What Was Alfred Wallace Contribution to the Theory of Evolution?


Martha Robinson

Alfred Russel Wallace was a British naturalist who made significant contributions to the field of biology, particularly in the area of evolution. Although he is often overshadowed by Charles Darwin, Wallace’s work was groundbreaking and helped to shape our current understanding of evolution. In this article, we will explore the key contributions that Wallace made to the theory of evolution.

Early Life and Career

Wallace was born in Usk, Wales in 1823. He grew up in a family of modest means and left school at the age of 14 to work as an apprentice surveyor. However, he had a keen interest in natural history and spent much of his free time collecting specimens in the countryside.

At the age of 25, Wallace set sail for South America with fellow naturalist Henry Walter Bates. The two spent four years exploring the Amazon rainforest and collecting thousands of specimens, including many new species of plants and animals.

Wallace’s Theory of Natural Selection

In 1858, while working in what is now Indonesia, Wallace sent a letter to Charles Darwin outlining his theory of natural selection. Darwin had been working on a similar theory for over twenty years but had not yet published his findings.

Darwin was shocked by Wallace’s letter and realized that he needed to publish his own work before someone else beat him to it. The two men presented their findings together at the Linnean Society in London later that year.

The Role of Isolation

One key contribution that Wallace made to the theory of evolution was his recognition of the role that isolation plays in speciation. He observed that when populations are separated geographically or ecologically from each other, they can evolve independently and eventually become distinct species.

This idea is known as “allopatric speciation” and is now widely accepted as an important mechanism for generating biodiversity.

The Wallace Line

Another important contribution that Wallace made was his discovery of the “Wallace Line”. This is a boundary that separates the flora and fauna of Asia and Australia, which are very different from each other.

Wallace recognized that this boundary represented a significant change in environmental conditions, which had caused the evolution of distinct groups of organisms on either side. This helped to support his theory of natural selection by showing how environmental factors can shape the evolution of species.


Although Wallace’s work was overshadowed by Darwin during his lifetime, he is now recognized as one of the most important naturalists of the 19th century. His contributions to the theory of evolution were groundbreaking and helped to shape our current understanding of how species evolve over time.

In addition to his work on evolution, Wallace also made significant contributions to other areas of biology, including biogeography and conservation. He was a passionate advocate for protecting natural habitats and recognizing the interconnectedness of all living things.


In conclusion, Alfred Russel Wallace’s contributions to the theory of evolution were significant and far-reaching. His recognition of the role that isolation plays in speciation and his discovery of the Wallace Line helped to support Darwin’s theory of natural selection and laid the foundation for much future research in evolutionary biology. Although he may not be as well-known as Darwin today, Wallace’s legacy continues to inspire new generations of scientists who are working to understand the diversity and complexity of life on Earth.