What is Natural Selection? A Clear Explanation of the Core of Darwin’s Theory of Evolution

Charles Darwin’s “On the Origin of Species,” published in 1859, revolutionized the history of biology. At its core is the concept of “natural selection.” This article will explain in detail the mechanism of natural selection and its importance.

The Basic Concept of Natural Selection

Natural selection refers to the process by which individuals best adapted to their environment survive and pass on their traits to the next generation. Through this mechanism, the characteristics of species change over time, leading to evolution.

The Process of Natural Selection

The process of natural selection consists of four main elements:

• Variation: Differences in traits exist among individuals of the same species
• Inheritance: Traits are passed from parents to offspring
• Competition: Due to limited resources, not all individuals can survive and reproduce
• Fitness: Individuals with traits suited to the environment have a higher probability of survival and reproduction

Darwin’s Insight

Darwin arrived at the concept of natural selection through his observations in the Galapagos Islands. He particularly noted that the beak shapes of finches differed from island to island. He concluded that these differences were the result of adaptation to each island’s environment.

Darwin developed the following reasoning:

• Variation exists among individuals
• Individuals with variations suited to the environment have a higher chance of survival and reproduction
• Advantageous variations are inherited by the next generation
• Over a long period, the characteristics of the entire species change

Concrete Examples of Natural Selection

Let’s look at some concrete examples to understand how natural selection works:

• Moths during the Industrial Revolution: In areas where trees darkened due to air pollution during the Industrial Revolution in England, the number of dark moths increased. This was because dark moths were less likely to be discovered by predators.
• Antibiotic-resistant bacteria: Due to the use of antibiotics, bacteria with resistance are selectively surviving and multiplying. This is an example of natural selection occurring in real-time.
• Long-necked giraffes: Giraffes with long necks had an advantage in survival as they could eat leaves from high places. Over a long period, individuals with long necks were selected, resulting in their current appearance.

The Relationship Between Natural Selection and Evolution

Natural selection is one of the mechanisms of evolution. However, not all evolution is due to natural selection. Other factors include genetic drift, gene flow, and mutations.

Characteristics of Natural Selection

• Causes adaptive changes
• Acts at a relatively fast pace
• Has directionality in response to environmental changes

Limitations and Misconceptions of Natural Selection

Natural selection has the following limitations:

• Can only select from existing variations
• Does not produce perfect adaptations
• Acts at the population level, not the individual level

There are also common misconceptions about natural selection:

The Simplistic Idea that “the Strong Survive”

This is a misconception. Natural selection doesn’t necessarily mean that “strong” individuals survive. Rather, individuals that are “more adapted” to that specific environment have a higher probability of survival. For example:

• In extremely cold environments, individuals with smaller bodies that can maintain body temperature might be more adaptive than larger, stronger individuals.
• In environments with scarce food, “weaker” individuals that consume less energy might be more likely to survive.
• In highly social species, individuals that are cooperative, not just strong, might have higher reproductive success.

In other words, “strength” is relative to the environment, and being simply strong is not always advantageous for survival.

The Misconception that Evolution Has a Purpose or Direction

Evolution does not have a specific purpose or direction; it is driven by the interaction between organisms and their environments.

The Idea that Human Evolution Has Stopped

This is also a big misconception. Humans, like other organisms, continue to evolve while adapting to their environment. Here are some concrete examples:

• Lactose tolerance: With the development of pastoral cultures, genes allowing adults to digest dairy products have spread. This is a relatively recent example of evolution.
• High-altitude adaptation: People living in high-altitude areas like Tibet and the Andes have genetic variations adapted to low-oxygen environments.
• Resistance to pathogens: Genes involved in immune responses to various infectious diseases are still subject to natural selection.
• Brain evolution: The human brain continues to evolve, with changes particularly seen in areas related to social cognition.

Furthermore, modern medical technologies and changes in living environments may be acting as new selective pressures. For example, the widespread use of cesarean sections has made it easier for genetic traits that make natural childbirth difficult to be passed on to the next generation.

Thus, human evolution has certainly not stopped. However, its speed and direction may differ from the past, and new adaptations are likely progressing in response to modern environments.

Natural Selection in Modern Evolutionary Biology

More than 150 years have passed since Darwin’s time, and our understanding of natural selection has deepened further. In modern evolutionary biology, research is being conducted from the following perspectives:

• Analysis of natural selection at the molecular level
• Mathematical modeling through population genetics
• The relationship between epigenetics and natural selection
• Comparison of artificial selection and natural selection

Social Impact of Natural Selection

The concept of natural selection has influenced various fields beyond biology:

• Medicine: Understanding the evolution of antibiotic resistance and cancer
• Agriculture: Breeding improvements and pest management
• Environmental conservation: Assessing the risk of species extinction
• Artificial Intelligence: Development of genetic algorithms

Conclusion

Natural selection is a powerful concept that explains the diversity and adaptation of living organisms. Beginning with Darwin’s insights, our understanding has been further deepened by modern science and technology. The understanding of natural selection continues to have a significant impact on our worldview and our relationship with nature.

The evolution of living organisms continues even now, and we humans are also under the influence of natural selection. By deepening our understanding of natural selection, we can gain insights into the mystery of life and its remarkable adaptive capabilities.