Charles Darwin’s theory of evolution is one of the most significant scientific discoveries in history. It explains how species have changed over time and how new species emerge. The basic tenet of Darwin’s theory is natural selection, which is the process by which organisms that are better adapted to their environment are more likely to survive and reproduce than those that are not.

Natural Selection

Natural selection is a fundamental concept in evolutionary biology. It states that organisms with advantageous traits have a greater chance of survival and reproduction than those without these traits.

For example, a bird with a longer beak may be better adapted to eat certain types of seeds than a bird with a shorter beak. Over time, the birds with longer beaks will have more offspring and pass on their advantageous trait to future generations.


Variation is another critical component of Darwin’s theory of evolution. All organisms within a species exhibit variation in their physical characteristics, such as height, weight, and coloration. This variation arises from differences in DNA sequences, which can lead to different traits being expressed.


Competition is also an essential factor in natural selection. As populations grow, resources become scarce, leading to competition among individuals for food, shelter, and mates. The individuals with advantageous traits are more likely to succeed in this competition and pass on their genes to the next generation.

Evolution by Natural Selection

Over time, natural selection can lead to significant changes within a population or even the emergence of new species altogether. For example, if an environmental change occurs that favors individuals with particular characteristics, such as resistance to disease or drought tolerance, then those characteristics will become more prevalent within the population over time.

Evidence for Evolution

There is abundant evidence supporting Darwin’s theory of evolution by natural selection. Fossil records show that species have changed over time and new species have emerged, such as the evolution of whales from land mammals. The distribution of species across different continents and islands also provides evidence for evolution, as similar species are often found in similar environments.


In conclusion, Darwin’s theory of evolution by natural selection is a fundamental concept in biology. It explains how organisms change over time and how new species emerge, providing a framework for understanding the diversity of life on Earth. Through the use of natural selection, variation, and competition, Darwin’s theory has shaped our understanding of the natural world and continues to influence scientific research today.