What Is Synthetic Theory of Evolution?


Vincent White

The synthetic theory of evolution, also known as the modern synthesis, is a scientific explanation for how evolution works. It was developed over several decades in the mid-20th century by combining the ideas of genetics, natural selection, and population biology. This theory represents a major shift from earlier ideas about evolution and has had a profound impact on our understanding of the natural world.


Before the synthetic theory of evolution, scientists had two main ideas about how evolution worked: Darwin’s theory of natural selection and Mendel’s laws of genetics. Darwin’s theory explained how species changed over time through adaptation to their environment, while Mendel’s laws described how traits were passed down from one generation to the next. However, these two theories didn’t fully explain how evolution worked.

It wasn’t until the early 20th century that scientists began to develop a more complete understanding of genetics and heredity. In 1900, Gregor Mendel’s work on pea plants was rediscovered and sparked renewed interest in genetics. Meanwhile, Thomas Hunt Morgan was studying fruit flies and discovered that genes were located on chromosomes.

Key Concepts

The synthetic theory of evolution built on these discoveries by combining them with Darwin’s theory of natural selection. The key concepts of this theory include:

  • Mutation: Mutations are changes in DNA that can create new alleles (variants) of genes.
  • Natural Selection: Natural selection is the process by which organisms with favorable traits survive and reproduce more successfully than those without those traits.
  • Genetic Drift: Genetic drift is the random fluctuation in allele frequencies in small populations.
  • Gene Flow: Gene flow is the movement of genes from one population to another via migration.


The synthetic theory of evolution has had a profound impact on our understanding of the natural world. It has helped us to explain many phenomena, including the evolution of antibiotic resistance in bacteria, the development of new species, and the genetic basis for many diseases.

Furthermore, this theory has paved the way for further research in genetics and evolutionary biology. Scientists continue to explore new questions about how evolution works and what factors influence it. By building on the foundations of the synthetic theory of evolution, they are advancing our understanding of life on Earth.


In conclusion, the synthetic theory of evolution represents a major breakthrough in our understanding of how species change over time. By combining Darwin’s theory with modern genetics, scientists have developed a comprehensive explanation for how evolution works. This theory continues to guide research in evolutionary biology and helps us to understand the diversity of life on our planet.