotes cooperation and social interactions, increasing the chances of survival for the entire group.
Dawkins’ theory also considers the importance of altruism in evolution. He argues that individuals who act in the interest of the group can contribute to the preservation of their genes, even if their behavior does not bring them direct benefit. An individual may help the survival of others, such as relatives or group members, at the cost of their own risks. In this context, if an individual with a green beard helps other members of their group survive, their actions could improve the overall success of the entire group, and these traits would be maintained and strengthened at the group level.
Considering evolution as a process that occurs on multiple levels allows us to include not only organisms but also broader evolutionary units such as populations, ecosystems, and even species. For example, within multicellular organisms or communities of organisms with similar traits (such as behavior or physical characteristics), there is a likelihood that these traits will be maintained through altruistic behavior that promotes the overall success of the group. However, such behavior is important not only for the survival of individual organisms but also for the propagation of their genes at the population level.
One vivid example of such a phenomenon can be symbiosis – a close, mutually beneficial coexistence of different species. When two or more species cooperate with each other, their chances of survival increase, and their traits can be supported and strengthened through evolutionary mechanisms. In this way, traits like the green beard, over the long term, can spread not only at the level of individual organisms but also within more complex biological systems, contributing to the overall survival of the group.
Today, it is believed that selection occurs on several levels:
Genetic level: Selection occurs at the level of individual genes. Genes that promote the successful survival and reproduction of their carriers become established in the population, passed down to future generations. This selection focuses on how specific genetic variations can increase their frequency in the population through their impact on the organism or on their copies in other organisms.
Individual level: Selection acts at the level of organisms. Individuals with traits that increase their chances of survival and successful reproduction are able to pass their genes to the next generation. This leads to the spread of beneficial adaptations within the population and the establishment of traits that enhance individual fitness.
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