How Is the Neutral Theory of Evolution Different Than the Theory of Evolution by Natural Selection?


Jane Flores

Evolution is a fascinating topic that has been the subject of much debate and discussion over the years. Two of the most prominent theories of evolution are the neutral theory and the theory of natural selection. While these two theories share some similarities, they are fundamentally different in their approach to understanding how species evolve over time.

What is the Neutral Theory of Evolution?

The neutral theory of evolution was first proposed by Japanese biologist Motoo Kimura in the 1960s. This theory suggests that most genetic mutations are neutral, meaning they have no effect on an organism’s fitness or survival. According to this theory, the majority of evolutionary changes occur due to genetic drift rather than natural selection.

Under this theory, genetic drift refers to random events that cause certain traits to become more or less common in a population over time. For example, if a small group of individuals migrates from one area to another, they may carry with them certain genetic traits that become more or less common in their new population due to chance events like mating patterns or environmental factors.

The neutral theory suggests that while natural selection can play a role in shaping evolution, it is not the primary force driving it. Instead, many evolutionary changes occur simply due to chance events and genetic drift.

What is the Theory of Evolution by Natural Selection?

The theory of evolution by natural selection was first proposed by Charles Darwin in his book “On The Origin Of Species” published in 1859. This theory suggests that species evolve over time through a process called natural selection. According to this process, organisms with advantageous traits are more likely to survive and reproduce than those without them.

For example, if a population of birds lives in an area with different types of seeds available for food, those birds with beaks better suited for cracking open certain seeds will be more likely to survive and pass on their genes for those beak traits to their offspring. Over time, this can lead to the evolution of new species with different physical and behavioral characteristics.

Unlike the neutral theory, natural selection emphasizes the importance of adaptation and fitness in shaping evolutionary changes. Organisms that are better adapted to their environment are more likely to survive and reproduce, passing on their advantageous traits to future generations.

How Are These Theories Different?

While both the neutral theory and the theory of natural selection offer insights into how species evolve over time, they differ in their fundamental approach to understanding evolution. The neutral theory emphasizes the role of chance events and genetic drift, while natural selection emphasizes the importance of adaptation and survival.

Another key difference between these theories is their level of focus. The neutral theory often looks at changes within a population at the molecular level, while natural selection often focuses on larger-scale changes in physical traits and behaviors.

Ultimately, both theories offer valuable insights into how evolution works, but they offer different perspectives on what drives evolutionary change. By understanding these theories, we can gain a deeper appreciation for the complexity of life and the many factors that shape its evolution over time.


In conclusion, while there is much debate about which theory offers a more complete picture of how species evolve over time, it is clear that both the neutral theory and the theory of natural selection have important contributions to make to our understanding of evolution. By continuing to explore these theories through research and experimentation, scientists can continue to unlock new insights into how life on Earth has evolved over millions of years.