What Is the Theory of Evolution by Natural Selection?


Jane Flores

Evolution is one of the most fascinating and awe-inspiring processes in the natural world. It is the process by which species change over time, adapting to their environment and developing new traits that help them survive and reproduce.

One of the most famous theories of evolution is the theory of evolution by natural selection, proposed by Charles Darwin in 1859. In this article, we will explore what this theory is all about.

What Is Evolution by Natural Selection?

Evolution by natural selection is a process that explains how species change over time. According to this theory, individuals within a population vary in their traits, and some of these traits are better suited to their environment than others. Individuals with advantageous traits are more likely to survive and reproduce, passing on these traits to their offspring.

Over time, these advantageous traits become more common in the population while disadvantageous ones become less common or disappear altogether. This process is known as natural selection because it is driven by the environment selecting for certain traits.

The Four Principles of Natural Selection

Darwin identified four principles that underlie the process of natural selection:

  • Variation: Individuals within a population vary in their traits.
  • Heredity: Some of these traits are passed down from parents to offspring.
  • Differential survival: Not all individuals survive and reproduce equally well.
  • Differential reproduction: Individuals with advantageous traits are more likely to survive and reproduce.

These principles work together to drive evolutionary change over time.

An Example: The Peppered Moth

One classic example of evolution by natural selection is the case of the peppered moth. Before the Industrial Revolution in England, most peppered moths had light-colored wings, which helped them blend in with the light-colored bark of trees where they rested during the day.

However, as industrial pollution darkened the bark of trees, a mutation that resulted in darker wings became more advantageous. Over time, the frequency of this mutation increased in the population, and dark-colored moths became more common than light-colored ones.


Evolution by natural selection is a powerful force that has shaped the diversity of life on our planet. By understanding how it works, we can better appreciate the amazing adaptations that make each species unique. Whether you are a biologist studying evolution or simply a curious observer of nature, this theory is an essential part of our understanding of the natural world.